// bank_panel.cpp — REAPER-facing docked grid (M5 Wave A/B + Phase B4). See
// bank_panel.h.
//
// Compiled into the reaper_reasampler MODULE. Includes reaper_plugin_functions.h
// WITHOUT REAPERAPI_IMPLEMENT — main.cpp owns the API pointers; here they are
// extern (CLAUDE.md §contract).
//
// What this file owns (all REAPER/SWELL/LICE-bound, hence DAW-verified, not unit
// tested):
//   * a SWELL dialog (IDD_BANK_PANEL) docked via DockWindowAddEx / undocked via
//     DockWindowRemove; toggled open/closed.
//   * WM_PAINT: a VERTICAL SPLIT (Phase B4) — the pool grid region on top, a
//     LICE-drawn named-banks tab-page region below (one tab per named bank, an
//     overflow/scroll strip), and two full-height toggles that collapse the split.
//     Each region reuses the M5 grid render loop (waveform thumbnails / empty state).
//   * per-sample PCM read via PCM_source fed to peaks::computeEnvelope at cell width.
//   * an in-memory thumbnail cache keyed by (sample id, draw width, bank generation).
//   * id-keyed bank management (create / rename / delete / evacuate / activate) and
//     sample move/copy — driven from a tab context menu and a drag — against the B1
//     BankBook model on g_session.book(), persisted via g_session.saveToActiveProject().
//
// READ-ONLY of the TIMELINE (load-bearing principle): this panel never inserts into
// the arrange. It DOES mutate the bank BOOK (create/rename/move/etc.) — that is the
// whole point of B4 — but only the index/model + ext-state, never the arrange, never
// a sample file on disk (bank ops are index-only; files stay put — CONTEXT.md §Multi-bank).
//
// THE PURE SEAMS: grid tiling / hit-test / selection math live in bank_grid; the
// mode-switch geometry in mode_switch; the named-banks TAB-STRIP layout, overflow/
// scroll, and hit-test in tab_strip. All three are unit-tested outside the DAW; only
// draw + input routing + the model calls live here.
//
// REFERENCE-INVALIDATION GUARDRAIL (CONTEXT.md §Multi-bank): a bank-structural
// mutation (create/delete/evacuate/activate/move) can reallocate the book's vector,
// so a BankIndex& / Bank* must NEVER be cached across one. Every handler below
// resolves fresh AFTER any mutation and passes bank IDS (not references) into the
// model ops.

#include "bank_panel.h"

#include <cstdint>
#include <cstdlib>  // std::abs (drag threshold)
#include <filesystem>
#include <string>
#include <unordered_map>
#include <vector>

#include "bank_book.h"
#include "bank_grid.h"
#include "bank_model.h"
#include "capture_paths.h"
#include "mode_switch.h"
#include "peaks.h"
#include "persist.h"
#include "tab_strip.h"
#include "tail_control.h"  // TailSetting, cycleTailMode, tailToggleLabel (pure)
#include "view.h"  // applyMode — the D2/D4 mode-activation entrypoint the switch fires

// SWELL / LICE. On macOS/Linux SWELL is provided by the host (SWELL_PROVIDED_BY_APP);
// on Windows we use native Win32 (windows.h first, then swell.h no-ops on _WIN32).
#ifdef _WIN32
#include <windows.h>
#include <windowsx.h>  // GET_X_LPARAM / GET_Y_LPARAM (SWELL supplies them on mac/linux)
#else
#include <pthread.h>
#endif
#include "wdltypes.h"
#include "swell/swell.h"
#include "lice/lice.h"

#include "resource.h"

#include "reaper_plugin.h"

#define REAPERAPI_MINIMAL
#define REAPERAPI_WANT_DockWindowAddEx
#define REAPERAPI_WANT_DockWindowActivate
#define REAPERAPI_WANT_DockWindowRemove
#define REAPERAPI_WANT_EnumProjects
#define REAPERAPI_WANT_GetMainHwnd
#define REAPERAPI_WANT_PCM_Source_CreateFromFile
#define REAPERAPI_WANT_PCM_Source_Destroy
#define REAPERAPI_WANT_PlayPreview
#define REAPERAPI_WANT_StopPreview
#define REAPERAPI_WANT_GetUserInputs
#define REAPERAPI_WANT_ShowMessageBox
#define REAPERAPI_WANT_genGuid
#define REAPERAPI_WANT_guidToString
#include "reaper_plugin_functions.h"

// main.cpp owns the module instance handle and REAPER's dispatch struct.
extern REAPER_PLUGIN_HINSTANCE g_hInst;
extern reaper_plugin_info_t*   g_rec;

namespace reasampler {

namespace {

namespace fs = std::filesystem;

// --- Layout / palette constants ----------------------------------------------

const GridSpec kGrid{/*cellWidth=*/140, /*cellHeight=*/84, /*gap=*/10};

constexpr int kMaxThumbnailFrames = 1 << 20;  // ~1M frames (~22s @ 48k)

const LICE_pixel kColBackground = LICE_RGBA(28, 28, 30, 255);
const LICE_pixel kColCellBg      = LICE_RGBA(44, 44, 48, 255);
const LICE_pixel kColCellBorder  = LICE_RGBA(70, 70, 76, 255);
const LICE_pixel kColWaveform    = LICE_RGBA(120, 200, 160, 255);
const LICE_pixel kColMidline     = LICE_RGBA(60, 60, 66, 255);
const LICE_pixel kColSelBg       = LICE_RGBA(38, 66, 58, 255);
const LICE_pixel kColSelBorder   = LICE_RGBA(120, 200, 160, 255);
const LICE_pixel kColFocusBorder = LICE_RGBA(210, 230, 220, 255);

// --- Mode-switch header (D5) --------------------------------------------------
constexpr int kHeaderHeight = 30;

const LICE_pixel kColHeaderBg      = LICE_RGBA(20, 20, 22, 255);
const LICE_pixel kColSegBg         = LICE_RGBA(44, 44, 48, 255);
const LICE_pixel kColSegActiveBg   = LICE_RGBA(58, 96, 84, 255);
const LICE_pixel kColSegBorder     = LICE_RGBA(70, 70, 76, 255);

const COLORREF kRgbSegText       = RGB(170, 170, 176);
const COLORREF kRgbSegActiveText = RGB(220, 235, 228);

// --- Tail-mode footer (T1 exposure) -------------------------------------------
constexpr int kFooterHeight = 26;

const LICE_pixel kColFooterBg     = LICE_RGBA(20, 20, 22, 255);
const LICE_pixel kColFooterBorder = LICE_RGBA(70, 70, 76, 255);
const COLORREF   kRgbFooterText   = RGB(190, 205, 198);

// --- Vertical split + region headers + tab strip (Phase B4) -------------------
//
// The client area, top to bottom: mode-switch header (kHeaderHeight) | split body |
// tail footer (kFooterHeight). The split body holds the pool region (top) and the
// named-banks region (bottom). Each region opens with a REGION HEADER band: a title,
// the active-bank readout, and a full-height toggle button. The named-banks region's
// header ALSO hosts the LICE tab strip and a "+" create button.
constexpr int kRegionHeaderHeight = 24;  // per-region title/toggle band
constexpr int kTabStripHeight     = 26;  // the named-banks tab strip band
constexpr int kSplitDividerHeight = 3;   // the horizontal divider between regions
constexpr int kFullHtBtnWidth     = 22;  // the square full-height toggle button
constexpr int kCreateBtnWidth     = 22;  // the "+" create-bank button

// Tab strip metrics (the pure tab_strip owns the math; these are its inputs).
const TabStripSpec kTabSpec{/*tabWidth=*/96, /*chevronWidth=*/20};

const LICE_pixel kColRegionHeaderBg = LICE_RGBA(24, 24, 26, 255);
const LICE_pixel kColRegionBorder   = LICE_RGBA(70, 70, 76, 255);
const LICE_pixel kColDivider        = LICE_RGBA(12, 12, 14, 255);
const LICE_pixel kColBtnBg          = LICE_RGBA(48, 48, 52, 255);
const LICE_pixel kColBtnBorder      = LICE_RGBA(90, 90, 96, 255);

const LICE_pixel kColTabBg          = LICE_RGBA(40, 40, 44, 255);
const LICE_pixel kColTabShownBg     = LICE_RGBA(58, 58, 64, 255);   // the shown tab (browsed)
const LICE_pixel kColTabActiveBg    = LICE_RGBA(58, 96, 84, 255);   // the ACTIVE bank (capture target)
const LICE_pixel kColTabBorder      = LICE_RGBA(70, 70, 76, 255);
const LICE_pixel kColTabActiveBorder= LICE_RGBA(150, 230, 190, 255);// active-tab accent
const LICE_pixel kColChevronBg      = LICE_RGBA(32, 32, 36, 255);
// Drop-target highlight during a drag (unmistakable accent over the destination).
const LICE_pixel kColDropTarget     = LICE_RGBA(90, 150, 120, 255);

const COLORREF kRgbRegionTitle   = RGB(200, 205, 210);
const COLORREF kRgbActiveReadout = RGB(150, 230, 190);  // "Active: …" accent
const COLORREF kRgbTabText       = RGB(200, 200, 205);
const COLORREF kRgbTabActiveText = RGB(230, 245, 238);
const COLORREF kRgbBtnText       = RGB(210, 215, 220);

// --- Panel state --------------------------------------------------------------

struct CachedThumbnail {
    Envelope envelope;
    int width = 0;
};

// Which of the two split regions currently owns the selection / receives keyboard
// input. The move/copy source is the focused region's displayed bank.
enum class Region { Pool, Banks };

// What a drag is dropping onto, resolved live under the pointer during a drag.
enum class DropKind { None, PoolRegion, Tab };

struct PanelState {
    ReaSamplerSession* session = nullptr;

    HWND hwnd = nullptr;
    bool open = false;

    std::string bankFingerprint;
    std::uint64_t generation = 0;

    std::unordered_map<std::string, CachedThumbnail> cache;

    // --- Selection (per focused region) ---------------------------------------
    // One live selection, scoped to `focusedRegion`. Switching regions moves the
    // selection with the focus (a click in the other region reseeds it there).
    Selection selection;
    int       selItemCount = 0;
    Region    focusedRegion = Region::Pool;

    // --- Vertical-split state -------------------------------------------------
    BankPanelFullHeight fullHeight = BankPanelFullHeight::Split;

    // The named bank whose grid the banks region shows (the SHOWN tab) — DISTINCT
    // from the active/capture-target bank (book().activeBankId()). Empty when there
    // are no named banks. Reconciled each fingerprint pass so it always names a live
    // named bank (or is empty).
    std::string shownBankId;

    // Tab-strip horizontal scroll offset (px), clamped to the strip's max each frame.
    int tabScroll = 0;

    // --- Drag (sample move between regions/onto a tab) ------------------------
    // A drag begins only after the pointer moves past a threshold from a press that
    // landed on a SELECTED grid cell — this is how it is disambiguated from the M5
    // multi-select drag (which begins immediately on any grid press). See onLBtnDown/
    // onMouseMove. dragging is true once the threshold is crossed.
    bool dragArmed = false;      // pressed on a selected cell; watching for threshold
    bool dragging = false;       // threshold crossed; a move-drag is in progress
    int  dragStartX = 0, dragStartY = 0;
    Region dragSourceRegion = Region::Pool;
    std::string dragSourceBankId;          // the bank the dragged samples come from
    std::vector<std::string> dragSampleIds;// snapshot of the selection at drag start
    DropKind dropKind = DropKind::None;    // live drop target under the pointer
    std::string dropBankId;                // destination bank id when dropKind==Tab

    // --- Tail-mode toggle -----------------------------------------------------
    TailSetting tail;

    // --- Audition preview -----------------------------------------------------
    preview_register_t preview{};
    PCM_source* previewSrc = nullptr;
    bool previewActive = false;
    bool previewInited = false;
};

PanelState g_panel;

void stopAudition();

// --- Current-project directory (mirrors persist.cpp's derivation) -------------
std::string currentProjectDir() {
    std::vector<char> buf(4096, '\0');
    EnumProjects(-1, buf.data(), static_cast<int>(buf.size()));
    std::string rpp(buf.data());
    if (rpp.empty()) return {};
    return normalizeSlashes(fs::path(rpp).parent_path().string());
}

// --- Book / bank accessors ----------------------------------------------------

BankBook* book() { return g_panel.session ? &g_panel.session->book() : nullptr; }

// The BankIndex a region currently displays. Pool region -> the pool; banks region ->
// the shown tab's bank (or nullptr when no named banks / the id went stale). Resolved
// FRESH every call (never cached across a mutation).
const BankIndex* indexForRegion(Region r) {
    BankBook* b = book();
    if (!b) return nullptr;
    if (r == Region::Pool) return &b->pool().index;
    if (g_panel.shownBankId.empty()) return nullptr;
    return b->index(g_panel.shownBankId);
}

// The bank id a region displays (pool id, or the shown tab's id; "" when none).
std::string bankIdForRegion(Region r) {
    if (r == Region::Pool) return std::string(kPoolBankId);
    return g_panel.shownBankId;
}

// The named banks in ordinal order (pool excluded) — the tabs. Resolved fresh.
std::vector<const Bank*> namedBanks() {
    std::vector<const Bank*> out;
    BankBook* b = book();
    if (!b) return out;
    for (const Bank& bk : b->banks())
        if (!bk.isPool()) out.push_back(&bk);
    return out;
}

// --- Thumbnail computation (unchanged from M5) --------------------------------

Envelope computeThumbnail(const std::string& absPath, int width) {
    if (width <= 0 || absPath.empty()) return {};

    PCM_source* src = PCM_Source_CreateFromFile(absPath.c_str());
    if (!src) return {};

    const int nch = src->GetNumChannels();
    const double srate = src->GetSampleRate();
    const double lengthSec = src->GetLength();
    if (nch <= 0 || srate < 1.0 || lengthSec <= 0.0) {
        PCM_Source_Destroy(src);
        return {};
    }

    std::int64_t totalFrames = static_cast<std::int64_t>(lengthSec * srate);
    if (totalFrames <= 0) { PCM_Source_Destroy(src); return {}; }
    int frames = totalFrames > kMaxThumbnailFrames
                     ? kMaxThumbnailFrames
                     : static_cast<int>(totalFrames);

    std::vector<ReaSample> buf(static_cast<std::size_t>(frames) * nch, 0.0);
    PCM_source_transfer_t block{};
    block.time_s = 0.0;
    block.samplerate = srate;
    block.nch = nch;
    block.length = frames;
    block.samples = buf.data();
    block.samples_out = 0;
    src->GetSamples(&block);

    PCM_Source_Destroy(src);

    const int got = block.samples_out;
    if (got <= 0) return {};

    const std::size_t sampleCount = static_cast<std::size_t>(got) * nch;
    std::vector<float> pcm(sampleCount);
    for (std::size_t i = 0; i < sampleCount; ++i)
        pcm[i] = static_cast<float>(buf[i]);

    return computeEnvelope(pcm, static_cast<std::size_t>(nch),
                           static_cast<std::size_t>(got),
                           static_cast<std::size_t>(width));
}

const Envelope& thumbnailFor(const Sample& sample, int width,
                             const std::string& projectDir) {
    ThumbnailKey key{sample.id, width, g_panel.generation};
    const std::string ks = thumbnailKeyString(key);

    auto it = g_panel.cache.find(ks);
    if (it != g_panel.cache.end()) return it->second.envelope;

    const std::string abs = resolveBankFile(projectDir, sample.relativePath);
    CachedThumbnail thumb;
    thumb.width = width;
    thumb.envelope = computeThumbnail(abs, width);
    auto ins = g_panel.cache.emplace(ks, std::move(thumb));
    return ins.first->second.envelope;
}

// --- Drawing: thumbnails (unchanged from M5) ----------------------------------

void drawThumbnail(LICE_IBitmap* bmp, const CellRect& rect, const Envelope& env,
                   bool selected, bool focused) {
    const LICE_pixel bg = selected ? kColSelBg : kColCellBg;
    LICE_pixel border = selected ? kColSelBorder : kColCellBorder;
    if (focused) border = kColFocusBorder;

    LICE_FillRect(bmp, rect.x, rect.y, rect.width, rect.height, bg, 1.0f, 0);
    LICE_DrawRect(bmp, rect.x, rect.y, rect.width, rect.height, border, 1.0f, 0);
    if (focused)
        LICE_DrawRect(bmp, rect.x + 1, rect.y + 1, rect.width - 2, rect.height - 2,
                      border, 1.0f, 0);

    if (env.empty()) {
        const int midY = rect.y + rect.height / 2;
        LICE_Line(bmp, rect.x + 2, midY, rect.x + rect.width - 2, midY,
                  kColMidline, 1.0f, 0, false);
        return;
    }

    const int channels = static_cast<int>(env.size());
    const int bandH = rect.height / channels;

    for (int ch = 0; ch < channels; ++ch) {
        const ChannelEnvelope& bins = env[ch];
        const int bandTop = rect.y + ch * bandH;
        const int midY = bandTop + bandH / 2;
        const double halfSpan = (bandH / 2) - 2;

        LICE_Line(bmp, rect.x + 2, midY, rect.x + rect.width - 2, midY,
                  kColMidline, 1.0f, 0, false);

        const int nbins = static_cast<int>(bins.size());
        if (nbins <= 0) continue;

        const int innerW = rect.width - 4;
        for (int i = 0; i < nbins; ++i) {
            const int x = rect.x + 2 + (nbins > 1 ? (i * (innerW - 1)) / (nbins - 1) : 0);
            int yMax = midY - static_cast<int>(bins[i].max * halfSpan);
            int yMin = midY - static_cast<int>(bins[i].min * halfSpan);
            if (yMax < bandTop) yMax = bandTop;
            if (yMin > bandTop + bandH - 1) yMin = bandTop + bandH - 1;
            LICE_Line(bmp, x, yMin, x, yMax, kColWaveform, 1.0f, 0, false);
        }
    }
}

// Draws a centered single-line label into a rect (COLORREF text).
void drawCenteredText(LICE_IBitmap* bmp, const RECT& rc, const char* text,
                      COLORREF color, UINT fmt) {
    HDC dc = bmp->getDC();
    if (!dc) return;
    RECT r = rc;
    SetTextColor(dc, color);
    SetBkMode(dc, TRANSPARENT);
    DrawText(dc, text, -1, &r, fmt | DT_VCENTER | DT_SINGLELINE | DT_END_ELLIPSIS);
}

// --- Mode-switch header (D5, unchanged) ---------------------------------------

HeaderRect panelHeader(int w) { return HeaderRect{0, 0, w, kHeaderHeight}; }

int modeCount() {
    if (!g_panel.session) return 0;
    return static_cast<int>(g_panel.session->view().modes().size());
}

void drawModeSwitch(LICE_IBitmap* bmp, int w) {
    if (!g_panel.session) return;
    const ViewModeModel& view = g_panel.session->view();
    const std::vector<Mode>& modes = view.modes().all();
    const int n = static_cast<int>(modes.size());

    LICE_FillRect(bmp, 0, 0, w, kHeaderHeight, kColHeaderBg, 1.0f, 0);
    if (n <= 0) return;

    const HeaderRect header = panelHeader(w);
    const std::vector<SegmentRect> segs = computeSegmentRects(header, n);
    if (segs.empty()) return;

    const std::string& activeId = view.activeModeId();
    HDC dc = bmp->getDC();

    for (int i = 0; i < n; ++i) {
        const SegmentRect& s = segs[static_cast<std::size_t>(i)];
        const Mode& mode = modes[static_cast<std::size_t>(i)];
        const bool active = mode.id == activeId;

        LICE_FillRect(bmp, s.x, s.y, s.width, s.height,
                      active ? kColSegActiveBg : kColSegBg, 1.0f, 0);
        LICE_DrawRect(bmp, s.x, s.y, s.width, s.height, kColSegBorder, 1.0f, 0);

        if (!dc) continue;
        RECT rc{s.x, s.y, s.x + s.width, s.y + s.height};
        SetTextColor(dc, active ? kRgbSegActiveText : kRgbSegText);
        SetBkMode(dc, TRANSPARENT);
        DrawText(dc, mode.displayName.c_str(), -1, &rc,
                 DT_CENTER | DT_VCENTER | DT_SINGLELINE | DT_END_ELLIPSIS);
    }
}

// --- Tail-mode footer (T1, unchanged) -----------------------------------------

RECT panelFooter(int w, int h) {
    RECT rc{};
    rc.left = 0;
    rc.right = w;
    rc.top = h - kFooterHeight;
    rc.bottom = h;
    if (rc.top < kHeaderHeight) rc.top = rc.bottom;
    return rc;
}

void drawTailFooter(LICE_IBitmap* bmp, int w, int h) {
    const RECT f = panelFooter(w, h);
    if (f.top >= f.bottom) return;

    LICE_FillRect(bmp, f.left, f.top, w, kFooterHeight, kColFooterBg, 1.0f, 0);
    LICE_Line(bmp, f.left, f.top, f.right, f.top, kColFooterBorder, 1.0f, 0, false);

    HDC dc = bmp->getDC();
    if (!dc) return;
    const std::string label = tailToggleLabel(g_panel.tail);
    RECT rc = f;
    rc.left += 8;
    SetTextColor(dc, kRgbFooterText);
    SetBkMode(dc, TRANSPARENT);
    DrawText(dc, label.c_str(), -1, &rc,
             DT_LEFT | DT_VCENTER | DT_SINGLELINE | DT_END_ELLIPSIS);
}

// --- Split geometry -----------------------------------------------------------
//
// Every rect below is derived from the client size + fullHeight state, and BOTH paint
// and hit-testing call these so they never drift. All are top-left origin.

// The body band between the mode-switch header and the tail footer.
RECT splitBody(int w, int h) {
    RECT rc{};
    rc.left = 0;
    rc.right = w;
    rc.top = kHeaderHeight;
    const RECT footer = panelFooter(w, h);
    rc.bottom = (footer.top < footer.bottom) ? footer.top : h;
    if (rc.bottom < rc.top) rc.bottom = rc.top;
    return rc;
}

// True when both regions are shown (the split is live). Otherwise one region fills
// the body.
bool poolShown() { return g_panel.fullHeight != BankPanelFullHeight::BanksOnly; }
bool banksShown() { return g_panel.fullHeight != BankPanelFullHeight::PoolOnly; }

// The pool region's rect (whole-region: header band + grid). Empty when hidden.
RECT poolRegionRect(int w, int h) {
    const RECT body = splitBody(w, h);
    if (!poolShown()) return RECT{0, 0, 0, 0};
    if (!banksShown()) return body;  // pool full-height: the whole body
    // Split: pool gets the top half (minus the divider).
    RECT rc = body;
    rc.bottom = body.top + (body.bottom - body.top - kSplitDividerHeight) / 2;
    if (rc.bottom < rc.top) rc.bottom = rc.top;
    return rc;
}

// The named-banks region's rect (whole-region: header band + tab strip + grid).
RECT banksRegionRect(int w, int h) {
    const RECT body = splitBody(w, h);
    if (!banksShown()) return RECT{0, 0, 0, 0};
    if (!poolShown()) return body;  // banks full-height: the whole body
    RECT rc = body;
    rc.top = body.top + (body.bottom - body.top - kSplitDividerHeight) / 2 +
             kSplitDividerHeight;
    if (rc.top > rc.bottom) rc.top = rc.bottom;
    return rc;
}

// A region's header band (the top kRegionHeaderHeight of the region).
RECT regionHeaderRect(const RECT& region) {
    RECT rc = region;
    rc.bottom = region.top + kRegionHeaderHeight;
    if (rc.bottom > region.bottom) rc.bottom = region.bottom;
    return rc;
}

// The named-banks region's tab strip (below its header band).
TabStripRect banksTabStripRect(const RECT& region) {
    const RECT hdr = regionHeaderRect(region);
    TabStripRect s;
    s.x = region.left;
    s.y = hdr.bottom;
    s.width = region.right - region.left;
    s.height = kTabStripHeight;
    if (s.y + s.height > region.bottom) s.height = region.bottom - s.y;
    if (s.height < 0) s.height = 0;
    return s;
}

// A region's grid viewport (below the header band, and below the tab strip for the
// banks region). This is where cells tile.
RECT regionGridRect(const RECT& region, bool isBanks) {
    RECT rc = region;
    rc.top = region.top + kRegionHeaderHeight;
    if (isBanks) rc.top += kTabStripHeight;
    if (rc.top > rc.bottom) rc.top = rc.bottom;
    return rc;
}

// The full-height toggle button rect inside a region header (right-aligned).
RECT fullHtBtnRect(const RECT& region) {
    const RECT hdr = regionHeaderRect(region);
    RECT rc = hdr;
    rc.right = hdr.right - 4;
    rc.left = rc.right - kFullHtBtnWidth;
    rc.top = hdr.top + 2;
    rc.bottom = hdr.bottom - 2;
    return rc;
}

// The "+" create-bank button rect inside the named-banks region header (left of the
// full-height button).
RECT createBtnRect(const RECT& region) {
    RECT ft = fullHtBtnRect(region);
    RECT rc = ft;
    rc.right = ft.left - 4;
    rc.left = rc.right - kCreateBtnWidth;
    return rc;
}

// The cell rects for a region's grid, translated into the region's grid viewport.
// Both paint and hit-testing call this. Empty when the index is null/empty.
std::vector<CellRect> regionCellRects(const RECT& region, bool isBanks,
                                      const BankIndex* index) {
    if (!index || index->empty()) return {};
    const RECT grid = regionGridRect(region, isBanks);
    const int w = grid.right - grid.left;
    if (w <= 0) return {};
    std::vector<CellRect> rects =
        computeCellRects(static_cast<int>(index->size()), w, kGrid);
    for (CellRect& r : rects) { r.x += grid.left; r.y += grid.top; }
    return rects;
}

// --- Drawing: a grid region ---------------------------------------------------

// Draws one region's grid of thumbnails (or an empty-state line) clipped to its
// viewport. `selectionOwner` is true when this region holds the live selection, so
// its cells show selection/focus chrome; the other region draws plain.
void drawRegionGrid(LICE_IBitmap* bmp, const RECT& region, bool isBanks,
                    const BankIndex* index, const std::string& emptyMsg,
                    bool selectionOwner, const std::string& projectDir) {
    const RECT grid = regionGridRect(region, isBanks);
    if (grid.bottom <= grid.top) return;

    if (!index || index->empty()) {
        drawCenteredText(bmp, grid, emptyMsg.c_str(), RGB(150, 150, 156), DT_CENTER);
        return;
    }

    const std::vector<Sample>& samples = index->all();
    const std::vector<CellRect> rects = regionCellRects(region, isBanks, index);
    const int binWidth = kGrid.cellWidth - 4;
    for (std::size_t i = 0; i < rects.size(); ++i) {
        const CellRect& rect = rects[i];
        if (rect.y >= grid.bottom) continue;   // below the viewport: skip (no scroll)
        const int idx = static_cast<int>(i);
        const bool selected = selectionOwner && g_panel.selection.contains(idx);
        const bool focused  = selectionOwner && g_panel.selection.focus == idx;
        const Envelope& env = thumbnailFor(samples[i], binWidth, projectDir);
        drawThumbnail(bmp, rect, env, selected, focused);
    }
}

// Draws a region header: title, the active-bank readout, and the full-height button.
void drawRegionHeader(LICE_IBitmap* bmp, const RECT& region, const char* title,
                      const std::string& activeName, bool poolBtnIsPool) {
    const RECT hdr = regionHeaderRect(region);
    LICE_FillRect(bmp, hdr.left, hdr.top, hdr.right - hdr.left,
                  hdr.bottom - hdr.top, kColRegionHeaderBg, 1.0f, 0);
    LICE_Line(bmp, hdr.left, hdr.bottom - 1, hdr.right, hdr.bottom - 1,
              kColRegionBorder, 1.0f, 0, false);

    // Title, left.
    RECT titleRc = hdr;
    titleRc.left += 8;
    titleRc.right = titleRc.left + 120;
    drawCenteredText(bmp, titleRc, title, kRgbRegionTitle, DT_LEFT);

    // Active-bank readout, centered — the UNMISTAKABLE indicator (settled B4
    // constraint). It names the active/capture-target bank in an accent color in
    // BOTH region headers, so the active bank is legible even when it is not the
    // shown tab and even when it is the pool (no tab exists for it).
    const std::string readout = "Active: " + activeName;
    RECT actRc = hdr;
    actRc.left = titleRc.right + 6;
    actRc.right = createBtnRect(region).left - 6;
    if (actRc.right > actRc.left)
        drawCenteredText(bmp, actRc, readout.c_str(), kRgbActiveReadout, DT_LEFT);

    // Full-height toggle button: an arrow glyph. In split it means "maximize this
    // region"; when this region is already full it means "restore the split".
    const RECT btn = fullHtBtnRect(region);
    LICE_FillRect(bmp, btn.left, btn.top, btn.right - btn.left,
                  btn.bottom - btn.top, kColBtnBg, 1.0f, 0);
    LICE_DrawRect(bmp, btn.left, btn.top, btn.right - btn.left,
                  btn.bottom - btn.top, kColBtnBorder, 1.0f, 0);
    const bool thisFull =
        poolBtnIsPool ? (g_panel.fullHeight == BankPanelFullHeight::PoolOnly)
                      : (g_panel.fullHeight == BankPanelFullHeight::BanksOnly);
    drawCenteredText(bmp, btn, thisFull ? "\xE2\x87\x85" : "\xE2\x87\x83",  // ⇅ / ⇃
                     kRgbBtnText, DT_CENTER);
}

// Draws the named-banks tab strip: one tab per named bank (ordinal order), the SHOWN
// tab highlighted, the ACTIVE bank's tab lit with the accent border, overflow
// chevrons when present, plus the "+" create button in the header. During a drag,
// the tab under the pointer gets the drop-target highlight.
void drawTabStrip(LICE_IBitmap* bmp, const RECT& region) {
    const TabStripRect strip = banksTabStripRect(region);
    if (strip.height <= 0) return;
    LICE_FillRect(bmp, strip.x, strip.y, strip.width, strip.height,
                  kColRegionHeaderBg, 1.0f, 0);

    const std::vector<const Bank*> tabs = namedBanks();
    const int n = static_cast<int>(tabs.size());
    if (n == 0) {
        RECT r{strip.x + 8, strip.y, strip.x + strip.width, strip.y + strip.height};
        drawCenteredText(bmp, r, "No named banks — click + to create one.",
                         RGB(140, 140, 146), DT_LEFT);
        return;
    }

    const TabStripLayout layout =
        computeTabStripLayout(strip, n, kTabSpec, g_panel.tabScroll);

    // Chevrons (drawn first so tabs sit above their inner edges).
    if (layout.overflow) {
        LICE_FillRect(bmp, strip.x, strip.y, kTabSpec.chevronWidth, strip.height,
                      kColChevronBg, 1.0f, 0);
        LICE_FillRect(bmp, strip.x + strip.width - kTabSpec.chevronWidth, strip.y,
                      kTabSpec.chevronWidth, strip.height, kColChevronBg, 1.0f, 0);
        RECT lc{strip.x, strip.y, strip.x + kTabSpec.chevronWidth,
                strip.y + strip.height};
        RECT rc{strip.x + strip.width - kTabSpec.chevronWidth, strip.y,
                strip.x + strip.width, strip.y + strip.height};
        drawCenteredText(bmp, lc, "\xE2\x80\xB9", kRgbTabText, DT_CENTER);  // ‹
        drawCenteredText(bmp, rc, "\xE2\x80\xBA", kRgbTabText, DT_CENTER);  // ›
    }

    const std::string activeId = book() ? book()->activeBankId() : std::string();
    const std::vector<TabRect> rects =
        computeTabRects(strip, n, kTabSpec, g_panel.tabScroll);
    for (const TabRect& tr : rects) {
        const Bank* bk = tabs[static_cast<std::size_t>(tr.index)];
        const bool shown = bk->id == g_panel.shownBankId;
        const bool active = bk->id == activeId;
        const bool dropHere = g_panel.dragging &&
                              g_panel.dropKind == DropKind::Tab &&
                              g_panel.dropBankId == bk->id;

        LICE_pixel bg = shown ? kColTabShownBg : kColTabBg;
        if (active) bg = kColTabActiveBg;
        if (dropHere) bg = kColDropTarget;
        LICE_FillRect(bmp, tr.x, tr.y, tr.width, tr.height, bg, 1.0f, 0);
        // The active bank's tab gets a bright accent border (unmistakable), distinct
        // from the shown tab's fill highlight — active ≠ shown, made visible.
        LICE_DrawRect(bmp, tr.x, tr.y, tr.width, tr.height,
                      active ? kColTabActiveBorder : kColTabBorder, 1.0f, 0);
        if (active)
            LICE_DrawRect(bmp, tr.x + 1, tr.y + 1, tr.width - 2, tr.height - 2,
                          kColTabActiveBorder, 1.0f, 0);

        RECT lr{tr.x + 4, tr.y, tr.x + tr.width - 4, tr.y + tr.height};
        drawCenteredText(bmp, lr, bk->displayName.c_str(),
                         active ? kRgbTabActiveText : kRgbTabText, DT_CENTER);
    }
}

// The active bank's display name (for the readout). "Pool" when the pool is active.
std::string activeBankName() {
    BankBook* b = book();
    if (!b) return std::string(kPoolBankName);
    const Bank* bk = b->bank(b->activeBankId());
    return bk ? bk->displayName : std::string(kPoolBankName);
}

// --- Full paint ---------------------------------------------------------------

void paintPanel(HWND hwnd, HDC hdc) {
    RECT cr{};
    GetClientRect(hwnd, &cr);
    const int w = cr.right - cr.left;
    const int h = cr.bottom - cr.top;
    if (w <= 0 || h <= 0) return;

    LICE_SysBitmap bmp(w, h);
    LICE_Clear(&bmp, kColBackground);

    const std::string projectDir = currentProjectDir();
    const std::string activeName = activeBankName();

    // Pool region (top).
    if (poolShown()) {
        const RECT region = poolRegionRect(w, h);
        drawRegionHeader(&bmp, region, "Pool", activeName, /*poolBtnIsPool=*/true);
        drawRegionGrid(&bmp, region, /*isBanks=*/false, indexForRegion(Region::Pool),
                       "No samples in the pool yet. Capture one to see it here.",
                       g_panel.focusedRegion == Region::Pool, projectDir);
        // Drop-target highlight for the pool region during a drag.
        if (g_panel.dragging && g_panel.dropKind == DropKind::PoolRegion) {
            const RECT grid = regionGridRect(region, false);
            LICE_DrawRect(&bmp, grid.left + 1, grid.top + 1,
                          grid.right - grid.left - 2, grid.bottom - grid.top - 2,
                          kColDropTarget, 1.0f, 0);
        }
    }

    // Split divider.
    if (poolShown() && banksShown()) {
        const RECT body = splitBody(w, h);
        const int dy = body.top + (body.bottom - body.top - kSplitDividerHeight) / 2;
        LICE_FillRect(&bmp, 0, dy, w, kSplitDividerHeight, kColDivider, 1.0f, 0);
    }

    // Named-banks region (bottom).
    if (banksShown()) {
        const RECT region = banksRegionRect(w, h);
        drawRegionHeader(&bmp, region, "Banks", activeName, /*poolBtnIsPool=*/false);
        // "+" create button (drawn as part of the banks header).
        const RECT cbtn = createBtnRect(region);
        LICE_FillRect(&bmp, cbtn.left, cbtn.top, cbtn.right - cbtn.left,
                      cbtn.bottom - cbtn.top, kColBtnBg, 1.0f, 0);
        LICE_DrawRect(&bmp, cbtn.left, cbtn.top, cbtn.right - cbtn.left,
                      cbtn.bottom - cbtn.top, kColBtnBorder, 1.0f, 0);
        drawCenteredText(&bmp, cbtn, "+", kRgbBtnText, DT_CENTER);

        drawTabStrip(&bmp, region);
        drawRegionGrid(&bmp, region, /*isBanks=*/true, indexForRegion(Region::Banks),
                       g_panel.shownBankId.empty()
                           ? "Select or create a named bank."
                           : "This bank is empty. Move samples here from the pool.",
                       g_panel.focusedRegion == Region::Banks, projectDir);
    }

    drawModeSwitch(&bmp, w);
    drawTailFooter(&bmp, w, h);

    BitBlt(hdc, 0, 0, w, h, bmp.getDC(), 0, 0, SRCCOPY);
}

// --- Bank-change detection ----------------------------------------------------

// A fingerprint of the WHOLE BOOK: for each bank, its id + display name + active flag
// + per-sample id/path. Catches every mutation the panel must redraw for: capture,
// project load, and B4's own create/rename/delete/move/activate.
std::string bookFingerprint() {
    BankBook* b = book();
    if (!b) return {};
    std::string fp = std::to_string(b->size());
    fp += '\x1e'; fp += b->activeBankId();
    for (const Bank& bk : b->banks()) {
        fp += '\x1d';
        fp += bk.id;
        fp += '\x1c';
        fp += bk.displayName;
        for (const Sample& s : bk.index.all()) {
            fp += '\x1f';
            fp += s.id;
            fp += '\x1f';
            fp += s.relativePath;
        }
    }
    return fp;
}

// Reconciles shownBankId against the live named banks: keep it if it still names a
// named bank; otherwise fall to the first named bank (or empty when none). Keeps the
// banks region always showing a valid tab. Never touches the ACTIVE bank.
void reconcileShownBank() {
    BankBook* b = book();
    if (!b) { g_panel.shownBankId.clear(); return; }
    if (!g_panel.shownBankId.empty()) {
        const Bank* bk = b->bank(g_panel.shownBankId);
        if (bk && !bk->isPool()) return;  // still valid
    }
    const std::vector<const Bank*> named = namedBanks();
    g_panel.shownBankId = named.empty() ? std::string() : named.front()->id;
}

bool refreshFingerprint() {
    if (!book()) return false;
    std::string fp = bookFingerprint();
    if (fp == g_panel.bankFingerprint) return false;
    g_panel.bankFingerprint = std::move(fp);
    ++g_panel.generation;
    g_panel.cache.clear();
    // The selection indexes into the OLD order; a change can invalidate those, so
    // clear it and stop any audition.
    if (!g_panel.selection.empty() || g_panel.selection.focus >= 0) {
        g_panel.selection = Selection{};
        stopAudition();
    }
    reconcileShownBank();
    const BankIndex* idx = indexForRegion(g_panel.focusedRegion);
    g_panel.selItemCount = idx ? static_cast<int>(idx->size()) : 0;
    return true;
}

// --- Audition preview (unchanged from M5) -------------------------------------

void initPreview() {
    if (g_panel.previewInited) return;
#ifdef _WIN32
    InitializeCriticalSection(&g_panel.preview.cs);
#else
    pthread_mutex_init(&g_panel.preview.mutex, nullptr);
#endif
    g_panel.previewInited = true;
}

void stopAudition() {
    if (g_panel.previewActive) {
        StopPreview(&g_panel.preview);
        g_panel.previewActive = false;
    }
    if (g_panel.previewSrc) {
        PCM_Source_Destroy(g_panel.previewSrc);
        g_panel.previewSrc = nullptr;
    }
    g_panel.preview.src = nullptr;
}

void deinitPreview() {
    if (!g_panel.previewInited) return;
#ifdef _WIN32
    DeleteCriticalSection(&g_panel.preview.cs);
#else
    pthread_mutex_destroy(&g_panel.preview.mutex);
#endif
    g_panel.previewInited = false;
}

// Auditions sample `idx` of the FOCUSED region's displayed bank.
void startAudition(int idx) {
    stopAudition();

    const BankIndex* index = indexForRegion(g_panel.focusedRegion);
    if (!index) return;
    const std::vector<Sample>& samples = index->all();
    if (idx < 0 || idx >= static_cast<int>(samples.size())) return;

    const std::string projectDir = currentProjectDir();
    const std::string abs = resolveBankFile(projectDir, samples[idx].relativePath);
    if (abs.empty()) return;

    PCM_source* src = PCM_Source_CreateFromFile(abs.c_str());
    if (!src) return;

    g_panel.preview.src = src;
    g_panel.preview.m_out_chan = 0;
    g_panel.preview.curpos = 0.0;
    g_panel.preview.loop = false;
    g_panel.preview.volume = 1.0;
    g_panel.preview.peakvol[0] = 0.0;
    g_panel.preview.peakvol[1] = 0.0;
    g_panel.preview.preview_track = nullptr;

    if (PlayPreview(&g_panel.preview) != 0) {
        g_panel.previewSrc = src;
        g_panel.previewActive = true;
    } else {
        PCM_Source_Destroy(src);
        g_panel.preview.src = nullptr;
    }
}

// --- Input helpers ------------------------------------------------------------

bool ctrlDown() { return (GetAsyncKeyState(VK_CONTROL) & 0x8000) != 0; }
bool shiftDown() { return (GetAsyncKeyState(VK_SHIFT) & 0x8000) != 0; }

void invalidatePanel() {
    if (g_panel.hwnd) InvalidateRect(g_panel.hwnd, nullptr, FALSE);
}

// The item count of the focused region's bank (0 when none).
int focusedItemCount() {
    const BankIndex* idx = indexForRegion(g_panel.focusedRegion);
    return idx ? static_cast<int>(idx->size()) : 0;
}

// Which region (if any) contains client point (x, y); returns false via `out` set to
// Pool by default when the point is in neither region body.
bool regionAt(int x, int y, Region& out) {
    RECT cr{};
    GetClientRect(g_panel.hwnd, &cr);
    const int w = cr.right - cr.left, h = cr.bottom - cr.top;
    if (poolShown()) {
        const RECT r = poolRegionRect(w, h);
        if (x >= r.left && x < r.right && y >= r.top && y < r.bottom) {
            out = Region::Pool; return true;
        }
    }
    if (banksShown()) {
        const RECT r = banksRegionRect(w, h);
        if (x >= r.left && x < r.right && y >= r.top && y < r.bottom) {
            out = Region::Banks; return true;
        }
    }
    return false;
}

// --- Bank management ops (id-keyed; drive the B1 model + persist) --------------
//
// Each op mutates g_session.book() then persists via saveToActiveProject(). After a
// STRUCTURAL mutation (create/delete/evacuate) any Bank*/BankIndex& is invalid — we
// resolve fresh, pass ids, and let the next refreshFingerprint repaint. persistBook
// no-ops on an unsaved project (matches the capture/B3 quiet-persist idiom).

void persistBook() {
    if (g_panel.session) g_panel.session->saveToActiveProject();
}

// REAPER's stock single-line input (comma-safe via the \x1f return separator, as B3).
bool promptText(const char* title, const char* caption, const std::string& initial,
                std::string& out) {
    std::vector<char> buf(512, '\0');
    std::snprintf(buf.data(), buf.size(), "%s", initial.c_str());
    const std::string captions = std::string(caption) + ",separator=\x1f";
    if (!GetUserInputs(title, 1, captions.c_str(), buf.data(),
                       static_cast<int>(buf.size())))
        return false;
    std::string s(buf.data());
    if (s.empty()) return false;
    out = std::move(s);
    return true;
}

// Mints a genuine REAPER GUID string as a stable bank id (same as B3 mintBankId).
std::string mintBankId() {
    GUID g{};
    genGuid(&g);
    char buf[64] = {0};
    guidToString(&g, buf);
    return std::string(buf);
}

void doCreateBank() {
    if (!book()) return;
    std::string name;
    if (!promptText("ReaSampler: create bank", "Bank name:", "", name)) return;
    const std::string id = mintBankId();
    if (!book()->createBank(id, name)) {
        ShowMessageBox("A bank with that name already exists.",
                       "ReaSampler: create bank", 0);
        return;
    }
    g_panel.shownBankId = id;             // show the freshly-created bank
    g_panel.focusedRegion = Region::Banks;
    persistBook();
    invalidatePanel();
}

void doRenameBank(const std::string& bankId) {
    if (!book()) return;
    const Bank* bk = book()->bank(bankId);
    if (!bk || bk->isPool()) return;
    const std::string current = bk->displayName;  // copy before any mutation
    std::string newName;
    if (!promptText("ReaSampler: rename bank", "New name:", current, newName)) return;
    if (!book()->renameBank(bankId, newName)) {
        ShowMessageBox("Another bank already uses that name.",
                       "ReaSampler: rename bank", 0);
        return;
    }
    persistBook();
    invalidatePanel();
}

// Delete with the RICHER confirm-on-non-empty affordance (B4): the confirm names the
// member count AND offers evacuate as the one-click alternative (Yes=delete anyway,
// No=evacuate-then-keep, Cancel=abort) — richer than B3's basic YESNO.
void doDeleteBank(const std::string& bankId) {
    if (!book()) return;
    const Bank* bk = book()->bank(bankId);
    if (!bk || bk->isPool()) return;
    const std::size_t members = bk->index.size();  // read BEFORE any mutation
    const std::string name = bk->displayName;

    if (members > 0) {
        const std::string msg =
            "\"" + name + "\" holds " + std::to_string(members) +
            (members == 1 ? " sample" : " samples") +
            ".\n\nYes  — delete the bank AND drop its samples (files are kept on disk "
            "but no bank references them until prune).\nNo   — Evacuate them to the "
            "pool first, then delete the empty bank (keeps the samples).\nCancel — "
            "do nothing.";
        // 3 == MB_YESNOCANCEL. 6=Yes, 7=No, 2=Cancel (SDK).
        const int r = ShowMessageBox(msg.c_str(),
                                     "ReaSampler: delete non-empty bank", 3);
        if (r == 2) return;                 // Cancel
        if (r == 7) {                       // No -> evacuate, then delete empty
            if (!book()->evacuate(bankId)) return;
            // book() may have reallocated; re-resolve nothing (we pass the id again).
        }
        // r == 6 (Yes) falls through to a plain delete (drops members).
    }
    if (!book()->deleteBank(bankId)) return;
    persistBook();
    // shownBankId is reconciled by the next fingerprint pass. If no named banks remain,
    // nudge focus to the pool so the selection has a valid home.
    if (namedBanks().empty()) g_panel.focusedRegion = Region::Pool;
    invalidatePanel();
}

void doEvacuateBank(const std::string& bankId) {
    if (!book()) return;
    const Bank* bk = book()->bank(bankId);
    if (!bk || bk->isPool()) return;
    if (!book()->evacuate(bankId)) return;
    persistBook();
    invalidatePanel();
}

void doActivateBank(const std::string& bankId) {
    if (!book()) return;
    if (!book()->setActiveBank(bankId)) return;  // rejects an unknown id
    persistBook();
    invalidatePanel();
}

// Move or copy `sampleIds` from `srcBankId` to `destBankId` (index-only). Both pass
// ids straight to the model op (no BankIndex& cached across the loop's mutations).
void transferSamples(const std::vector<std::string>& sampleIds,
                     const std::string& srcBankId, const std::string& destBankId,
                     bool copy) {
    if (!book()) return;
    if (sampleIds.empty() || srcBankId == destBankId) return;
    if (!book()->bank(srcBankId) || !book()->bank(destBankId)) return;
    for (const std::string& sid : sampleIds) {
        if (copy) book()->copySample(sid, srcBankId, destBankId);
        else      book()->moveSample(sid, srcBankId, destBankId);
    }
    persistBook();
    // The selection indexed into the source; after a move those indices are stale, so
    // clear it (the fingerprint pass will also clear, but do it now for immediacy).
    g_panel.selection = Selection{};
    invalidatePanel();
}

// The selection's sample ids resolved against the FOCUSED region's bank (source of a
// move/copy). Returns ids in bank order; empty when nothing selected.
std::vector<std::string> focusedSelectionIds() {
    std::vector<std::string> ids;
    const BankIndex* idx = indexForRegion(g_panel.focusedRegion);
    if (!idx) return ids;
    const std::vector<Sample>& samples = idx->all();
    const int count = static_cast<int>(samples.size());
    for (int i : g_panel.selection.indices)
        if (i >= 0 && i < count) ids.push_back(samples[static_cast<std::size_t>(i)].id);
    return ids;
}

// --- Popup menus --------------------------------------------------------------
//
// SWELL/Win32 both expose CreatePopupMenu / InsertMenu (SWELL aliases SWELL_InsertMenu
// -> InsertMenu) / TrackPopupMenu(TPM_RETURNCMD) / DestroyMenu. We build a menu of
// (label -> small int command), track it at screen coords, and switch on the return.
// Menu command ids are LOCAL to the popup (not REAPER action ids) — TPM_RETURNCMD
// hands the chosen id straight back, so no hookcommand routing is involved.

// Appends a string item (id) to `menu` at its end. Portable over Win32/SWELL: both
// accept InsertMenu(menu, pos, MF_BYPOSITION|MF_STRING, id, text) with a negative
// position appending. Win32 and SWELL both treat pos < 0 as an append.
void menuAppend(HMENU menu, unsigned int id, const char* text, bool grayed = false) {
    UINT flags = MF_BYPOSITION | MF_STRING;
    if (grayed) flags |= MF_GRAYED;
    InsertMenu(menu, -1, flags, id, text);
}
void menuSeparator(HMENU menu) {
    InsertMenu(menu, -1, MF_BYPOSITION | MF_SEPARATOR, 0, nullptr);
}

// Menu command ids (local to a popup).
enum : unsigned int {
    kMenuNone = 0,
    kMenuActivate = 100,
    kMenuRename,
    kMenuDelete,
    kMenuEvacuate,
    kMenuCreate,
    kMenuMoveBase = 1000,   // move-to-bank: kMenuMoveBase + destination index
    kMenuCopyBase = 2000,   // copy-to-bank: kMenuCopyBase + destination index
};

// Shows the right-click context menu for a named-bank TAB: activate / rename / delete
// / evacuate that bank, plus a create entry. Drives the id-keyed ops.
void showTabMenu(int screenX, int screenY, const std::string& bankId) {
    if (!book()) return;
    const Bank* bk = book()->bank(bankId);
    if (!bk || bk->isPool()) return;
    const bool isActive = book()->activeBankId() == bankId;
    const bool nonEmpty = !bk->index.empty();

    HMENU menu = CreatePopupMenu();
    menuAppend(menu, kMenuActivate,
               isActive ? "Active (capture target)" : "Activate (make capture target)",
               /*grayed=*/isActive);
    menuSeparator(menu);
    menuAppend(menu, kMenuRename, "Rename\xE2\x80\xA6");
    menuAppend(menu, kMenuEvacuate, "Evacuate to pool", /*grayed=*/!nonEmpty);
    menuAppend(menu, kMenuDelete, "Delete\xE2\x80\xA6");
    menuSeparator(menu);
    menuAppend(menu, kMenuCreate, "New bank\xE2\x80\xA6");

    const int cmd = TrackPopupMenu(menu, TPM_RETURNCMD, screenX, screenY, 0,
                                   g_panel.hwnd, nullptr);
    DestroyMenu(menu);

    switch (cmd) {
        case kMenuActivate: doActivateBank(bankId); break;
        case kMenuRename:   doRenameBank(bankId); break;
        case kMenuEvacuate: doEvacuateBank(bankId); break;
        case kMenuDelete:   doDeleteBank(bankId); break;
        case kMenuCreate:   doCreateBank(); break;
        default: break;
    }
}

// Shows the move/copy menu for the current selection (the SOURCE is the focused
// region's bank). Lists every OTHER bank (pool + named) as a move destination, then a
// copy submenu-free flat list (copy entries follow the move block). Move is the
// default (listed first); copy is the deliberate secondary act.
void showSelectionMenu(int screenX, int screenY) {
    const std::vector<std::string> sel = focusedSelectionIds();
    if (sel.empty()) return;
    const std::string srcId = bankIdForRegion(g_panel.focusedRegion);

    // Destinations: pool + named banks, excluding the source. Ordinal order.
    struct Dest { std::string id; std::string name; };
    std::vector<Dest> dests;
    if (srcId != std::string(kPoolBankId))
        dests.push_back({std::string(kPoolBankId), std::string(kPoolBankName)});
    for (const Bank* bk : namedBanks())
        if (bk->id != srcId) dests.push_back({bk->id, bk->displayName});

    HMENU menu = CreatePopupMenu();
    if (dests.empty()) {
        menuAppend(menu, kMenuNone, "No other bank to move to", /*grayed=*/true);
        TrackPopupMenu(menu, TPM_RETURNCMD, screenX, screenY, 0, g_panel.hwnd, nullptr);
        DestroyMenu(menu);
        return;
    }

    const std::string label = std::to_string(sel.size()) +
                              (sel.size() == 1 ? " sample" : " samples");
    menuAppend(menu, kMenuNone, ("Move " + label + " to:").c_str(), /*grayed=*/true);
    for (std::size_t i = 0; i < dests.size(); ++i)
        menuAppend(menu, kMenuMoveBase + static_cast<unsigned int>(i),
                   ("  " + dests[i].name).c_str());
    menuSeparator(menu);
    menuAppend(menu, kMenuNone, ("Copy " + label + " to:").c_str(), /*grayed=*/true);
    for (std::size_t i = 0; i < dests.size(); ++i)
        menuAppend(menu, kMenuCopyBase + static_cast<unsigned int>(i),
                   ("  " + dests[i].name).c_str());

    const int cmd = TrackPopupMenu(menu, TPM_RETURNCMD, screenX, screenY, 0,
                                   g_panel.hwnd, nullptr);
    DestroyMenu(menu);
    if (cmd >= static_cast<int>(kMenuMoveBase) &&
        cmd < static_cast<int>(kMenuMoveBase + dests.size())) {
        transferSamples(sel, srcId, dests[cmd - kMenuMoveBase].id, /*copy=*/false);
    } else if (cmd >= static_cast<int>(kMenuCopyBase) &&
               cmd < static_cast<int>(kMenuCopyBase + dests.size())) {
        transferSamples(sel, srcId, dests[cmd - kMenuCopyBase].id, /*copy=*/true);
    }
}

// --- Click routing ------------------------------------------------------------

// Handles a header/tab-strip/button click for the banks region. Returns true if the
// click was consumed (a region-chrome hit), false to fall through to grid selection.
bool handleBanksChromeClick(int x, int y, const RECT& region) {
    // Full-height toggle button.
    const RECT ftb = fullHtBtnRect(region);
    if (x >= ftb.left && x < ftb.right && y >= ftb.top && y < ftb.bottom) {
        bankPanelToggledBanksFullHeight();
        return true;
    }
    // "+" create button.
    const RECT cb = createBtnRect(region);
    if (x >= cb.left && x < cb.right && y >= cb.top && y < cb.bottom) {
        doCreateBank();
        return true;
    }
    // Tab strip: chevrons scroll, a tab click SHOWS that bank (browse — NOT activate).
    const TabStripRect strip = banksTabStripRect(region);
    const std::vector<const Bank*> tabs = namedBanks();
    const int n = static_cast<int>(tabs.size());
    const TabHit hit = hitTestTabStrip(x, y, strip, n, kTabSpec, g_panel.tabScroll);
    if (hit.kind == TabHitKind::ScrollLeft || hit.kind == TabHitKind::ScrollRight) {
        const TabStripLayout layout =
            computeTabStripLayout(strip, n, kTabSpec, g_panel.tabScroll);
        const int step = kTabSpec.tabWidth;
        const int desired = g_panel.tabScroll +
                            (hit.kind == TabHitKind::ScrollLeft ? -step : step);
        g_panel.tabScroll = clampTabScroll(desired, layout);
        invalidatePanel();
        return true;
    }
    if (hit.kind == TabHitKind::Tab) {
        const Bank* bk = tabs[static_cast<std::size_t>(hit.index)];
        if (bk->id != g_panel.shownBankId) {
            g_panel.shownBankId = bk->id;          // browse: show this bank's grid
            g_panel.selection = Selection{};        // grid changed — reset selection
            stopAudition();
        }
        g_panel.focusedRegion = Region::Banks;
        invalidatePanel();
        return true;
    }
    return false;
}

// Handles the pool region's full-height toggle. Returns true if consumed.
bool handlePoolChromeClick(int x, int y, const RECT& region) {
    const RECT ftb = fullHtBtnRect(region);
    if (x >= ftb.left && x < ftb.right && y >= ftb.top && y < ftb.bottom) {
        bankPanelToggledPoolFullHeight();
        return true;
    }
    return false;
}

// Applies a left-click at (x, y): route to mode switch / footer / region chrome /
// grid selection, and arm a potential drag when the click lands on a selected cell.
void handleClick(int x, int y) {
    RECT cr{};
    GetClientRect(g_panel.hwnd, &cr);
    const int w = cr.right - cr.left, h = cr.bottom - cr.top;

    // Mode-switch header (D5) takes precedence.
    if (g_panel.session) {
        const int seg = hitTestSegment(x, y, panelHeader(w), modeCount());
        if (seg >= 0) {
            const std::vector<Mode>& modes = g_panel.session->view().modes().all();
            if (seg < static_cast<int>(modes.size())) {
                applyMode(g_panel.session->view(),
                          modes[static_cast<std::size_t>(seg)].id, nullptr);
                invalidatePanel();
            }
            return;
        }
    }

    // Tail footer: a click anywhere cycles the tail mode.
    const RECT f = panelFooter(w, h);
    if (f.top < f.bottom && x >= f.left && x < f.right && y >= f.top && y < f.bottom) {
        g_panel.tail.mode = cycleTailMode(g_panel.tail.mode);
        invalidatePanel();
        return;
    }

    // Region chrome (headers, tab strip, buttons).
    if (poolShown()) {
        const RECT pr = poolRegionRect(w, h);
        if (y >= pr.top && y < regionGridRect(pr, false).top) {
            if (handlePoolChromeClick(x, y, pr)) return;
        }
    }
    if (banksShown()) {
        const RECT br = banksRegionRect(w, h);
        if (y >= br.top && y < regionGridRect(br, true).top) {
            if (handleBanksChromeClick(x, y, br)) return;
        }
    }

    // Grid selection. Resolve which region's grid the point is in.
    Region reg = Region::Pool;
    if (!regionAt(x, y, reg)) return;
    const bool isBanks = reg == Region::Banks;
    const RECT region = isBanks ? banksRegionRect(w, h) : poolRegionRect(w, h);
    const BankIndex* index = indexForRegion(reg);
    const std::vector<CellRect> rects = regionCellRects(region, isBanks, index);
    const int hit = hitTestCell(x, y, rects);
    const int count = index ? static_cast<int>(index->size()) : 0;

    // Switching focus region reseeds the selection there.
    if (g_panel.focusedRegion != reg) {
        g_panel.focusedRegion = reg;
        g_panel.selection = Selection{};
        stopAudition();
    }

    if (hit < 0) {
        if (!g_panel.selection.empty() || g_panel.selection.focus >= 0) {
            g_panel.selection = Selection{};
            stopAudition();
        }
        invalidatePanel();
        return;
    }

    // If the pressed cell is already SELECTED and no modifier is held, arm a drag —
    // the actual selection change is deferred to LBUTTONUP if no drag begins (so a
    // plain click on a multi-selection can start a drag without collapsing it first).
    // Otherwise apply the click immediately. This is the M5-multi-select-drag
    // disambiguation: M5 has no cell drag; a drag here begins only from a selected
    // cell past a movement threshold (see onMouseMove), so plain click/shift/ctrl
    // multi-select is untouched.
    const bool onSelected = g_panel.selection.contains(hit);
    if (onSelected && !ctrlDown() && !shiftDown()) {
        g_panel.dragArmed = true;
        g_panel.dragStartX = x;
        g_panel.dragStartY = y;
        g_panel.dragSourceRegion = reg;
        // Keep the current (multi-)selection as the drag payload candidate.
        g_panel.selection.focus = hit;  // move the caret to the pressed cell
        invalidatePanel();
        return;
    }

    g_panel.selection = applyClick(g_panel.selection, hit, ctrlDown(), shiftDown(), count);
    g_panel.selItemCount = count;
    invalidatePanel();
}

// The column count for a region's current grid width (nav needs the layout's wrap).
int columnsForRegion(Region reg) {
    RECT cr{};
    GetClientRect(g_panel.hwnd, &cr);
    const int w = cr.right - cr.left, h = cr.bottom - cr.top;
    const RECT region = reg == Region::Banks ? banksRegionRect(w, h)
                                             : poolRegionRect(w, h);
    const RECT grid = regionGridRect(region, reg == Region::Banks);
    return columnsForWidth(grid.right - grid.left, kGrid);
}

bool isOurWindow(HWND hwnd) {
    for (HWND w = hwnd; w; w = GetParent(w))
        if (w == g_panel.hwnd) return true;
    return false;
}

bool handleKey(int vk) {
    const int count = focusedItemCount();
    if (count <= 0) return false;

    switch (vk) {
        case VK_LEFT:
        case VK_RIGHT:
        case VK_UP:
        case VK_DOWN: {
            const NavKey nk = vk == VK_LEFT    ? NavKey::Left
                              : vk == VK_RIGHT ? NavKey::Right
                              : vk == VK_UP    ? NavKey::Up
                                               : NavKey::Down;
            g_panel.selection = navigate(g_panel.selection, nk,
                                         columnsForRegion(g_panel.focusedRegion),
                                         count, shiftDown());
            g_panel.selItemCount = count;
            invalidatePanel();
            return true;
        }
        case VK_RETURN:
        case VK_SPACE:
            if (g_panel.selection.focus >= 0)
                startAudition(g_panel.selection.focus);
            return true;
        case VK_ESCAPE:
            stopAudition();
            return true;
        default:
            return false;
    }
}

int translateAccel(MSG* msg, accelerator_register_t* /*ctx*/) {
    if (!msg || msg->message != WM_KEYDOWN) return 0;
    if (!g_panel.open || !g_panel.hwnd) return 0;
    if (!isOurWindow(GetFocus())) return 0;
    return handleKey(static_cast<int>(msg->wParam)) ? 1 : 0;
}

accelerator_register_t g_accel{translateAccel, true, nullptr};
bool g_accelRegistered = false;

void registerAccel() {
    if (g_accelRegistered || !g_rec) return;
    g_rec->Register("accelerator", &g_accel);
    g_accelRegistered = true;
}

void unregisterAccel() {
    if (!g_accelRegistered || !g_rec) return;
    g_rec->Register("-accelerator", &g_accel);
    g_accelRegistered = false;
}

// --- Drag (move between regions/onto a tab) -----------------------------------

constexpr int kDragThreshold = 5;  // px the pointer must move to begin a drag

// Resolves the drop target under client (x, y) during a drag, updating dropKind /
// dropBankId. A drop onto the pool region -> the pool; onto a named tab -> that bank;
// anywhere else -> none.
void updateDropTarget(int x, int y) {
    RECT cr{};
    GetClientRect(g_panel.hwnd, &cr);
    const int w = cr.right - cr.left, h = cr.bottom - cr.top;

    g_panel.dropKind = DropKind::None;
    g_panel.dropBankId.clear();

    if (banksShown()) {
        const RECT br = banksRegionRect(w, h);
        const TabStripRect strip = banksTabStripRect(br);
        const std::vector<const Bank*> tabs = namedBanks();
        const TabHit hit = hitTestTabStrip(x, y, strip,
                                           static_cast<int>(tabs.size()), kTabSpec,
                                           g_panel.tabScroll);
        if (hit.kind == TabHitKind::Tab) {
            g_panel.dropKind = DropKind::Tab;
            g_panel.dropBankId = tabs[static_cast<std::size_t>(hit.index)]->id;
            return;
        }
    }
    if (poolShown()) {
        const RECT pr = poolRegionRect(w, h);
        const RECT grid = regionGridRect(pr, false);
        if (x >= grid.left && x < grid.right && y >= grid.top && y < grid.bottom) {
            g_panel.dropKind = DropKind::PoolRegion;
            return;
        }
    }
}

void onMouseMove(int x, int y) {
    if (g_panel.dragArmed && !g_panel.dragging) {
        if (std::abs(x - g_panel.dragStartX) > kDragThreshold ||
            std::abs(y - g_panel.dragStartY) > kDragThreshold) {
            // Threshold crossed — begin the drag. Snapshot the payload NOW.
            g_panel.dragging = true;
            g_panel.dragSourceBankId = bankIdForRegion(g_panel.dragSourceRegion);
            g_panel.dragSampleIds = focusedSelectionIds();
            SetCapture(g_panel.hwnd);
        }
    }
    if (g_panel.dragging) {
        updateDropTarget(x, y);
        invalidatePanel();
    }
}

// Commits (or abandons) a drag on button-up. A drop onto a DIFFERENT bank moves the
// dragged samples there; a drop onto the source bank / dead space is a no-op. Ctrl
// held at drop = copy (the deliberate secondary), else move.
void onLBtnUp(int x, int y) {
    if (g_panel.dragging) {
        updateDropTarget(x, y);
        std::string destId;
        if (g_panel.dropKind == DropKind::PoolRegion) destId = std::string(kPoolBankId);
        else if (g_panel.dropKind == DropKind::Tab)   destId = g_panel.dropBankId;

        if (!destId.empty() && destId != g_panel.dragSourceBankId &&
            !g_panel.dragSampleIds.empty()) {
            transferSamples(g_panel.dragSampleIds, g_panel.dragSourceBankId, destId,
                            /*copy=*/ctrlDown());
        }
        if (GetCapture() == g_panel.hwnd) ReleaseCapture();
    } else if (g_panel.dragArmed) {
        // Press-release on a selected cell with no drag: treat as a plain click that
        // collapses the multi-selection to the pressed cell (standard behavior).
        const BankIndex* idx = indexForRegion(g_panel.focusedRegion);
        const int count = idx ? static_cast<int>(idx->size()) : 0;
        const int focus = g_panel.selection.focus;
        if (focus >= 0)
            g_panel.selection = applyClick(g_panel.selection, focus, false, false, count);
    }
    g_panel.dragArmed = false;
    g_panel.dragging = false;
    g_panel.dropKind = DropKind::None;
    g_panel.dropBankId.clear();
    invalidatePanel();
}

// A right-click: on a named tab -> the tab management menu; on a grid cell of the
// focused region with a selection -> the move/copy menu.
void handleRightClick(int x, int y) {
    RECT cr{};
    GetClientRect(g_panel.hwnd, &cr);
    const int w = cr.right - cr.left, h = cr.bottom - cr.top;

    // Tab management menu.
    if (banksShown()) {
        const RECT br = banksRegionRect(w, h);
        const TabStripRect strip = banksTabStripRect(br);
        const std::vector<const Bank*> tabs = namedBanks();
        const TabHit hit = hitTestTabStrip(x, y, strip,
                                           static_cast<int>(tabs.size()), kTabSpec,
                                           g_panel.tabScroll);
        if (hit.kind == TabHitKind::Tab) {
            POINT pt{x, y};
            ClientToScreen(g_panel.hwnd, &pt);
            showTabMenu(pt.x, pt.y, tabs[static_cast<std::size_t>(hit.index)]->id);
            return;
        }
    }

    // Grid selection menu (move/copy). Only when the right-click lands in the focused
    // region's grid and there is a selection.
    Region reg = Region::Pool;
    if (regionAt(x, y, reg) && reg == g_panel.focusedRegion &&
        !g_panel.selection.empty()) {
        POINT pt{x, y};
        ClientToScreen(g_panel.hwnd, &pt);
        showSelectionMenu(pt.x, pt.y);
    }
}

// --- Dialog proc + docking ----------------------------------------------------

WDL_DLGRET dlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
        case WM_PAINT: {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hwnd, &ps);
            paintPanel(hwnd, hdc);
            EndPaint(hwnd, &ps);
            return 0;
        }
        case WM_LBUTTONDOWN: {
            SetFocus(hwnd);
            handleClick(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
            return 0;
        }
        case WM_MOUSEMOVE:
            onMouseMove(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
            return 0;
        case WM_LBUTTONUP:
            onLBtnUp(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
            return 0;
        case WM_RBUTTONDOWN:
            SetFocus(hwnd);
            handleRightClick(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
            return 0;
        case WM_CAPTURECHANGED:
            // Capture lost before a drag began (e.g. pointer left window pre-threshold
            // and button released outside) — disarm so the state doesn't stay stale.
            if (g_panel.dragArmed && !g_panel.dragging) {
                g_panel.dragArmed = false;
                invalidatePanel();
            }
            return 0;
        case WM_DESTROY:
            if (GetCapture() == hwnd) ReleaseCapture();
            stopAudition();
            g_panel.selection = Selection{};
            g_panel.dragArmed = g_panel.dragging = false;
            g_panel.hwnd = nullptr;
            g_panel.open = false;
            return 0;
        default:
            break;
    }
    return 0;
}

void openPanel() {
    if (g_panel.open && g_panel.hwnd) {
        DockWindowActivate(g_panel.hwnd);
        return;
    }
    initPreview();

    g_panel.hwnd = CreateDialogParam(g_hInst, MAKEINTRESOURCE(IDD_BANK_PANEL),
                                     GetMainHwnd(), dlgProc, 0);
    if (!g_panel.hwnd) return;

    DockWindowAddEx(g_panel.hwnd, "ReaSampler Bank", "reasampler_bank_panel", true);
    DockWindowActivate(g_panel.hwnd);
    g_panel.open = true;

    registerAccel();

    reconcileShownBank();
    refreshFingerprint();
}

void closePanel() {
    if (GetCapture() == g_panel.hwnd) ReleaseCapture();
    stopAudition();
    g_panel.selection = Selection{};
    g_panel.dragArmed = g_panel.dragging = false;
    unregisterAccel();
    if (g_panel.hwnd) {
        DockWindowRemove(g_panel.hwnd);
        DestroyWindow(g_panel.hwnd);
        g_panel.hwnd = nullptr;
    }
    g_panel.open = false;
}

}  // namespace

// --- Public API ---------------------------------------------------------------

void bankPanelInit(ReaSamplerSession* session) {
    g_panel.session = session;
}

void bankPanelToggle() {
    if (g_panel.open)
        closePanel();
    else
        openPanel();
}

bool bankPanelIsOpen() {
    return g_panel.open;
}

std::vector<std::string> bankPanelSelectedSampleIds() {
    return focusedSelectionIds();
}

std::string bankPanelSelectedSourceBankId() {
    // The focused region's displayed bank is the move/copy source. Default to the
    // pool (a safe source) when nothing is selected / the panel never opened.
    if (g_panel.selection.empty()) return std::string(kPoolBankId);
    const std::string id = bankIdForRegion(g_panel.focusedRegion);
    return id.empty() ? std::string(kPoolBankId) : id;
}

void bankPanelRefresh() {
    if (!g_panel.open || !g_panel.hwnd) return;
    if (refreshFingerprint())
        InvalidateRect(g_panel.hwnd, nullptr, FALSE);
}

TailSetting bankPanelTailSetting() {
    TailSetting s = g_panel.tail;
    s.manualMs = clampManualMs(s.manualMs);
    return s;
}

BankPanelFullHeight bankPanelFullHeight() {
    return g_panel.fullHeight;
}

static void setFullHeight(BankPanelFullHeight target) {
    g_panel.fullHeight =
        (g_panel.fullHeight == target) ? BankPanelFullHeight::Split : target;
    if (g_panel.hwnd) InvalidateRect(g_panel.hwnd, nullptr, FALSE);
}

void bankPanelToggledPoolFullHeight() {
    setFullHeight(BankPanelFullHeight::PoolOnly);
}

void bankPanelToggledBanksFullHeight() {
    setFullHeight(BankPanelFullHeight::BanksOnly);
}

void bankPanelShutdown() {
    closePanel();
    deinitPreview();
    g_panel.cache.clear();
    g_panel.session = nullptr;
}

}  // namespace reasampler