// See view.h. Compiled into the reaper_reasampler module; includes
// reaper_plugin_functions.h without REAPERAPI_IMPLEMENT (main.cpp owns that).
// Tree arithmetic lives in view_tree (pure), one track's park/restore in view_park
// and the lane writes in view_lanes; this file owns the plan iteration, parent
// visibility, and the one undo block they all ride.

#include "shell/view/view.h"

#include <map>
#include <set>
#include <string>
#include <vector>

#include "core/view/solo_cache.h"
#include "core/view/view_tree.h"
#include "shell/view/fx_reclaim.h"
#include "shell/view/view_lanes.h"
#include "shell/view/view_park.h"
#include "shell/view/view_reconcile.h"
#include "shell/view/view_solo.h"
#include "shell/view/view_tracks.h"

#define REAPERAPI_MINIMAL
#define REAPERAPI_WANT_EnumProjects
#define REAPERAPI_WANT_GetPlayStateEx
#define REAPERAPI_WANT_Undo_BeginBlock2
#define REAPERAPI_WANT_Undo_EndBlock2
#define REAPERAPI_WANT_TrackList_AdjustWindows
#define REAPERAPI_WANT_UpdateArrange
#define REAPERAPI_WANT_UpdateTimeline
#define REAPERAPI_WANT_ValidatePtr2
#include "reaper_plugin_functions.h"

namespace reasampler {

using view::buildFolderTree;
using view::TrackFolderEntry;

namespace {

// GetPlayStateEx bitmask. SDK: &1 playing, &2 paused, &4 recording — paused is
// deliberately excluded, nothing is moving there.
constexpr int kTransportMoving = 1 | 4;

// applyMode is reachable from the load tick, the actions and render_in_place. Nothing
// it calls is known to pump the message loop now that the FX writes are gone, but a
// re-entrant apply would plan against the same model the outer loop is iterating and
// consume records out from under it — one dropped call is cheaper than that. Fail closed.
bool g_applying = false;
struct ApplyLatch {
    ApplyLatch() { g_applying = true; }
    ~ApplyLatch() { g_applying = false; }
    ApplyLatch(const ApplyLatch&) = delete;
    ApplyLatch& operator=(const ApplyLatch&) = delete;
};

} // namespace

bool transportBlocksModeSwitch(ReaProject* proj) {
    return (GetPlayStateEx(proj) & kTransportMoving) != 0;
}

bool modeApplyInProgress() { return g_applying; }

namespace {

bool applyModeImpl(ViewModeModel& model, const std::string& targetModeId, ReaProject* proj) {
    if (g_applying) return false;  // see ApplyLatch; same fail-closed shape as the guards below
    ApplyLatch latch;

    if (!model.modes().contains(targetModeId)) {
        return false;  // reject before touching the project — no partial apply
    }

    // Pinned ONCE: resolving "current project" independently at the begin and the end
    // would let a tab switch mid-apply open the block on one project and close it on
    // another.
    ReaProject* const project = proj ? proj : EnumProjects(-1, nullptr, 0);
    if (!ValidatePtr2(nullptr, project, "ReaProject*")) return false;

    // The discriminator behind both halves of the contract in view.h. A gate placed
    // unconditionally here would break tagging and the project-load reapply during
    // playback; a solo round on every reapply would flicker the user's solo on every
    // membership edit.
    const std::string outgoingModeId = model.activeModeId();
    const bool realSwitch = targetModeId != outgoingModeId;

    if (realSwitch && transportBlocksModeSwitch(project)) {
        return false;  // same fail-closed shape as the mode-exists guard above
    }

    TrackHandles handleByGuid;
    std::vector<TrackFolderEntry> entries = readFolderEntries(project, handleByGuid);
    const TrackByGuid trackByGuid = indexHandles(handleByGuid);
    FolderTree tree = buildFolderTree(entries);

    // Prune records for tracks no longer in the live enumeration before planning
    // (membership is intentionally left alone — see model.reconcile). Because
    // reapply-on-load routes through applyMode, this also reconciles on project open.
    std::set<std::string> liveGuids;
    for (const auto& kv : handleByGuid) liveGuids.insert(kv.first);
    model.reconcile(liveGuids);

    // Read before any write, and while activeModeId() still names the mode being left.
    const std::map<std::string, int> outgoingSolo =
        realSwitch ? view::soloedTracks(readTrackSolos(handleByGuid))
                   : std::map<std::string, int>{};

    TogglePlan plan = model.planToggle(tree, targetModeId);

    // Target is guaranteed registered (checked at entry); fall back to the id
    // defensively if that ever changes.
    const Mode* targetMode = model.modes().query(targetModeId);
    const std::string undoLabel =
        "ReaSampler: activate " +
        (targetMode ? targetMode->displayName : targetModeId) + " view";

    bool laneModeChanged = false;
    bool wrote = false;  // anything at all this apply changed — see applyMintsUndoPoint
    std::vector<std::string> exposedNames;  // named while handles are fresh, reported after the block

    Undo_BeginBlock2(project);
    {
        UiRefreshHold uiHold;  // every write below lands with the TCP/MCP frozen

        // DISJOIN THE SOLO SURFACES. Both this clear and the replay after
        // setActiveMode ride the existing undo block — one mode toggle stays one Ctrl-Z.
        if (realSwitch) {
            model.soloCache().store(outgoingModeId, outgoingSolo);
            clearTrackSolos(handleByGuid, outgoingSolo);
        }

        // PARK / RESTORE: view_park owns one track's whole move. Flags only — the
        // parked chain stays online until the reclaimer reaches it.
        for (const TrackPlan& tp : plan.park) {
            if (tp.flags.empty()) continue;  // every op in a TrackPlan targets one track
            const std::string& guid = tp.flags.front().guid;
            MediaTrack* tr = resolve(trackByGuid, guid);
            if (!tr) continue;  // stale/deleted GUID — prune
            const TrackParkResult r = parkTrack(model, guid, tr, tp.flags);
            if (r.wrote) wrote = true;
            // Named here, not after the block: TrackList_AdjustWindows below can
            // invalidate the handle.
            if (r.exposed) exposedNames.push_back(trackDisplayName(tr));
        }

        for (const TrackPlan& tp : plan.restore) {
            if (tp.flags.empty()) continue;
            const std::string& guid = tp.flags.front().guid;
            MediaTrack* tr = resolve(trackByGuid, guid);
            if (!tr) continue;  // stale/deleted GUID — prune
            if (restoreTrack(model, guid, tr, tp.flags)) wrote = true;
        }

        // MANAGED LANES: the active mode's lane plays+shows, every other managed lane
        // is silenced+hidden. Empty on a D1-only project — byte-identical there.
        const LaneApplyResult lanes = applyLaneOps(trackByGuid, plan.lanes);
        laneModeChanged = lanes.freeMode;
        if (lanes.wrote) wrote = true;

        // PARENT VISIBILITY (never parked): recomputed every toggle, never recorded.
        // Only the two visibility flags — never mainSend/FX on a parent.
        std::set<std::string> visible = model.visibleTracks(tree, targetModeId);
        for (const FolderNode& node : tree.nodes) {
            if (!node.isParent) continue;
            MediaTrack* tr = resolve(trackByGuid, node.guid);
            if (!tr) continue;  // stale GUID — prune
            const double show = visible.count(node.guid) ? 1.0 : 0.0;
            if (writeIfChanged(tr, "B_SHOWINTCP", show)) wrote = true;
            if (writeIfChanged(tr, "B_SHOWINMIXER", show)) wrote = true;
        }

        model.setActiveMode(targetModeId);

        // Replay + consume, before the single relayout below picks the change up.
        // Dropped against `visible` (computed above for parent visibility), not the
        // park plan: a folder parent can be hidden without being parked, and a hidden
        // track must not receive a replayed solo it carries no visible control to undo.
        if (realSwitch) {
            if (const std::map<std::string, int>* cached = model.soloCache().query(targetModeId)) {
                restoreTrackSolos(handleByGuid, *cached, liveGuids, visible);
                model.soloCache().clear(targetModeId);
            }
        }
    }

    // Force REAPER to rebuild the TCP/MCP now rather than on the next user
    // interaction — AdjustWindows(false) is the full relayout tracks appearing and
    // disappearing owes.
    TrackList_AdjustWindows(false);
    UpdateArrange();

    // UpdateTimeline() is owed only when a track was actually toggled into fixed lanes
    // this apply (SDK requirement for I_FREEMODE changes).
    if (laneModeChanged) UpdateTimeline();

    const bool mint = applyMintsUndoPoint(realSwitch, wrote);
    Undo_EndBlock2(project, mint ? undoLabel.c_str() : "", mint ? kViewUndoMask : 0);

    // After the undo block: an EXPOSE report is a console message, not a project
    // write, and must not join what a Ctrl-Z rolls back.
    reportExposedTracks(project, exposedNames);

    // The tool's own account of what it just left driven — the only one that survives
    // an undo rolling the model back underneath it.
    noteAppliedState(project, model);

    return true;
}

} // namespace

bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject* proj) {
    const bool applied = applyModeImpl(model, targetModeId, proj);

    // Every membership, snapshot and active-mode mutation in the system reaches the
    // project through this call, so this is the whole invalidation surface: the
    // reclaimer's queue is a cache of what the FX chains SHOULD be, never state.
    //
    // Dropped on a REFUSAL too, and that is the load-bearing half. Callers mutate the
    // model FIRST and reapply to make it visible (design_view_actions' tag/untag/
    // show-both, render_in_place, the load tick), and every one of them discards this
    // return — so a refusal is exactly the case where the mutation stands and nothing
    // else would drop a queue that now converges toward the mode the user just left.
    // The cost when the refusal followed no mutation is one re-derivation on the timer.
    invalidateFxReclaim();
    return applied;
}

} // namespace reasampler