reasampler/src/persist.h

#pragma once
// persist — the REAPER-facing bridge between the in-memory BankIndex and project
// ext state (CLAUDE.md §load-bearing split; CONTEXT.md §Persistence & paths).
//
// Save: serialize the BankIndex JSON -> SetProjExtState under namespace
//   "reasampler" (ext state lives inside the .rpp, so the index travels with the
//   project for free).
// Load: on project load, GetProjExtState -> bank_model::deserialize -> in-memory
//   BankIndex, then resolve each entry's bank file against the CURRENT project
//   dir (project-relative resolution — a project opened from a new location still
//   finds its bank).
// Save-As: when the project path changes, relocate the physical bank folder so
//   the wavs end up under the new .rpp (the index's relative paths stay valid).
//
// The header is REAPER-free (no SDK types leak here): callers interact through a
// ReaSamplerSession that owns the bank and the persist lifecycle. All REAPER API
// calls live in persist.cpp. It depends on bank_model (pure) for JSON round-trip
// and capture_paths (pure) for the path arithmetic it drives.

#include <string>

#include "bank_model.h"
#include "tail_control.h"
#include "view_mode_model.h"

namespace reasampler {

// The ext-state namespace the index JSON is stored under. FOREVER-STABLE once
// shipped: changing it orphans every already-saved project's index.
inline constexpr const char* kProjExtNamespace = "reasampler";

// The ext-state key the index JSON is stored under (one key holds the whole
// serialized BankIndex). FOREVER-STABLE for the same reason.
inline constexpr const char* kProjExtIndexKey = "bank_index";

// The ext-state key the Design-View ViewModeModel JSON is stored under (one key
// holds the whole serialized model: modes + membership + show-both + snapshots +
// active mode). Distinct from kProjExtIndexKey — one namespace, two keys.
// FOREVER-STABLE: changing it orphans every already-saved project's view state.
inline constexpr const char* kProjExtViewKey = "view_state";

// The ext-state key the docked panel's TailSetting JSON (mode + manualMs) is stored
// under, so the tail choice travels inside the .rpp and loads per project. Distinct
// from the index/view keys — one namespace, three keys. FOREVER-STABLE: changing it
// orphans every already-saved project's tail setting (which then falls back to the
// default — graceful, but the user's saved choice would be lost).
inline constexpr const char* kProjExtTailKey = "tail_setting";

// The ext-state key holding a GUID we mint per project to establish CONTENT-BASED
// project identity (REAPER exposes no stable per-project GUID). poll() uses it to
// tell a genuine Save-As (same GUID, new .rpp path) apart from a project switch
// onto a recycled ReaProject* pointer (different GUID). FOREVER-STABLE: changing
// it strands the identity of every already-saved project. See persist.cpp.
inline constexpr const char* kProjExtGuidKey = "project_guid";

// Owns the session's BankIndex and drives persistence against the active REAPER
// project. One instance lives for the extension's lifetime (main.cpp). It tracks
// the project identity it last saw so the timer tick can detect a project load
// (a different project became active) and a Save-As (SAME project, path changed):
//
//   * project load       -> load the index from ext state, resolve bank paths
//   * Save-As (new dir)   -> relocate the bank folder under the new .rpp
//
// Identity is layered GUID-PRIMARY: the minted GUID (content-based identity of
// record, immune to REAPER recycling a closed project's ReaProject* address) is
// checked FIRST, and the live pointer disambiguates only the same-GUID case — a
// forked sibling (same GUID, different object -> Load) vs a genuine Save-As (same
// GUID, same object, new path -> relocate). GUID-first catches pointer recycling
// (a reopened/new project reusing the previous address with a different GUID — the
// W12 defect that stopped the bank reloading); the pointer catches forks (Save-As
// copies our GUID onto a distinct object — the W10 defect that clobbered a bank).
//
// The bank itself is exposed for the capture/action layer to mutate; persist
// only reads it on save and replaces it on load.
class ReaSamplerSession {
public:
    ReaSamplerSession() = default;

    // The in-memory bank. The action/capture layer adds captures here; persist
    // serializes it on save and replaces it on project load.
    BankIndex& bank() { return bank_; }
    const BankIndex& bank() const { return bank_; }

    // The in-memory Design-View model. The view/action layer mutates it (tag,
    // toggle, snapshot); persist serializes it on save and replaces it on project
    // load — exactly as it treats the bank. D3 persists MODEL STATE only; applying
    // visibility/processing (reapply-on-open) is D4's job, not this member's.
    ViewModeModel& view() { return view_; }
    const ViewModeModel& view() const { return view_; }

    // The docked panel's tail setting (mode + manualMs), authoritative here — NOT in
    // panel state — so it travels inside the .rpp: persist serializes it on save and
    // replaces it on project load exactly as it treats the bank and view model. The
    // panel reads/writes it through this seam (bank_panel holds the session), and the
    // capture actions read it via bankPanelTailSetting. Default None / 2 s manual for
    // an unsaved or pre-feature project (no stored key -> this default survives load).
    TailSetting& tail() { return tail_; }
    const TailSetting& tail() const { return tail_; }

    // Serialize the current bank to the active project's ext state (namespace
    // "reasampler"). Non-destructive beyond writing our own ext-state key. Safe
    // to call when there is no active/saved project (it no-ops).
    void saveToActiveProject();

    // Poll the active project. Detects a project load (active project changed)
    // and a Save-As (active project's .rpp path changed) and reacts accordingly.
    // Intended to be driven by REAPER's "timer" register. Idempotent per tick.
    void poll();

    // Load signal for the D4 reapply-on-open glue. poll() raises this whenever it
    // (re)loads the view model from a project — prime, a project switch/open, or a
    // forked-sibling load. consumeLoadSignal() returns true ONCE per load and clears
    // it, so the integration layer (main.cpp) can react by reapplying the saved
    // active mode's visibility exactly once, then goes quiet on idle ticks.
    //
    // Signal-based seam by design: persist stays MODEL-ONLY (it never calls the view
    // shell), so there is no persist -> view dependency. main.cpp owns the glue —
    // it drives both persist.poll() and view::applyMode, so the reapply wiring lives
    // where those two already meet. D3 deliberately deferred exactly this to D4.
    bool consumeLoadSignal();

private:
    BankIndex bank_;

    // The Design-View model. Default-constructed = Arrange + Design seeded, active
    // = Arrange; loadFromProject leaves this default when a project has no stored
    // view_state (older project), so an absent key is graceful, not a crash.
    ViewModeModel view_;

    // The tail setting. Default None / kDefaultManualTailMs; loadFromProject resets it
    // to this default when a project has no stored tail_setting key (older / never-
    // adjusted project), so an absent key is graceful. Peer to bank_/view_.
    TailSetting tail_;

    // The project identity last observed by poll(), used to detect load/Save-As.
    // The GUID is the PRIMARY signal (a different stored GUID = a different project
    // of record = Load, immune to pointer recycling). The pointer disambiguates the
    // same-GUID case (different object = forked sibling -> Load; same object + new
    // path -> Save-As) and drives forked-sibling re-divergence; the path tells a
    // Save-As from an idle tick.
    // Held as void* so the header stays REAPER-free; it is a compared-only opaque
    // handle (never dereferenced), so a stale/recycled address is harmless.
    void*       lastProject_ = nullptr;   // last active ReaProject* (opaque; compare only)
    std::string lastGuid_;                // "" until the first saved project is seen
    std::string lastRppPath_;             // .rpp path last seen for lastProject_
    bool        primed_ = false;          // false until the first poll() observes state
    bool        loadPending_ = false;     // raised by loadFromProject; drained by consumeLoadSignal

    // Load the index from the given project's ext state and resolve bank paths
    // against projectDir. Replaces the in-memory bank. projectDir empty -> clears
    // the bank (unsaved project has no resolvable bank).
    void loadFromProject(void* proj, const std::string& projectDir);
};

} // namespace reasampler