reasampler/src/capture.h

#pragma once
// capture — the REAPER-facing capture shell (CLAUDE.md §load-bearing split).
//
// This header declares the capture *seam* the later milestones fill:
//   * CaptureRequest    — everything a capture needs, source-mode-agnostic.
//   * ICaptureBackend   — the SYNCHRONOUS interface OfflineRenderBackend implements
//                         (headless, immediate, returns a finished Sample).
//   * OfflineRenderBackend — the deterministic default; drives the offline scopes.
//   * RealtimeRecordBackend — the ASYNC realtime seam (begin/tick/abort), driven
//                         across timer ticks; deliberately NOT an ICaptureBackend
//                         (see the SEAM CHOICE note at its declaration).
//
// It includes bank_model (pure) to hand back a populated Sample, but NO REAPER
// headers — the .cpp is the REAPER-facing translation unit. Keeping this header
// REAPER-free lets callers (main.cpp, future actions.cpp) depend on the seam
// without dragging the SDK into every include site.

#include <memory>
#include <string>
#include <vector>

#include "bank_model.h"

// MediaTrack is forward-declared (like track_guid.h) so this header stays
// REAPER-free while RealtimeRecordBackend::begin can take the resolved source
// MediaTrack* to tap. The pointers are opaque here — never dereferenced in a
// pure/header context; only the REAPER-facing capture_realtime.cpp touches them.
class MediaTrack;

namespace reasampler {

// Audio bit-depth for the rendered wav. 32-bit float is the M3 default —
// rationale lives in capture.cpp next to the sink-config bytes.
enum class WavBitDepth {
    Int16,
    Int24,
    Float32,
};

// One capture, independent of source mode. Populated by the caller (the action
// handler in M3; the action family in M7) and consumed by a backend.
//
// M3 fills only the fields the master-mix/time-selection path needs; the rest
// are declared now so M7/M8 do not reshape the struct (they are the seam).
struct CaptureRequest {
    SourceMode sourceMode = SourceMode::MasterMix;

    // Sample-accurate render bounds in project seconds. For the M3 spike these
    // come straight from the time selection (GetSet_LoopTimeRange) — NO rounding.
    double startSeconds = 0.0;
    double endSeconds   = 0.0;

    // 1.0 = fully wet, 0.0 = fully dry. All three-scope capture actions set this to 1.0 (wet).
    // The field is kept as the seam for future true-dry work (M10 null test):
    // true pre-FX dry offline is NOT available via RENDER_SETTINGS — it requires
    // FX-bypass-around-render or the M8 realtime pre-FX path, and will be
    // designed alongside the M10 null test. Also recorded on the Sample.
    double wetDry = 1.0;

    // Track GUID(s) the capture came from, when the source mode is track-scoped
    // (SelectedTracks). Empty for master/items/razor. The action layer (M7)
    // resolves the selection to canonical GUID strings and passes them here; the
    // backend copies them onto the Sample (it does NOT itself read the selection —
    // it stays source-agnostic, driven entirely by the request).
    std::vector<std::string> trackGuids;

    // Render tail. Default OFF for the spike (exact bounds, no added silence —
    // precision invariant). M7 makes this bindable.
    bool   renderTail   = false;
    double tailMs       = 0.0;

    // Output format. 0 sampleRate => follow project rate (deterministic: the
    // project rate is fixed for a given project).
    int         sampleRate   = 0;
    int         channelCount = 2;
    WavBitDepth bitDepth      = WavBitDepth::Float32;

    // Human base name for the file stem; sanitized by capture_paths. The unique
    // tag (disambiguator) is supplied separately by the backend caller so the
    // pure naming logic stays testable.
    std::string baseName  = "capture";
    std::string uniqueTag;  // e.g. a timestamp/counter; may be empty
};

// Outcome of a capture attempt. `Ok` carries the populated Sample; every failure
// is an explicit code (never a thrown exception across the REAPER boundary) so
// the action handler can log a precise reason.
enum class CaptureStatus {
    Ok,
    NoProject,          // no active project to render / resolve a bank folder
    EmptyRange,         // start >= end: nothing to render
    UnsupportedMode,    // backend does not implement this source mode (M3 scope)
    UnsupportedFormat,  // requested bit depth has no known REAPER blob (M3: Float32 only)
    RenderFailed,       // the render action ran but produced no output file
    TransportBusy,      // realtime backend: transport already playing/recording — refused
};

struct CaptureResult {
    CaptureStatus status = CaptureStatus::RenderFailed;
    Sample        sample;        // valid only when status == Ok
    std::string   message;       // human-readable detail for the console log
};

// The capture seam. One method: run a request, return a populated Sample (or a
// failure code). Backends are non-destructive — they must restore any global
// state they touch before returning (OfflineRenderBackend snapshots/restores the
// RENDER_* project settings).
class ICaptureBackend {
public:
    virtual ~ICaptureBackend() = default;
    virtual CaptureResult capture(const CaptureRequest& request) = 0;
};

// Deterministic offline-render backend. Drives the full offline source family —
// master mix / time selection, selected tracks, selected items, razor area — all
// wet-only (render_settings.h) with optional tail. The source selection + range
// are resolved by the caller (the action layer) and handed in via the
// CaptureRequest; the backend drives RENDER_* and never reads the DAW selection
// itself. SourceMode::Realtime returns UnsupportedMode (that is the M8 backend).
class OfflineRenderBackend : public ICaptureBackend {
public:
    CaptureResult capture(const CaptureRequest& request) override;
};

// --- Realtime-record backend: the ASYNC seam ---------------------------------
//
// A realtime record is inherently asynchronous: CSurf_OnRecord starts the transport
// on REAPER's audio thread and returns immediately — it does NOT block until the
// range completes, which takes (end - start) wall-clock seconds. Blocking the main
// thread for that duration freezes REAPER's UI, so the realtime backend is DRIVEN
// ACROSS TIMER TICKS instead: begin() starts and returns at once; tick() (called
// from the same OnTimer that runs session.poll()) advances the in-flight record and
// reports when it is done.
//
// SEAM CHOICE (surfaced): RealtimeRecordBackend deliberately does NOT implement the
// synchronous ICaptureBackend — that interface returns a finished Sample from one
// call, which no longer fits a record that spans ticks. The two backends have
// genuinely different lifecycles (offline is headless + immediate; realtime is
// transport-driven + async), so forcing a shared async interface would make offline
// fake a lifecycle it does not have (its tick() would always be Done on the first
// call — dead code / an LSP smell). Offline stays synchronous and unchanged; the
// realtime backend owns this small bespoke async seam, driven by exactly one caller
// (main.cpp's OnTimer). This is the split-sync/async fork, chosen over a unified
// async interface for that reason.

// One tick's verdict from the in-flight record.
enum class RealtimeTickStatus {
    InProgress,  // still recording — call tick() again next timer tick
    Done,        // finished (range end reached, or the user stopped) — `result` is set
    Failed,      // an error tore the capture down — `result.message` explains
};

struct RealtimeTickResult {
    RealtimeTickStatus status = RealtimeTickStatus::InProgress;
    CaptureResult      result;  // meaningful only when status == Done or Failed
};

// The opaque in-flight capture state. Owns the snapshot of everything to restore
// (temp track + its receive sends from the source tracks, other tracks' I_RECARM,
// transport, edit cursor, time selection) and the record's own project handle.
// Defined in
// capture_realtime.cpp; the header stays REAPER-free (no MediaTrack*/ReaProject*
// leaks here) by holding it behind a forward-declared type + unique_ptr.
//
// restore()/teardown is idempotent and lives ON THIS OBJECT (not a function-scope
// RAII guard) because the record spans ticks — no single stack frame outlives it.
// Every terminal path (normal completion, user stop, error, project switch, unload)
// funnels through the same single restore, safe to call once from whichever fires.
class RealtimeCaptureState;

// Out-of-line deleter so callers (main.cpp) can own a unique_ptr to the opaque
// RealtimeCaptureState WITHOUT its full (REAPER-typed) definition — the delete is
// compiled in capture_realtime.cpp where the type is complete, keeping this header
// REAPER-free (load-bearing split).
struct RealtimeCaptureStateDeleter {
    void operator()(RealtimeCaptureState* p) const noexcept;
};
using RealtimeCaptureHandle =
    std::unique_ptr<RealtimeCaptureState, RealtimeCaptureStateDeleter>;

// Realtime-record backend — captures by RECORDING in realtime (transport-driven)
// into a hidden temp track, then moves the recorded file into the bank as a Sample.
// For sources offline render cannot do (hardware, performed FX) and as the true
// pre-FX-dry path (I_RECMODE_FLAGS &3==1 — the only pre-FX tap in the SDK; offline
// render has none). Dialog-free: never invokes the offline-render progress window.
//
// Non-bit-identical by nature (it is realtime); offline stays the deterministic
// default. Non-destructive across EVERY terminal path — the review gate — which is
// harder here than offline because the record spans ticks: the snapshot + restore
// live on RealtimeCaptureState, not a function-scope RAII destructor.
//
// SCOPE (this increment): TRACK scope only — records the selected track's OWN
// output (item + that track's own FX + its own fader/pan, PRE-parent), matching
// offline's track scope. This needs NO FxBypassGuard: a send tapping a track's
// output is naturally PRE-parent (the parent has not summed it yet), so the tap is
// chain-independent by construction. Item realtime is deferred (UnsupportedMode).
class RealtimeRecordBackend {
public:
    // Starts a realtime record: validates the request (track scope, non-empty range,
    // at least one source track, active + saved project, transport idle), snapshots
    // all state to restore, creates the hidden temp track, routes a send FROM each
    // source track INTO the temp track, arms, and CSurf_OnRecord — then returns
    // IMMEDIATELY (no wait, no UI block). `sourceTracks` are the selected tracks to
    // tap (resolved by the action layer — the CaptureRequest itself stays REAPER-free,
    // carrying only the provenance GUIDs). On success the returned unique_ptr owns the
    // in-flight state; drive it with tick(). On a validation/setup failure returns
    // nullptr and fills `outFailure` with the CaptureStatus + message (nothing was
    // left mutated — begin() restores on its own failure paths).
    RealtimeCaptureHandle begin(const CaptureRequest& request,
                                const std::vector<MediaTrack*>& sourceTracks,
                                CaptureResult& outFailure);

    // Advances the in-flight record one tick. Reads the transport (bound to the
    // record's OWN project handle so a project switch cannot confuse it), and on a
    // terminal verdict stops the transport, finalizes the recorded file into the
    // bank Sample (Done) or reports the failure (Failed), then restores ALL
    // snapshotted state. Returns InProgress while the record is still running.
    // After Done/Failed the state is spent — the caller drops the unique_ptr.
    RealtimeTickResult tick(RealtimeCaptureState& state);

    // Force-terminate an in-flight record NOW without waiting for the range end:
    // stops the transport, finalizes whatever was captured (best effort) or abandons
    // it, and restores ALL snapshotted state. For the shutdown / project-switch
    // paths (extension unload, a new project became active) where the record must
    // not leak a temp track / armed track / altered transport into the user's
    // project. Idempotent — safe even if a prior tick already tore the state down.
    RealtimeTickResult abort(RealtimeCaptureState& state);
};

} // namespace reasampler