ten31-transcripts/Ten31Transcripts/Session/SessionController.swift

import Foundation
import Combine
import AppKit
import CoreGraphics

struct SessionInfo: Equatable {
    let folder: URL
    let mixedURL: URL
    let duration: Double
    let selfSpanCount: Int
}

/// Owns a single recording session: creates the session folder, drives
/// `AudioRecorder` start/stop, tracks elapsed time, and writes the Phase-1
/// preview of mic-VAD self spans. Detection/visual/backend wiring come later.
///
/// The lifecycle is serialized through an explicit state machine so start and
/// stop can never interleave (`.starting` → `.recording` → `.finishing`).
@MainActor
final class SessionController: ObservableObject {
    enum State: Equatable {
        case idle
        case starting
        case recording
        case finishing
        case error(String)
    }

    /// Backend transcription status for the most recent session.
    enum TranscriptStatus: Equatable {
        case idle
        case processing(Int, Int)              // chunk done, total
        case done(speakers: Int, segments: Int)
        case failed(String)
    }

    /// Set in init so `AppDelegate.applicationShouldTerminate` can finalize a
    /// recording in progress before the app quits.
    static weak var shared: SessionController?

    @Published private(set) var state: State = .idle
    @Published private(set) var elapsed: TimeInterval = 0
    @Published private(set) var lastSession: SessionInfo?
    /// Live input peak levels (0…1) while recording, for the UI meters.
    @Published private(set) var micLevel: Float = 0
    @Published private(set) var systemLevel: Float = 0
    /// Surfaced after a session if system audio stopped early.
    @Published private(set) var warning: String?
    /// Mirrored from `CallDetector` for the UI.
    @Published private(set) var detectionStatus: CallDetector.Status = .disabled
    /// Backend transcription status for the last session.
    @Published private(set) var transcriptStatus: TranscriptStatus = .idle

    private let settings: AppSettings
    private var voiceprints: VoiceprintStore
    private let detector = CallDetector()
    private var cancellables = Set<AnyCancellable>()
    private var currentLabel = "manual"
    /// Inputs needed to (re)process the last finished session through the backend.
    private struct ProcessInputs {
        let folder: URL
        let sessionId: String
        let app: String
        let mixedURL: URL
        let selfSpans: [VADSpan]
    }
    private var lastProcess: ProcessInputs?
    private var processTask: Task<Void, Never>?
    private var recorder: AudioRecorder?
    private var currentFolder: URL?
    private var startTime: Date?
    private var timer: Timer?
    /// True when the current session was started by call detection (not the user).
    private var autoStarted = false
    /// Set if a detected call ends while we're still in `.starting`.
    private var pendingAutoStop = false
    /// The in-flight start or stop Task, so `prepareForTermination` can await it.
    private var lifecycleTask: Task<Void, Never>?
    /// Bumped each time a start/stop Task is spawned (Task is a value type, so this
    /// is how `prepareForTermination` detects a newly-spawned transition).
    private var lifecycleGeneration = 0

    init(settings: AppSettings) {
        self.settings = settings
        self.voiceprints = VoiceprintStore(
            fileURL: settings.outputFolderURL.appendingPathComponent("voiceprints.json"))
        SessionController.shared = self

        detector.onCallStart = { [weak self] app in self?.handleCallStart(app) }
        detector.onCallEnd = { [weak self] in self?.handleCallEnd() }
        detector.$status
            .sink { [weak self] status in self?.detectionStatus = status }
            .store(in: &cancellables)
        // Re-point the voiceprint DB if the output folder changes. The in-flight
        // pipeline keeps its own captured reference, so this can't disrupt a run.
        settings.$outputFolderPath
            .dropFirst()
            .sink { [weak self] path in
                guard let self else { return }
                let dir = URL(fileURLWithPath: (path as NSString).expandingTildeInPath, isDirectory: true)
                self.voiceprints = VoiceprintStore(fileURL: dir.appendingPathComponent("voiceprints.json"))
            }
            .store(in: &cancellables)
        settings.$autoRecordOnDetection
            .sink { [weak self] on in
                guard let self else { return }
                if on {
                    self.detector.enable()
                } else {
                    self.detector.disable()
                    // Don't leave an auto-started session running with no detector —
                    // handle both .recording and the in-flight .starting case.
                    if self.autoStarted {
                        switch self.state {
                        case .recording: self.stop()
                        case .starting:  self.pendingAutoStop = true
                        default:         break
                        }
                    }
                }
            }
            .store(in: &cancellables)
    }

    // MARK: - Auto-detection

    private func handleCallStart(_ app: CallDetector.DetectedApp) {
        guard settings.autoRecordOnDetection else { return }
        switch state {
        case .idle, .error: start(label: app.label, auto: true)
        case .starting, .recording, .finishing: break   // don't disturb an active session
        }
    }

    private func handleCallEnd() {
        // Only auto-stop a session we auto-started; never a manual recording.
        guard autoStarted else { return }
        switch state {
        case .recording: stop()
        case .starting:  pendingAutoStop = true   // resolved when start() completes
        case .idle, .error, .finishing: break
        }
    }

    var isBusy: Bool {
        state == .starting || state == .recording || state == .finishing
    }

    func toggle() {
        switch state {
        case .idle, .error: start()
        case .recording: stop()
        case .starting, .finishing: break   // ignore taps mid-transition
        }
    }

    // MARK: - Start / Stop

    private func start(label: String = "manual", auto: Bool = false) {
        let folder: URL
        do {
            folder = try makeSessionFolder(label: label)
        } catch {
            fail("Couldn't create session folder: \(error.localizedDescription)")
            return
        }
        currentFolder = folder
        currentLabel = label
        autoStarted = auto
        pendingAutoStop = false
        let recorder = AudioRecorder(
            micURL: folder.appendingPathComponent("mic.wav"),
            systemURL: folder.appendingPathComponent("system.wav"),
            mixedURL: folder.appendingPathComponent("mixed_mono_16k.wav"))
        self.recorder = recorder
        warning = nil
        state = .starting

        lifecycleGeneration += 1
        lifecycleTask = Task {
            do {
                try await recorder.start()        // self-tears-down if it throws
                self.state = .recording
                self.startTime = Date()
                self.startTimer()
                // A detected call may have ended while we were still starting.
                if self.pendingAutoStop {
                    self.pendingAutoStop = false
                    self.stop()
                }
            } catch {
                self.handleStartFailure(error)
            }
        }
    }

    /// Map a recorder start failure to an actionable message. The common case is
    /// Screen Recording getting re-checked after a rebuild (the SCStream auth
    /// check fails even though CGPreflight reports granted), so re-prompt and open
    /// the right Settings pane rather than show a cryptic TCC error.
    private func handleStartFailure(_ error: Error) {
        let msg = error.localizedDescription.lowercased()
        let screenIssue = msg.contains("declined") || msg.contains("tcc")
            || msg.contains("screen") || msg.contains("permission")
        if screenIssue {
            _ = CGRequestScreenCaptureAccess()
            if let url = URL(string: "x-apple.systempreferences:com.apple.preference.security?Privacy_ScreenCapture") {
                NSWorkspace.shared.open(url)
            }
            fail("Screen Recording needs re-approval for this build. Toggle Ten31Transcripts off then on in System Settings ▸ Screen Recording, then restart the app.")
        } else {
            fail("Couldn't start recording: \(error.localizedDescription)")
        }
    }

    private func stop() {
        guard let recorder else { return }
        state = .finishing
        stopTimer()
        lifecycleGeneration += 1
        lifecycleTask = Task {
            let result = await recorder.stop()
            self.finish(result)
        }
    }

    private func finish(_ result: RecordingResult) {
        recorder = nil
        micLevel = 0
        systemLevel = 0
        warning = result.systemNote.map { "System audio stopped early: \($0)" }
        transcriptStatus = .idle
        if let folder = currentFolder {
            writeSelfSpans(result, to: folder)
            lastSession = SessionInfo(
                folder: folder, mixedURL: result.mixedURL,
                duration: result.duration, selfSpanCount: result.selfSpans.count)
            lastProcess = ProcessInputs(
                folder: folder, sessionId: folder.lastPathComponent, app: currentLabel,
                mixedURL: result.mixedURL, selfSpans: result.selfSpans)
        }
        let autoSend = settings.autoSendOnStop
        currentFolder = nil
        autoStarted = false
        pendingAutoStop = false
        elapsed = 0
        state = .idle
        if autoSend { processLastSession() }
    }

    // MARK: - Backend transcription

    /// Send the last finished session to the backend → `speakers.json`. Uses the
    /// mic-VAD self spans as the timeline for now; visual segments (Phase 3–4) get
    /// merged in once the adapters land. Safe to call manually ("Send to backend")
    /// or automatically on stop.
    func processLastSession() {
        guard let inputs = lastProcess else { return }
        if case .processing = transcriptStatus { return }
        transcriptStatus = .processing(0, 1)

        let settings = self.settings
        let voiceprints = self.voiceprints
        processTask = Task {
            let pipeline = TranscriptPipeline(
                baseURL: settings.backendBaseURL,
                skipTLS: settings.skipTLSVerification,
                voiceprints: voiceprints)
            let timeline = TranscriptPipeline.timeline(
                fromSelfSpans: inputs.selfSpans, selfName: settings.selfName)
            do {
                let speakers = try await pipeline.process(
                    sessionFolder: inputs.folder, sessionId: inputs.sessionId, app: inputs.app,
                    mixedURL: inputs.mixedURL, timeline: timeline,
                    progress: { done, total in
                        await MainActor.run { self.transcriptStatus = .processing(done, total) }
                    })
                self.transcriptStatus = .done(speakers: speakers.speakers.count, segments: speakers.segments.count)
            } catch is CancellationError {
                self.transcriptStatus = .idle
            } catch {
                self.transcriptStatus = .failed(error.localizedDescription)
            }
        }
    }

    private func fail(_ message: String) {
        recorder = nil
        currentFolder = nil
        autoStarted = false
        pendingAutoStop = false
        stopTimer()
        micLevel = 0
        systemLevel = 0
        elapsed = 0
        state = .error(message)
    }

    /// Called from `applicationShouldTerminate`: flush any in-progress session so
    /// its WAV headers are finalized before the process exits. Handles quit while
    /// `.starting` and `.finishing`, not just `.recording`.
    func prepareForTermination() async {
        // Cancel any in-flight backend transcription (audio is already saved; the
        // user can resend). The pipeline's checkCancellation + defer clean up chunks.
        processTask?.cancel()
        // Drain whatever lifecycle Task is in flight until nothing is busy. A Stop
        // click landing in an await window can spawn a new stop Task, so loop
        // rather than awaiting a single captured task.
        while isBusy {
            let gen = lifecycleGeneration
            await lifecycleTask?.value
            if state == .recording, let recorder {
                state = .finishing
                stopTimer()
                finish(await recorder.stop())
            } else if lifecycleGeneration == gen {
                break   // settled: no new transition was spawned
            }
        }
    }

    // MARK: - Timer

    private func startTimer() {
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] _ in
            Task { @MainActor in
                guard let self else { return }
                if let start = self.startTime { self.elapsed = Date().timeIntervalSince(start) }
                if let recorder = self.recorder {
                    let levels = recorder.currentLevels()
                    self.micLevel = levels.mic
                    self.systemLevel = levels.system
                }
            }
        }
    }

    private func stopTimer() {
        timer?.invalidate()
        timer = nil
    }

    // MARK: - Files

    private func makeSessionFolder(label: String) throws -> URL {
        let base = settings.outputFolderURL.appendingPathComponent("sessions", isDirectory: true)
        let folder = base.appendingPathComponent("\(Self.timestamp())_\(label)", isDirectory: true)
        try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
        return folder
    }

    private static func timestamp() -> String {
        let f = DateFormatter()
        f.locale = Locale(identifier: "en_US_POSIX")
        f.dateFormat = "yyyy-MM-dd'T'HH-mm-ss"
        return f.string(from: Date())
    }

    /// Phase-1 preview of the mic-VAD "self" spans (the eventual
    /// `visual_timeline.json` `mic_vad` segments). Lets us eyeball VAD quality.
    private func writeSelfSpans(_ result: RecordingResult, to folder: URL) {
        let segments = result.selfSpans.map { span -> [String: Any] in
            ["start": span.start, "end": span.end, "name": "self",
             "confidence": span.confidence, "source": "mic_vad"]
        }
        let object: [String: Any] = [
            "note": "Phase 1 mic-VAD self spans (preview of visual_timeline segments)",
            "t0_unix": result.t0Unix,
            "duration_sec": result.duration,
            "self_spans": segments,
        ]
        if let data = try? JSONSerialization.data(withJSONObject: object,
                                                  options: [.prettyPrinted, .sortedKeys]) {
            try? data.write(to: folder.appendingPathComponent("self_vad.json"))
        }
    }
}