import AppKit
import Foundation
import AVFoundation
import ScreenCaptureKit
import CoreMedia

final class MeetingRecordingManager: NSObject {
    static let shared = MeetingRecordingManager()

    struct RecordedMeeting: Codable, Equatable, Identifiable {
        let id: String
        let startedAt: Date
        let endedAt: Date
        let sourceURLString: String?
        /// Human-readable title for UI and for the saved file base name (older index entries omit this key).
        let meetingDisplayName: String?
        let audioFilename: String
        /// Apple Speech transcript (timeline text). Omitted in older `index.json` entries.
        let transcriptText: String?
        let transcriptError: String?

        var audioFilenameURLSafe: String { audioFilename }

        var resolvedDisplayTitle: String {
            let raw = meetingDisplayName?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
            return raw.isEmpty ? "Meeting recording" : raw
        }
    }

    enum RecordingError: Error, LocalizedError {
        case alreadyRecording
        case notRecording
        case microphonePermissionDenied
        case noShareableContent
        case systemAudioUnavailable(String)
        case exportFailed
        case micCaptureFailed(String)

        var errorDescription: String? {
            switch self {
            case .alreadyRecording:
                return "A recording is already in progress. Stop it first, then start again."
            case .notRecording:
                return "Nothing is being recorded right now."
            case .microphonePermissionDenied:
                return "Microphone access was denied. Turn it on in System Settings → Privacy & Security → Microphone for this app."
            case .noShareableContent:
                return "Could not access a display for system audio capture."
            case .systemAudioUnavailable(let reason):
                return "System audio capture failed (\(reason)). Microphone-only recording may still work."
            case .exportFailed:
                return "Could not save the recording file. Check free disk space and try again."
            case .micCaptureFailed(let reason):
                return "Microphone recording failed: \(reason)"
            }
        }
    }

    static let recordingsDidChangeNotification = Notification.Name("MeetingRecordingManager.recordingsDidChange")
    static let recordingStateDidChangeNotification = Notification.Name("MeetingRecordingManager.recordingStateDidChange")
    static let transcriptionDidBeginNotification = Notification.Name("MeetingRecordingManager.transcriptionDidBegin")
    static let transcriptionDidEndNotification = Notification.Name("MeetingRecordingManager.transcriptionDidEnd")

    private let encoder: JSONEncoder = {
        let e = JSONEncoder()
        e.outputFormatting = [.prettyPrinted, .sortedKeys]
        e.dateEncodingStrategy = .iso8601
        return e
    }()

    private let decoder: JSONDecoder = {
        let d = JSONDecoder()
        d.dateDecodingStrategy = .iso8601
        return d
    }()

    private(set) var recordings: [RecordedMeeting] = []
    private(set) var isRecording: Bool = false

    private var recordingID: String?
    private var recordingStartedAt: Date?
    private var recordingSourceURLString: String?
    private var pendingMeetingDisplayName: String?

    /// Microphone capture (same approach as meetings_app: `AVAudioRecorder` → AAC `.m4a`).
    private var micRecorder: AVAudioRecorder?

    /// System audio capture (ScreenCaptureKit + `AVAssetWriter` AAC, aligned with meetings_app).
    private var systemAudioRecorder: AnyObject?

    // Output
    private var outputAudioURL: URL?

    private override init() {
        super.init()
        loadRecordingsFromDisk()
    }

    // MARK: - Public API

    func recordingsDirectoryURL() throws -> URL {
        let fm = FileManager.default
        let appSupport = try fm.url(
            for: .applicationSupportDirectory,
            in: .userDomainMask,
            appropriateFor: nil,
            create: true
        )
        // Sandboxed apps: `appSupport` is inside the app container (Finder: ~/Library/Containers/…/Data/Library/Application Support/).
        // Use bundle ID so the folder matches this app (not a generic name).
        let bundleFolder = Bundle.main.bundleIdentifier ?? "zoom_app"
        let dir = appSupport.appendingPathComponent(bundleFolder, isDirectory: true)
            .appendingPathComponent("Recordings", isDirectory: true)
        if fm.fileExists(atPath: dir.path) == false {
            try fm.createDirectory(at: dir, withIntermediateDirectories: true)
        }
        return dir
    }

    func audioURL(for recording: RecordedMeeting) throws -> URL {
        try recordingsDirectoryURL().appendingPathComponent(recording.audioFilename)
    }

    /// Full path to the Recordings folder (sandboxed apps: inside `~/Library/Containers/…/Data/Library/Application Support/`).
    var recordingsDirectoryPath: String {
        (try? recordingsDirectoryURL().path) ?? ""
    }

    func revealRecordingsInFinder() {
        guard let url = try? recordingsDirectoryURL() else { return }
        NSWorkspace.shared.open(url)
    }

    func startRecording(sourceURL: URL?, meetingDisplayName: String? = nil) async throws {
        if isRecording { throw RecordingError.alreadyRecording }

        let micGranted = await AVCaptureDevice.requestAccess(for: .audio)
        if micGranted == false { throw RecordingError.microphonePermissionDenied }

        let id = UUID().uuidString
        let startedAt = Date()
        let dir = try recordingsDirectoryURL()

        let micURL = dir.appendingPathComponent("\(id)-mic.m4a")
        let sysURL = dir.appendingPathComponent("\(id)-system.m4a")
        let displayTitle = Self.resolvedMeetingTitle(explicit: meetingDisplayName, sourceURL: sourceURL)
        let outBase = Self.uniqueSanitizedFileURL(directory: dir, baseName: displayTitle, idSuffix: id, extension: "m4a")

        recordingID = id
        recordingStartedAt = startedAt
        recordingSourceURLString = sourceURL?.absoluteString
        pendingMeetingDisplayName = displayTitle
        outputAudioURL = outBase

        do {
            try startMicRecorder(to: micURL)
            if #available(macOS 13.0, *) {
                let recorder = ZoomMeetingSystemAudioRecorder(outputURL: sysURL)
                systemAudioRecorder = recorder
                do {
                    try await recorder.start()
                } catch {
                    systemAudioRecorder = nil
                }
            } else {
                systemAudioRecorder = nil
            }
        } catch {
            stopMicRecorder()
            if #available(macOS 13.0, *), let r = systemAudioRecorder as? ZoomMeetingSystemAudioRecorder {
                try? await r.stop()
            }
            systemAudioRecorder = nil
            recordingID = nil
            recordingStartedAt = nil
            recordingSourceURLString = nil
            pendingMeetingDisplayName = nil
            outputAudioURL = nil
            throw error
        }

        isRecording = true
        NotificationCenter.default.post(name: Self.recordingStateDidChangeNotification, object: self)
    }

    func stopRecording() async throws {
        guard isRecording else { throw RecordingError.notRecording }
        guard let id = recordingID, let startedAt = recordingStartedAt, let outURL = outputAudioURL else {
            throw RecordingError.exportFailed
        }

        let endedAt = Date()
        let dir = try recordingsDirectoryURL()
        let micURL = dir.appendingPathComponent("\(id)-mic.m4a")
        let sysURL = dir.appendingPathComponent("\(id)-system.m4a")

        stopMicRecorder()
        if #available(macOS 13.0, *), let r = systemAudioRecorder as? ZoomMeetingSystemAudioRecorder {
            try? await r.stop()
        }
        systemAudioRecorder = nil

        let mixedURL = try await finalizeMeetingAudio(systemURL: sysURL, microphoneURL: micURL, outputURL: outURL)

        // Cleanup intermediates (ignore failures).
        try? FileManager.default.removeItem(at: micURL)
        try? FileManager.default.removeItem(at: sysURL)

        let displayName = pendingMeetingDisplayName
        let rec = RecordedMeeting(
            id: id,
            startedAt: startedAt,
            endedAt: endedAt,
            sourceURLString: recordingSourceURLString,
            meetingDisplayName: displayName,
            audioFilename: mixedURL.lastPathComponent,
            transcriptText: nil,
            transcriptError: nil
        )
        recordings.insert(rec, at: 0)
        saveRecordingsToDisk()
        scheduleAppleTranscription(for: rec)

        recordingID = nil
        recordingStartedAt = nil
        recordingSourceURLString = nil
        pendingMeetingDisplayName = nil
        outputAudioURL = nil

        isRecording = false
        NotificationCenter.default.post(name: Self.recordingStateDidChangeNotification, object: self)
        NotificationCenter.default.post(name: Self.recordingsDidChangeNotification, object: self)
    }

    // MARK: - Persistence

    private func indexURL() throws -> URL {
        try recordingsDirectoryURL().appendingPathComponent("index.json")
    }

    private func loadRecordingsFromDisk() {
        do {
            let url = try indexURL()
            guard FileManager.default.fileExists(atPath: url.path) else { return }
            let data = try Data(contentsOf: url)
            recordings = try decoder.decode([RecordedMeeting].self, from: data)
        } catch {
            recordings = []
        }
    }

    /// Runs Apple Speech on the saved mixed audio; updates `recordings` and posts `recordingsDidChangeNotification` when finished.
    private func scheduleAppleTranscription(for recording: RecordedMeeting) {
        let recordingId = recording.id
        let filename = recording.audioFilename
        let locales = TranscriptionLanguagePreferences.localesForAppleTranscription()
        Task {
            await performAppleTranscription(recordingId: recordingId, audioFilename: filename, locales: locales)
        }
    }

    private func performAppleTranscription(recordingId: String, audioFilename: String, locales: [Locale]) async {
        NotificationCenter.default.post(
            name: Self.transcriptionDidBeginNotification,
            object: self,
            userInfo: ["recordingId": recordingId]
        )
        defer {
            NotificationCenter.default.post(
                name: Self.transcriptionDidEndNotification,
                object: self,
                userInfo: ["recordingId": recordingId]
            )
        }

        let service = MeetingTranscriptionService()
        do {
            let dir = try recordingsDirectoryURL()
            let audioURL = dir.appendingPathComponent(audioFilename)
            let segments = try await service.transcribeMeeting(micURL: audioURL, systemURL: nil, locales: locales)
            let text = segments.renderedTimelineText()
            await MainActor.run {
                applyTranscript(recordingId: recordingId, text: text.isEmpty ? nil : text, error: nil)
            }
        } catch {
            await MainActor.run {
                applyTranscript(recordingId: recordingId, text: nil, error: error.localizedDescription)
            }
        }
    }

    private func applyTranscript(recordingId: String, text: String?, error: String?) {
        guard let idx = recordings.firstIndex(where: { $0.id == recordingId }) else { return }
        let old = recordings[idx]
        let updated = RecordedMeeting(
            id: old.id,
            startedAt: old.startedAt,
            endedAt: old.endedAt,
            sourceURLString: old.sourceURLString,
            meetingDisplayName: old.meetingDisplayName,
            audioFilename: old.audioFilename,
            transcriptText: text,
            transcriptError: error
        )
        recordings[idx] = updated
        saveRecordingsToDisk()
        NotificationCenter.default.post(name: Self.recordingsDidChangeNotification, object: self)
    }

    private func saveRecordingsToDisk() {
        do {
            let url = try indexURL()
            let data = try encoder.encode(recordings)
            try data.write(to: url, options: [.atomic])
        } catch {
            NSLog("MeetingRecordingManager: failed to save index.json — \(error.localizedDescription)")
        }
    }

    // MARK: - Mic capture (meetings_app-style)

    private func startMicRecorder(to outputURL: URL) throws {
        try? FileManager.default.removeItem(at: outputURL)
        let settings: [String: Any] = [
            AVFormatIDKey: kAudioFormatMPEG4AAC,
            AVSampleRateKey: 48_000,
            AVNumberOfChannelsKey: 1,
            AVEncoderBitRateKey: 128_000,
            AVEncoderAudioQualityKey: AVAudioQuality.max.rawValue
        ]
        let recorder = try AVAudioRecorder(url: outputURL, settings: settings)
        recorder.prepareToRecord()
        guard recorder.record() else {
            throw RecordingError.micCaptureFailed("AVAudioRecorder could not start.")
        }
        micRecorder = recorder
    }

    private func stopMicRecorder() {
        micRecorder?.stop()
        micRecorder = nil
    }

    // MARK: - Finalize / mix (meetings_app-style)

    private func fileSize(at url: URL) -> Int64 {
        let attrs = try? FileManager.default.attributesOfItem(atPath: url.path)
        return attrs?[.size] as? Int64 ?? 0
    }

    private func hasAudioPayload(at url: URL, minBytes: Int64 = 10_000) -> Bool {
        guard FileManager.default.fileExists(atPath: url.path) else { return false }
        return fileSize(at: url) >= minBytes
    }

    private func finalizeMeetingAudio(systemURL: URL, microphoneURL: URL, outputURL: URL) async throws -> URL {
        let fm = FileManager.default
        if fm.fileExists(atPath: outputURL.path) {
            try? fm.removeItem(at: outputURL)
        }

        let hasSystem = hasAudioPayload(at: systemURL)
        let hasMic = hasAudioPayload(at: microphoneURL)

        if hasSystem && hasMic {
            do {
                try await mixAudioFiles(systemURL: systemURL, microphoneURL: microphoneURL, destinationURL: outputURL)
                return outputURL
            } catch {
                // Fall through to single-track handling.
            }
        }

        let chosenURL: URL?
        if hasSystem {
            chosenURL = systemURL
        } else if hasMic {
            chosenURL = microphoneURL
        } else {
            chosenURL = nil
        }

        guard let chosenURL else {
            throw RecordingError.exportFailed
        }

        if chosenURL.path != outputURL.path {
            try? fm.removeItem(at: outputURL)
            do {
                try fm.copyItem(at: chosenURL, to: outputURL)
            } catch {
                return chosenURL
            }
        }
        return outputURL
    }

    private func mixAudioFiles(systemURL: URL, microphoneURL: URL, destinationURL: URL) async throws {
        try? FileManager.default.removeItem(at: destinationURL)

        let composition = AVMutableComposition()
        guard let systemTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid),
              let micTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid) else {
            throw RecordingError.exportFailed
        }

        let systemAsset = AVURLAsset(url: systemURL)
        let micAsset = AVURLAsset(url: microphoneURL)

        if let src = systemAsset.tracks(withMediaType: .audio).first {
            let duration = systemAsset.duration
            if duration.isValid && !duration.isIndefinite && duration.seconds > 0 {
                try systemTrack.insertTimeRange(CMTimeRange(start: .zero, duration: duration), of: src, at: .zero)
            }
        }
        if let src = micAsset.tracks(withMediaType: .audio).first {
            let duration = micAsset.duration
            if duration.isValid && !duration.isIndefinite && duration.seconds > 0 {
                try micTrack.insertTimeRange(CMTimeRange(start: .zero, duration: duration), of: src, at: .zero)
            }
        }

        guard let export = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A) else {
            throw RecordingError.exportFailed
        }

        let systemMix = AVMutableAudioMixInputParameters(track: systemTrack)
        systemMix.setVolume(1.0, at: .zero)
        let micMix = AVMutableAudioMixInputParameters(track: micTrack)
        micMix.setVolume(1.35, at: .zero)
        let audioMix = AVMutableAudioMix()
        audioMix.inputParameters = [systemMix, micMix]

        export.outputURL = destinationURL
        export.outputFileType = .m4a
        export.audioMix = audioMix
        await withCheckedContinuation { continuation in
            export.exportAsynchronously {
                continuation.resume()
            }
        }
        if export.status != .completed {
            throw export.error ?? RecordingError.exportFailed
        }
    }

    // MARK: - Meeting title + filenames

    /// Trimmed explicit name from the join sheet, otherwise a stable label from the Zoom URL (meeting id, instant meeting, etc.).
    static func resolvedMeetingTitle(explicit: String?, sourceURL: URL?) -> String {
        if let t = explicit?.trimmingCharacters(in: .whitespacesAndNewlines), t.isEmpty == false {
            return t
        }
        if let url = sourceURL {
            return derivedDisplayTitle(from: url)
        }
        return "Zoom meeting"
    }

    static func derivedDisplayTitle(from url: URL) -> String {
        let path = url.path.lowercased()
        if path.contains("/start/") || path.contains("videomeeting") {
            return "Instant meeting"
        }
        let parts = url.path.split(separator: "/").map(String.init)
        for (i, segment) in parts.enumerated() {
            let s = segment.lowercased()
            if (s == "j" || s == "join" || s == "wc" || s == "my") && i + 1 < parts.count {
                let next = parts[i + 1].filter(\.isNumber)
                if next.count >= 9 { return "Meeting \(next)" }
            }
        }
        if let last = parts.last {
            let digits = last.filter(\.isNumber)
            if digits.count >= 9 { return "Meeting \(digits)" }
        }
        return "Zoom meeting"
    }

    /// Safe file base: filesystem-safe, bounded length, then made unique in `directory` if needed.
    static func uniqueSanitizedFileURL(directory: URL, baseName: String, idSuffix: String, extension ext: String) -> URL {
        let sanitized = sanitizeFileBaseName(baseName)
        let shortID = String(idSuffix.replacingOccurrences(of: "-", with: "").prefix(8))
        let fm = FileManager.default
        for attempt in 0..<50 {
            let suffix = attempt == 0 ? "" : "_\(attempt)"
            let name = "\(sanitized)_\(shortID)\(suffix).\(ext)"
            let url = directory.appendingPathComponent(name)
            if fm.fileExists(atPath: url.path) == false {
                return url
            }
        }
        return directory.appendingPathComponent("\(sanitized)_\(shortID)_\(UUID().uuidString.prefix(8)).\(ext)")
    }

    private static func sanitizeFileBaseName(_ raw: String) -> String {
        let trimmed = raw.trimmingCharacters(in: .whitespacesAndNewlines)
        let collapsed = trimmed.replacingOccurrences(of: "\\s+", with: " ", options: .regularExpression)
        let invalid = CharacterSet(charactersIn: "/:\\?%*|\"<>")
        let cleaned = collapsed.unicodeScalars.map { invalid.contains($0) ? "_" : Character($0) }
        let joined = String(cleaned).trimmingCharacters(in: CharacterSet(charactersIn: " ._"))
        let base = joined.isEmpty ? "Zoom_meeting" : joined
        let maxLen = 72
        if base.count <= maxLen { return base }
        let idx = base.index(base.startIndex, offsetBy: maxLen)
        return String(base[..<idx]).trimmingCharacters(in: CharacterSet(charactersIn: " ._"))
    }
}

// MARK: - System audio (meetings_app-style)

@available(macOS 13.0, *)
private final class ZoomMeetingSystemAudioRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
    private let outputURL: URL
    private var stream: SCStream?
    private var writer: AVAssetWriter?
    private var writerInput: AVAssetWriterInput?
    private let outputQueue = DispatchQueue(label: "zoom_app.system.audio.capture")
    private var didStartSession = false

    init(outputURL: URL) {
        self.outputURL = outputURL
    }

    func start() async throws {
        try? FileManager.default.removeItem(at: outputURL)
        let content = try await SCShareableContent.excludingDesktopWindows(false, onScreenWindowsOnly: true)
        guard let display = content.displays.first else {
            throw MeetingRecordingManager.RecordingError.noShareableContent
        }

        let writer = try AVAssetWriter(outputURL: outputURL, fileType: .m4a)
        let inputSettings: [String: Any] = [
            AVFormatIDKey: kAudioFormatMPEG4AAC,
            AVSampleRateKey: 48_000,
            AVNumberOfChannelsKey: 2,
            AVEncoderBitRateKey: 128_000
        ]
        let input = AVAssetWriterInput(mediaType: .audio, outputSettings: inputSettings)
        input.expectsMediaDataInRealTime = true
        guard writer.canAdd(input) else {
            throw MeetingRecordingManager.RecordingError.systemAudioUnavailable("Cannot add audio writer input.")
        }
        writer.add(input)
        self.writer = writer
        self.writerInput = input
        didStartSession = false

        let filter = SCContentFilter(display: display, excludingApplications: [], exceptingWindows: [])
        let config = SCStreamConfiguration()
        config.width = 2
        config.height = 2
        config.minimumFrameInterval = CMTime(value: 1, timescale: 2)
        config.queueDepth = 1
        config.capturesAudio = true
        config.sampleRate = 48_000
        config.channelCount = 2
        config.excludesCurrentProcessAudio = true

        let stream = SCStream(filter: filter, configuration: config, delegate: self)
        self.stream = stream
        try stream.addStreamOutput(self, type: .audio, sampleHandlerQueue: outputQueue)
        try await stream.startCapture()
    }

    func stop() async throws {
        if let stream {
            try? await stream.stopCapture()
            self.stream = nil
        }
        writerInput?.markAsFinished()
        guard let writer else { return }
        await withCheckedContinuation { continuation in
            writer.finishWriting {
                continuation.resume()
            }
        }
        self.writer = nil
        self.writerInput = nil
    }

    func stream(_ stream: SCStream, didStopWithError error: Error) {
        // Capture may stop on permission changes or display changes; caller handles lifecycle.
    }

    func stream(_ stream: SCStream, didOutputSampleBuffer sampleBuffer: CMSampleBuffer, of outputType: SCStreamOutputType) {
        guard outputType == .audio else { return }
        guard CMSampleBufferDataIsReady(sampleBuffer) else { return }
        guard let writer = writer, let input = writerInput else { return }

        if writer.status == .unknown {
            writer.startWriting()
        }
        if writer.status == .writing {
            let pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
            if !didStartSession {
                writer.startSession(atSourceTime: pts)
                didStartSession = true
            }
            if input.isReadyForMoreMediaData {
                input.append(sampleBuffer)
            }
        }
    }
}