import AudioMatrix
import AVFoundation
import Foundation
import MusubiCore
import NDIKit
import Observation

/// App-side glue for the audio matrix: NDI audio receivers, meters, talk key and stats.
@MainActor @Observable
final class AudioController {
    let matrix = AudioMatrix()
    let talkKey = TalkKey()

    /// Smoothed peak meters in dBFS (route ID → level), updated 20× per second.
    private(set) var meters: [UUID: Float] = [:]
    private(set) var channelMeters: [String: Float] = [:] // "<deviceUID>#<channel>"
    private(set) var dropouts: [UUID: Int] = [:]
    /// Highest peak per route since the last stats line.
    private(set) var minutePeaks: [UUID: Float] = [:]
    var selectedDeviceUID: String?

    private var ndiReceivers: [String: NDIReceiver] = [:]
    private var meterTimer: Timer?
    private var diagnosticsTimer: Timer?
    private let recorder = AudioStatsRecorder()

    init() {
        selectedDeviceUID = Self.preferredOutput(in: matrix.outputDevices)?.uid
        talkKey.onChange = { [weak self] active in self?.matrix.talkActive = active }
        talkKey.register()
        meterTimer = Timer.scheduledTimer(withTimeInterval: 0.05, repeats: true) { [weak self] _ in
            MainActor.assumeIsolated { self?.updateMeters() }
        }
        diagnosticsTimer = Timer.scheduledTimer(withTimeInterval: 10, repeats: true) { [weak self] _ in
            MainActor.assumeIsolated { self?.logDiagnostics() }
        }
    }

    var selectedDevice: AudioDevice? {
        matrix.outputDevices.first { $0.uid == selectedDeviceUID } ?? Self.preferredOutput(in: matrix.outputDevices)
    }

    func add(_ source: AudioMatrix.SourceRef, channel: Int) {
        guard let device = selectedDevice else { return }
        if case .input = source {
            AVCaptureDevice.requestAccess(for: .audio) { _ in }
        }
        matrix.addRoute(source, deviceUID: device.uid, channel: channel)
        syncNDIReceivers()
    }

    func remove(_ id: UUID) {
        matrix.removeRoute(id)
        syncNDIReceivers()
    }

    func label(for source: AudioMatrix.SourceRef) -> String {
        switch source {
        case .ndi(let name): Source.defaultLabel(for: name)
        case .input(let uid): matrix.devices.first { $0.uid == uid }?.name ?? uid
        }
    }

    /// One audio-only NDI receiver per NDI source that has routes.
    private func syncNDIReceivers() {
        let wanted = Set(matrix.ndiFanouts.keys)
        for name in ndiReceivers.keys where !wanted.contains(name) {
            ndiReceivers.removeValue(forKey: name)?.stop()
        }
        for name in wanted where ndiReceivers[name] == nil {
            guard let fanout = matrix.ndiFanouts[name] else { continue }
            ndiReceivers[name] = NDIReceiver(
                source: Source(ndiName: name), receiverName: "Musubi Ton", bandwidth: .audioOnly,
                onAudio: { chunk in
                    fanout.push(planar: chunk.data, channelStride: chunk.channelStride, channels: chunk.channels,
                                frames: chunk.frames, sampleRate: chunk.sampleRate)
                }
            )
            Log.audio.info("NDI audio receiver for \(name, privacy: .public)")
        }
    }

    private func updateMeters() {
        let fall: Float = 1.2 // dB per tick
        for route in matrix.routes {
            let peak = matrix.takePeak(route.id)
            meters[route.id] = max(peak, (meters[route.id] ?? Level.floorDB) - fall)
            minutePeaks[route.id] = max(peak, minutePeaks[route.id] ?? Level.floorDB)
            dropouts[route.id] = matrix.dropouts(route.id)
        }
        meters = meters.filter { id, _ in matrix.routes.contains { $0.id == id } }
        if let device = selectedDevice {
            for channel in 0..<device.outputChannels {
                let key = "\(device.uid)#\(channel)"
                let peak = matrix.takeChannelPeak(deviceUID: device.uid, channel: channel)
                channelMeters[key] = max(peak, (channelMeters[key] ?? Level.floorDB) - fall)
            }
        }
        recorder.recordIfDue(controller: self)
    }

    private func logDiagnostics() {
        for route in matrix.routes {
            guard let d = matrix.diagnostics(route.id) else { continue }
            Log.audio.info("\(self.label(for: route.source), privacy: .public): buffered \(d.bufferedFrames) underruns \(d.underruns) overruns \(d.overruns) correction \(String(format: "%+.0f ppm", d.correction * 1_000_000), privacy: .public)")
        }
    }

    func resetMinutePeaks() {
        minutePeaks.removeAll()
    }

    /// Applies `--audio-route` launch arguments.
    func applyLaunchRoutes(_ arguments: [String] = ProcessInfo.processInfo.arguments) {
        for route in AudioRouteArgument.parse(arguments) {
            guard let device = matrix.outputDevices.first(where: { $0.name.localizedCaseInsensitiveContains(route.device) }),
                  route.channel <= device.outputChannels
            else {
                Log.audio.error("--audio-route: no output \(route.device, privacy: .public) with channel \(route.channel)")
                continue
            }
            let source: AudioMatrix.SourceRef
            switch route.kind {
            case .ndi:
                source = .ndi(name: route.source)
            case .input:
                guard let input = matrix.inputDevices.first(where: { $0.name.localizedCaseInsensitiveContains(route.source) }) else {
                    Log.audio.error("--audio-route: no input \(route.source, privacy: .public)")
                    continue
                }
                source = .input(deviceUID: input.uid)
            }
            selectedDeviceUID = device.uid
            add(source, channel: route.channel - 1)
        }
    }

    func ndiAudioInfo(_ name: String) -> NDIReceiver.Snapshot? {
        ndiReceivers[name]?.snapshot
    }

    /// MOTU first, then any multi-channel interface, then the system default.
    private static func preferredOutput(in devices: [AudioDevice]) -> AudioDevice? {
        devices.first { $0.name.localizedCaseInsensitiveContains("MOTU") || $0.name.localizedCaseInsensitiveContains("M2") }
            ?? devices.first { $0.name.localizedCaseInsensitiveContains("USB") }
            ?? devices.first
    }
}

/// Appends one CSV line per audio route and minute to ~/Library/Logs/Musubi/audio-<date>.csv.
@MainActor
final class AudioStatsRecorder {
    private var lastWrite = Date()
    private let directory = FileManager.default.homeDirectoryForCurrentUser.appending(path: "Library/Logs/Musubi")

    func recordIfDue(controller: AudioController) {
        let now = Date()
        guard now.timeIntervalSince(lastWrite) >= 60 else { return }
        lastWrite = now
        let routes = controller.matrix.routes
        guard !routes.isEmpty else { return }

        var lines = ""
        for route in routes {
            let source: String = switch route.source {
            case .ndi(let name): "ndi:\(name)"
            case .input(let uid): "input:\(uid)"
            }
            var rate = 0
            if case .ndi(let name) = route.source { rate = controller.ndiAudioInfo(name)?.audioSampleRate ?? 0 }
            let peak = controller.minutePeaks[route.id] ?? Level.floorDB
            lines += "\(now.ISO8601Format()),\"\(source)\",\"\(route.deviceUID)\",\(route.channel + 1),\(rate),\(controller.dropouts[route.id] ?? 0),\(String(format: "%.1f", peak)),\(route.gainDB),\(route.muted)\n"
        }
        controller.resetMinutePeaks()
        let file = directory.appending(path: "audio-\(now.formatted(.iso8601.year().month().day())).csv")
        do {
            try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
            if !FileManager.default.fileExists(atPath: file.path) {
                try "time,source,device,channel,source_rate,dropouts,peak_dbfs,gain_db,muted\n".write(to: file, atomically: true, encoding: .utf8)
            }
            let handle = try FileHandle(forWritingTo: file)
            defer { try? handle.close() }
            try handle.seekToEnd()
            try handle.write(contentsOf: Data(lines.utf8))
        } catch {
            Log.audio.error("Audio CSV: \(error.localizedDescription, privacy: .public)")
        }
    }
}