import Foundation
#if canImport(FoundationNetworking)
import FoundationNetworking
#endif
import ForgeCamera
import ForgeGrade
import ForgeColor

/// ARRI REST endpoint paths — single source of truth for this driver.
/// NOTE: shapes modeled on ARRI's documented Camera Companion/REST API family;
/// verify + correct against hardware/API docs in macOS phase. Sim mirrors these.
enum ArriPaths {
    static let systemInfo = "/api/v1/system/info"
    static let recordingStatus = "/api/v1/recording/status"
    static let metadata = "/api/v1/camera/metadata"
    static let lookCurrent = "/api/v1/look/current"
}

/// ALEXA 35 driver: REST over IP. Polls rec state + metadata, pushes CDL+LUT looks.
public actor ArriDriver: CameraDriver {
    public nonisolated let capabilities = CameraCapabilities(
        vendor: .arri,
        supportsNativeCDL: true,
        lut3dSizes: [17, 33, 65],
        metadataFields: [.clipName, .exposureIndex, .whiteBalance, .tint, .fps, .timecode])

    private let host: String
    private let port: Int
    private let pollInterval: Duration
    private let session: URLSession

    private var pollTask: Task<Void, Never>?
    private var lastState = CameraState(connection: .disconnected)

    private var stateContinuations: [UUID: AsyncStream<CameraState>.Continuation] = [:]

    public init(host: String, port: Int, pollInterval: Duration = .milliseconds(150)) {
        self.host = host
        self.port = port
        self.pollInterval = pollInterval
        let config = URLSessionConfiguration.ephemeral
        config.timeoutIntervalForRequest = 3
        session = URLSession(configuration: config)
    }

    public nonisolated var state: AsyncStream<CameraState> {
        AsyncStream { continuation in
            let id = UUID()
            Task { await self.register(id: id, continuation: continuation) }
            continuation.onTermination = { _ in
                Task { await self.unregister(id: id) }
            }
        }
    }

    private func register(id: UUID, continuation: AsyncStream<CameraState>.Continuation) {
        stateContinuations[id] = continuation
    }

    private func unregister(id: UUID) {
        stateContinuations.removeValue(forKey: id)
    }

    private func emit(_ s: CameraState) {
        lastState = s
        for c in stateContinuations.values {
            c.yield(s)
        }
    }

    // MARK: HTTP

    private func url(_ path: String) -> URL {
        URL(string: "http://\(host):\(port)\(path)")!
    }

    /// Completion-handler dataTask wrapped in a continuation. The async
    /// URLSession API hangs intermittently on Linux (dead-connection reuse);
    /// the completion path always fires — success, error, or timeout.
    private func perform(_ req: URLRequest) async throws -> (Data, HTTPURLResponse) {
        try await withCheckedThrowingContinuation { cont in
            let task = session.dataTask(with: req) { data, resp, err in
                if let err {
                    cont.resume(throwing: err)
                    return
                }
                guard let http = resp as? HTTPURLResponse else {
                    cont.resume(throwing: CameraError.connectionFailed("no HTTP response"))
                    return
                }
                cont.resume(returning: (data ?? Data(), http))
            }
            task.resume()
        }
    }

    private func getJSON(_ path: String) async throws -> [String: Any] {
        let (data, http) = try await perform(URLRequest(url: url(path)))
        guard http.statusCode == 200 else {
            throw CameraError.connectionFailed("GET \(path) -> \(http.statusCode)")
        }
        guard let obj = try JSONSerialization.jsonObject(with: data) as? [String: Any] else {
            throw CameraError.connectionFailed("GET \(path): bad JSON")
        }
        return obj
    }

    private func putJSON(_ path: String, body: Data) async throws {
        var req = URLRequest(url: url(path))
        req.httpMethod = "PUT"
        req.httpBody = body
        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
        let (_, http) = try await perform(req)
        guard http.statusCode == 200 else {
            throw CameraError.pushFailed("PUT \(path) -> \(http.statusCode)")
        }
    }

    // MARK: CameraDriver

    public func connect() async throws {
        // Verify camera reachable via system info.
        do {
            _ = try await getJSON(ArriPaths.systemInfo)
        } catch {
            throw CameraError.connectionFailed("system info unreachable: \(error)")
        }
        emit(CameraState(connection: .connected))
        startPolling()
    }

    public func disconnect() async {
        pollTask?.cancel()
        pollTask = nil
        emit(CameraState(connection: .disconnected))
    }

    public func push(look: FlattenedLook) async throws {
        if let lut = look.lut, !capabilities.lut3dSizes.contains(lut.size) {
            throw CameraError.unsupportedLook("LUT size \(lut.size) not in \(capabilities.lut3dSizes)")
        }
        var payload: [String: Any] = [:]
        if let cdl = look.cdl {
            payload["cdl"] = [
                "slope": [cdl.slope.x, cdl.slope.y, cdl.slope.z],
                "offset": [cdl.offset.x, cdl.offset.y, cdl.offset.z],
                "power": [cdl.power.x, cdl.power.y, cdl.power.z],
                "saturation": cdl.saturation,
            ]
        }
        if let lut = look.lut {
            payload["lut3dSize"] = lut.size
            payload["lut3dTable"] = lut.table
        }
        let body = try JSONSerialization.data(withJSONObject: payload, options: [.sortedKeys])
        try await putJSON(ArriPaths.lookCurrent, body: body)
    }

    // MARK: Polling

    private func startPolling() {
        pollTask?.cancel()
        pollTask = Task {
            while !Task.isCancelled {
                await pollOnce()
                try? await Task.sleep(for: pollInterval)
            }
        }
    }

    private func pollOnce() async {
        do {
            let rec = try await getJSON(ArriPaths.recordingStatus)
            let md = try await getJSON(ArriPaths.metadata)
            let newState = CameraState(
                connection: .connected,
                isRecording: rec["recording"] as? Bool ?? false,
                clipName: rec["clipName"] as? String,
                metadata: CameraMetadata(
                    exposureIndex: md["exposureIndex"] as? Int,
                    whiteBalance: md["whiteBalance"] as? Int,
                    tint: md["tint"] as? Int,
                    fps: md["fps"] as? Double,
                    timecode: md["timecode"] as? String))
            if newState != lastState {
                emit(newState)
            }
        } catch {
            if lastState.connection == .connected {
                emit(CameraState(connection: .disconnected))
            }
        }
    }
}