import Flutter
import UIKit
import AVFoundation

public class VideoDecodePlugin: NSObject, FlutterPlugin, FlutterTexture {
    private var channel: FlutterMethodChannel?
    private var registrar: FlutterPluginRegistrar?
    private var decoder: VideoDecoder?
    private var textureId: Int64?
    private var textureRegistry: FlutterTextureRegistry?
    private var latestPixelBuffer: CVPixelBuffer?
    private let textureQueue = DispatchQueue(label: "video_decode_plugin.texture.queue")
    private var cachedSps: Data?
    private var cachedPps: Data?
    private var hasNotifiedFlutter = false

    public static func register(with registrar: FlutterPluginRegistrar) {
        let channel = FlutterMethodChannel(name: "video_decode_plugin", binaryMessenger: registrar.messenger())
        let instance = VideoDecodePlugin()
        instance.channel = channel
        instance.registrar = registrar
        instance.textureRegistry = registrar.textures()
        registrar.addMethodCallDelegate(instance, channel: channel)
    }

    public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        switch call.method {
        case "initDecoder":
            handleInitDecoder(call: call, result: result)
        case "decodeFrame":
            handleDecodeFrame(call: call, result: result)
        case "releaseDecoder":
            handleReleaseDecoder(call: call, result: result)
        default:
            result(FlutterMethodNotImplemented)
        }
    }

    /// 初始化解码器
    private func handleInitDecoder(call: FlutterMethodCall, result: @escaping FlutterResult) {
        guard let args = call.arguments as? [String: Any],
              let width = args["width"] as? Int,
              let height = args["height"] as? Int,
              let codecType = args["codecType"] as? String else {
            result(FlutterError(code: "INVALID_ARGS", message: "参数错误", details: nil))
            return
        }
        // 释放旧解码器和纹理
        decoder?.release()
        decoder = nil
        if let tid = textureId {
            textureRegistry?.unregisterTexture(tid)
            textureId = nil
        }
        // 注册Flutter纹理
        guard let registry = textureRegistry else {
            result(FlutterError(code: "NO_TEXTURE_REGISTRY", message: "无法获取纹理注册表", details: nil))
            return
        }
        let textureId = registry.register(self)
        self.textureId = textureId
        // 创建解码器
        let decoder = VideoDecoder(width: width, height: height, codecType: codecType)
        self.decoder = decoder
        decoder.onFrameDecoded = { [weak self] pixelBuffer, _ in
            guard let self = self else { return }
            self.textureQueue.async {
                self.latestPixelBuffer = pixelBuffer
                self.textureRegistry?.textureFrameAvailable(self.textureId ?? 0)
                if !self.hasNotifiedFlutter {
                    self.hasNotifiedFlutter = true
                    DispatchQueue.main.async {
                        self.channel?.invokeMethod("onFrameRendered", arguments: ["textureId": self.textureId ?? 0])
                    }
                }
            }
        }
        print("[VideoDecodePlugin] 解码器初始化成功，textureId=\(textureId)")
        result(textureId)
    }

    /// 新增：去除NALU起始码的工具方法（增强日志与健壮性）
    private func stripStartCode(_ data: Data) -> Data {
        let originalLen = data.count
        let naluType: UInt8 = {
            if data.count > 4 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x00 && data[3] == 0x01 {
                return data[4] & 0x1F
            } else if data.count > 3 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x01 {
                return data[3] & 0x1F
            }
            return 0
        }()
        var stripped: Data = data
        if data.count > 4 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x00 && data[3] == 0x01 {
            stripped = data.subdata(in: 4..<data.count)
        } else if data.count > 3 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x01 {
            stripped = data.subdata(in: 3..<data.count)
        }
        let strippedLen = stripped.count
        let strippedType: UInt8 = stripped.count > 0 ? (stripped[0] & 0x1F) : 0
        if strippedLen < 3 || (strippedType != 7 && strippedType != 8) {
            print("[VideoDecodePlugin][警告] strip后NALU长度或类型异常，type=", strippedType, "len=", strippedLen)
        }
        // 只在异常时输出警告，不再输出详细内容
        return stripped
    }

    /// 解码视频帧
    private func handleDecodeFrame(call: FlutterMethodCall, result: @escaping FlutterResult) {
        guard let args = call.arguments as? [String: Any],
              let frameData = args["frameData"] as? FlutterStandardTypedData,
              let frameType = args["frameType"] as? Int,
              let timestamp = args["timestamp"] as? Int,
              let frameSeq = args["frameSeq"] as? Int else {
            result(FlutterError(code: "INVALID_ARGS", message: "参数错误", details: nil))
            return
        }
        let refIFrameSeq = args["refIFrameSeq"] as? Int
        let data = frameData.data

        // 解析NALU类型
        let naluType: UInt8 = {
            if data.count > 4 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x00 && data[3] == 0x01 {
                return data[4] & 0x1F
            } else if data.count > 3 && data[0] == 0x00 && data[1] == 0x00 && data[2] == 0x01 {
                return data[3] & 0x1F
            }
            return 0
        }()

        print("[VideoDecodePlugin][调试] handleDecodeFrame: frameType=\(frameType), naluType=\(naluType), cachedSpsLen=\(cachedSps?.count ?? 0), cachedPpsLen=\(cachedPps?.count ?? 0)")

        // 缓存SPS/PPS（去除起始码）并立即尝试初始化解码器
        if naluType == 7 { // SPS
            // 只缓存，不再输出详细日志
            cachedSps = stripStartCode(data)
            result(true)
            return
        } else if naluType == 8 { // PPS
            // 只缓存，不再输出详细日志
            cachedPps = stripStartCode(data)
            result(true)
            return
        } else if naluType == 5 { // IDR/I帧
            // 先提取第一个合法NALU，直接推送
            let firstNalu = extractFirstValidNalu(data)
            if firstNalu.isEmpty { return }
            print("[VideoDecodePlugin] 发送I帧, 长度: \(firstNalu.count), 头部: \(firstNalu.prefix(8).map { String(format: "%02X", $0) }.joined(separator: " ")), cachedSps长度: \(cachedSps?.count ?? 0), cachedPps长度: \(cachedPps?.count ?? 0)")
            decoder?.decodeFrame(frameData: firstNalu, frameType: frameType, timestamp: Int64(timestamp), frameSeq: frameSeq, refIFrameSeq: refIFrameSeq, sps: cachedSps, pps: cachedPps)
        } else {
            // 先提取第一个合法NALU，直接推送
            let firstNalu = extractFirstValidNalu(data)
            if firstNalu.isEmpty { return }
            print("[VideoDecodePlugin] 发送P/B帧, 长度: \(firstNalu.count), 头部: \(firstNalu.prefix(8).map { String(format: "%02X", $0) }.joined(separator: " "))")
            decoder?.decodeFrame(frameData: firstNalu, frameType: frameType, timestamp: Int64(timestamp), frameSeq: frameSeq, refIFrameSeq: refIFrameSeq)
        }
        result(true)
    }

    /// 释放解码器资源
    private func handleReleaseDecoder(call: FlutterMethodCall, result: @escaping FlutterResult) {
        decoder?.release()
        decoder = nil
        if let tid = textureId {
            textureRegistry?.unregisterTexture(tid)
            textureId = nil
        }
        latestPixelBuffer = nil
        hasNotifiedFlutter = false
        print("[VideoDecodePlugin] 解码器和纹理已释放")
        result(true)
    }

    // MARK: - FlutterTexture协议实现
    public func copyPixelBuffer() -> Unmanaged<CVPixelBuffer>? {
        var pixelBuffer: CVPixelBuffer?
        textureQueue.sync {
            pixelBuffer = self.latestPixelBuffer
        }
        if let pb = pixelBuffer {
            return Unmanaged.passRetained(pb)
        }
        return nil
    }

    // 新增side_data检测工具
    private func checkNaluForSideData(_ nalu: Data, naluType: UInt8) -> Bool {
        if (naluType == 5 && nalu.count > 10000) || (naluType != 7 && naluType != 8 && nalu.count > 10000) {
            print("[VideoDecodePlugin][警告] NALU长度异常，可能包含side_data，type=\(naluType)，len=\(nalu.count)")
            return true
        }
        return false
    }

    // 新增：提取第一个合法NALU工具
    private func extractFirstValidNalu(_ nalu: Data) -> Data {
        guard let start = nalu.range(of: Data([0x00, 0x00, 0x00, 0x01]))?.lowerBound else {
            print("[VideoDecodePlugin][警告] NALU无AnnexB起始码，丢弃该帧")
            return Data()
        }
        let searchRange = (start+4)..<nalu.count
        if let next = nalu[searchRange].range(of: Data([0x00, 0x00, 0x00, 0x01]))?.lowerBound {
            let end = searchRange.lowerBound + next
            return nalu[start..<end]
        } else {
            return nalu[start..<nalu.count]
        }
    }
}