"use client";

/**
 * 语音预览:把麦克风接到后端 /ws/voice(WebRTC 信令),听到助手实时回应。
 *
 * 走原生 RTCPeerConnection + 一条 ws 信令通道,与后端 voice_webrtc.py 的约定对齐:
 *   client → {type:"offer",         payload:{pc_id, sdp, type, assistant_id}}
 *   server → {type:"answer",        payload:{pc_id, sdp, type}}
 *   client → {type:"ice-candidate", payload:{pc_id, candidate:{...}}}
 * 音频本身走 WebRTC 媒体流(Opus),不经 ws;后端 TTS 帧从 ontrack 拿到直接播放。
 *
 * 另开一条 data channel 与后端管线(pipeline.py)互通应用消息:
 *   client → {type:"user-text",  text}                          文字输入(打断并触发新回复)
 *   server → {type:"transcript", role, content, timestamp}      用户/助手最终转写(聊天记录)
 *
 * 纯本机(localhost)即可跑:localhost 是 secure context,麦克风可用,ws 用明文。
 * 局域网/别的设备要 https+wss,见 deploy/README.md。
 */

import { useCallback, useEffect, useRef, useState } from "react";

import { API_BASE } from "@/lib/api";

export type VoicePreviewStatus = "idle" | "connecting" | "connected" | "failed";

export type ChatMessage = {
  id: string;
  role: "user" | "assistant";
  content: string;
  /** 后端给的 ISO 时间戳 */
  timestamp: string;
  sequence: number;
  turnId?: string;
  streaming?: boolean;
};

// http→ws、https→wss,自动跟随 API 基址(同源反代时也对)
function wsBaseUrl(): string {
  const url = new URL(API_BASE, window.location.origin);
  url.protocol = url.protocol === "https:" ? "wss:" : "ws:";
  return url.toString().replace(/\/$/, "");
}

function generatePcId(): string {
  const bytes = new Uint8Array(16);
  crypto.getRandomValues(bytes);
  return (
    "PC-" +
    Array.from(bytes)
      .map((b) => b.toString(16).padStart(2, "0"))
      .join("")
  );
}

function errorMessage(error: unknown, fallback: string): string {
  if (error instanceof Error && error.message) return error.message;
  return fallback;
}

function messageOrder(message: ChatMessage): number {
  const timestamp = Date.parse(message.timestamp);
  return Number.isNaN(timestamp) ? Number.MAX_SAFE_INTEGER : timestamp;
}

function sortMessages(messages: ChatMessage[]): ChatMessage[] {
  return messages.sort(
    (a, b) => messageOrder(a) - messageOrder(b) || a.sequence - b.sequence,
  );
}

function microphoneErrorMessage(error: unknown): string {
  if (error instanceof DOMException) {
    if (error.name === "NotAllowedError") {
      return "麦克风权限被拒绝，请在浏览器网站设置中允许 localhost 使用麦克风。";
    }
    if (error.name === "NotFoundError") {
      return "未检测到可用麦克风，请连接或启用麦克风后重试。";
    }
    if (error.name === "NotReadableError") {
      return "麦克风正被其他应用占用，或系统未允许浏览器访问麦克风。";
    }
  }
  return errorMessage(error, "无法访问麦克风。");
}

export function useVoicePreview(
  assistantId: string | null,
  onNodeActive?: (nodeId: string | null) => void,
) {
  const [status, setStatus] = useState<VoicePreviewStatus>("idle");
  const [error, setError] = useState<string | null>(null);
  const [micWarning, setMicWarning] = useState<string | null>(null);
  const [localStream, setLocalStream] = useState<MediaStream | null>(null);
  // 远端(助手 TTS)媒体流:除挂到 <audio> 播放外,也暴露给波形可视化
  const [remoteStream, setRemoteStream] = useState<MediaStream | null>(null);
  const [messages, setMessages] = useState<ChatMessage[]>([]);
  // 可选麦克风列表与当前选择(空串表示交给浏览器选默认设备)
  const [audioInputs, setAudioInputs] = useState<MediaDeviceInfo[]>([]);
  const [selectedDeviceId, setSelectedDeviceId] = useState<string>("");
  const selectedDeviceIdRef = useRef("");
  const audioRef = useRef<HTMLAudioElement | null>(null);
  const pcRef = useRef<RTCPeerConnection | null>(null);
  const wsRef = useRef<WebSocket | null>(null);
  const dataChannelRef = useRef<RTCDataChannel | null>(null);
  const localStreamRef = useRef<MediaStream | null>(null);
  const startingRef = useRef(false);
  const messageSeqRef = useRef(0);
  // 后端主动结束(工作流走到结束节点)标记:据此把随后的断开当作正常结束而非报错
  const endedByServerRef = useRef(false);
  // 工作流激活节点回调存进 ref,避免把它挂进 connect 依赖反复重建连接
  const onNodeActiveRef = useRef(onNodeActive);
  useEffect(() => {
    onNodeActiveRef.current = onNodeActive;
  }, [onNodeActive]);

  // 枚举可用麦克风。未授权前 label 为空,授权(连接)后再刷新即可拿到名称。
  const refreshDevices = useCallback(async () => {
    if (!navigator.mediaDevices?.enumerateDevices) return;
    try {
      const devices = await navigator.mediaDevices.enumerateDevices();
      // 未授权时设备可能没有 deviceId(空串),无法选择,直接过滤掉
      const inputs = devices.filter((d) => d.kind === "audioinput" && d.deviceId);
      setAudioInputs(inputs);
      // 选中的设备已被拔出时,回退到浏览器默认设备
      if (
        selectedDeviceIdRef.current &&
        !inputs.some((d) => d.deviceId === selectedDeviceIdRef.current)
      ) {
        setSelectedDeviceId("");
      }
    } catch {
      /* 忽略枚举失败 */
    }
  }, []);

  // connect/refreshDevices 在回调里读最新选择,避免把它们挂进依赖反复重建
  useEffect(() => {
    selectedDeviceIdRef.current = selectedDeviceId;
  }, [selectedDeviceId]);

  useEffect(() => {
    if (!navigator.mediaDevices?.enumerateDevices) return;
    // eslint-disable-next-line react-hooks/set-state-in-effect
    void refreshDevices();
    navigator.mediaDevices.addEventListener("devicechange", refreshDevices);
    return () => {
      navigator.mediaDevices.removeEventListener("devicechange", refreshDevices);
    };
  }, [refreshDevices]);

  const releaseResources = useCallback(() => {
    const ws = wsRef.current;
    wsRef.current = null;
    if (ws) {
      ws.onclose = null;
      ws.onerror = null;
      ws.onmessage = null;
      ws.close();
    }

    const channel = dataChannelRef.current;
    dataChannelRef.current = null;
    if (channel) {
      channel.onopen = null;
      channel.onmessage = null;
      channel.close();
    }

    const pc = pcRef.current;
    pcRef.current = null;
    if (pc) {
      pc.onconnectionstatechange = null;
      pc.onicecandidate = null;
      pc.oniceconnectionstatechange = null;
      pc.ontrack = null;
      pc.close();
    }

    localStreamRef.current?.getTracks().forEach((track) => track.stop());
    localStreamRef.current = null;
    if (audioRef.current) audioRef.current.srcObject = null;
    startingRef.current = false;
    onNodeActiveRef.current?.(null);
  }, []);

  const disconnect = useCallback(() => {
    releaseResources();
    setLocalStream(null);
    setRemoteStream(null);
    setError(null);
    setMicWarning(null);
    setStatus("idle");
  }, [releaseResources]);

  const fail = useCallback(
    (message: string) => {
      releaseResources();
      setLocalStream(null);
      setRemoteStream(null);
      setError(message);
      setStatus("failed");
    },
    [releaseResources],
  );

  // 连接断开时:若是后端主动收尾(call-ended),按正常结束处理(不报错);
  // 否则按异常失败处理。
  const closeOnRemoteEnd = useCallback(
    (message: string) => {
      if (endedByServerRef.current) {
        disconnect();
      } else {
        fail(message);
      }
    },
    [disconnect, fail],
  );

  const connect = useCallback(async () => {
    if (startingRef.current || pcRef.current || wsRef.current) return;
    if (!assistantId) {
      setError("请先保存助手，再开始语音预览。");
      setStatus("failed");
      return;
    }
    startingRef.current = true;
    setError(null);
    setMicWarning(null);
    setMessages([]); // 新会话清空上一轮聊天记录
    endedByServerRef.current = false;
    setStatus("connecting");

    // 麦克风是可选的:获取失败时继续建立仅接收后端音频的 WebRTC 会话。
    let stream: MediaStream | null = null;
    if (window.isSecureContext && navigator.mediaDevices?.getUserMedia) {
      try {
        const audioConstraints: MediaTrackConstraints = {
          echoCancellation: true,
          noiseSuppression: true,
          autoGainControl: true,
        };
        // 指定了具体设备就强制用它,否则交给浏览器选默认麦克风
        if (selectedDeviceIdRef.current) {
          audioConstraints.deviceId = { exact: selectedDeviceIdRef.current };
        }
        stream = await navigator.mediaDevices.getUserMedia({
          audio: audioConstraints,
        });
        // 授权后 label 才可见,刷新列表把真实设备名补上
        void refreshDevices();
      } catch (mediaError) {
        setMicWarning(microphoneErrorMessage(mediaError));
      }
    } else {
      setMicWarning("当前页面无法访问麦克风，已进入仅收听模式。");
    }
    if (stream) {
      localStreamRef.current = stream;
      setLocalStream(stream);
    }

    const pcId = generatePcId();
    const ws = new WebSocket(`${wsBaseUrl()}/ws/voice`);
    wsRef.current = ws;

    ws.onmessage = async (event) => {
      try {
        const msg = JSON.parse(event.data);
        if (msg.type === "answer") {
          await pcRef.current?.setRemoteDescription({
            type: "answer",
            sdp: msg.payload.sdp,
          });
        } else if (msg.type === "ice-candidate" && msg.payload?.candidate) {
          // 后端当前不主动 trickle,留兼容
          try {
            await pcRef.current?.addIceCandidate(msg.payload.candidate);
          } catch {
            /* 忽略迟到/重复 candidate */
          }
        } else if (msg.type === "error") {
          fail(msg.payload?.message || "后端无法启动语音会话。");
        }
      } catch {
        /* 非 JSON / 未知消息,忽略 */
      }
    };

    try {
      // 1) 等 ws 连上
      await new Promise<void>((resolve, reject) => {
        ws.onopen = () => resolve();
        ws.onerror = (e) => reject(e);
        ws.onclose = () => reject(new Error("语音信令连接已关闭。"));
      });
      // 连上后,信令异常或关闭都结束当前会话并保留失败状态。
      ws.onerror = () => {
        if (wsRef.current === ws) fail("语音信令连接失败。");
      };
      ws.onclose = () => {
        if (wsRef.current === ws) closeOnRemoteEnd("语音信令连接已断开。");
      };

      // 2) 建 PeerConnection(纯 STUN,本机/局域网够用)
      const pc = new RTCPeerConnection({
        iceServers: [{ urls: "stun:stun.l.google.com:19302" }],
      });
      pcRef.current = pc;

      pc.onicecandidate = (e) => {
        if (ws.readyState !== WebSocket.OPEN) return;
        ws.send(
          JSON.stringify({
            type: "ice-candidate",
            payload: {
              pc_id: pcId,
              candidate: e.candidate
                ? {
                    candidate: e.candidate.candidate,
                    sdpMid: e.candidate.sdpMid,
                    sdpMLineIndex: e.candidate.sdpMLineIndex,
                  }
                : null,
            },
          }),
        );
      };

      // 应用消息通道:收后端转写(聊天记录),发文字输入。
      // 由浏览器侧主动创建,后端 SmallWebRTCConnection 的 on("datachannel") 会接住。
      const channel = pc.createDataChannel("chat");
      dataChannelRef.current = channel;
      channel.onopen = () => {
        channel.send(JSON.stringify({ type: "client-ready" }));
      };
      channel.onmessage = (event) => {
        try {
          const msg = JSON.parse(event.data);
          if (
            msg?.type === "assistant-text-start" &&
            typeof msg.turn_id === "string"
          ) {
            messageSeqRef.current += 1;
            const next: ChatMessage = {
              id: `assistant-${msg.turn_id}`,
              role: "assistant",
              content: "",
              timestamp:
                typeof msg.timestamp === "string"
                  ? msg.timestamp
                  : new Date().toISOString(),
              sequence: messageSeqRef.current,
              turnId: msg.turn_id,
              streaming: true,
            };
            setMessages((prev) => sortMessages([...prev, next]));
          } else if (
            msg?.type === "assistant-text-delta" &&
            typeof msg.turn_id === "string" &&
            typeof msg.delta === "string"
          ) {
            setMessages((prev) =>
              prev.map((message) =>
                message.turnId === msg.turn_id
                  ? { ...message, content: message.content + msg.delta }
                  : message,
              ),
            );
          } else if (
            msg?.type === "assistant-text-end" &&
            typeof msg.turn_id === "string"
          ) {
            setMessages((prev) =>
              prev.map((message) =>
                message.turnId === msg.turn_id
                  ? {
                      ...message,
                      content:
                        typeof msg.content === "string"
                          ? msg.content
                          : message.content,
                      streaming: false,
                    }
                  : message,
              ),
            );
          } else if (
            msg?.type === "transcript" &&
            (msg.role === "user" || msg.role === "assistant") &&
            typeof msg.content === "string" &&
            msg.content.trim()
          ) {
            messageSeqRef.current += 1;
            const next: ChatMessage = {
              id: `msg-${messageSeqRef.current}`,
              role: msg.role,
              content: msg.content,
              timestamp:
                typeof msg.timestamp === "string"
                  ? msg.timestamp
                  : new Date().toISOString(),
              sequence: messageSeqRef.current,
            };
            setMessages((prev) => sortMessages([...prev, next]));
          } else if (
            msg?.type === "node-active" &&
            typeof msg.nodeId === "string"
          ) {
            // 工作流:后端报告当前激活节点,交给画布高亮
            onNodeActiveRef.current?.(msg.nodeId);
          } else if (msg?.type === "call-ended") {
            // 后端走到结束节点、正常收尾:随后的断开按正常结束处理,不报错
            endedByServerRef.current = true;
            onNodeActiveRef.current?.(null);
          }
        } catch {
          /* 非 JSON / 未知消息,忽略 */
        }
      };

      pc.ontrack = (e) => {
        if (e.track.kind !== "audio") return;
        const remote = e.streams[0] ?? new MediaStream([e.track]);
        setRemoteStream(remote);
        if (audioRef.current) {
          audioRef.current.srcObject = remote;
          void audioRef.current.play().catch(() => {});
        }
      };

      pc.onconnectionstatechange = () => {
        if (pcRef.current !== pc) return;
        if (pc.connectionState === "connected") setStatus("connected");
        else if (pc.connectionState === "failed")
          closeOnRemoteEnd("WebRTC 音频连接失败。");
        else if (pc.connectionState === "closed")
          closeOnRemoteEnd("WebRTC 音频连接已断开。");
      };

      pc.oniceconnectionstatechange = () => {
        if (pcRef.current !== pc) return;
        const st = pc.iceConnectionState;
        if (st === "connected" || st === "completed") setStatus("connected");
        else if (st === "failed") closeOnRemoteEnd("WebRTC 音频连接失败。");
        else if (st === "disconnected")
          closeOnRemoteEnd("WebRTC 音频连接已断开。");
      };

      // 3) 有麦克风时双向音频；否则明确声明只接收后端音频。
      if (stream) {
        stream.getTracks().forEach((track) => pc.addTrack(track, stream));
      } else {
        pc.addTransceiver("audio", { direction: "recvonly" });
      }

      // 4) 生成 offer 并发给后端(assistant_id 在 payload 顶层)
      const offer = await pc.createOffer();
      await pc.setLocalDescription(offer);
      const localDescription = pc.localDescription;
      if (!localDescription?.sdp) {
        throw new Error("浏览器无法创建 WebRTC offer。");
      }
      ws.send(
        JSON.stringify({
          type: "offer",
          payload: {
            pc_id: pcId,
            sdp: localDescription.sdp,
            type: localDescription.type,
            assistant_id: assistantId,
          },
        }),
      );
    } catch (connectionError) {
      fail(errorMessage(connectionError, "无法连接语音服务。"));
    } finally {
      startingRef.current = false;
    }
  }, [assistantId, fail, closeOnRemoteEnd, refreshDevices]);

  // 选择麦克风:更新选择;若会话正在发送麦克风音频,则用 WebRTC replaceTrack
  // 热切换轨道(无需重新协商),并把波形可视化重新接到新流。
  // 未连接时仅记下选择,留待下次 connect 生效。
  const selectDevice = useCallback(
    async (deviceId: string) => {
      setSelectedDeviceId(deviceId);
      selectedDeviceIdRef.current = deviceId;

      const pc = pcRef.current;
      if (!pc) return;
      // 只有本就在发送麦克风音频(存在 audio sender 轨道)时才热切换;
      // 仅收听模式下加麦克风需重新协商,这里不处理,留到下次连接。
      const sender = pc
        .getSenders()
        .find((s) => s.track?.kind === "audio");
      if (!sender) return;

      try {
        const audioConstraints: MediaTrackConstraints = {
          echoCancellation: true,
          noiseSuppression: true,
          autoGainControl: true,
        };
        if (deviceId) audioConstraints.deviceId = { exact: deviceId };
        const newStream = await navigator.mediaDevices.getUserMedia({
          audio: audioConstraints,
        });
        // 切换期间可能已断开,丢弃刚拿到的流
        if (pcRef.current !== pc) {
          newStream.getTracks().forEach((t) => t.stop());
          return;
        }
        const newTrack = newStream.getAudioTracks()[0];
        if (!newTrack) {
          newStream.getTracks().forEach((t) => t.stop());
          return;
        }
        await sender.replaceTrack(newTrack);
        // 旧轨道停掉,新流替换(波形/分析器随 localStream 变化自动重连)
        localStreamRef.current?.getTracks().forEach((t) => t.stop());
        localStreamRef.current = newStream;
        setLocalStream(newStream);
        setMicWarning(null);
      } catch (mediaError) {
        setMicWarning(microphoneErrorMessage(mediaError));
      }
    },
    [],
  );

  // 发送文字消息:后端先打断当前播报,再按用户输入触发新回复。
  // 成功返回 true;通道未就绪(未开始对话/连接中)返回 false。
  const sendText = useCallback((text: string): boolean => {
    const trimmed = text.trim();
    const channel = dataChannelRef.current;
    if (!trimmed || !channel || channel.readyState !== "open") return false;
    channel.send(JSON.stringify({ type: "user-text", text: trimmed }));
    return true;
  }, []);

  // 卸载时收尾
  useEffect(() => releaseResources, [releaseResources]);

  return {
    status,
    error,
    micWarning,
    localStream,
    remoteStream,
    messages,
    audioInputs,
    selectedDeviceId,
    setSelectedDeviceId,
    selectDevice,
    sendText,
    connect,
    disconnect,
    audioRef,
  };
}