import { useCallback, useEffect, useRef, useState } from "preact/hooks";
import type { AgentState, ClientMessage, LogLine, ServerMessage, ToastItem } from "../types";

const BACKEND_URL = import.meta.env.VITE_BACKEND_URL ?? "";

let toastIdCounter = 0;
let logIdCounter = 0;

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------

export interface WebRTCState {
  connected: boolean;
  connecting: boolean;
  agentState: AgentState;
  logLines: LogLine[];
  toasts: ToastItem[];
  voiceStatus: string;
  statusVisible: boolean;
  remoteAudioEl: HTMLAudioElement | null;
  remoteStream: MediaStream | null;
  sendJson(msg: ClientMessage): void;
  dismissToast(id: number): void;
  connect(): Promise<void>;
}

type AppendLine = (role: string, text: string, timestamp: string) => void;
type AddToast = (item: Omit<ToastItem, "id">) => number;
type SetAgentState = (updater: (prev: AgentState) => AgentState) => void;

// ---------------------------------------------------------------------------
// Message handlers (pure functions, outside hook to reduce complexity)
// ---------------------------------------------------------------------------

function handleTypedMessage(
  msg: Extract<ServerMessage, { type: string }>,
  setAgentState: SetAgentState,
  appendLine: AppendLine,
  addToast: AddToast,
): void {
  if (msg.type === "agent_state") {
    const s = (msg as { type: "agent_state"; state: AgentState }).state;
    setAgentState((prev) => (prev === "listening" ? prev : s));
    return;
  }
  if (msg.type === "message") {
    const mm = msg as { type: "message"; content: string; is_progress: boolean };
    if (!mm.is_progress) appendLine("nanobot", mm.content, "");
    return;
  }
  if (msg.type === "toast") {
    const tm = msg as {
      type: "toast";
      kind: "text" | "image";
      content: string;
      title: string;
      duration_ms: number;
    };
    addToast({
      kind: tm.kind,
      content: tm.content,
      title: tm.title,
      durationMs: tm.duration_ms ?? 6000,
    });
    return;
  }
  if (msg.type === "choice") {
    const cm = msg as {
      type: "choice";
      request_id: string;
      question: string;
      choices: string[];
      title: string;
    };
    addToast({
      kind: "choice",
      content: "",
      title: cm.title || "",
      durationMs: 0,
      requestId: cm.request_id,
      question: cm.question,
      choices: cm.choices,
    });
    return;
  }
  if (msg.type === "error") {
    appendLine("system", (msg as { type: "error"; error: string }).error, "");
  }
  // pong and rtc-* are no-ops
}

function parseLegacyToast(text: string, addToast: AddToast): void {
  console.log("[toast] parseLegacyToast raw text:", text);
  try {
    const t = JSON.parse(text);
    console.log("[toast] parsed toast object:", t);
    addToast({
      kind: t.kind || "text",
      content: t.content || "",
      title: t.title || "",
      durationMs: typeof t.duration_ms === "number" ? t.duration_ms : 6000,
    });
  } catch {
    console.log("[toast] JSON parse failed, using raw text as content");
    addToast({ kind: "text", content: text, title: "", durationMs: 6000 });
  }
}

function parseLegacyChoice(text: string, addToast: AddToast): void {
  try {
    const c = JSON.parse(text);
    addToast({
      kind: "choice",
      content: "",
      title: c.title || "",
      durationMs: 0,
      requestId: c.request_id || "",
      question: c.question || "",
      choices: Array.isArray(c.choices) ? c.choices : [],
    });
  } catch {
    /* ignore malformed */
  }
}

function handleLegacyMessage(
  rm: { role: string; text: string; timestamp?: string },
  setAgentState: SetAgentState,
  appendLine: AppendLine,
  addToast: AddToast,
): void {
  const role = (rm.role || "system").toString();
  const text = (rm.text || "").toString();
  const ts = rm.timestamp || "";

  if (role === "agent-state") {
    const newState = text.trim() as AgentState;
    setAgentState((prev) => (prev === "listening" ? prev : newState));
    return;
  }
  if (role === "toast") {
    parseLegacyToast(text, addToast);
    return;
  }
  if (role === "choice") {
    parseLegacyChoice(text, addToast);
    return;
  }
  if (role === "wisper") return; // suppress debug
  appendLine(role, text, ts);
}

// ---------------------------------------------------------------------------
// WebRTC helpers
// ---------------------------------------------------------------------------

async function acquireMicStream(): Promise<MediaStream> {
  try {
    return await navigator.mediaDevices.getUserMedia({
      audio: {
        channelCount: 1,
        sampleRate: 48000,
        echoCancellation: true,
        noiseSuppression: true,
        autoGainControl: false,
      },
      video: false,
    });
  } catch {
    return navigator.mediaDevices.getUserMedia({ audio: true, video: false });
  }
}

function waitForIceComplete(pc: RTCPeerConnection): Promise<void> {
  return new Promise<void>((resolve) => {
    if (pc.iceGatheringState === "complete") {
      resolve();
      return;
    }
    const check = () => {
      if (pc.iceGatheringState === "complete") {
        pc.removeEventListener("icegatheringstatechange", check);
        resolve();
      }
    };
    pc.addEventListener("icegatheringstatechange", check);
    setTimeout(resolve, 5000); // safety timeout
  });
}

async function exchangeSdp(
  localDesc: RTCSessionDescription,
): Promise<{ sdp: string; rtcType: string }> {
  const rtcUrl = BACKEND_URL ? `${BACKEND_URL}/rtc/offer` : "/rtc/offer";
  const resp = await fetch(rtcUrl, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ sdp: localDesc.sdp, rtcType: localDesc.type }),
  });
  if (!resp.ok) throw new Error(`/rtc/offer returned ${resp.status}`);
  return resp.json() as Promise<{ sdp: string; rtcType: string }>;
}

// ---------------------------------------------------------------------------
// Hook internals
// ---------------------------------------------------------------------------

interface RTCRefs {
  pcRef: { current: RTCPeerConnection | null };
  dcRef: { current: RTCDataChannel | null };
  remoteAudioRef: { current: HTMLAudioElement | null };
  micSendersRef: { current: RTCRtpSender[] };
}

interface RTCCallbacks {
  setConnected: (v: boolean) => void;
  setConnecting: (v: boolean) => void;
  setRemoteStream: (s: MediaStream | null) => void;
  showStatus: (text: string, persistMs?: number) => void;
  appendLine: AppendLine;
  onDcMessage: (raw: string) => void;
  closePC: () => void;
}

async function runConnect(refs: RTCRefs, cbs: RTCCallbacks): Promise<void> {
  if (refs.pcRef.current) return;
  if (!window.RTCPeerConnection) {
    cbs.showStatus("WebRTC unavailable in this browser.", 4000);
    return;
  }
  cbs.setConnecting(true);
  cbs.showStatus("Connecting...");

  let micStream: MediaStream | null = null;
  try {
    micStream = await acquireMicStream();
    micStream.getAudioTracks().forEach((t) => {
      t.enabled = false;
    });

    const pc = new RTCPeerConnection({ iceServers: [{ urls: "stun:stun.l.google.com:19302" }] });
    refs.pcRef.current = pc;

    const newRemoteStream = new MediaStream();
    cbs.setRemoteStream(newRemoteStream);
    if (refs.remoteAudioRef.current) {
      refs.remoteAudioRef.current.srcObject = newRemoteStream;
      refs.remoteAudioRef.current.play().catch(() => {});
    }

    pc.ontrack = (event) => {
      if (event.track.kind !== "audio") return;
      newRemoteStream.addTrack(event.track);
      refs.remoteAudioRef.current?.play().catch(() => {});
    };

    const dc = pc.createDataChannel("app", { ordered: true });
    refs.dcRef.current = dc;
    dc.onopen = () => {
      cbs.setConnected(true);
      cbs.setConnecting(false);
      cbs.showStatus("Hold anywhere to talk", 2500);
      cbs.appendLine("system", "Connected.", new Date().toISOString());
    };
    dc.onclose = () => {
      cbs.appendLine("system", "Disconnected.", new Date().toISOString());
      cbs.closePC();
    };
    dc.onmessage = (e) => cbs.onDcMessage(e.data as string);

    const stream = micStream;
    stream.getAudioTracks().forEach((track) => {
      pc.addTrack(track, stream);
    });
    refs.micSendersRef.current = pc.getSenders().filter((s) => s.track?.kind === "audio");

    const offer = await pc.createOffer();
    await pc.setLocalDescription(offer);
    await waitForIceComplete(pc);

    const localDesc = pc.localDescription;
    if (!localDesc) throw new Error("No local description after ICE gathering");
    const answer = await exchangeSdp(localDesc);
    await pc.setRemoteDescription({ type: answer.rtcType as RTCSdpType, sdp: answer.sdp });
  } catch (err) {
    cbs.appendLine("system", `Connection failed: ${err}`, new Date().toISOString());
    cbs.showStatus("Connection failed.", 3000);
    cbs.closePC();
    if (micStream)
      micStream.getTracks().forEach((t) => {
        t.stop();
      });
  }
}

// ---------------------------------------------------------------------------
// Message state sub-hook
// ---------------------------------------------------------------------------

interface MessageState {
  agentState: AgentState;
  logLines: LogLine[];
  toasts: ToastItem[];
  appendLine: AppendLine;
  addToast: AddToast;
  dismissToast: (id: number) => void;
  onDcMessage: (raw: string) => void;
}

function useMessageState(): MessageState {
  const [agentState, setAgentState] = useState<AgentState>("idle");
  const [logLines, setLogLines] = useState<LogLine[]>([]);
  const [toasts, setToasts] = useState<ToastItem[]>([]);

  const appendLine = useCallback((role: string, text: string, timestamp: string) => {
    setLogLines((prev) => {
      const next = [
        ...prev,
        { id: logIdCounter++, role, text, timestamp: timestamp || new Date().toISOString() },
      ];
      return next.length > 250 ? next.slice(next.length - 250) : next;
    });
  }, []);

  const addToast = useCallback((item: Omit<ToastItem, "id">) => {
    const id = toastIdCounter++;
    setToasts((prev) => [{ ...item, id }, ...prev]);
    return id;
  }, []);

  const dismissToast = useCallback((id: number) => {
    setToasts((prev) => prev.filter((t) => t.id !== id));
  }, []);

  const onDcMessage = useCallback(
    (raw: string) => {
      console.log("[dc] onDcMessage raw:", raw);
      let msg: ServerMessage;
      try {
        msg = JSON.parse(raw);
      } catch {
        console.log("[dc] JSON parse failed for raw message");
        return;
      }
      if ("type" in msg) {
        console.log("[dc] typed message, type:", (msg as { type: string }).type);
        handleTypedMessage(
          msg as Extract<ServerMessage, { type: string }>,
          setAgentState,
          appendLine,
          addToast,
        );
      } else {
        console.log("[dc] legacy message, role:", (msg as { role: string }).role);
        handleLegacyMessage(
          msg as { role: string; text: string; timestamp?: string },
          setAgentState,
          appendLine,
          addToast,
        );
      }
    },
    [appendLine, addToast],
  );

  return { agentState, logLines, toasts, appendLine, addToast, dismissToast, onDcMessage };
}

// ---------------------------------------------------------------------------
// Hook
// ---------------------------------------------------------------------------

export function useWebRTC(): WebRTCState {
  const [connected, setConnected] = useState(false);
  const [connecting, setConnecting] = useState(false);
  const [voiceStatus, setVoiceStatus] = useState("");
  const [statusVisible, setStatusVisible] = useState(false);
  const [remoteStream, setRemoteStream] = useState<MediaStream | null>(null);

  const pcRef = useRef<RTCPeerConnection | null>(null);
  const dcRef = useRef<RTCDataChannel | null>(null);
  const remoteAudioRef = useRef<HTMLAudioElement | null>(null);
  const statusTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const micSendersRef = useRef<RTCRtpSender[]>([]);

  const { agentState, logLines, toasts, appendLine, dismissToast, onDcMessage } = useMessageState();

  // Create audio element once
  useEffect(() => {
    const audio = new Audio();
    audio.autoplay = true;
    (audio as HTMLAudioElement & { playsInline: boolean }).playsInline = true;
    remoteAudioRef.current = audio;
    return () => {
      audio.srcObject = null;
    };
  }, []);

  useEffect(() => {
    const handler = (e: Event) => {
      const enabled = (e as CustomEvent<{ enabled: boolean }>).detail?.enabled ?? false;
      micSendersRef.current.forEach((sender) => {
        if (sender.track) sender.track.enabled = enabled;
      });
    };
    window.addEventListener("nanobot-mic-enable", handler);
    return () => window.removeEventListener("nanobot-mic-enable", handler);
  }, []);

  const showStatus = useCallback((text: string, persistMs = 0) => {
    setVoiceStatus(text);
    setStatusVisible(true);
    if (statusTimerRef.current) clearTimeout(statusTimerRef.current);
    if (persistMs > 0) {
      statusTimerRef.current = setTimeout(() => setStatusVisible(false), persistMs);
    }
  }, []);

  const sendJson = useCallback((msg: ClientMessage) => {
    const dc = dcRef.current;
    if (!dc || dc.readyState !== "open") return;
    dc.send(JSON.stringify(msg));
  }, []);

  const closePC = useCallback(() => {
    dcRef.current?.close();
    dcRef.current = null;
    pcRef.current?.close();
    pcRef.current = null;
    micSendersRef.current = [];
    setConnected(false);
    setConnecting(false);
    if (remoteAudioRef.current) remoteAudioRef.current.srcObject = null;
    setRemoteStream(null);
  }, []);

  const connect = useCallback(async () => {
    const refs: RTCRefs = { pcRef, dcRef, remoteAudioRef, micSendersRef };
    const cbs: RTCCallbacks = {
      setConnected,
      setConnecting,
      setRemoteStream,
      showStatus,
      appendLine,
      onDcMessage,
      closePC,
    };
    await runConnect(refs, cbs);
  }, [setConnected, setConnecting, setRemoteStream, showStatus, appendLine, onDcMessage, closePC]);

  return {
    connected,
    connecting,
    agentState,
    logLines,
    toasts,
    voiceStatus,
    statusVisible,
    remoteAudioEl: remoteAudioRef.current,
    remoteStream,
    sendJson,
    dismissToast,
    connect,
  };
}