import { useEffect, useRef, useState } from "react";
import { getLang, useT } from "../i18n";
import { toast } from "../dialogs";
import { get } from "../api";
import { Icon } from "./Icon";

/* Web Speech API (Chrome/Edge/Safari; Firefox has none). */
type Recognition = {
  lang: string;
  continuous: boolean;
  interimResults: boolean;
  start(): void;
  stop(): void;
  onresult: ((e: any) => void) | null;
  onend: (() => void) | null;
  onerror: ((e: any) => void) | null;
};
const Impl: (new () => Recognition) | undefined = (window as any).SpeechRecognition ?? (window as any).webkitSpeechRecognition;

export const voiceSupported = () => !!Impl;

/** Server-side transcription is on (server.transcribe_model) – for browsers without dictation. */
function useServerSpeech(): boolean {
  const [on, setOn] = useState(false);
  useEffect(() => {
    if (Impl) return;
    get<{ transcribe?: boolean }>("/config")
      .then((c) => setOn(!!c.transcribe))
      .catch(() => undefined);
  }, []);
  return on;
}

/** Record with the microphone; the audio is transcribed by the server. */
function RecorderButton({ onText, onInterim }: { onText: (text: string) => void; onInterim: (text: string) => void }) {
  const t = useT();
  const [state, setState] = useState<"idle" | "recording" | "sending">("idle");
  const rec = useRef<MediaRecorder | null>(null);
  useEffect(() => () => rec.current?.stream.getTracks().forEach((x) => x.stop()), []);

  const toggle = async () => {
    if (state === "recording") {
      rec.current?.stop();
      return;
    }
    if (state === "sending") return;
    try {
      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
      const r = new MediaRecorder(stream);
      const chunks: Blob[] = [];
      r.ondataavailable = (e) => e.data.size && chunks.push(e.data);
      r.onstop = async () => {
        stream.getTracks().forEach((x) => x.stop());
        setState("sending");
        onInterim(t("voice.transcribing"));
        try {
          const blob = new Blob(chunks, { type: r.mimeType || "audio/webm" });
          const res = await fetch(`/api/transcribe?lang=${getLang()}`, { method: "POST", credentials: "same-origin", headers: { "Content-Type": blob.type }, body: blob });
          const data = await res.json().catch(() => ({}));
          if (!res.ok) throw new Error(data.error ?? data.message ?? `HTTP ${res.status}`);
          if (data.text) onText(String(data.text));
        } catch (e: any) {
          toast(`${t("voice.error")}: ${e.message}`);
        } finally {
          onInterim("");
          setState("idle");
        }
      };
      rec.current = r;
      r.start();
      setState("recording");
    } catch {
      toast(t("voice.denied"));
    }
  };

  return (
    <button
      type="button"
      className={`ghost small voice-btn ${state === "recording" ? "on" : ""}`}
      disabled={state === "sending"}
      onClick={() => void toggle()}
      title={t(state === "recording" ? "voice.stop" : "voice.start")}
      aria-label={t(state === "recording" ? "voice.stop" : "voice.start")}
      aria-pressed={state === "recording"}
    >
      <Icon name="mic" />
    </button>
  );
}

const LOCALES: Record<string, string> = { de: "de-DE", en: "en-US" };

/** Microphone button: dictated text is appended to the message. */
export function VoiceButton(props: { onText: (text: string) => void; onInterim: (text: string) => void }) {
  const server = useServerSpeech();
  if (!Impl) return server ? <RecorderButton {...props} /> : null;
  return <BrowserVoiceButton {...props} />;
}

function BrowserVoiceButton({ onText, onInterim }: { onText: (text: string) => void; onInterim: (text: string) => void }) {
  const t = useT();
  const [listening, setListening] = useState(false);
  const rec = useRef<Recognition | null>(null);

  useEffect(() => () => rec.current?.stop(), []);
  if (!Impl) return null;

  const toggle = () => {
    if (listening) {
      rec.current?.stop();
      return;
    }
    const r = new Impl!();
    r.lang = LOCALES[getLang()] ?? navigator.language;
    r.continuous = true;
    r.interimResults = true;
    r.onresult = (e: any) => {
      let interim = "";
      for (let i = e.resultIndex; i < e.results.length; i++) {
        const res = e.results[i];
        if (res.isFinal) onText(res[0].transcript.trim());
        else interim += res[0].transcript;
      }
      onInterim(interim);
    };
    r.onerror = (e: any) => {
      if (e.error === "not-allowed" || e.error === "service-not-allowed") toast(t("voice.denied"));
      else if (e.error !== "no-speech" && e.error !== "aborted") toast(`${t("voice.error")}: ${e.error}`);
    };
    r.onend = () => {
      setListening(false);
      onInterim("");
    };
    rec.current = r;
    r.start();
    setListening(true);
  };

  return (
    <button type="button" className={`ghost small voice-btn ${listening ? "on" : ""}`} onClick={toggle} title={t(listening ? "voice.stop" : "voice.start")} aria-label={t(listening ? "voice.stop" : "voice.start")} aria-pressed={listening}>
      <Icon name="mic" />
    </button>
  );
}