import { useCallback, useEffect, useRef, useState } from 'react';
import { z } from 'zod';

// Speech Recognition Event Schemas
const SpeechRecognitionAlternativeSchema = z.object({
  transcript: z.string(),
  confidence: z.number(),
});

const SpeechRecognitionResultItemSchema = z.object({
  0: SpeechRecognitionAlternativeSchema,
  isFinal: z.boolean(),
  length: z.number().optional(),
});

const SpeechRecognitionResultListSchema = z.array(SpeechRecognitionResultItemSchema);

const SpeechRecognitionEventSchema = z.object({
  resultIndex: z.number(),
  results: SpeechRecognitionResultListSchema,
});

const SpeechRecognitionErrorEventSchema = z.object({
  error: z.enum([
    'no-speech',
    'aborted',
    'audio-capture',
    'network',
    'not-allowed',
    'service-not-allowed',
    'bad-grammar',
    'language-not-supported',
  ]),
  message: z.string().optional(),
});

// FIX: Define SpeechRecognition interface and add constructors to the window object to fix type errors.
// The Web Speech API is not part of standard TypeScript typings.
interface SpeechRecognition extends EventTarget {
  continuous: boolean;
  interimResults: boolean;
  lang: string;
  onresult: (event: z.infer<typeof SpeechRecognitionEventSchema>) => void;
  onerror: (event: z.infer<typeof SpeechRecognitionErrorEventSchema>) => void;
  onend: () => void;
  start: () => void;
  stop: () => void;
}

declare global {
  interface Window {
    SpeechRecognition: { new (): SpeechRecognition };
    webkitSpeechRecognition: { new (): SpeechRecognition };
  }
}

export const useSpeechRecognition = (lang = 'ru-RU') => {
  const [isListening, setIsListening] = useState(false);
  const [transcript, setTranscript] = useState('');
  const recognitionRef = useRef<SpeechRecognition | null>(null);

  useEffect(() => {
    if (typeof window === 'undefined') return;

    const SpeechRecognition = window.SpeechRecognition || window.webkitSpeechRecognition;
    if (!SpeechRecognition) {
      console.warn('Speech Recognition is not supported by this browser.');
      return;
    }

    const recognition = new SpeechRecognition();
    recognition.continuous = true;
    recognition.interimResults = true;
    recognition.lang = lang;

    recognition.onresult = (event) => {
      try {
        const validatedEvent = SpeechRecognitionEventSchema.parse(event);
        let finalTranscript = '';
        for (let i = validatedEvent.resultIndex; i < validatedEvent.results.length; ++i) {
          const transcriptPart = validatedEvent.results[i][0].transcript;
          if (validatedEvent.results[i].isFinal) {
            finalTranscript += transcriptPart;
          }
        }
        setTranscript(finalTranscript);
      } catch (error) {
        console.error('Speech recognition event validation failed:', error);
      }
    };

    recognition.onerror = (event) => {
      try {
        const validatedEvent = SpeechRecognitionErrorEventSchema.parse(event);
        console.error('Speech recognition error:', validatedEvent.error);
        setIsListening(false);
      } catch (error) {
        console.error('Speech recognition error event validation failed:', error);
        setIsListening(false);
      }
    };

    recognition.onend = () => {
      if (recognitionRef.current) {
        setIsListening(false);
      }
    };

    recognitionRef.current = recognition;

    return () => {
      if (recognitionRef.current) {
        recognitionRef.current.stop();
      }
      recognitionRef.current = null;
    };
  }, [lang]);

  const startListening = useCallback(() => {
    if (recognitionRef.current && !isListening) {
      setTranscript('');
      recognitionRef.current.start();
      setIsListening(true);
    }
  }, [isListening]);

  const stopListening = useCallback(() => {
    if (recognitionRef.current && isListening) {
      recognitionRef.current.stop();
      setIsListening(false);
    }
  }, [isListening]);

  const isSupported = !!(
    typeof window !== 'undefined' &&
    (window.SpeechRecognition || window.webkitSpeechRecognition)
  );

  return { isListening, transcript, startListening, stopListening, isSupported };
};