src/app/py-detect/py-detect.component.ts

import { Component, OnDestroy, OnInit, signal, ViewChild, ElementRef } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Router, NavigationStart } from '@angular/router';
import { Subscription } from 'rxjs';

declare global {
  interface Window {
    webkitSpeechRecognition?: any;
    SpeechRecognition?: any;
  }
}

type QAResult = {
  question: string;
  transcript: string;
  language: string;
  avgPitchHz: number | null;
  avgVolume: number | null;   // 0..1 (rough RMS)
  audioUrl: string;
  startedAt: number;
  endedAt: number;
};

@Component({
  standalone: true,
  selector: 'app-py-detect',
  imports: [CommonModule],
  templateUrl: './py-detect.component.html',
  styleUrls: ['./py-detect.component.css']
})
export class PyDetectComponent implements OnInit, OnDestroy {

  // ---- UI state ----
  status = signal<'idle' | 'asking' | 'listening' | 'processing'>('idle');
  autoMode = signal(true); // Auto Next is always enabled
  micOn = signal(false);
  ttsEnabled = signal(true); // Speak Questions is always enabled
  recognizerReady = signal(false);

  // ---- TTS active flag ----
  private isActive = false;

  // ---- Q/A data ----
  currentQuestion = signal<string>('');
  questionIndex = signal<number>(0);
  log: QAResult[] = [];


  // ---- Constructor with Router Injection ----
  private routerSubscription?: Subscription;

  constructor(private router: Router) {
    // Cancel TTS on any navigation away
    this.routerSubscription = this.router.events.subscribe(event => {
      if (event instanceof NavigationStart) {
        if (window.speechSynthesis) {
          window.speechSynthesis.cancel();
        }
      }
    });
  }

  // ---- Recording/analysis handles ----
  private mediaStream?: MediaStream;
  private mediaRecorder?: MediaRecorder;
  private audioChunks: Blob[] = [];

  private audioCtx?: AudioContext;
  private analyser?: AnalyserNode;
  private sourceNode?: MediaStreamAudioSourceNode;

  private pitchSamples: number[] = [];
  private volumeSamples: number[] = [];
  private analyserBuffer?: Float32Array;
  private analyserTimer?: any;

  // ---- Speech Recognition ----
  private recognition?: any;  // webkitSpeechRecognition
  private transcriptSoFar = '';
  private detectedLang = 'auto';

  // ---- Settings ----
  private maxAnswerMs = 10_000; // per answer recording window
  private silenceTimeout?: any;  // Declare silenceTimeout here

  private analyserWindowMs = 100;  // Declare analyserWindowMs property

  // Example question source (replace with API call when ready)
  private seedQuestions = [
    'Please introduce yourself in two sentences.',
    'What motivates you to take on challenging tasks?',
    'Describe a situation where you solved a tough problem.',
    'How do you handle disagreements in a team?',
    'What is a recent technology you learned and why?'
  ];

  // Button state signals
  startDisabled = signal(false); // Always enabled
  stopDisabled = signal(true);
  resumeDisabled = signal(true);
  submitDisabled = signal(true);

  // Add missing public methods and properties for template binding
  public videoStatus: string = '';
  public videoStream?: MediaStream;
  public videoRecorder?: MediaRecorder;
  @ViewChild('videoElement', { static: false }) videoElement?: ElementRef<HTMLVideoElement>;
  public videoChunks: Blob[] = [];
  public videoAnswers: Blob[] = [];

  // Navigate back to the homepage
  navigateHome() {
    if (window.speechSynthesis) {
      window.speechSynthesis.cancel(); // Stop any TTS audio immediately on navigation
    }
    this.router.navigate(['/']);  // Navigates to the root (homepage)
  }

  // Navigate to the info page
  goToInfoPage() {
    if (window.speechSynthesis) {
      window.speechSynthesis.cancel(); // Stop any TTS audio immediately on navigation
    }
    this.router.navigate(['/infopage']);
  }

  // ======== Lifecycle ========
  ngOnInit(): void {
    this.isActive = true;
  }

  ngOnDestroy(): void {
    this.isActive = false;
    if (this.routerSubscription) {
      this.routerSubscription.unsubscribe();
    }
    this.cleanupAll();
    this.stopVideoRecording();
    this.micOn.set(false); // Stop mic indicator
    this.recognizerReady.set(false); // Stop recognizer indicator
    this.videoStatus = '';
    if (this.videoStream) {
      this.videoStream.getTracks().forEach(t => t.stop());
      this.videoStream = undefined;
    }
    this.videoRecorder = undefined;
    if (window.speechSynthesis) {
      window.speechSynthesis.cancel(); // Stop any TTS audio
    }
  }

  // ======== Main flow ========
  async start(): Promise<void> {
    if (this.status() !== 'idle') return;
    this.status.set('asking');
    this.setupRecognition();
    this.recognizerReady.set(!!this.recognition);
    await this.startCamera();
    this.startDisabled.set(false); // Always enabled
    this.stopDisabled.set(false);
    this.resumeDisabled.set(true);
    this.submitDisabled.set(true);
    this.autoMode.set(true); // Enable auto mode for continuous questions
    this.nextQuestionLoopRunning = true;
    this.nextQuestionLoop();
  }

  stopAll(): void {
    this.autoMode.set(false); // Stop auto mode to halt question loop
    this.nextQuestionLoopRunning = false;
    if (this.videoRecorder && this.videoRecorder.state === 'recording') {
      this.videoRecorder.stop();
    }
    if (this.mediaRecorder && this.mediaRecorder.state !== 'inactive') {
      this.cleanupRecording();
    }
    this.stopRecognition();
    if (window.speechSynthesis) {
      window.speechSynthesis.cancel(); // Stop any TTS audio
    }
    // Stop and clear video stream
    if (this.videoStream) {
      this.videoStream.getTracks().forEach(t => t.stop());
      this.videoStream = undefined;
      if (this.videoElement?.nativeElement) {
        this.videoElement.nativeElement.srcObject = null;
      }
    }
    this.videoRecorder = undefined;
    this.videoStatus = '';
    this.micOn.set(false);
    this.recognizerReady.set(false);
    this.status.set('idle');
    this.startDisabled.set(false); // Always enabled
    this.stopDisabled.set(false); // Ensure Stop button is enabled after stopping
    this.resumeDisabled.set(false);
    this.submitDisabled.set(false);
  }

  public resume() {
    // Start camera if not already started
    this.startCamera();
    // Resume video recording if paused
    if (this.videoRecorder && this.videoRecorder.state === 'paused') {
      this.videoRecorder.resume();
      this.videoStatus = 'Recording...';
      this.stopDisabled.set(false);
      this.resumeDisabled.set(true);
      this.submitDisabled.set(true);
    }
    // Resume question loop if stopped
    if (this.status() === 'idle') {
      this.autoMode.set(true);
      this.nextQuestionLoopRunning = true;
      this.startDisabled.set(false);
      this.stopDisabled.set(false);
      this.resumeDisabled.set(true);
      this.submitDisabled.set(true);
      this.nextQuestionLoop();
    }
  }

  public submitAll() {
    this.stopAll();
    this.stopVideoRecording();
    this.videoStatus = 'Submitted!';
    this.startDisabled.set(true);
    this.stopDisabled.set(true);
    this.resumeDisabled.set(true);
    this.submitDisabled.set(true);
    // TODO: Upload all videoAnswers to backend

    // Example: Calculate dummy percentages (replace with real logic)
    const truePercentage = 70;
    const falsePercentage = 30;
    this.router.navigate(['/validationpage'], { state: { truePercentage, falsePercentage } });
  }

  private nextQuestionLoopRunning = false;

  private async nextQuestionLoop(): Promise<void> {
    while (this.autoMode() && this.nextQuestionLoopRunning) {
      // 1) Get next question
      const q = await this.fetchNextQuestion();
      this.currentQuestion.set(q);
      this.status.set('asking');
      if (this.ttsEnabled()) {
        await this.speak(q);
      }
      this.status.set('listening');
      await this.startVideoRecording();
      const startedAt = Date.now();
      let silenceTimer: any;
      let userSpoke = false;
      this.transcriptSoFar = '';
      this.startRecognition('en-IN');
      const speechPromise = new Promise<void>((resolve) => {
        const checkSpeech = () => {
          if (this.transcriptSoFar.trim().length > 0) {
            userSpoke = true;
            clearTimeout(silenceTimer);
            resolve();
          } else {
            silenceTimer = setTimeout(() => resolve(), 5000);
          }
        };
        const poll = () => {
          checkSpeech();
          if (!userSpoke && silenceTimer && this.nextQuestionLoopRunning) setTimeout(poll, 500);
        };
        poll();
      });
      await speechPromise;
      this.stopRecognition();
      this.stopVideoRecording();
      const { audioUrl, avgPitchHz, avgVolume, transcript, language } =
        await this.captureAnswerWithAnalysis(this.maxAnswerMs);
      const endedAt = Date.now();
      this.log.push({
        question: q,
        transcript,
        language,
        avgPitchHz,
        avgVolume,
        audioUrl,
        startedAt,
        endedAt
      });
      this.questionIndex.set(this.questionIndex() + 1);
      this.status.set('processing');
      await this.sleep(700);
    }
    this.status.set('idle');
    this.stopVideoRecording();
    this.startDisabled.set(false);
    this.stopDisabled.set(true);
    this.resumeDisabled.set(false);
    this.submitDisabled.set(false);
  }

  // ======== Question source ========
  private async fetchNextQuestion(): Promise<string> {
    // Replace this with HTTP call to your backend if needed.
    // Example: const { question } = await this.http.get<{question:string}>('/api/next-question').toPromise();
    const i = this.questionIndex() % this.seedQuestions.length;
    return this.seedQuestions[i];
  }

  // ======== TTS (question playback) ========
  private speak(text: string): Promise<void> {
    return new Promise<void>((resolve) => {
      if (!this.isActive) return resolve(); // Only play TTS if component is active
      const synth = window.speechSynthesis;
      if (!synth) return resolve(); // gracefully continue without TTS

      const utter = new SpeechSynthesisUtterance(text);
      // Optional voice selection: pick an Indian English voice if available
      const prefer = ['en-IN', 'en-GB', 'en-US'];
      const voices = synth.getVoices();
      const v = voices.find(v =>
        prefer.includes(v.lang) || v.lang.toLowerCase().startsWith('en'));
      if (v) utter.voice = v;

      utter.rate = 1.0;
      utter.pitch = 1.0;
      utter.onend = () => resolve();
      utter.onerror = () => resolve(); // do not block flow
      synth.cancel(); // ensure clean queue
      synth.speak(utter);
    });
  }

  // ======== Recording + Recognition + Analysis ========
  private async captureAnswerWithAnalysis(ms: number): Promise<{
    audioUrl: string; avgPitchHz: number | null; avgVolume: number | null; transcript: string; language: string;
  }> {
    // reset buffers
    this.audioChunks = [];
    this.pitchSamples = [];
    this.volumeSamples = [];
    this.transcriptSoFar = '';
    this.detectedLang = 'auto';

    // 1) mic stream
    this.mediaStream = await navigator.mediaDevices.getUserMedia({
      audio: { channelCount: 1, echoCancellation: true, noiseSuppression: true },
      video: false
    });
    this.micOn.set(true);

    // 2) prepare MediaRecorder
    const mime = this.chooseMimeType();
    this.mediaRecorder = new MediaRecorder(this.mediaStream, { mimeType: mime });
    this.mediaRecorder.ondataavailable = (e) => {
      if (e.data && e.data.size > 0) this.audioChunks.push(e.data);
    };

    // 3) start recognition (if available)
    this.startRecognition('en-IN');

    // 4) start analysis
    await this.startAnalyser(this.mediaStream);

    // 5) record for fixed window
    const recordPromise = new Promise<void>((resolve) => {
      this.mediaRecorder!.onstop = () => resolve();
      this.mediaRecorder!.start(200); // gather chunks
      setTimeout(() => {
        if (this.mediaRecorder && this.mediaRecorder.state !== 'inactive') {
          this.mediaRecorder.stop();
        }
      }, ms);
    });

    await recordPromise;

    // 6) stop analysis + recognition + mic
    this.stopAnalyser();
    this.stopRecognition();
    this.cleanupMediaStream();
    this.micOn.set(false);

    // 7) build audio URL
    const blob = new Blob(this.audioChunks, { type: mime });
    const audioUrl = URL.createObjectURL(blob);

    // 8) aggregate metrics
    const avgPitchHz = this.averageNonZero(this.pitchSamples) ?? null;
    const avgVolume = this.averageNonZero(this.volumeSamples) ?? null;

    const transcript = this.transcriptSoFar.trim();
    const language = this.detectedLang;

    return { audioUrl, avgPitchHz, avgVolume, transcript, language };
  }

  private waitForSilenceOrContinue() {
    if (this.silenceTimeout) clearTimeout(this.silenceTimeout);
    this.silenceTimeout = setTimeout(() => {
      this.stopAll();
    }, 5000); // Timeout after 5 seconds of silence
  }


  private chooseMimeType(): string {
    const candidates = [
      'audio/webm;codecs=opus',
      'audio/webm',
      'audio/mp4',
      'audio/mpeg'
    ];
    for (const c of candidates) {
      if (MediaRecorder.isTypeSupported(c)) return c;
    }
    return '';
  }

  // ======== Web Audio analysis (pitch + volume) ========
  private async startAnalyser(stream: MediaStream) {
    this.audioCtx = new (window.AudioContext || (window as any).webkitAudioContext)();
    this.sourceNode = this.audioCtx.createMediaStreamSource(stream);
    this.analyser = this.audioCtx.createAnalyser();
    this.analyser.fftSize = 2048;
    this.sourceNode.connect(this.analyser);

    this.analyserBuffer = new Float32Array(this.analyser.fftSize);

    const tick = () => {
      if (!this.analyser || !this.analyserBuffer) return;
      this.analyser.getFloatTimeDomainData(this.analyserBuffer);

      const pitch = this.estimatePitchFromAutocorrelation(
        this.analyserBuffer, this.audioCtx!.sampleRate
      );
      const vol = this.rootMeanSquare(this.analyserBuffer);

      if (pitch) this.pitchSamples.push(pitch);
      this.volumeSamples.push(vol);

      this.analyserTimer = setTimeout(tick, this.analyserWindowMs);
    };
    tick();
  }

  private stopAnalyser() {
    if (this.analyserTimer) clearTimeout(this.analyserTimer);
    this.analyserTimer = null;
    if (this.sourceNode) { try { this.sourceNode.disconnect(); } catch { } }
    if (this.analyser) { try { this.analyser.disconnect(); } catch { } }
    if (this.audioCtx) { try { this.audioCtx.close(); } catch { } }
    this.sourceNode = undefined;
    this.analyser = undefined;
    this.audioCtx = undefined;
  }

  // Simple autocorrelation-based pitch estimator
  private estimatePitchFromAutocorrelation(buf: Float32Array, sampleRate: number): number | null {
    // 1) normalize
    let size = buf.length;
    let rms = 0;
    for (let i = 0; i < size; i++) rms += buf[i] * buf[i];
    rms = Math.sqrt(rms / size);
    if (rms < 0.01) return null; // too quiet

    // 2) autocorrelation
    const MAX_SAMPLES = Math.floor(size / 2);
    let bestOffset = -1;
    let bestCorr = 0;
    let lastCorr = 1;

    for (let offset = 1; offset < MAX_SAMPLES; offset++) {
      let corr = 0;
      for (let i = 0; i < MAX_SAMPLES; i++) {
        corr += Math.abs(buf[i] - buf[i + offset]);
      }
      corr = 1 - (corr / MAX_SAMPLES);
      if (corr > 0.9 && corr > lastCorr) {
        bestCorr = corr;
        bestOffset = offset;
      }
      lastCorr = corr;
    }
    if (bestOffset > 0) {
      const freq = sampleRate / bestOffset;
      if (freq >= 50 && freq <= 400) return Math.round(freq); // human speech band (rough)
    }
    return null;
  }

  private rootMeanSquare(buf: Float32Array): number {
    let sum = 0;
    for (let i = 0; i < buf.length; i++) sum += buf[i] * buf[i];
    return Math.sqrt(sum / buf.length); // 0..~0.5 typical speech
  }

  private averageNonZero(arr: number[]): number | undefined {
    const f = arr.filter(x => x && isFinite(x));
    if (!f.length) return undefined;
    return Math.round((f.reduce((a, b) => a + b, 0) / f.length) * 100) / 100;
  }

  // ======== Speech Recognition ========
  private setupRecognition() {
    const Ctor = window.webkitSpeechRecognition || window.SpeechRecognition;
    if (!Ctor) return;

    this.recognition = new Ctor();
    this.recognition.continuous = true;
    this.recognition.interimResults = false;  // Disable interim results (only final results)

    this.recognition.onresult = (event: any) => {
      let finalText = '';

      // Loop over all result sets, but only process final results
      for (let i = event.resultIndex; i < event.results.length; i++) {
        const result = event.results[i];
        // Get the transcript of the final recognized word
        if (result.isFinal) {
          finalText += result[0].transcript.trim(); // Append final result and clean up
        }
      }

      // Clean up the result by removing filler words (optional)
      this.transcriptSoFar = this.removeFillerWords(finalText.trim());
    };

    this.recognition.onerror = (error: any) => {
      console.error('Speech recognition error', error);
    };

    this.recognition.onend = () => {
      console.log('Speech recognition has ended');
    };
  }

  private removeFillerWords(text: string): string {
    const fillerWords = ['um', 'ah', 'like', 'you know', 'so', 'actually', 'basically'];
    const regex = new RegExp(`\\b(${fillerWords.join('|')})\\b`, 'gi');
    return text.replace(regex, '').replace(/\s+/g, ' ').trim();  // Clean extra spaces after removal
  }

  private startRecognition(lang: string) {
    if (!this.recognition) return;
    try {
      this.recognition.lang = lang; // set your target language; change to 'ta-IN' for Tamil, etc.
      this.recognition.start();
    } catch { /* ignore double-start */ }
  }

  private stopRecognition() {
    if (!this.recognition) return;
    try { this.recognition.stop(); } catch { /* ignore */ }
  }

  // ======== Clean-up ========
  private cleanupMediaStream() {
    if (this.mediaStream) {
      this.mediaStream.getTracks().forEach(t => t.stop());
    }
    this.mediaStream = undefined;
  }

  private cleanupRecording() {
    try { if (this.mediaRecorder && this.mediaRecorder.state !== 'inactive') this.mediaRecorder.stop(); } catch { }
    this.mediaRecorder = undefined;
    this.audioChunks = [];
    this.stopAnalyser();
    this.cleanupMediaStream();
  }

  private cleanupAll() {
    this.stopRecognition();
    this.cleanupRecording();
  }

  // ======== Helpers ========
  private sleep(ms: number) { return new Promise(res => setTimeout(res, ms)); }

  public async startCamera() {
    if (!this.videoStream) {
      this.videoStream = await navigator.mediaDevices.getUserMedia({ video: true, audio: false });
      if (this.videoElement?.nativeElement) {
        this.videoElement.nativeElement.srcObject = this.videoStream;
      }
    }
  }

  public async startVideoRecording() {
    if (!this.videoStream) return;
    this.videoChunks = [];
    this.videoRecorder = new MediaRecorder(this.videoStream, { mimeType: 'video/webm' });
    this.videoRecorder.ondataavailable = (e) => {
      if (e.data && e.data.size > 0) this.videoChunks.push(e.data);
    };
    this.videoRecorder.onstart = () => {
      this.videoStatus = 'Recording...';
    };
    this.videoRecorder.onstop = () => {
      this.videoStatus = 'Stopped';
      const videoBlob = new Blob(this.videoChunks, { type: 'video/webm' });
      this.videoAnswers.push(videoBlob);
    };
    this.videoRecorder.start();
  }

  public stopVideoRecording() {
    if (this.videoRecorder && this.videoRecorder.state !== 'inactive') {
      this.videoRecorder.stop();
    }
  }
}