Ecobot_Scoala_Verde/frontend/js/audio.js

class AudioHandler {
    constructor() {
        this.mediaRecorder = null;
        this.audioChunks = [];
        this.isRecording = false;
        this.audioContext = null;
        this.selectedMicId = localStorage.getItem('selectedMicId') || null;
        this.selectedSpeakerId = localStorage.getItem('selectedSpeakerId') || null;
        this.micGain = parseFloat(localStorage.getItem('micGain') || '3.0');
    }

    async init() {
        const constraints = {
            audio: this.selectedMicId
                ? {
                    deviceId: { exact: this.selectedMicId },
                    autoGainControl: true,
                    noiseSuppression: true,
                    echoCancellation: true,
                }
                : {
                    autoGainControl: true,
                    noiseSuppression: true,
                    echoCancellation: true,
                },
        };

        const stream = await navigator.mediaDevices.getUserMedia(constraints);

        // Apply gain boost through Web Audio API
        const ctx = new AudioContext();
        const source = ctx.createMediaStreamSource(stream);
        const gainNode = ctx.createGain();
        gainNode.gain.value = this.micGain;
        const dest = ctx.createMediaStreamDestination();

        source.connect(gainNode);
        gainNode.connect(dest);

        this._liveAudioCtx = ctx;
        this._liveGainNode = gainNode;

        this.mediaRecorder = new MediaRecorder(dest.stream, { mimeType: 'audio/webm' });

        this.mediaRecorder.ondataavailable = (event) => {
            this.audioChunks.push(event.data);
        };
    }

    setMic(deviceId) {
        this.selectedMicId = deviceId;
        localStorage.setItem('selectedMicId', deviceId);
    }

    setSpeaker(deviceId) {
        this.selectedSpeakerId = deviceId;
        localStorage.setItem('selectedSpeakerId', deviceId);
    }

    setGain(value) {
        this.micGain = value;
        localStorage.setItem('micGain', value.toString());
        if (this._liveGainNode) {
            this._liveGainNode.gain.value = value;
        }
    }

    startRecording() {
        this.audioChunks = [];
        this.mediaRecorder.start();
        this.isRecording = true;
    }

    stopRecording() {
        return new Promise((resolve) => {
            this.mediaRecorder.onstop = async () => {
                const blob = new Blob(this.audioChunks, { type: 'audio/webm' });
                const wavBlob = await this.convertToWav(blob);
                resolve(wavBlob);
            };
            this.mediaRecorder.stop();
            this.isRecording = false;
        });
    }

    async convertToWav(blob) {
        if (!this.audioContext) {
            this.audioContext = new AudioContext({ sampleRate: 16000 });
        }

        const arrayBuffer = await blob.arrayBuffer();
        const audioBuffer = await this.audioContext.decodeAudioData(arrayBuffer);

        const numChannels = 1;
        const sampleRate = 16000;
        const bitsPerSample = 16;

        const offlineCtx = new OfflineAudioContext(numChannels, audioBuffer.duration * sampleRate, sampleRate);
        const source = offlineCtx.createBufferSource();
        source.buffer = audioBuffer;
        source.connect(offlineCtx.destination);
        source.start();

        const resampled = await offlineCtx.startRendering();
        const samples = resampled.getChannelData(0);

        // Normalize audio - find peak and scale up
        let peak = 0;
        for (let i = 0; i < samples.length; i++) {
            const abs = Math.abs(samples[i]);
            if (abs > peak) peak = abs;
        }
        const normalizeGain = peak > 0.01 ? 0.9 / peak : 1;

        const dataLength = samples.length * (bitsPerSample / 8);
        const buffer = new ArrayBuffer(44 + dataLength);
        const view = new DataView(buffer);

        this.writeString(view, 0, 'RIFF');
        view.setUint32(4, 36 + dataLength, true);
        this.writeString(view, 8, 'WAVE');
        this.writeString(view, 12, 'fmt ');
        view.setUint32(16, 16, true);
        view.setUint16(20, 1, true);
        view.setUint16(22, numChannels, true);
        view.setUint32(24, sampleRate, true);
        view.setUint32(28, sampleRate * numChannels * (bitsPerSample / 8), true);
        view.setUint16(32, numChannels * (bitsPerSample / 8), true);
        view.setUint16(34, bitsPerSample, true);
        this.writeString(view, 36, 'data');
        view.setUint32(40, dataLength, true);

        let offset = 44;
        for (let i = 0; i < samples.length; i++) {
            const amplified = samples[i] * normalizeGain;
            const s = Math.max(-1, Math.min(1, amplified));
            view.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
            offset += 2;
        }

        return new Blob([buffer], { type: 'audio/wav' });
    }

    writeString(view, offset, string) {
        for (let i = 0; i < string.length; i++) {
            view.setUint8(offset + i, string.charCodeAt(i));
        }
    }

    playAudioFromBase64(base64Data, mimeType = 'audio/mpeg') {
        return new Promise((resolve) => {
            const byteChars = atob(base64Data);
            const byteArray = new Uint8Array(byteChars.length);
            for (let i = 0; i < byteChars.length; i++) {
                byteArray[i] = byteChars.charCodeAt(i);
            }
            const blob = new Blob([byteArray], { type: mimeType });
            const url = URL.createObjectURL(blob);
            const audio = new Audio(url);

            if (this.selectedSpeakerId && audio.setSinkId) {
                audio.setSinkId(this.selectedSpeakerId).catch(() => {});
            }

            audio.onended = () => {
                URL.revokeObjectURL(url);
                resolve();
            };
            audio.play();
        });
    }
}