app/server.js

const express = require('express');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { exec } = require('child_process');
const fetch = require('node-fetch');
const FormData = require('form-data');

const app = express();
const port = 3000;

const uploadsDir = path.join(__dirname, 'uploads');
const publicDir = path.join(__dirname, 'public');

if (!fs.existsSync(uploadsDir)) {
    fs.mkdirSync(uploadsDir, { recursive: true });
}

if (!fs.existsSync(publicDir)) {
    fs.mkdirSync(publicDir, { recursive: true });
}

const storage = multer.memoryStorage();
const upload = multer({ storage: storage });

app.use(express.static(publicDir));
app.use(express.json());

const getNextFolderNumber = () => {
    const folders = fs.readdirSync(uploadsDir).filter(file => fs.statSync(path.join(uploadsDir, file)).isDirectory());
    const folderNumbers = folders.map(folder => parseInt(folder)).filter(num => !isNaN(num));
    return folderNumbers.length > 0 ? Math.max(...folderNumbers) + 1 : 1;
};

let sentenceIndex = 0;
let audioPaths = [];

app.post('/save-audio', upload.single('audio'), async (req, res) => {
    const nextFolderNumber = getNextFolderNumber();
    const folderPath = path.join(uploadsDir, nextFolderNumber.toString());
    if (!fs.existsSync(folderPath)) {
        fs.mkdirSync(folderPath, { recursive: true });
    }

    const rawAudioPath = path.join(folderPath, `audio_${sentenceIndex}.webm`);
    const wavAudioPath = path.join(folderPath, `audio_${sentenceIndex}.wav`);
    const transcriptionPath = path.join(folderPath, `transcription_${sentenceIndex}.txt`);

    fs.writeFileSync(rawAudioPath, req.file.buffer);
    fs.writeFileSync(transcriptionPath, req.body.transcript);

    const ffmpegCommand = `ffmpeg -i ${rawAudioPath} -ar 44100 -ac 1 ${wavAudioPath}`;
    exec(ffmpegCommand, async (error, stdout, stderr) => {
        if (error) {
            console.error(`Error converting audio to WAV: ${stderr}`);
            return res.status(500).send('Error converting audio to WAV');
        }

        fs.unlinkSync(rawAudioPath);

        const formData = new FormData();
        formData.append('original_path', fs.createReadStream(wavAudioPath));
        formData.append('text', req.body.transcript);
        formData.append('lang', 'en');
        formData.append('target_lang', 'es');

        try {
            const response = await fetch('http://localhost:8000/process-audio/', {
                method: 'POST',
                body: formData,
                headers: formData.getHeaders()
            });

            if (response.ok) {
                const result = await response.json();
                console.log(result);
                audioPaths.push(result.audio_path);
                sentenceIndex++;
                // Serve the audio file from the public directory
                const publicAudioPath = path.join(publicDir, path.basename(result.audio_path));
                fs.copyFileSync(result.audio_path, publicAudioPath);
                res.status(200).json({ audio_path: `/public/${path.basename(result.audio_path)}`, translation: result.translation });
            } else {
                console.error('Failed to process the file via FastAPI');
                res.status(500).send('Failed to process the file via FastAPI');
            }
        } catch (error) {
            console.error('Error calling FastAPI:', error);
            res.status(500).send('Error calling FastAPI');
        }
    });
});

app.get('/concatenate-audio', (req, res) => {
    const folderPath = path.join(uploadsDir, getNextFolderNumber().toString());
    const finalAudioPath = path.join(folderPath, 'final_audio.wav');
    const concatCommand = `ffmpeg -y -i "concat:${audioPaths.join('|')}" -acodec copy ${finalAudioPath}`;
    exec(concatCommand, (concatError, concatStdout, concatStderr) => {
        if (concatError) {
            console.error(`Error concatenating audio files: ${concatStderr}`);
            return res.status(500).send('Error concatenating audio files');
        }

        res.status(200).json({ audio_path: finalAudioPath });
    });
});

app.listen(port, () => {
    console.log(`Server running at http://localhost:${port}`);
});