const express = require("express");
const axios = require("axios");
const fs = require("fs");
const path = require("path");
const crypto = require("crypto");
const ffmpeg = require("fluent-ffmpeg"); // will use system ffmpeg

const app = express();
const PORT = 7860;

// Ensure output folder exists
const outputDir = path.join(__dirname, "output");
if (!fs.existsSync(outputDir)) fs.mkdirSync(outputDir);

// Serve converted files
app.use("/output", express.static(outputDir));

// Generate random hex filename
function randomHex(len = 16) {
    return crypto.randomBytes(len).toString("hex");
}

app.get("/convert", async (req, res) => {
    try {
        const { url } = req.query;
        if (!url) return res.status(400).json({ error: "Missing audio URL" });

        const m4aPath = path.join(__dirname, `${randomHex()}.m4a`);
        const mp3Path = path.join(outputDir, `${randomHex()}.mp3`);

        // Download the m4a file
        const response = await axios({
            method: "GET",
            url,
            responseType: "stream"
        });

        const writer = fs.createWriteStream(m4aPath);
        response.data.pipe(writer);

        writer.on("finish", () => {
            ffmpeg(m4aPath)
                .toFormat("mp3")
                .on("end", () => {
                    fs.unlinkSync(m4aPath); // cleanup temp file
                    const fileUrl = `${req.protocol}://${req.get("host")}/output/${path.basename(mp3Path)}`;
                    res.json({ mp3: fileUrl });
                })
                .on("error", err => {
                    console.error("FFmpeg error:", err);
                    res.status(500).json({ error: "Conversion failed" });
                })
                .save(mp3Path);
        });

        writer.on("error", err => {
            console.error("Download error:", err);
            res.status(500).json({ error: "Failed to download file" });
        });

    } catch (err) {
        console.error(err);
        res.status(500).json({ error: "Internal server error" });
    }
});

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