const express = require("express");
const axios = require("axios");
const fs = require("fs");
const path = require("path");
const https = require("https");
const { exec } = require("child_process"); // For FFmpeg execution

const app = express();
const PORT = 7860;
const DOWNLOAD_DIR = path.join(__dirname, "downloads");

// Ensure the downloads directory exists
if (!fs.existsSync(DOWNLOAD_DIR)) {
    fs.mkdirSync(DOWNLOAD_DIR, { recursive: true });
}

// Axios instance to ignore SSL certificate verification
const axiosInstance = axios.create({
    httpsAgent: new https.Agent({ rejectUnauthorized: false })
});

// Function to extract filename from URL or headers
const getFileName = (fileUrl, headers) => {
    let filename = path.basename(new URL(fileUrl).pathname);

    if (headers["content-disposition"]) {
        const match = headers["content-disposition"].match(/filename="(.+)"/);
        if (match) {
            filename = match[1];
        }
    }

    return filename.replace(/[<>:"/\\|?*]+/g, ""); // Remove invalid characters
};

// Function to delete file after a delay (default: 10 minutes)
const scheduleFileDeletion = (filePath, delay = 600000) => {
    setTimeout(() => {
        fs.unlink(filePath, (err) => {
            if (!err) {
                console.log(`✅ Deleted file: ${filePath}`);
            }
        });
    }, delay);
};

// Function to convert MKV to MP4 using FFmpeg
const convertToMp4 = (inputPath, outputPath) => {
    return new Promise((resolve, reject) => {
        const command = `ffmpeg -i "${inputPath}" -c:v copy -c:a aac -strict experimental "${outputPath}"`;
        exec(command, (error, stdout, stderr) => {
            if (error) {
                console.error(`❌ FFmpeg error: ${error.message}`);
                reject(error);
            } else {
                console.log(`✅ Conversion complete: ${outputPath}`);
                resolve(outputPath);
            }
        });
    });
};

// API Route to download, convert, and serve .mp4 files
app.get("/download", async (req, res) => {
    const fileUrl = req.query.url;
    if (!fileUrl) {
        return res.status(400).json({ error: "❌ Missing URL parameter" });
    }

    try {
        console.log(`⬇️ Downloading: ${fileUrl}`);

        // Request file with forced download handling
        const response = await axiosInstance({
            url: fileUrl,
            method: "GET",
            responseType: "stream",
            headers: {
                "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
                "Accept": "*/*"
            }
        });

        // Extract correct filename
        const originalFilename = getFileName(fileUrl, response.headers);
        const originalFilePath = path.join(DOWNLOAD_DIR, originalFilename);

        // Determine new filename if conversion is needed
        const isMkv = originalFilename.toLowerCase().endsWith(".mkv");
        const mp4Filename = isMkv ? originalFilename.replace(/\.mkv$/, ".mp4") : originalFilename;
        const mp4FilePath = path.join(DOWNLOAD_DIR, mp4Filename);

        // Pipe response stream to file
        const writer = fs.createWriteStream(originalFilePath);
        response.data.pipe(writer);

        writer.on("finish", async () => {
            // Dynamically get the host URL from request headers
            const hostUrl = `${req.protocol}://${req.get("host")}`;
            
            if (isMkv) {
                // Convert MKV to MP4
                try {
                    await convertToMp4(originalFilePath, mp4FilePath);
                    fs.unlinkSync(originalFilePath); // Remove original MKV after conversion
                } catch (error) {
                    return res.status(500).json({ error: "❌ Conversion failed" });
                }
            }

            const servedUrl = `${hostUrl}/files/${mp4Filename}`;
            scheduleFileDeletion(mp4FilePath); // Auto-delete after 10 minutes

            console.log(`✅ Download & conversion complete: ${servedUrl}`);
            return res.json({ message: "Download & conversion complete", fileUrl: servedUrl });
        });

        writer.on("error", (err) => {
            console.error("❌ Error writing file:", err);
            return res.status(500).json({ error: "Error saving file" });
        });

    } catch (error) {
        console.error("❌ Download error:", error.message);
        return res.status(500).json({ error: "Failed to download file" });
    }
});

// Serve files from downloads directory (publicly accessible)
app.use("/files", express.static(DOWNLOAD_DIR));

// Start the server
app.listen(PORT, () => {
    console.log(`🚀 Server running on port ${PORT}`);
});