const express = require('express');
const nodeHtmlToImage = require('node-html-to-image');
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');

const app = express();
const PORT = 3000;
const CACHE_DIR = path.join(__dirname, 'cache');

// Create cache directory if it doesn't exist
if (!fs.existsSync(CACHE_DIR)) {
    fs.mkdirSync(CACHE_DIR);
}

app.use(express.json());

function hashConfig(config) {
    const configString = JSON.stringify(config);
    return crypto.createHash('sha256').update(configString).digest('hex');
}

function getCachePath(hash) {
    return path.join(CACHE_DIR, `${hash}.png`);
}

function getCachedImage(config) {
    const hash = hashConfig(config);
    const cachePath = getCachePath(hash);

    if (fs.existsSync(cachePath)) {
        // Update file modification time to mark as recently accessed
        const now = new Date();
        fs.utimesSync(cachePath, now, now);
        return fs.readFileSync(cachePath);
    }

    return null;
}

function cacheImage(config, imageBuffer) {
    const hash = hashConfig(config);
    const cachePath = getCachePath(hash);
    fs.writeFileSync(cachePath, imageBuffer);
}

function clearCache() {
    if (!fs.existsSync(CACHE_DIR)) {
        return;
    }

    const files = fs.readdirSync(CACHE_DIR);
    files.forEach(file => {
        const filePath = path.join(CACHE_DIR, file);
        fs.unlinkSync(filePath);
    });

    console.log(`Cleared ${files.length} cached image(s)`);
}

function cleanupOldCache() {
    const ONE_DAY = 24 * 60 * 60 * 1000; // 24 hours in milliseconds
    const now = Date.now();

    if (!fs.existsSync(CACHE_DIR)) {
        return;
    }

    const files = fs.readdirSync(CACHE_DIR);

    let deletedCount = 0;
    files.forEach(file => {
        const filePath = path.join(CACHE_DIR, file);
        const stats = fs.statSync(filePath);

        // Check if file was last modified more than 24 hours ago
        if (now - stats.mtime.getTime() > ONE_DAY) {
            fs.unlinkSync(filePath);
            deletedCount++;
        }
    });

    if (deletedCount > 0) {
        console.log(`Cleaned up ${deletedCount} cached image(s)`);
    }
}

function formatTimestamp(epoch) {
    const date = new Date(epoch * 1000);

    const hours = date.getHours();
    const minutes = date.getMinutes().toString().padStart(2, '0');
    const ampm = hours >= 12 ? 'PM' : 'AM';
    const hour12 = hours % 12 || 12;

    const months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
    const month = months[date.getMonth()];
    const day = date.getDate();
    const year = date.getFullYear();

    return `${hour12}:${minutes} ${ampm} · ${month} ${day}, ${year}`;
}

async function generateQuoteBuffer(config) {
    const htmlTemplate = fs.readFileSync(path.join(__dirname, 'quote.html'), 'utf8');

    const configScript = `
        <script>
            window.tweetConfig = ${JSON.stringify(config)};
        </script>
    `;

    const modifiedHtml = htmlTemplate.replace('</head>', `${configScript}</head>`);

    const image = await nodeHtmlToImage({
        html: modifiedHtml,
        puppeteerArgs: {
            args: ['--no-sandbox'],
            defaultViewport: {
                width: 3240,
                height: 3240
            }
        },
        beforeScreenshot: async (page) => {
            await new Promise(resolve => setTimeout(resolve, 500));
        }
    });

    return image;
}

// GET endpoint - use query parameters
app.get('/generate', async (req, res) => {
    try {
        const timestamp = req.query.timestamp ? formatTimestamp(parseInt(req.query.timestamp)) : formatTimestamp(Date.now() / 1000);

        const config = {
            displayName: req.query.displayName || "Anonymous",
            username: req.query.username || "@anonymous",
            avatarUrl: req.query.avatarUrl || "",
            text: req.query.text || "No text provided",
            imageUrl: req.query.imageUrl || null,
            timestamp: timestamp,
            viewsCount: req.query.viewsCount || "0"
        };

        // Check cache first
        let image = getCachedImage(config);
        let fromCache = true;

        if (!image) {
            // Generate new image
            image = await generateQuoteBuffer(config);
            cacheImage(config, image);
            fromCache = false;
        }

        res.setHeader('Content-Type', 'image/png');
        res.setHeader('X-Cache', fromCache ? 'HIT' : 'MISS');
        res.send(image);
    } catch (error) {
        console.error(error);
        res.status(500).json({ error: 'Failed to generate image' });
    }
});

// POST endpoint - use request body
app.post('/generate', async (req, res) => {
    try {
        const timestamp = req.body.timestamp ? formatTimestamp(parseInt(req.body.timestamp)) : formatTimestamp(Date.now() / 1000);

        const config = {
            displayName: req.body.displayName || "Anonymous",
            username: req.body.username || "@anonymous",
            avatarUrl: req.body.avatarUrl || "",
            text: req.body.text || "No text provided",
            imageUrl: req.body.imageUrl || null,
            timestamp: timestamp,
            viewsCount: req.body.viewsCount || "0"
        };

        // Check cache first
        let image = getCachedImage(config);
        let fromCache = true;

        if (!image) {
            // Generate new image
            image = await generateQuoteBuffer(config);
            cacheImage(config, image);
            fromCache = false;
        }

        res.setHeader('Content-Type', 'image/png');
        res.setHeader('X-Cache', fromCache ? 'HIT' : 'MISS');
        res.send(image);
    } catch (error) {
        console.error(error);
        res.status(500).json({ error: 'Failed to generate image' });
    }
});

// Health check endpoint
app.get('/health', (req, res) => {
    res.status(200).json({ status: 'ok' });
});

// Clear all cache on startup
clearCache();

// Run cleanup every hour
setInterval(() => {
    cleanupOldCache();
}, 60 * 60 * 1000);

app.listen(PORT, () => {
    console.log(`Quote generator API running on http://localhost:${PORT}`);
    console.log(`GET:  http://localhost:${PORT}/generate?text=Hello&displayName=Test&username=@test&timestamp=1735574400`);
    console.log(`POST: http://localhost:${PORT}/generate`);
    console.log(`Cache cleared on startup, cleanup runs every hour`);
});