const express = require('express');
const bodyParser = require('body-parser');
const CRI = require('chrome-remote-interface');
const fs = require('fs');
const path = require('path');

const LOGS_DIR = path.join(__dirname, 'logs');
const LOG_FILE = path.join(LOGS_DIR, 'spooler.log');
const ERROR_LOG_FILE = path.join(LOGS_DIR, 'errors.log');
const METRICS_LOG_FILE = path.join(LOGS_DIR, 'metrics.log');

const CONFIG = {
    port: 3030,
    chromePort: 42020,
    maxConcurrent: 5,
    maxQueueSize: 100,
    jobCleanupMinutes: 60,
    jobRetentionMs: 60 * 60 * 1000
};

function logInfo(message, data = null) {
    const timestamp = new Date().toISOString();
    const logEntry = `[${timestamp}] [INFO] ${message}${data ? ' ' + JSON.stringify(data) : ''}\n`;
    fs.appendFileSync(LOG_FILE, logEntry);
    console.log(`[INFO] ${message}`, data || '');
}

function logWarn(message, data = null) {
    const timestamp = new Date().toISOString();
    const logEntry = `[${timestamp}] [WARN] ${message}${data ? ' ' + JSON.stringify(data) : ''}\n`;
    fs.appendFileSync(LOG_FILE, logEntry);
    console.warn(`[WARN] ${message}`, data || '');
}

function logError(message, error = null) {
    const timestamp = new Date().toISOString();
    const logEntry = `[${timestamp}] [ERROR] ${message}${error ? ' ' + error.message + '\n' + error.stack : ''}\n`;
    fs.appendFileSync(ERROR_LOG_FILE, logEntry);
    fs.appendFileSync(LOG_FILE, logEntry);
    console.error(`[ERROR] ${message}`, error || '');
}

class PDFQueue {
    constructor() {
        this.queue = [];
        this.processing = new Set();
        this.jobs = new Map();
        this.chrome = null;
        this.connected = false;
        this.cleanupInterval = null;
    }

    async initialize() {
        try {
            //this.chrome = await CRI({ port: CONFIG.chromePort });
            this.chrome = await CRI({ port: CONFIG.chromePort, host: '127.0.0.1' });
            this.connected = true;
            logInfo('Chrome CDP connected', { port: CONFIG.chromePort });
        } catch (error) {
            this.connected = false;
            logError('Chrome CDP connection failed', error);
            throw error;
        }

        this.startCleanup();
    }

    addJob(html, filename) {
        if (this.queue.length >= CONFIG.maxQueueSize) {
            logError('Queue full', { size: this.queue.length, max: CONFIG.maxQueueSize });
            throw new Error('Queue is full, please try again later');
        }

        const jobId = `job_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
        const job = {
            id: jobId,
            html,
            filename: filename || `${jobId}.pdf`,
            status: 'queued',
            createdAt: Date.now(),
            startedAt: null,
            completedAt: null,
            processingTime: null,
            error: null,
            pdfUrl: null
        };

        this.queue.push(job);
        this.jobs.set(jobId, job);

        this.processQueue();
        return job;
    }

    async processQueue() {
        while (this.processing.size < CONFIG.maxConcurrent && this.queue.length > 0) {
            const job = this.queue.shift();
            this.processJob(job);
        }
    }

    async processJob(job) {
        this.processing.add(job.id);
        job.status = 'processing';
        job.startedAt = Date.now();

        try {
            if (!this.connected) {
                await this.initialize();
            }

            const { Page } = this.chrome;

            await Page.enable();
            await Page.setContent(job.html);

            const pdf = await Page.printToPDF({
                format: 'A4',
                printBackground: true,
                margin: { top: 0, bottom: 0, left: 0, right: 0 }
            });

            const outputPath = path.join(__dirname, 'data/pdfs', job.filename);
            fs.writeFileSync(outputPath, Buffer.from(pdf.data, 'base64'));

            job.status = 'completed';
            job.completedAt = Date.now();
            job.processingTime = (job.completedAt - job.startedAt) / 1000;
            job.pdfUrl = `/node_spooler/data/pdfs/${job.filename}`;

            logInfo('PDF generated successfully', {
                jobId: job.id,
                filename: job.filename,
                processingTime: job.processingTime
            });

            this.logMetrics(job);

        } catch (error) {
            job.status = 'error';
            job.error = error.message;
            job.completedAt = Date.now();

            const errorPath = path.join(__dirname, 'data/error', `${job.id}.json`);
            fs.writeFileSync(errorPath, JSON.stringify(job, null, 2));

            logError('PDF generation failed', {
                jobId: job.id,
                filename: job.filename,
                error: error.message
            });

            if (error.message.includes('Chrome') || error.message.includes('CDP')) {
                await this.handleChromeCrash();
            }
        }

        this.processing.delete(job.id);
        this.processQueue();
    }

    async handleChromeCrash() {
        logWarn('Chrome crashed, attempting restart...');

        this.queue.forEach(job => job.status = 'queued');
        this.processing.clear();
        this.connected = false;

        for (let i = 0; i < 3; i++) {
            try {
                await this.initialize();
                logInfo('Chrome restarted successfully');
                return;
            } catch (error) {
                logError(`Chrome restart attempt ${i + 1} failed`, error);
                await new Promise(resolve => setTimeout(resolve, 2000));
            }
        }

        logError('Chrome restart failed after 3 attempts');
    }

    startCleanup() {
        this.cleanupInterval = setInterval(() => {
            this.cleanupOldJobs();
        }, CONFIG.jobCleanupMinutes * 60 * 1000);
    }

    cleanupOldJobs() {
        const now = Date.now();
        const jobsToDelete = [];

        for (const [jobId, job] of this.jobs) {
            if (job.status === 'completed' || job.status === 'error') {
                const age = now - job.completedAt;
                if (age > CONFIG.jobRetentionMs) {
                    jobsToDelete.push(jobId);
                }
            }
        }

        jobsToDelete.forEach(jobId => {
            this.jobs.delete(jobId);
        });

        if (jobsToDelete.length > 0) {
            logInfo('Cleaned up old jobs', { count: jobsToDelete.length });
        }
    }

    logMetrics(job) {
        const timestamp = new Date().toISOString();
        const logEntry = `[${timestamp}] ${job.id} status=${job.status} time=${job.processingTime}s filename=${job.filename}\n`;
        fs.appendFileSync(METRICS_LOG_FILE, logEntry);
    }

    getJob(jobId) {
        return this.jobs.get(jobId);
    }

    getStats() {
        const allJobs = Array.from(this.jobs.values());
        const completedJobs = allJobs.filter(j => j.status === 'completed');
        const errorJobs = allJobs.filter(j => j.status === 'error');

        const avgTime = completedJobs.length > 0
            ? completedJobs.reduce((sum, j) => sum + j.processingTime, 0) / completedJobs.length
            : 0;

        return {
            queueSize: this.queue.length,
            processing: this.processing.size,
            completed: completedJobs.length,
            errors: errorJobs.length,
            avgProcessingTime: avgTime,
            maxQueueSize: CONFIG.maxQueueSize
        };
    }
}

const app = express();
app.use(bodyParser.json());

app.use('/node_spooler/data', express.static(path.join(__dirname, 'data')));

const queue = new PDFQueue();

async function startServer() {
    try {
        await queue.initialize();
    } catch (error) {
        logError('Failed to connect to Chrome', error);
        console.error('Please start Chrome with: "C:/Program Files/Google/Chrome/Application/chrome.exe" --headless --disable-gpu --remote-debugging-port=42020');
        process.exit(1);
    }

    app.post('/api/pdf/generate', async (req, res) => {
        try {
            const { html, filename } = req.body;

            if (!html) {
                return res.status(400).json({
                    success: false,
                    error: 'HTML content is required'
                });
            }

            const job = queue.addJob(html, filename);

            res.json({
                success: true,
                jobId: job.id,
                status: job.status,
                message: 'Job added to queue'
            });

        } catch (error) {
            logError('API error', error);
            res.status(500).json({
                success: false,
                error: error.message
            });
        }
    });

    app.get('/api/pdf/status/:jobId', (req, res) => {
        const { jobId } = req.params;
        const job = queue.getJob(jobId);

        if (!job) {
            return res.status(404).json({
                success: false,
                error: 'Job not found'
            });
        }

        res.json({
            success: true,
            jobId: job.id,
            status: job.status,
            progress: job.status === 'completed' ? 100 : (job.status === 'processing' ? 50 : 0),
            pdfUrl: job.pdfUrl,
            error: job.error
        });
    });

    app.get('/api/queue/stats', (req, res) => {
        const stats = queue.getStats();
        res.json({
            success: true,
            ...stats
        });
    });

    app.get('/api/cleanup', (req, res) => {
        res.json({
            success: true,
            message: 'Please run cleanup manually: npm run cleanup'
        });
    });

    app.listen(CONFIG.port, 'localhost', () => {
        logInfo(`PDF Spooler started on port ${CONFIG.port}`);
    });
}

startServer().catch(error => {
    logError('Server startup failed', error);
    process.exit(1);
});