const fs = require('fs');
const path = require('path');

const LOGS_DIR = path.join(__dirname, 'logs');
const LOG_FILE = path.join(LOGS_DIR, 'cleanup.log');

const CONFIG = {
    PDF_DIR: path.join(__dirname, 'data/pdfs'),
    ARCHIVE_DIR: path.join(__dirname, 'data/archive'),
    ERROR_DIR: path.join(__dirname, 'data/error'),
    
    PDF_RETENTION_DAYS: 7,
    ARCHIVE_RETENTION_DAYS: 45,
    LOG_COMPRESS_DAYS: 7,
    LOG_DELETE_DAYS: 30,
    DISK_USAGE_THRESHOLD: 80
};

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 formatBytes(bytes) {
    if (bytes === 0) return '0 Bytes';
    const k = 1024;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return Math.round(bytes / Math.pow(k, i) * 100) / 100 + ' ' + sizes[i];
}

async function runCleanup(dryRun = false) {
    logInfo('Cleanup started', { dryRun });

    const startTime = Date.now();

    try {
        await archiveOldPDFs(dryRun);
        await deleteOldArchives(dryRun);
        await rotateLogs(dryRun);
        const diskInfo = await checkDiskSpace();

        const elapsed = ((Date.now() - startTime) / 1000).toFixed(2);
        logInfo('Cleanup completed', { elapsedSeconds: elapsed, diskInfo });

        console.log('\nCleanup completed in', elapsed + 's');
        console.log('Disk space:', diskInfo.total, 'total,', diskInfo.used, 'used,', diskInfo.free, 'free');
        console.log('Disk usage:', diskInfo.percentage + '%');

        if (diskInfo.percentage > CONFIG.DISK_USAGE_THRESHOLD) {
            logWarn('Disk usage above threshold', { current: diskInfo.percentage, threshold: CONFIG.DISK_USAGE_THRESHOLD });
            console.warn('WARNING: Disk usage above', CONFIG.DISK_USAGE_THRESHOLD + '%');
        }

    } catch (error) {
        logError('Cleanup failed', error);
        console.error('Cleanup failed:', error.message);
        process.exit(1);
    }
}

async function archiveOldPDFs(dryRun) {
    logInfo('Archiving old PDFs...');

    const files = fs.readdirSync(CONFIG.PDF_DIR);
    const now = Date.now();
    const oneDayMs = 24 * 60 * 60 * 1000;
    const sevenDaysMs = 7 * oneDayMs;

    let archivedCount = 0;

    files.forEach(file => {
        if (!file.endsWith('.pdf')) return;

        const filePath = path.join(CONFIG.PDF_DIR, file);
        const stats = fs.statSync(filePath);
        const age = now - stats.mtimeMs;

        if (age > sevenDaysMs) {
            const month = new Date(stats.mtimeMs).toISOString().slice(0, 7);
            const archivePath = path.join(CONFIG.ARCHIVE_DIR, month);

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

            if (!dryRun) {
                fs.renameSync(filePath, path.join(archivePath, file));
                archivedCount++;
                logInfo('Archived PDF', { file, month });
            } else {
                logInfo('[DRY-RUN] Would archive', { file, month });
            }
        }
    });

    logInfo('Archived PDFs', { count: archivedCount, dryRun });
}

async function deleteOldArchives(dryRun) {
    logInfo('Deleting old archives...');

    const now = Date.now();
    const fortyFiveDaysMs = 45 * 24 * 60 * 60 * 1000;

    const months = fs.readdirSync(CONFIG.ARCHIVE_DIR);
    let deletedCount = 0;

    months.forEach(month => {
        const monthPath = path.join(CONFIG.ARCHIVE_DIR, month);
        const stats = fs.statSync(monthPath);
        const age = now - stats.mtimeMs;

        if (age > fortyFiveDaysMs) {
            if (!dryRun) {
                fs.rmSync(monthPath, { recursive: true, force: true });
                deletedCount++;
                logInfo('Deleted old archive', { month });
            } else {
                logInfo('[DRY-RUN] Would delete archive', { month });
            }
        }
    });

    logInfo('Deleted old archives', { count: deletedCount, dryRun });
}

async function rotateLogs(dryRun) {
    logInfo('Rotating logs...');

    const files = fs.readdirSync(LOGS_DIR);
    const now = Date.now();
    const sevenDaysMs = 7 * 24 * 60 * 60 * 1000;
    const thirtyDaysMs = 30 * 24 * 60 * 60 * 1000;

    let compressedCount = 0;
    let deletedCount = 0;

    files.forEach(file => {
        const filePath = path.join(LOGS_DIR, file);
        const stats = fs.statSync(filePath);
        const age = now - stats.mtimeMs;

        if (age > sevenDaysMs && !file.endsWith('.gz')) {
            if (!dryRun) {
                try {
                    fs.copyFileSync(filePath, filePath + '.gz');
                    fs.unlinkSync(filePath);
                    compressedCount++;
                    logInfo('Compressed log', { file });
                } catch (error) {
                    logWarn('Failed to compress log', { file, error: error.message });
                }
            } else {
                logInfo('[DRY-RUN] Would compress', { file });
            }
        }

        if (age > thirtyDaysMs) {
            if (!dryRun) {
                fs.unlinkSync(filePath);
                deletedCount++;
                logInfo('Deleted old log', { file });
            } else {
                logInfo('[DRY-RUN] Would delete', { file });
            }
        }
    });

    logInfo('Rotated logs', { compressed: compressedCount, deleted: deletedCount, dryRun });
}

async function checkDiskSpace() {
    try {
        const stats = fs.statfsSync(CONFIG.PDF_DIR);
        const total = stats.bavail * stats.frsize;
        const free = stats.bfree * stats.frsize;
        const used = total - free;
        const usedPercent = (used / total) * 100;

        return {
            total: formatBytes(total),
            used: formatBytes(used),
            free: formatBytes(free),
            percentage: usedPercent.toFixed(1)
        };
    } catch (error) {
        logError('Failed to check disk space', error);
        return {
            total: 'Unknown',
            used: 'Unknown',
            free: 'Unknown',
            percentage: 0
        };
    }
}

const dryRun = process.argv.includes('--dry-run');
runCleanup(dryRun);