/**
 * Cleanup Command Handler
 *
 * Removes old CLIProxy logs to free up disk space.
 * Supports both main logs and error request logs with age-based filtering.
 * Logs can accumulate to several GB without user awareness.
 */

import * as fs from 'fs';
import * as path from 'path';
import { getCliproxyDir } from '../cliproxy/config-generator';
import { info, ok, warn } from '../utils/ui';

/** Default age in days for error log cleanup */
const DEFAULT_ERROR_LOG_AGE_DAYS = 7;

/** Get the CLIProxy logs directory */
function getLogsDir(): string {
  return path.join(getCliproxyDir(), 'logs');
}

/** Format bytes to human-readable size */
function formatBytes(bytes: number): string {
  if (bytes === 0) return '0 B';
  const units = ['B', 'KB', 'MB', 'GB', 'TB'];
  const i = Math.floor(Math.log(bytes) / Math.log(1024));
  return `${(bytes / Math.pow(1024, i)).toFixed(2)} ${units[i]}`;
}

/** Calculate total size of a directory */
function getDirSize(dirPath: string): number {
  if (!fs.existsSync(dirPath)) return 0;

  let totalSize = 0;
  const files = fs.readdirSync(dirPath);

  for (const file of files) {
    const filePath = path.join(dirPath, file);
    try {
      const stats = fs.lstatSync(filePath); // Use lstat to detect symlinks
      if (stats.isFile() && !stats.isSymbolicLink()) {
        totalSize += stats.size;
      } else if (stats.isDirectory() && !stats.isSymbolicLink()) {
        totalSize += getDirSize(filePath);
      }
      // Skip symlinks for safety
    } catch {
      // File may have been deleted between readdir and stat - skip
    }
  }

  return totalSize;
}

/** Count files in a directory */
function countFiles(dirPath: string): number {
  if (!fs.existsSync(dirPath)) return 0;
  let count = 0;
  const entries = fs.readdirSync(dirPath);

  for (const entry of entries) {
    const filePath = path.join(dirPath, entry);
    try {
      const stats = fs.lstatSync(filePath);
      if (stats.isFile() && !stats.isSymbolicLink()) {
        count++;
      }
    } catch {
      // File may have been deleted - skip
    }
  }
  return count;
}

/** Delete all regular files in a directory (skips symlinks for safety) */
function cleanDirectory(dirPath: string): { deleted: number; freedBytes: number } {
  if (!fs.existsSync(dirPath)) return { deleted: 0, freedBytes: 0 };

  let deleted = 0;
  let freedBytes = 0;
  const files = fs.readdirSync(dirPath);

  for (const file of files) {
    const filePath = path.join(dirPath, file);
    try {
      const stats = fs.lstatSync(filePath);

      // Only delete regular files, skip symlinks for security
      if (stats.isFile() && !stats.isSymbolicLink()) {
        freedBytes += stats.size;
        fs.unlinkSync(filePath);
        deleted++;
      }
    } catch {
      // File may have been deleted or inaccessible - skip
    }
  }

  return { deleted, freedBytes };
}

/** Error log file info */
interface ErrorLogInfo {
  name: string;
  path: string;
  size: number;
  mtime: Date;
  ageInDays: number;
}

/** Get error log files with metadata */
function getErrorLogFiles(logsDir: string): ErrorLogInfo[] {
  if (!fs.existsSync(logsDir)) return [];

  const now = Date.now();
  const files: ErrorLogInfo[] = [];
  const entries = fs.readdirSync(logsDir);

  for (const entry of entries) {
    // Only process error-*.log files
    if (!entry.startsWith('error-') || !entry.endsWith('.log')) continue;

    const filePath = path.join(logsDir, entry);
    try {
      const stats = fs.lstatSync(filePath);
      if (stats.isFile() && !stats.isSymbolicLink()) {
        const ageMs = now - stats.mtime.getTime();
        files.push({
          name: entry,
          path: filePath,
          size: stats.size,
          mtime: stats.mtime,
          ageInDays: Math.floor(ageMs / (1000 * 60 * 60 * 24)),
        });
      }
    } catch {
      // File may have been deleted - skip
    }
  }

  // Sort by age, oldest first
  return files.sort((a, b) => b.ageInDays - a.ageInDays);
}

/** Delete error logs older than specified days */
function cleanErrorLogs(
  logsDir: string,
  maxAgeDays: number
): { deleted: number; freedBytes: number; kept: number } {
  const files = getErrorLogFiles(logsDir);
  let deleted = 0;
  let freedBytes = 0;
  let kept = 0;

  for (const file of files) {
    if (file.ageInDays >= maxAgeDays) {
      try {
        fs.unlinkSync(file.path);
        deleted++;
        freedBytes += file.size;
      } catch {
        // File may be locked or already deleted
      }
    } else {
      kept++;
    }
  }

  return { deleted, freedBytes, kept };
}

/** Print help for cleanup command */
function printHelp(): void {
  console.log('');
  console.log('Usage: ccs cleanup [options]');
  console.log('');
  console.log('Remove old CLIProxy logs to free up disk space.');
  console.log('');
  console.log('Options:');
  console.log('  --errors      Clean error request logs (error-*.log files)');
  console.log('  --days=N      Delete error logs older than N days (default: 7)');
  console.log('  --dry-run     Show what would be deleted without deleting');
  console.log('  --force       Skip confirmation prompt');
  console.log('  --help, -h    Show this help message');
  console.log('');
  console.log('Examples:');
  console.log('  ccs cleanup              Interactive main log cleanup');
  console.log('  ccs cleanup --errors     Clean error logs older than 7 days');
  console.log('  ccs cleanup --errors --days=3   Clean error logs older than 3 days');
  console.log('  ccs cleanup --errors --dry-run  Preview error log cleanup');
  console.log('  ccs cleanup --dry-run    Preview main log cleanup');
  console.log('  ccs cleanup --force      Clean main logs without confirmation');
  console.log('');
}

/**
 * Handle cleanup command
 */
export async function handleCleanupCommand(args: string[]): Promise<void> {
  // Handle help
  if (args.includes('--help') || args.includes('-h')) {
    printHelp();
    return;
  }

  const dryRun = args.includes('--dry-run');
  const force = args.includes('--force');
  const cleanErrors = args.includes('--errors');
  const logsDir = getLogsDir();

  // Parse --days=N option
  let maxAgeDays = DEFAULT_ERROR_LOG_AGE_DAYS;
  const daysArg = args.find((arg) => arg.startsWith('--days='));
  if (daysArg) {
    const parsed = parseInt(daysArg.split('=')[1], 10);
    if (isNaN(parsed) || parsed < 1) {
      console.log(warn('Invalid --days value. Must be a positive integer.'));
      return;
    }
    maxAgeDays = parsed;
  }

  // Route to error log cleanup or main log cleanup
  if (cleanErrors) {
    await handleErrorLogCleanup(logsDir, maxAgeDays, dryRun, force);
  } else {
    await handleMainLogCleanup(logsDir, dryRun, force);
  }
}

/**
 * Handle error log cleanup (error-*.log files)
 */
async function handleErrorLogCleanup(
  logsDir: string,
  maxAgeDays: number,
  dryRun: boolean,
  force: boolean
): Promise<void> {
  // Check if logs directory exists
  if (!fs.existsSync(logsDir)) {
    console.log(info('No CLIProxy logs directory found.'));
    return;
  }

  // Get error log files
  const errorLogs = getErrorLogFiles(logsDir);
  if (errorLogs.length === 0) {
    console.log(info('No error logs found.'));
    return;
  }

  // Calculate what would be deleted
  const toDelete = errorLogs.filter((f) => f.ageInDays >= maxAgeDays);
  const toKeep = errorLogs.filter((f) => f.ageInDays < maxAgeDays);
  const totalDeleteSize = toDelete.reduce((sum, f) => sum + f.size, 0);

  console.log('');
  console.log(`Error Logs: ${logsDir}`);
  console.log(`  Total:    ${errorLogs.length} files`);
  console.log(
    `  To delete: ${toDelete.length} files older than ${maxAgeDays} days (${formatBytes(totalDeleteSize)})`
  );
  console.log(`  To keep:   ${toKeep.length} files newer than ${maxAgeDays} days`);
  console.log('');

  if (toDelete.length === 0) {
    console.log(info(`No error logs older than ${maxAgeDays} days.`));
    return;
  }

  // Show oldest files in dry-run or verbose mode
  if (dryRun || toDelete.length <= 5) {
    console.log('Files to delete:');
    for (const file of toDelete.slice(0, 10)) {
      console.log(`  ${file.name} (${file.ageInDays}d old, ${formatBytes(file.size)})`);
    }
    if (toDelete.length > 10) {
      console.log(`  ... and ${toDelete.length - 10} more`);
    }
    console.log('');
  }

  if (dryRun) {
    console.log(info('Dry run - no files deleted.'));
    return;
  }

  // Confirm unless --force
  if (!force) {
    const readline = await import('readline');
    const rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
    });

    const answer = await new Promise<string>((resolve) => {
      rl.question(
        `Delete ${toDelete.length} error logs older than ${maxAgeDays} days (${formatBytes(totalDeleteSize)})? [y/N] `,
        resolve
      );
    });
    rl.close();

    if (answer.toLowerCase() !== 'y') {
      console.log('Cancelled.');
      return;
    }
  }

  // Perform cleanup
  const { deleted, freedBytes, kept } = cleanErrorLogs(logsDir, maxAgeDays);
  console.log(ok(`Deleted ${deleted} error logs, freed ${formatBytes(freedBytes)}`));
  if (kept > 0) {
    console.log(info(`Kept ${kept} recent error logs (less than ${maxAgeDays} days old)`));
  }
}

/**
 * Handle main log cleanup (main.log and rotated files)
 */
async function handleMainLogCleanup(
  logsDir: string,
  dryRun: boolean,
  force: boolean
): Promise<void> {
  // Check if logs directory exists
  if (!fs.existsSync(logsDir)) {
    console.log(info('No CLIProxy logs found.'));
    return;
  }

  // Calculate current size
  const currentSize = getDirSize(logsDir);
  const fileCount = countFiles(logsDir);

  if (fileCount === 0) {
    console.log(info('No log files to clean.'));
    return;
  }

  console.log('');
  console.log(`CLIProxy Logs: ${logsDir}`);
  console.log(`  Files: ${fileCount}`);
  console.log(`  Size:  ${formatBytes(currentSize)}`);
  console.log('');

  if (dryRun) {
    console.log(info('Dry run - no files deleted.'));
    console.log(`Would delete ${fileCount} files (${formatBytes(currentSize)})`);
    return;
  }

  // Confirm unless --force
  if (!force) {
    const readline = await import('readline');
    const rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
    });

    const answer = await new Promise<string>((resolve) => {
      rl.question(`Delete ${fileCount} log files (${formatBytes(currentSize)})? [y/N] `, resolve);
    });
    rl.close();

    if (answer.toLowerCase() !== 'y') {
      console.log('Cancelled.');
      return;
    }
  }

  // Perform cleanup
  const { deleted, freedBytes } = cleanDirectory(logsDir);
  console.log(ok(`Deleted ${deleted} files, freed ${formatBytes(freedBytes)}`));

  // Suggest disabling logging if it was enabled
  if (deleted > 0) {
    console.log('');
    console.log(warn('Tip: CLIProxy logging is now disabled by default.'));
    console.log('     Run `ccs doctor --fix` to update your config.');
  }
}