import path from 'path';
import { promises as fsPromises } from 'fs';
import { NodeRegistry } from './NodeRegistry';

/**
 * Resolves the writable Sencho data directory (same one DatabaseService /
 * CryptoService use). Recomputed lazily so test harnesses that override
 * `process.env.DATA_DIR` after module load still take effect.
 */
function getBackupBaseDir(): string {
  const dataDir = process.env.DATA_DIR || path.join(process.cwd(), 'data');
  return path.join(dataDir, 'backups');
}

import { isDebugEnabled } from '../utils/debug';

/**
 * FileSystemService - local-only file I/O for compose stack management.
 *
 * In the Distributed API model, remote node file operations are handled
 * by the remote Sencho instance itself. This service only operates on
 * the local filesystem.
 */
export class FileSystemService {
  private baseDir: string;

  constructor(nodeId?: number) {
    this.baseDir = NodeRegistry.getInstance().getComposeDir(
      nodeId ?? NodeRegistry.getInstance().getDefaultNodeId()
    );
  }

  public static getInstance(nodeId?: number): FileSystemService {
    return new FileSystemService(nodeId);
  }

  async hasComposeFile(dir: string): Promise<boolean> {
    const composeFiles = ['compose.yaml', 'compose.yml', 'docker-compose.yaml', 'docker-compose.yml'];
    for (const file of composeFiles) {
      try {
        await fsPromises.access(path.join(dir, file));
        return true;
      } catch {
        // continue
      }
    }
    return false;
  }

  private async getComposeFilePath(stackName: string): Promise<string> {
    const stackDir = path.join(this.baseDir, stackName);
    const composeFiles = ['compose.yaml', 'compose.yml', 'docker-compose.yaml', 'docker-compose.yml'];
    for (const file of composeFiles) {
      const filePath = path.join(stackDir, file);
      try {
        await fsPromises.access(filePath);
        if (isDebugEnabled()) console.debug('[FileSystemService:debug] Resolved compose file', { stackName, file });
        return filePath;
      } catch {
        // continue
      }
    }
    throw new Error(`No compose file found for stack: ${stackName}`);
  }

  async getStacks(): Promise<string[]> {
    try {
      const items = await fsPromises.readdir(this.baseDir, { withFileTypes: true });
      const stackNames: string[] = [];

      for (const item of items) {
        if (!item.isDirectory()) continue;
        if (!item.name || typeof item.name !== 'string') continue;

        const stackDir = path.join(this.baseDir, item.name);
        if (await this.hasComposeFile(stackDir)) {
          stackNames.push(item.name);
        }
      }

      return stackNames;
    } catch (error: any) {
      console.warn(`[FileSystemService] Failed to list stacks: ${error.message}`);
      return [];
    }
  }

  async getStackContent(stackName: string): Promise<string> {
    try {
      const filePath = await this.getComposeFilePath(stackName);
      return await fsPromises.readFile(filePath, 'utf-8');
    } catch (error) {
      console.error('Error reading stack content:', error);
      throw new Error(`Failed to read stack: ${stackName}`);
    }
  }

  async saveStackContent(stackName: string, content: string): Promise<void> {
    const filePath = path.join(this.baseDir, stackName, 'compose.yaml');
    try {
      await fsPromises.writeFile(filePath, content, 'utf-8');
    } catch (error) {
      console.error('Error writing file:', error);
      throw new Error(`Failed to save stack: ${stackName}`);
    }
  }

  async envExists(stackName: string): Promise<boolean> {
    try {
      await fsPromises.access(path.join(this.baseDir, stackName, '.env'));
      return true;
    } catch {
      return false;
    }
  }

  async readFile(filePath: string, encoding: BufferEncoding = 'utf-8'): Promise<string> {
    return fsPromises.readFile(filePath, encoding);
  }

  async writeFile(filePath: string, content: string, encoding: BufferEncoding = 'utf-8'): Promise<void> {
    return fsPromises.writeFile(filePath, content, encoding);
  }

  async access(filePath: string): Promise<void> {
    return fsPromises.access(filePath);
  }

  async getEnvContent(stackName: string): Promise<string> {
    const envPath = path.join(this.baseDir, stackName, '.env');
    try {
      return await fsPromises.readFile(envPath, 'utf-8');
    } catch (error) {
      console.error('Error reading env file:', error);
      throw new Error(`Failed to read env file for stack: ${stackName}`);
    }
  }

  async saveEnvContent(stackName: string, content: string): Promise<void> {
    const envPath = path.join(this.baseDir, stackName, '.env');
    try {
      await fsPromises.writeFile(envPath, content, 'utf-8');
    } catch (error) {
      console.error('Error writing env file:', error);
      throw new Error(`Failed to save env file for stack: ${stackName}`);
    }
  }

  async createStack(stackName: string): Promise<void> {
    if (!stackName || !/^[a-zA-Z0-9_-]+$/.test(stackName)) {
      throw new Error('Stack name must contain only alphanumeric characters, underscores, or hyphens');
    }

    const stackDir = path.join(this.baseDir, stackName);

    try {
      await fsPromises.access(stackDir);
      throw new Error(`Stack "${stackName}" already exists`);
    } catch (error: any) {
      if (error.message.includes('already exists')) throw error;
    }

    await fsPromises.mkdir(stackDir, { recursive: true });

    const boilerplate = `services:
  app:
    image: nginx:latest
    ports:
      - "8080:80"
    restart: always
`;
    try {
      await fsPromises.writeFile(path.join(stackDir, 'compose.yaml'), boilerplate, 'utf-8');
    } catch (error) {
      console.error('Error creating stack:', error);
      throw new Error(`Failed to create stack: ${stackName}`);
    }
  }

  public async deleteStack(stackName: string): Promise<void> {
    const stackDir = path.join(this.baseDir, stackName);
    try {
      await fsPromises.rm(stackDir, { recursive: true, force: true });
    } catch (error: unknown) {
      const fsError = error as NodeJS.ErrnoException;
      if (fsError.code === 'ENOENT') return;
      console.error('Error deleting stack directory:', fsError.message);
      throw new Error(`Failed to delete stack directory: ${fsError.message}`);
    }
  }

  getBaseDir(): string {
    return this.baseDir;
  }

  async migrateFlatToDirectory(): Promise<void> {
    try {
      try {
        await fsPromises.access(this.baseDir);
      } catch {
        await fsPromises.mkdir(this.baseDir, { recursive: true });
        return;
      }

      const items = await fsPromises.readdir(this.baseDir, { withFileTypes: true });

      for (const item of items) {
        if (!item.isFile()) continue;
        if (!item.name.endsWith('.yml') && !item.name.endsWith('.yaml')) continue;

        const stackName = item.name.replace(/\.(yml|yaml)$/, '');
        const stackDir = path.join(this.baseDir, stackName);

        try {
          await fsPromises.access(stackDir);
          continue;
        } catch {
          // Directory doesn't exist, proceed
        }

        await fsPromises.mkdir(stackDir, { recursive: true });

        const oldComposePath = path.join(this.baseDir, item.name);
        const newComposePath = path.join(stackDir, 'compose.yaml');
        await fsPromises.rename(oldComposePath, newComposePath);

        const oldEnvPath = path.join(this.baseDir, `${stackName}.env`);
        const newEnvPath = path.join(stackDir, '.env');
        try {
          await fsPromises.access(oldEnvPath);
          await fsPromises.rename(oldEnvPath, newEnvPath);
        } catch (e: unknown) {
          const code = (e as NodeJS.ErrnoException)?.code;
          if (code !== 'ENOENT') {
            console.warn(`[FileSystemService] Could not migrate env file for ${stackName}:`, (e as Error).message);
          }
        }

      }
    } catch (error) {
      console.error('Migration error:', error);
    }
  }

  /**
   * Backup stack files (compose.yaml + .env) into Sencho's data dir.
   *
   * Backups live at <DATA_DIR>/backups/<stackName>/ (NOT inside the user's
   * compose folder) so the operation always succeeds even when the stack
   * folder is owned by another UID (e.g., a container running as root has
   * chowned its bind mount). DATA_DIR is the same writable location that
   * holds sencho.db and encryption.key.
   */
  async backupStackFiles(stackName: string): Promise<void> {
    const debug = isDebugEnabled();
    const t0 = Date.now();
    const stackDir = path.join(this.baseDir, stackName);
    const backupDir = path.join(getBackupBaseDir(), stackName);
    await fsPromises.mkdir(backupDir, { recursive: true });

    // Copy compose file
    const composeFiles = ['compose.yaml', 'compose.yml', 'docker-compose.yaml', 'docker-compose.yml'];
    for (const file of composeFiles) {
      const src = path.join(stackDir, file);
      try {
        await fsPromises.access(src);
        await fsPromises.copyFile(src, path.join(backupDir, file));
      } catch (e: unknown) {
        const code = (e as NodeJS.ErrnoException)?.code;
        if (code !== 'ENOENT') {
          console.warn(`[FileSystemService] Could not back up ${file}:`, (e as Error).message);
        }
      }
    }

    // Copy .env if it exists
    const envSrc = path.join(stackDir, '.env');
    try {
      await fsPromises.access(envSrc);
      await fsPromises.copyFile(envSrc, path.join(backupDir, '.env'));
    } catch (e: unknown) {
      const code = (e as NodeJS.ErrnoException)?.code;
      if (code !== 'ENOENT') {
        console.warn('[FileSystemService] Could not back up .env:', (e as Error).message);
      }
    }

    // Write timestamp marker
    await fsPromises.writeFile(path.join(backupDir, '.timestamp'), Date.now().toString(), 'utf-8');
    if (debug) console.debug(`[FileSystemService:debug] Backup completed in ${Date.now() - t0}ms`, { stackName });
  }

  async restoreStackFiles(stackName: string): Promise<void> {
    const debug = isDebugEnabled();
    const t0 = Date.now();
    const stackDir = path.join(this.baseDir, stackName);
    const backupDir = path.join(getBackupBaseDir(), stackName);

    const items = await fsPromises.readdir(backupDir);
    for (const item of items) {
      if (item === '.timestamp') continue;
      await fsPromises.copyFile(path.join(backupDir, item), path.join(stackDir, item));
    }
    if (debug) console.debug(`[FileSystemService:debug] Restore completed in ${Date.now() - t0}ms`, { stackName, files: items.filter(i => i !== '.timestamp') });
  }

  async getBackupInfo(stackName: string): Promise<{ exists: boolean; timestamp: number | null }> {
    const backupDir = path.join(getBackupBaseDir(), stackName);
    try {
      await fsPromises.access(backupDir);
      const tsFile = path.join(backupDir, '.timestamp');
      try {
        const ts = await fsPromises.readFile(tsFile, 'utf-8');
        return { exists: true, timestamp: parseInt(ts, 10) || null };
      } catch (e) {
        console.warn('[FileSystemService] Backup timestamp file unreadable:', (e as Error).message);
        return { exists: true, timestamp: null };
      }
    } catch {
      return { exists: false, timestamp: null };
    }
  }
}