/**
 * Node.js filesystem provider for SmartFS
 * Uses Node.js fs/promises and fs.watch APIs
 */

import * as fs from 'fs/promises';
import * as fsSync from 'fs';
import * as pathModule from 'path';
import { Readable, Writable } from 'stream';

import type {
  ISmartFsProvider,
  IProviderCapabilities,
  TWatchCallback,
  IWatcherHandle,
} from '../interfaces/mod.provider.js';

import type {
  IFileStats,
  IDirectoryEntry,
  IReadOptions,
  IWriteOptions,
  IStreamOptions,
  ICopyOptions,
  IListOptions,
  IWatchOptions,
  ITransactionOperation,
  IWatchEvent,
  TWatchEventType,
} from '../interfaces/mod.types.js';

/**
 * Node.js filesystem provider
 */
export class SmartFsProviderNode implements ISmartFsProvider {
  public readonly name = 'node';

  public readonly capabilities: IProviderCapabilities = {
    supportsWatch: true,
    supportsAtomic: true,
    supportsTransactions: true,
    supportsStreaming: true,
    supportsSymlinks: true,
    supportsPermissions: true,
  };

  // --- File Operations ---

  public async readFile(path: string, options?: IReadOptions): Promise<Buffer | string> {
    const encoding = options?.encoding === 'buffer' ? undefined : (options?.encoding as BufferEncoding);
    if (encoding) {
      return fs.readFile(path, { encoding });
    }
    return fs.readFile(path);
  }

  public async writeFile(path: string, content: string | Buffer, options?: IWriteOptions): Promise<void> {
    const encoding = options?.encoding === 'buffer' ? undefined : (options?.encoding as BufferEncoding);
    const mode = options?.mode;

    if (options?.atomic) {
      // Atomic write: write to temp file, then rename
      const tempPath = `${path}.tmp.${Date.now()}.${Math.random().toString(36).slice(2)}`;
      try {
        await fs.writeFile(tempPath, content, { encoding, mode });
        await fs.rename(tempPath, path);
      } catch (error) {
        // Clean up temp file on error
        try {
          await fs.unlink(tempPath);
        } catch {
          // Ignore cleanup errors
        }
        throw error;
      }
    } else {
      await fs.writeFile(path, content, { encoding, mode });
    }
  }

  public async appendFile(path: string, content: string | Buffer, options?: IWriteOptions): Promise<void> {
    const encoding = options?.encoding === 'buffer' ? undefined : (options?.encoding as BufferEncoding);
    const mode = options?.mode;
    await fs.appendFile(path, content, { encoding, mode });
  }

  public async deleteFile(path: string): Promise<void> {
    await fs.unlink(path);
  }

  public async copyFile(from: string, to: string, options?: ICopyOptions): Promise<void> {
    // Copy the file
    await fs.copyFile(from, to);

    // Preserve timestamps if requested
    if (options?.preserveTimestamps) {
      const stats = await fs.stat(from);
      await fs.utimes(to, stats.atime, stats.mtime);
    }
  }

  public async moveFile(from: string, to: string, options?: ICopyOptions): Promise<void> {
    try {
      // Try rename first (fastest if on same filesystem)
      await fs.rename(from, to);

      // Preserve timestamps if requested
      if (options?.preserveTimestamps) {
        const stats = await fs.stat(to);
        await fs.utimes(to, stats.atime, stats.mtime);
      }
    } catch (error: any) {
      if (error.code === 'EXDEV') {
        // Cross-device move: copy then delete
        await this.copyFile(from, to, options);
        await this.deleteFile(from);
      } else {
        throw error;
      }
    }
  }

  public async fileExists(path: string): Promise<boolean> {
    try {
      await fs.access(path);
      return true;
    } catch {
      return false;
    }
  }

  public async fileStat(path: string): Promise<IFileStats> {
    const stats = await fs.stat(path);
    return this.convertStats(stats);
  }

  public async createReadStream(path: string, options?: IStreamOptions): Promise<ReadableStream<Uint8Array>> {
    const nodeStream = fsSync.createReadStream(path, {
      highWaterMark: options?.chunkSize || options?.highWaterMark,
    });

    return this.nodeReadableToWeb(nodeStream);
  }

  public async createWriteStream(path: string, options?: IStreamOptions): Promise<WritableStream<Uint8Array>> {
    const nodeStream = fsSync.createWriteStream(path, {
      highWaterMark: options?.chunkSize || options?.highWaterMark,
    });

    return this.nodeWritableToWeb(nodeStream);
  }

  // --- Directory Operations ---

  public async listDirectory(path: string, options?: IListOptions): Promise<IDirectoryEntry[]> {
    const entries: IDirectoryEntry[] = [];

    if (options?.recursive) {
      await this.listDirectoryRecursive(path, entries, options);
    } else {
      const dirents = await fs.readdir(path, { withFileTypes: true });

      for (const dirent of dirents) {
        const entryPath = pathModule.join(path, dirent.name);
        const entry: IDirectoryEntry = {
          name: dirent.name,
          path: entryPath,
          isFile: dirent.isFile(),
          isDirectory: dirent.isDirectory(),
          isSymbolicLink: dirent.isSymbolicLink(),
        };

        // Apply filter
        if (options?.filter && !this.matchesFilter(entry, options.filter)) {
          continue;
        }

        // Add stats if requested
        if (options?.includeStats) {
          try {
            entry.stats = await this.fileStat(entryPath);
          } catch {
            // Ignore stat errors
          }
        }

        entries.push(entry);
      }
    }

    return entries;
  }

  private async listDirectoryRecursive(
    path: string,
    entries: IDirectoryEntry[],
    options?: IListOptions,
  ): Promise<void> {
    const dirents = await fs.readdir(path, { withFileTypes: true });

    for (const dirent of dirents) {
      const entryPath = pathModule.join(path, dirent.name);
      const entry: IDirectoryEntry = {
        name: dirent.name,
        path: entryPath,
        isFile: dirent.isFile(),
        isDirectory: dirent.isDirectory(),
        isSymbolicLink: dirent.isSymbolicLink(),
      };

      // Apply filter
      if (options?.filter && !this.matchesFilter(entry, options.filter)) {
        // Skip this entry but continue recursion for directories
        if (dirent.isDirectory()) {
          await this.listDirectoryRecursive(entryPath, entries, options);
        }
        continue;
      }

      // Add stats if requested
      if (options?.includeStats) {
        try {
          entry.stats = await this.fileStat(entryPath);
        } catch {
          // Ignore stat errors
        }
      }

      entries.push(entry);

      // Recurse into subdirectories
      if (dirent.isDirectory()) {
        await this.listDirectoryRecursive(entryPath, entries, options);
      }
    }
  }

  public async createDirectory(path: string, options?: { recursive?: boolean; mode?: number }): Promise<void> {
    await fs.mkdir(path, {
      recursive: options?.recursive,
      mode: options?.mode,
    });
  }

  public async deleteDirectory(path: string, options?: { recursive?: boolean }): Promise<void> {
    await fs.rm(path, {
      recursive: options?.recursive ?? true,
      force: true,
    });
  }

  public async directoryExists(path: string): Promise<boolean> {
    try {
      const stats = await fs.stat(path);
      return stats.isDirectory();
    } catch {
      return false;
    }
  }

  public async directoryStat(path: string): Promise<IFileStats> {
    const stats = await fs.stat(path);
    return this.convertStats(stats);
  }

  // --- Watch Operations ---

  public async watch(path: string, callback: TWatchCallback, options?: IWatchOptions): Promise<IWatcherHandle> {
    const watcher = fsSync.watch(
      path,
      {
        recursive: options?.recursive,
      },
      async (eventType, filename) => {
        if (!filename) return;

        const fullPath = pathModule.join(path, filename);

        // Apply filter
        if (options?.filter && !this.matchesPathFilter(fullPath, options.filter)) {
          return;
        }

        // Determine event type
        let type: TWatchEventType = 'change';
        try {
          await fs.access(fullPath);
          type = eventType === 'rename' ? 'add' : 'change';
        } catch {
          type = 'delete';
        }

        // Get stats if available
        let stats: IFileStats | undefined;
        if (type !== 'delete') {
          try {
            stats = await this.fileStat(fullPath);
          } catch {
            // Ignore stat errors
          }
        }

        const event: IWatchEvent = {
          type,
          path: fullPath,
          timestamp: new Date(),
          stats,
        };

        await callback(event);
      },
    );

    return {
      stop: async () => {
        watcher.close();
      },
    };
  }

  // --- Transaction Operations ---

  public async prepareTransaction(operations: ITransactionOperation[]): Promise<ITransactionOperation[]> {
    const prepared: ITransactionOperation[] = [];

    for (const op of operations) {
      const preparedOp = { ...op };

      // Create backup for rollback
      try {
        const exists = await this.fileExists(op.path);
        if (exists) {
          const content = await this.readFile(op.path);
          const stats = await this.fileStat(op.path);
          preparedOp.backup = {
            existed: true,
            content: Buffer.isBuffer(content) ? content : Buffer.from(content),
            stats,
          };
        } else {
          preparedOp.backup = {
            existed: false,
          };
        }
      } catch {
        preparedOp.backup = {
          existed: false,
        };
      }

      prepared.push(preparedOp);
    }

    return prepared;
  }

  public async executeTransaction(operations: ITransactionOperation[]): Promise<void> {
    for (const op of operations) {
      try {
        switch (op.type) {
          case 'write':
            await this.writeFile(op.path, op.content!, { encoding: op.encoding });
            break;
          case 'append':
            await this.appendFile(op.path, op.content!, { encoding: op.encoding });
            break;
          case 'delete':
            await this.deleteFile(op.path);
            break;
          case 'copy':
            await this.copyFile(op.path, op.targetPath!);
            break;
          case 'move':
            await this.moveFile(op.path, op.targetPath!);
            break;
        }
      } catch (error) {
        // On error, rollback the transaction
        await this.rollbackTransaction(operations);
        throw error;
      }
    }
  }

  public async rollbackTransaction(operations: ITransactionOperation[]): Promise<void> {
    // Rollback in reverse order
    for (let i = operations.length - 1; i >= 0; i--) {
      const op = operations[i];
      if (!op.backup) continue;

      try {
        if (op.backup.existed && op.backup.content) {
          // Restore original content
          await this.writeFile(op.path, op.backup.content);
        } else if (!op.backup.existed) {
          // Delete file that was created
          try {
            await this.deleteFile(op.path);
          } catch {
            // Ignore errors
          }
        }
      } catch {
        // Ignore rollback errors
      }
    }
  }

  // --- Path Operations ---

  public normalizePath(path: string): string {
    return pathModule.normalize(path);
  }

  public joinPath(...segments: string[]): string {
    return pathModule.join(...segments);
  }

  // --- Helper Methods ---

  private convertStats(stats: fsSync.Stats): IFileStats {
    return {
      size: stats.size,
      birthtime: stats.birthtime,
      mtime: stats.mtime,
      atime: stats.atime,
      isFile: stats.isFile(),
      isDirectory: stats.isDirectory(),
      isSymbolicLink: stats.isSymbolicLink(),
      mode: stats.mode,
    };
  }

  private matchesFilter(
    entry: IDirectoryEntry,
    filter: string | RegExp | ((entry: IDirectoryEntry) => boolean),
  ): boolean {
    if (typeof filter === 'function') {
      return filter(entry);
    } else if (filter instanceof RegExp) {
      return filter.test(entry.name);
    } else {
      // Simple glob-like pattern matching
      const pattern = filter.replace(/\*/g, '.*');
      const regex = new RegExp(`^${pattern}$`);
      return regex.test(entry.name);
    }
  }

  private matchesPathFilter(
    path: string,
    filter: string | RegExp | ((path: string) => boolean),
  ): boolean {
    if (typeof filter === 'function') {
      return filter(path);
    } else if (filter instanceof RegExp) {
      return filter.test(path);
    } else {
      // Simple glob-like pattern matching
      const pattern = filter.replace(/\*/g, '.*');
      const regex = new RegExp(`^${pattern}$`);
      return regex.test(path);
    }
  }

  // --- Stream Conversion Helpers ---

  private nodeReadableToWeb(nodeStream: Readable): ReadableStream<Uint8Array> {
    return new ReadableStream({
      start(controller) {
        nodeStream.on('data', (chunk: Buffer) => {
          controller.enqueue(new Uint8Array(chunk));
        });

        nodeStream.on('end', () => {
          controller.close();
        });

        nodeStream.on('error', (error) => {
          controller.error(error);
        });
      },
      cancel() {
        nodeStream.destroy();
      },
    });
  }

  private nodeWritableToWeb(nodeStream: Writable): WritableStream<Uint8Array> {
    return new WritableStream({
      write(chunk) {
        return new Promise((resolve, reject) => {
          const canContinue = nodeStream.write(Buffer.from(chunk));
          if (canContinue) {
            resolve();
          } else {
            nodeStream.once('drain', resolve);
            nodeStream.once('error', reject);
          }
        });
      },
      close() {
        return new Promise((resolve, reject) => {
          nodeStream.end();
          nodeStream.once('finish', resolve);
          nodeStream.once('error', reject);
        });
      },
      abort(reason) {
        nodeStream.destroy(new Error(reason));
      },
    });
  }
}