/**
 * Rust filesystem provider for SmartFS
 * Uses a Rust binary via smartrust IPC for XFS-safe filesystem operations.
 * All metadata-changing operations (rename, unlink, create) fsync the parent
 * directory, guaranteeing durability on XFS and other delayed-logging filesystems.
 */

import * as plugins from '../smartfs.plugins.js';
import { fileURLToPath } from 'node:url';

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

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

// ── IPC command type map ────────────────────────────────────────────────────

interface IFileStatsJson {
  size: number;
  birthtime: string;
  mtime: string;
  atime: string;
  isFile: boolean;
  isDirectory: boolean;
  isSymbolicLink: boolean;
  mode: number;
}

interface IDirectoryEntryJson {
  name: string;
  path: string;
  isFile: boolean;
  isDirectory: boolean;
  isSymbolicLink: boolean;
  stats?: IFileStatsJson;
}

interface IBatchOp {
  type: string;
  path: string;
  targetPath?: string;
  content?: string;
  encoding?: string;
  atomic?: boolean;
  mode?: number;
  overwrite?: boolean;
  recursive?: boolean;
}

interface IBatchResult {
  index: number;
  success: boolean;
  error?: string;
}

interface ITransactionOpJson {
  type: string;
  path: string;
  targetPath?: string;
  content?: string;
  encoding?: string;
}

type TSmartFsCommands = {
  readFile: { params: { path: string; encoding?: string }; result: { content: string; isBuffer?: boolean } };
  writeFile: { params: { path: string; content: string; atomic?: boolean; mode?: number; encoding?: string }; result: void };
  appendFile: { params: { path: string; content: string; encoding?: string }; result: void };
  deleteFile: { params: { path: string }; result: void };
  copyFile: { params: { from: string; to: string; overwrite?: boolean; preserveTimestamps?: boolean }; result: void };
  moveFile: { params: { from: string; to: string; overwrite?: boolean; preserveTimestamps?: boolean }; result: void };
  fileExists: { params: { path: string }; result: boolean };
  fileStat: { params: { path: string }; result: IFileStatsJson };
  listDirectory: { params: { path: string; recursive?: boolean; includeStats?: boolean; filter?: string }; result: IDirectoryEntryJson[] };
  createDirectory: { params: { path: string; recursive?: boolean; mode?: number }; result: void };
  deleteDirectory: { params: { path: string; recursive?: boolean }; result: void };
  directoryExists: { params: { path: string }; result: boolean };
  directoryStat: { params: { path: string }; result: IFileStatsJson };
  watch: { params: { path: string; id: string; recursive?: boolean }; result: void };
  unwatchAll: { params: Record<string, never>; result: void };
  batch: { params: { operations: IBatchOp[] }; result: IBatchResult[] };
  executeTransaction: { params: { operations: ITransactionOpJson[] }; result: void };
  normalizePath: { params: { path: string }; result: string };
  joinPath: { params: { segments: string[] }; result: string };
  readFileStream: { params: { path: string; chunkSize?: number }; result: { totalBytes: number }; chunk: string };
  writeStreamBegin: { params: { path: string; atomic?: boolean; mode?: number }; result: { streamId: string } };
  writeStreamChunk: { params: { streamId: string; data: string; last: boolean }; result: void };
  ping: { params: Record<string, never>; result: { pong: boolean } };
};

// ── Provider class ──────────────────────────────────────────────────────────

export class SmartFsProviderRust implements ISmartFsProvider {
  public readonly name = 'rust';

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

  private bridge: plugins.smartrust.RustBridge<TSmartFsCommands>;
  private initialized = false;
  private watchCallbacks = new Map<string, TWatchCallback>();
  private watchCounter = 0;

  constructor(options?: { binaryPath?: string }) {
    // Build search paths for the binary
    const localPaths: string[] = [];
    const currentDir = plugins.path.dirname(fileURLToPath(import.meta.url));
    const packageDir = plugins.path.resolve(currentDir, '../../');

    // Check dist_rust/ first (production), then rust/target/ (development)
    const suffix = SmartFsProviderRust.getPlatformSuffix();
    if (suffix) {
      localPaths.push(plugins.path.join(packageDir, 'dist_rust', `smartfs-bin_${suffix}`));
    }
    localPaths.push(plugins.path.join(packageDir, 'dist_rust', 'smartfs-bin'));
    localPaths.push(plugins.path.join(packageDir, 'rust', 'target', 'release', 'smartfs-bin'));
    localPaths.push(plugins.path.join(packageDir, 'rust', 'target', 'debug', 'smartfs-bin'));

    this.bridge = new plugins.smartrust.RustBridge<TSmartFsCommands>({
      binaryName: 'smartfs-bin',
      cliArgs: ['--management'],
      requestTimeoutMs: 30_000,
      readyTimeoutMs: 10_000,
      localPaths,
      searchSystemPath: false,
      ...(options?.binaryPath ? { binaryPath: options.binaryPath } : {}),
    });

    // Listen for watch events from Rust
    this.bridge.on('management:watch', (data: any) => {
      // Event name is "watch:<id>", data contains the watch event
      // The smartrust bridge strips the "management:" prefix
    });
  }

  private static getPlatformSuffix(): string | null {
    const archMap: Record<string, string> = { x64: 'amd64', arm64: 'arm64' };
    const os = process.platform;
    const arch = archMap[process.arch];
    if (!arch) return null;
    return `${os}_${arch}`;
  }

  private async ensureRunning(): Promise<void> {
    if (!this.initialized) {
      const started = await this.bridge.spawn();
      if (!started) {
        throw new Error('SmartFsProviderRust: failed to start smartfs-bin');
      }
      this.initialized = true;

      // The bridge already inherits .on() from EventEmitter.
      // Watch events from Rust arrive as 'management:watch:<id>'.
    }
  }

  /**
   * Shut down the Rust binary.
   */
  public async shutdown(): Promise<void> {
    if (this.initialized) {
      this.bridge.kill();
      this.initialized = false;
    }
  }

  // ── File Operations ───────────────────────────────────────────────────

  public async readFile(path: string, options?: IReadOptions): Promise<Buffer | string> {
    await this.ensureRunning();
    const encoding = options?.encoding || 'utf8';
    const result = await this.bridge.sendCommand('readFile', { path, encoding });

    if (result.isBuffer) {
      // Decode base64 back to Buffer
      return Buffer.from(result.content, 'base64');
    }

    if (encoding === 'buffer') {
      return Buffer.from(result.content, 'base64');
    }

    return result.content;
  }

  public async writeFile(path: string, content: string | Buffer, options?: IWriteOptions): Promise<void> {
    await this.ensureRunning();
    const contentStr = Buffer.isBuffer(content) ? content.toString('base64') : content;
    const encoding = Buffer.isBuffer(content) ? 'base64' : (options?.encoding || undefined);

    await this.bridge.sendCommand('writeFile', {
      path,
      content: contentStr,
      atomic: options?.atomic,
      mode: options?.mode,
      encoding,
    });
  }

  public async appendFile(path: string, content: string | Buffer, options?: IWriteOptions): Promise<void> {
    await this.ensureRunning();
    const contentStr = Buffer.isBuffer(content) ? content.toString('base64') : content;
    const encoding = Buffer.isBuffer(content) ? 'base64' : (options?.encoding || undefined);

    await this.bridge.sendCommand('appendFile', {
      path,
      content: contentStr,
      encoding,
    });
  }

  public async deleteFile(path: string): Promise<void> {
    await this.ensureRunning();
    await this.bridge.sendCommand('deleteFile', { path });
  }

  public async copyFile(from: string, to: string, options?: ICopyOptions): Promise<void> {
    await this.ensureRunning();
    await this.bridge.sendCommand('copyFile', {
      from,
      to,
      overwrite: options?.overwrite,
      preserveTimestamps: options?.preserveTimestamps,
    });
  }

  public async moveFile(from: string, to: string, options?: ICopyOptions): Promise<void> {
    await this.ensureRunning();
    await this.bridge.sendCommand('moveFile', {
      from,
      to,
      overwrite: options?.overwrite,
      preserveTimestamps: options?.preserveTimestamps,
    });
  }

  public async fileExists(path: string): Promise<boolean> {
    await this.ensureRunning();
    return this.bridge.sendCommand('fileExists', { path });
  }

  public async fileStat(path: string): Promise<IFileStats> {
    await this.ensureRunning();
    const stats = await this.bridge.sendCommand('fileStat', { path });
    return this.convertStats(stats);
  }

  public async createReadStream(path: string, options?: IStreamOptions): Promise<ReadableStream<Uint8Array>> {
    await this.ensureRunning();
    const chunkSize = options?.chunkSize || options?.highWaterMark || 65536;

    const streaming = this.bridge.sendCommandStreaming('readFileStream', {
      path,
      chunkSize,
    });

    const iterator = streaming[Symbol.asyncIterator]();

    return new ReadableStream({
      async pull(controller) {
        const { value, done } = await iterator.next();
        if (done) {
          controller.close();
          return;
        }
        // value is a base64-encoded string chunk
        const buffer = Buffer.from(value as string, 'base64');
        controller.enqueue(new Uint8Array(buffer));
      },
    });
  }

  public async createWriteStream(path: string, options?: IStreamOptions): Promise<WritableStream<Uint8Array>> {
    await this.ensureRunning();
    const { streamId } = await this.bridge.sendCommand('writeStreamBegin', {
      path,
      atomic: undefined,
    });

    const bridge = this.bridge;
    return new WritableStream({
      async write(chunk) {
        const base64 = Buffer.from(chunk).toString('base64');
        await bridge.sendCommand('writeStreamChunk', {
          streamId,
          data: base64,
          last: false,
        });
      },
      async close() {
        await bridge.sendCommand('writeStreamChunk', {
          streamId,
          data: '',
          last: true,
        });
      },
    });
  }

  // ── Directory Operations ──────────────────────────────────────────────

  public async listDirectory(path: string, options?: IListOptions): Promise<IDirectoryEntry[]> {
    await this.ensureRunning();

    // Convert function filter to string pattern for IPC
    let filter: string | undefined;
    if (options?.filter) {
      if (typeof options.filter === 'string') {
        filter = options.filter;
      } else if (options.filter instanceof RegExp) {
        // Prefix with "regex:" so Rust treats it as a raw regex pattern
        filter = `regex:${options.filter.source}`;
      }
      // Function filters can't be serialized — filter client-side after receiving
    }

    const entries = await this.bridge.sendCommand('listDirectory', {
      path,
      recursive: options?.recursive,
      includeStats: options?.includeStats,
      filter,
    });

    let result: IDirectoryEntry[] = entries.map((e: any) => ({
      name: e.name,
      path: e.path,
      isFile: e.isFile,
      isDirectory: e.isDirectory,
      isSymbolicLink: e.isSymbolicLink,
      stats: e.stats ? this.convertStats(e.stats) : undefined,
    }));

    // Apply function filter client-side if needed
    if (typeof options?.filter === 'function') {
      result = result.filter(options.filter);
    }

    return result;
  }

  public async createDirectory(path: string, options?: { recursive?: boolean; mode?: number }): Promise<void> {
    await this.ensureRunning();
    await this.bridge.sendCommand('createDirectory', {
      path,
      recursive: options?.recursive ?? true,
      mode: options?.mode,
    });
  }

  public async deleteDirectory(path: string, options?: { recursive?: boolean }): Promise<void> {
    await this.ensureRunning();
    await this.bridge.sendCommand('deleteDirectory', {
      path,
      recursive: options?.recursive ?? true,
    });
  }

  public async directoryExists(path: string): Promise<boolean> {
    await this.ensureRunning();
    return this.bridge.sendCommand('directoryExists', { path });
  }

  public async directoryStat(path: string): Promise<IFileStats> {
    await this.ensureRunning();
    const stats = await this.bridge.sendCommand('directoryStat', { path });
    return this.convertStats(stats);
  }

  // ── Watch Operations ──────────────────────────────────────────────────

  public async watch(path: string, callback: TWatchCallback, options?: IWatchOptions): Promise<IWatcherHandle> {
    await this.ensureRunning();

    const watchId = `w_${++this.watchCounter}`;
    this.watchCallbacks.set(watchId, callback);

    // Listen for events from this watch
    const eventName = `management:watch:${watchId}`;
    this.bridge.on(eventName, async (data: any) => {
      const cb = this.watchCallbacks.get(watchId);
      if (!cb) return;

      // Apply filter
      if (options?.filter) {
        if (typeof options.filter === 'function') {
          if (!options.filter(data.path)) return;
        } else if (options.filter instanceof RegExp) {
          if (!options.filter.test(data.path)) return;
        } else if (typeof options.filter === 'string') {
          const pattern = options.filter.replace(/\*/g, '.*');
          if (!new RegExp(`^${pattern}$`).test(data.path)) return;
        }
      }

      await cb({
        type: data.type,
        path: data.path,
        timestamp: new Date(data.timestamp),
        stats: data.stats ? this.convertStats(data.stats) : undefined,
      });
    });

    await this.bridge.sendCommand('watch', {
      path,
      id: watchId,
      recursive: options?.recursive,
    });

    return {
      stop: async () => {
        this.watchCallbacks.delete(watchId);
        this.bridge.removeAllListeners(eventName);
      },
    };
  }

  // ── Transaction Operations ────────────────────────────────────────────

  public async prepareTransaction(operations: ITransactionOperation[]): Promise<ITransactionOperation[]> {
    // Prepare backups client-side by reading current state
    const prepared: ITransactionOperation[] = [];

    for (const op of operations) {
      const preparedOp = { ...op };
      try {
        const exists = await this.fileExists(op.path);
        if (exists) {
          const content = await this.readFile(op.path, { encoding: 'buffer' });
          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> {
    await this.ensureRunning();

    const opsJson: ITransactionOpJson[] = operations.map((op) => ({
      type: op.type,
      path: op.path,
      targetPath: op.targetPath,
      content: op.content ? (Buffer.isBuffer(op.content) ? op.content.toString('utf8') : op.content) : undefined,
      encoding: op.encoding,
    }));

    await this.bridge.sendCommand('executeTransaction', { operations: opsJson });
  }

  public async rollbackTransaction(operations: ITransactionOperation[]): Promise<void> {
    // Rollback in reverse order using backups
    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) {
          await this.writeFile(op.path, op.backup.content);
        } else if (!op.backup.existed) {
          try {
            await this.deleteFile(op.path);
          } catch {
            // Ignore
          }
        }
      } catch {
        // Ignore rollback errors
      }
    }
  }

  // ── Path Operations ───────────────────────────────────────────────────

  public normalizePath(path: string): string {
    // Path operations are synchronous in the interface, so use local implementation
    return plugins.path.normalize(path);
  }

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

  // ── Helpers ───────────────────────────────────────────────────────────

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

  private parseTimestamp(ts: string): Date {
    // Rust sends "<unix_secs>.<millis>Z" format
    if (ts.endsWith('Z') && ts.includes('.')) {
      const [secsStr, millisStr] = ts.slice(0, -1).split('.');
      const secs = parseInt(secsStr, 10);
      const millis = parseInt(millisStr, 10);
      return new Date(secs * 1000 + millis);
    }
    return new Date(ts);
  }
}