/**
 * Directory builder for fluent directory operations
 */

import * as crypto from 'crypto';
import type { ISmartFsProvider } from '../interfaces/mod.provider.js';
import type {
  TFileMode,
  IFileStats,
  IDirectoryEntry,
  IListOptions,
  ITreeHashOptions,
} from '../interfaces/mod.types.js';

/**
 * Directory builder class for fluent directory operations
 * Configuration methods return `this` for chaining
 * Action methods return Promises for execution
 */
export class SmartFsDirectory {
  private provider: ISmartFsProvider;
  private path: string;

  // Configuration options
  private options: {
    recursive?: boolean;
    mode?: TFileMode;
    filter?: string | RegExp | ((entry: IDirectoryEntry) => boolean);
    includeStats?: boolean;
    // Copy/move options
    applyFilter?: boolean;
    overwrite?: boolean;
    preserveTimestamps?: boolean;
    onConflict?: 'merge' | 'error' | 'replace';
  } = {
    // Defaults for copy/move
    applyFilter: true,
    overwrite: false,
    preserveTimestamps: false,
    onConflict: 'merge',
  };

  constructor(provider: ISmartFsProvider, path: string) {
    this.provider = provider;
    this.path = this.provider.normalizePath(path);
  }

  // --- Configuration Methods (return this for chaining) ---

  /**
   * Enable recursive operations (for list, create, delete)
   */
  public recursive(): this {
    this.options.recursive = true;
    return this;
  }

  /**
   * Set directory permissions/mode
   * @param mode - Directory mode (e.g., 0o755)
   */
  public mode(mode: TFileMode): this {
    this.options.mode = mode;
    return this;
  }

  /**
   * Filter directory entries
   * @param filter - String pattern, RegExp, or filter function
   *
   * @example
   * ```typescript
   * // String pattern (glob-like)
   * .filter('*.ts')
   *
   * // RegExp
   * .filter(/\.ts$/)
   *
   * // Function
   * .filter(entry => entry.isFile && entry.name.endsWith('.ts'))
   * ```
   */
  public filter(filter: string | RegExp | ((entry: IDirectoryEntry) => boolean)): this {
    this.options.filter = filter;
    return this;
  }

  /**
   * Include file statistics in directory listings
   */
  public includeStats(): this {
    this.options.includeStats = true;
    return this;
  }

  /**
   * Control whether filter() is applied during copy/move operations
   * @param apply - If true, only copy/move files matching filter; if false, copy/move all files
   * @default true
   */
  public applyFilter(apply: boolean = true): this {
    this.options.applyFilter = apply;
    return this;
  }

  /**
   * Control whether to overwrite existing files during copy/move
   * @param overwrite - If true, overwrite existing files; if false, throw error on conflict
   * @default false
   */
  public overwrite(overwrite: boolean = true): this {
    this.options.overwrite = overwrite;
    return this;
  }

  /**
   * Control whether to preserve file timestamps during copy/move
   * @param preserve - If true, preserve original timestamps; if false, use current time
   * @default false
   */
  public preserveTimestamps(preserve: boolean = true): this {
    this.options.preserveTimestamps = preserve;
    return this;
  }

  /**
   * Control behavior when target directory already exists
   * @param behavior - 'merge' to merge contents, 'error' to throw, 'replace' to delete and recreate
   * @default 'merge'
   */
  public onConflict(behavior: 'merge' | 'error' | 'replace'): this {
    this.options.onConflict = behavior;
    return this;
  }

  // --- Action Methods (return Promises) ---

  /**
   * List directory contents
   * @returns Array of directory entries
   */
  public async list(): Promise<IDirectoryEntry[]> {
    const listOptions: IListOptions = {
      recursive: this.options.recursive,
      filter: this.options.filter,
      includeStats: this.options.includeStats,
    };
    return this.provider.listDirectory(this.path, listOptions);
  }

  /**
   * Create the directory
   */
  public async create(): Promise<void> {
    return this.provider.createDirectory(this.path, {
      recursive: this.options.recursive,
      mode: this.options.mode,
    });
  }

  /**
   * Delete the directory
   */
  public async delete(): Promise<void> {
    return this.provider.deleteDirectory(this.path, {
      recursive: this.options.recursive,
    });
  }

  /**
   * Check if the directory exists
   * @returns True if directory exists
   */
  public async exists(): Promise<boolean> {
    return this.provider.directoryExists(this.path);
  }

  /**
   * Get directory statistics
   * @returns Directory stats
   */
  public async stat(): Promise<IFileStats> {
    return this.provider.directoryStat(this.path);
  }

  /**
   * Copy the directory to a new location
   * @param targetPath - Destination path
   *
   * @example
   * ```typescript
   * // Basic copy
   * await fs.directory('/source').copy('/target');
   *
   * // Copy with options
   * await fs.directory('/source')
   *   .recursive()
   *   .filter('*.ts')
   *   .overwrite(true)
   *   .preserveTimestamps(true)
   *   .copy('/target');
   *
   * // Copy all files (ignore filter)
   * await fs.directory('/source')
   *   .applyFilter(false)
   *   .copy('/target');
   * ```
   */
  public async copy(targetPath: string): Promise<void> {
    const normalizedTarget = this.provider.normalizePath(targetPath);

    // Handle conflict behavior
    const targetExists = await this.provider.directoryExists(normalizedTarget);
    if (targetExists) {
      if (this.options.onConflict === 'error') {
        throw new Error(`EEXIST: directory already exists: ${normalizedTarget}`);
      }
      if (this.options.onConflict === 'replace') {
        await this.provider.deleteDirectory(normalizedTarget, { recursive: true });
      }
      // 'merge' (default) - continue and overwrite based on file settings
    }

    // Create target directory
    await this.provider.createDirectory(normalizedTarget, { recursive: true });

    // List entries (always recursive for copy, respects filter based on applyFilter option)
    const listOptions: IListOptions = {
      recursive: true,
      filter: this.options.applyFilter ? this.options.filter : undefined,
      includeStats: false,
    };
    const entries = await this.provider.listDirectory(this.path, listOptions);

    // Process entries - sort to ensure directories are created before their contents
    const sortedEntries = entries.sort((a, b) => a.path.localeCompare(b.path));

    for (const entry of sortedEntries) {
      const relativePath = entry.path.substring(this.path.length);
      const targetEntryPath = this.provider.joinPath(normalizedTarget, relativePath);

      if (entry.isDirectory) {
        await this.provider.createDirectory(targetEntryPath, { recursive: true });
      } else {
        // Ensure parent directory exists
        const parentPath = targetEntryPath.substring(0, targetEntryPath.lastIndexOf('/'));
        if (parentPath && parentPath !== normalizedTarget) {
          await this.provider.createDirectory(parentPath, { recursive: true });
        }
        // Copy file using provider
        await this.provider.copyFile(entry.path, targetEntryPath, {
          preserveTimestamps: this.options.preserveTimestamps,
          overwrite: this.options.overwrite,
        });
      }
    }
  }

  /**
   * Move the directory to a new location
   * @param targetPath - Destination path
   *
   * @example
   * ```typescript
   * // Basic move
   * await fs.directory('/source').move('/target');
   *
   * // Move with conflict handling
   * await fs.directory('/source')
   *   .onConflict('replace')
   *   .move('/target');
   * ```
   */
  public async move(targetPath: string): Promise<void> {
    // Copy first using current configuration
    await this.copy(targetPath);

    // Delete source (always recursive, regardless of filter - this matches mv behavior)
    await this.provider.deleteDirectory(this.path, { recursive: true });
  }

  /**
   * Get the directory path
   */
  public getPath(): string {
    return this.path;
  }

  /**
   * Compute a hash of all files in the directory tree
   * Uses configured filter and recursive options
   * @param options - Hash options (algorithm defaults to 'sha256')
   * @returns Hex-encoded hash string
   *
   * @example
   * ```typescript
   * // Hash all files recursively
   * const hash = await fs.directory('/assets').recursive().treeHash();
   *
   * // Hash only TypeScript files
   * const hash = await fs.directory('/src').filter('*.ts').recursive().treeHash();
   *
   * // Use different algorithm
   * const hash = await fs.directory('/data').recursive().treeHash({ algorithm: 'sha512' });
   * ```
   */
  public async treeHash(options?: ITreeHashOptions): Promise<string> {
    const { algorithm = 'sha256' } = options ?? {};
    const hash = crypto.createHash(algorithm);

    // Get all entries using existing filter/recursive configuration
    const entries = await this.list();

    // Filter to files only and sort by path for deterministic ordering
    const files = entries
      .filter((entry) => entry.isFile)
      .sort((a, b) => a.path.localeCompare(b.path));

    // Hash each file's relative path and contents
    for (const file of files) {
      // Compute relative path from directory root
      const relativePath = file.path.slice(this.path.length + 1);

      // Hash the relative path (with null separator)
      hash.update(relativePath + '\0');

      // Stream file contents and update hash incrementally
      const stream = await this.provider.createReadStream(file.path);
      const reader = stream.getReader();
      while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        hash.update(value);
      }
    }

    return hash.digest('hex');
  }
}