/**
 * Transaction builder for atomic multi-file operations
 */

import type { ISmartFsProvider } from '../interfaces/mod.provider.js';
import type { ITransactionOperation, TEncoding } from '../interfaces/mod.types.js';

/**
 * Transaction file operation builder
 * Allows chaining file operations within a transaction
 */
class TransactionFileBuilder {
  constructor(
    private transaction: SmartFsTransaction,
    private path: string,
  ) {}

  /**
   * Write content to the file in this transaction
   * @param content - Content to write
   * @param encoding - Optional encoding
   */
  public write(content: string | Buffer, encoding?: TEncoding): SmartFsTransaction {
    this.transaction.addOperation({
      type: 'write',
      path: this.path,
      content,
      encoding,
    });
    return this.transaction;
  }

  /**
   * Append content to the file in this transaction
   * @param content - Content to append
   * @param encoding - Optional encoding
   */
  public append(content: string | Buffer, encoding?: TEncoding): SmartFsTransaction {
    this.transaction.addOperation({
      type: 'append',
      path: this.path,
      content,
      encoding,
    });
    return this.transaction;
  }

  /**
   * Delete the file in this transaction
   */
  public delete(): SmartFsTransaction {
    this.transaction.addOperation({
      type: 'delete',
      path: this.path,
    });
    return this.transaction;
  }

  /**
   * Copy the file to a new location in this transaction
   * @param targetPath - Destination path
   */
  public copy(targetPath: string): SmartFsTransaction {
    this.transaction.addOperation({
      type: 'copy',
      path: this.path,
      targetPath,
    });
    return this.transaction;
  }

  /**
   * Move the file to a new location in this transaction
   * @param targetPath - Destination path
   */
  public move(targetPath: string): SmartFsTransaction {
    this.transaction.addOperation({
      type: 'move',
      path: this.path,
      targetPath,
    });
    return this.transaction;
  }
}

/**
 * Transaction builder class for atomic multi-file operations
 * Build up a set of operations, then commit atomically
 * Supports rollback on failure
 */
export class SmartFsTransaction {
  private provider: ISmartFsProvider;
  private operations: ITransactionOperation[] = [];
  private committed = false;
  private rolledBack = false;

  constructor(provider: ISmartFsProvider) {
    this.provider = provider;
  }

  /**
   * Add a file operation to the transaction
   * @param path - Path to the file
   * @returns TransactionFileBuilder for chaining operations
   *
   * @example
   * ```typescript
   * await fs.transaction()
   *   .file('/file1.txt').write('content1')
   *   .file('/file2.txt').delete()
   *   .commit()
   * ```
   */
  public file(path: string): TransactionFileBuilder {
    const normalizedPath = this.provider.normalizePath(path);
    return new TransactionFileBuilder(this, normalizedPath);
  }

  /**
   * Add an operation to the transaction (internal)
   */
  public addOperation(operation: ITransactionOperation): void {
    if (this.committed) {
      throw new Error('Cannot add operations to a committed transaction');
    }
    if (this.rolledBack) {
      throw new Error('Cannot add operations to a rolled back transaction');
    }
    this.operations.push(operation);
  }

  /**
   * Commit the transaction
   * All operations are executed atomically
   * If any operation fails, all operations are rolled back
   */
  public async commit(): Promise<void> {
    if (this.committed) {
      throw new Error('Transaction already committed');
    }
    if (this.rolledBack) {
      throw new Error('Cannot commit a rolled back transaction');
    }

    if (this.operations.length === 0) {
      this.committed = true;
      return;
    }

    try {
      // Prepare transaction (create backups for rollback)
      const preparedOperations = await this.provider.prepareTransaction(this.operations);
      this.operations = preparedOperations;

      // Execute the transaction
      await this.provider.executeTransaction(this.operations);

      this.committed = true;
    } catch (error) {
      // Rollback on error
      await this.rollback();
      throw error;
    }
  }

  /**
   * Rollback the transaction
   * Reverts all operations that have been executed
   */
  public async rollback(): Promise<void> {
    if (this.committed) {
      throw new Error('Cannot rollback a committed transaction');
    }
    if (this.rolledBack) {
      throw new Error('Transaction already rolled back');
    }

    if (this.operations.length === 0) {
      this.rolledBack = true;
      return;
    }

    await this.provider.rollbackTransaction(this.operations);
    this.rolledBack = true;
  }

  /**
   * Get all operations in the transaction
   */
  public getOperations(): readonly ITransactionOperation[] {
    return this.operations;
  }

  /**
   * Check if the transaction has been committed
   */
  public isCommitted(): boolean {
    return this.committed;
  }

  /**
   * Check if the transaction has been rolled back
   */
  public isRolledBack(): boolean {
    return this.rolledBack;
  }
}