/**
 * @angular-modernizer/plugin-angular - Form Modernization Transformation Rule
 *
 * Transform rule that modernizes Angular reactive forms to use current best practices.
 * This is part of the modernization to improve form handling and maintainability.
 *
 * Philosophy: "Thin Rule, Thick Orchestrator"
 * - The rule is a minimal wrapper
 * - All business logic lives in the orchestrator
 * - The rule handles the plugin protocol (TransformRule interface)
 */

import type {
  TransformRule,
  TransformContext,
  TransformResult,
} from '@angular-modernizer/plugin-system';
import type { PublicApi } from '@angular-modernizer/api';
import { FormModernizationOrchestrator } from '../orchestrators/form-modernization-orchestrator.js';

/**
 * Transform rule for modernizing Angular reactive forms.
 *
 * @remarks
 * This rule implements the {@link TransformRule} interface and serves as the
 * bridge between the Angular Modernizer's plugin system and the form
 * modernization orchestrator. It follows the "Thin Rule, Thick Orchestrator" pattern
 * where the rule handles protocol compliance while delegating all business logic
 * to the {@link FormModernizationOrchestrator}.
 *
 * ## What It Does
 *
 * The rule orchestrates the modernization of:
 * - **FormBuilder usage**: Updates deprecated patterns to modern syntax
 * - **FormControl/FormGroup initialization**: Modernizes form control creation
 * - **Form validation**: Updates validation patterns to current best practices
 * - **Form submission**: Modernizes form submission handling
 *
 * ## Example Usage
 *
 * This rule is typically not used directly, but rather accessed through the
 * {@link AngularPlugin}:
 *
 * ```typescript
 * const plugin = new AngularPlugin();
 * const rules = plugin.getTransformRules();
 * const rule = rules.find(r => r.id === 'angular:form-modernization');
 * const result = await rule.transform(context);
 * ```
 *
 * ## Transformation Behavior
 *
 * **FormBuilder Patterns**:
 * ```typescript
 * // Before
 * constructor(private fb: FormBuilder) {}
 * ngOnInit() {
 *   this.form = this.fb.group({
 *     name: ['', Validators.required],
 *     email: ['', [Validators.required, Validators.email]]
 *   });
 * }
 *
 * // After
 * form = new FormGroup({
 *   name: new FormControl('', Validators.required),
 *   email: new FormControl('', [Validators.required, Validators.email])
 * });
 * ```
 *
 * **FormControl Initialization**:
 * ```typescript
 * // Before
 * this.control = new FormControl(null);
 *
 * // After
 * this.control = new FormControl('');
 * ```
 *
 * @see {@link FormModernizationOrchestrator} for transformation logic
 * @see {@link TransformRule} for the interface contract
 * @see {@link AngularPlugin} for plugin integration
 *
 * @public
 */
export class FormModernizationRule implements TransformRule {
  /**
   * Unique rule identifier.
   * Format: "plugin-name:rule-name"
   */
  public readonly id = 'angular:form-modernization';

  /**
   * Human-readable rule name.
   */
  public readonly name = 'Form Modernization';

  /**
   * Rule description.
   */
  public readonly description =
    'Modernizes Angular reactive forms to use current best practices and syntax';

  /**
   * Rule category for grouping.
   */
  public readonly category = 'modernization';

  /**
   * Tags for filtering and search.
   */
  public readonly tags = [
    'angular',
    'forms',
    'reactive-forms',
    'formbuilder',
    'validation',
    'modernization',
    'refactoring',
  ];

  /**
   * The orchestrator that performs the actual transformation.
   */
  private readonly orchestrator = new FormModernizationOrchestrator();

  /**
   * Transform a source file by modernizing reactive forms patterns.
   *
   * @remarks
   * This method implements the {@link TransformRule.transform} contract.
   * It delegates to the {@link FormModernizationOrchestrator} for the actual
   * transformation work, then packages the result into a {@link TransformResult}.
   *
   * The method:
   * 1. Captures the file's initial state
   * 2. Invokes the orchestrator to perform the modernization
   * 3. Detects whether the file was modified
   * 4. Returns a standardized {@link TransformResult}
   *
   * ## Return Value
   *
   * The transform result includes:
   * - `modified`: Whether the file was changed
   * - `message`: A human-readable summary
   * - `filePath`: The path to the transformed file
   * - `ruleId`: This rule's identifier
   *
   * @param context - Transform context with file, project, and API access
   *
   * @returns Promise resolving to the transformation result
   *
   * @example
   * ```typescript
   * const rule = new FormModernizationRule();
   * const result = await rule.transform(context);
   *
   * if (result.modified) {
   *   console.info(`Modernized forms: ${result.filePath}`);
   * }
   * ```
   *
   * @public
   */
  async transform(
    context: TransformContext<PublicApi>,
  ): Promise<TransformResult> {
    const { sourceFile, filePath } = context;

    // Check if this transformation type is requested
    const pluginConfig = context.config[
      '@angular-modernizer/plugin-angular'
    ] as Record<string, unknown> | undefined;
    if (pluginConfig?.['transformationType'] !== 'form-modernization') {
      return {
        ruleId: this.id,
        modified: false,
        message: 'Transformation type not applicable',
        filePath,
      };
    }

    // Capture initial state to detect modifications
    const initialText = sourceFile.getFullText();

    // Run the orchestrator
    this.orchestrator.run(context);

    // Detect if the file was modified
    const modified = sourceFile.getFullText() !== initialText;

    // Return the result
    return {
      ruleId: this.id,
      modified,
      message: modified
        ? `Successfully modernized reactive forms patterns`
        : `No reactive forms patterns found to modernize`,
      filePath,
    };
  }
}