/**
 * @angular-modernizer/plugin-angular - Constructor to Inject Transformation Rule
 *
 * Transform rule that converts Angular constructor injection to inject() function calls.
 * This is part of the modernization to standalone components and services.
 *
 * 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 { ConstructorToInjectOrchestrator } from '../orchestrators/constructor-to-inject-orchestrator.js';

/**
 * Transform rule for converting constructor injection to inject() function calls.
 *
 * @remarks
 * This rule implements the {@link TransformRule} interface and serves as the
 * bridge between the Angular Modernizer's plugin system and the constructor
 * to inject orchestrator. It follows the "Thin Rule, Thick Orchestrator" pattern
 * where the rule handles protocol compliance while delegating all business logic
 * to the {@link ConstructorToInjectOrchestrator}.
 *
 * ## What It Does
 *
 * The rule orchestrates the conversion of:
 * - **Constructor parameters**: Converts `constructor(private http: HttpClient)` to `private http = inject(HttpClient)`
 * - **Import statements**: Adds `inject` import from `@angular/core` if not present
 * - **Constructor cleanup**: Removes or simplifies empty constructors
 *
 * ## 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:constructor-to-inject');
 * const result = await rule.transform(context);
 * ```
 *
 * @see {@link ConstructorToInjectOrchestrator} for transformation logic
 * @see {@link TransformRule} for the interface contract
 * @see {@link AngularPlugin} for plugin integration
 *
 * @public
 */
export class ConstructorToInjectRule implements TransformRule {
  /**
   * Unique rule identifier.
   * Format: "plugin-name:rule-name"
   */
  public readonly id = 'angular:constructor-to-inject';

  /**
   * Human-readable rule name.
   */
  public readonly name = 'Constructor to Inject Migration';

  /**
   * Rule description.
   */
  public readonly description =
    'Converts Angular constructor injection to inject() function calls for standalone compatibility';

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

  /**
   * Tags for filtering and search.
   */
  public readonly tags = [
    'angular',
    'standalone',
    'dependency-injection',
    'inject',
    'constructor',
    'modernization',
  ];

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

  /**
   * Transform a source file by converting constructor injection to inject() calls.
   *
   * @remarks
   * This method implements the {@link TransformRule.transform} contract.
   * It delegates to the {@link ConstructorToInjectOrchestrator} 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 conversion
   * 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 ConstructorToInjectRule();
   * const result = await rule.transform(context);
   *
   * if (result.modified) {
   *   console.info(`Converted constructor injection: ${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'] !== 'constructor-to-inject') {
      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 converted constructor injection to inject() calls`
        : `No constructor injection found to convert`,
      filePath,
    };
  }
}