/**
 * @angular-modernizer/plugin-angular - Static Class to Functions Transform Rule
 *
 * Transforms static-only classes into module-level function/const exports.
 *
 * @example
 * // Before
 * export class StringHelper {
 *   static isEmpty(s: string): boolean { return s.length === 0; }
 * }
 *
 * // After
 * export function isEmpty(s: string): boolean { return s.length === 0; }
 */
import type {
  TransformRule,
  TransformContext,
  TransformResult,
} from '@angular-modernizer/plugin-system';
import type { PublicApi } from '@angular-modernizer/api';
import { StaticClassTransformOrchestrator } from '../orchestrators/static-class-transform.orchestrator.js';

export class StaticClassTransformRule implements TransformRule {
  public readonly id = 'angular:static-class-to-functions';
  public readonly name = 'Static Class to Functions Transform';
  public readonly description =
    'Transforms static-only classes into module-level functions and const exports';
  public readonly category = 'refactoring';
  public readonly tags = [
    'angular',
    'refactoring',
    'functional',
    'tree-shaking',
    'static',
  ];

  private readonly orchestrator = new StaticClassTransformOrchestrator();

  async transform(
    context: TransformContext<PublicApi>,
  ): Promise<TransformResult> {
    const { sourceFile, filePath } = context;

    if (filePath.endsWith('.d.ts')) {
      return {
        ruleId: this.id,
        modified: false,
        message: 'Skipped declaration file',
        filePath,
      };
    }

    const initialText = sourceFile.getFullText();
    const stats = this.orchestrator.run(context);
    const modified = sourceFile.getFullText() !== initialText;

    return {
      ruleId: this.id,
      modified,
      message: modified
        ? `Transformed ${stats.classesTransformed} static class(es) → ${stats.functionsCreated} function(s), ${stats.constantsCreated} constant(s); ${stats.inFileRefsUpdated} in-file + ${stats.crossFileCallersUpdated} cross-file reference(s) updated`
        : 'No static-only classes found',
      filePath,
      changeCount: stats.classesTransformed,
    };
  }
}