import { type MethodDeclaration } from 'ts-morph';
import { type CrossServiceCall } from './cross-service-call-detector.js';

/**
 * Rewrites method bodies to use injected services for cross-service calls.
 *
 * Transforms:
 * - `this.sortUsers(users)` → `this.transformationService.sortUsers(users)`
 */
export class MethodCallRewriter {
  /**
   * Rewrites cross-service calls in a method body.
   *
   * @param method - Method to rewrite
   * @param crossServiceCalls - Cross-service calls detected in this method
   * @param servicePropertyMap - Map of service name to property name (e.g., 'TransformationService' → 'transformationService')
   * @returns Rewritten method body text
   */
  rewriteMethodBody(
    method: MethodDeclaration,
    crossServiceCalls: CrossServiceCall[],
    servicePropertyMap: Map<string, string>,
  ): string {
    let methodBody = method.getBodyText() ?? '';

    // Group calls by target service for efficient rewriting
    const callsByService = new Map<string, CrossServiceCall[]>();
    for (const call of crossServiceCalls) {
      if (!callsByService.has(call.targetService)) {
        callsByService.set(call.targetService, []);
      }
      callsByService.get(call.targetService)!.push(call);
    }

    // Rewrite calls for each service
    for (const [targetService, calls] of callsByService.entries()) {
      const servicePropertyName = servicePropertyMap.get(targetService);
      if (!servicePropertyName) {
        continue;
      }

      for (const call of calls) {
        // Replace: this.methodName( → this.serviceProperty.methodName(
        const pattern = new RegExp(
          String.raw`\bthis\.${call.methodName}\s*\(`,
          'g',
        );
        const replacement = `this.${servicePropertyName}.${call.methodName}(`;
        methodBody = methodBody.replace(pattern, replacement);
      }
    }

    return methodBody;
  }

  /**
   * Converts service name to property name.
   *
   * @param serviceName - Service name (e.g., 'TransformationService')
   * @returns Property name (e.g., 'transformationService')
   */
  toPropertyName(serviceName: string): string {
    // Convert to camelCase (keep Service suffix for clarity)
    return serviceName.charAt(0).toLowerCase() + serviceName.slice(1);
  }
}