// src/services/angular-generator.service.ts
import { Injectable } from '@nestjs/common';
import { ConfigService } from './config.service';
import * as path from 'path';
import * as fs from 'fs';
import { promises as fsPromises } from 'fs';

interface NamingConvention {
  singular: string;    // product
  plural: string;      // products
  pascal: string;      // Product
  camel: string;       // product
  title: string;       // Product
  kebab: string;       // product
}

@Injectable()
export class AngularGeneratorService {
  constructor(private readonly configService: ConfigService) {}

  public async generate(tableName: string): Promise<void> {
    console.log(`Generating Angular module for table: ${tableName}...`);
    const names = this.getNamingConvention(tableName);
    const config = this.configService.get();
    const adminRoot = path.resolve(process.cwd(), config.admin.path);
    // We'll place all generated files for a feature in one folder
    const featureDir = path.join(adminRoot, 'src', 'app', 'features', names.plural);

    try {
      // Generate each part of the feature module
      await this.generateModel(names, featureDir);
      await this.generateService(names, featureDir);
      await this.generateFilterComponent(names, featureDir);
      await this.generateListComponent(names, featureDir);
      // We will add the Details/Grid components later to keep this step focused

      console.log(`✅ Angular files for "${tableName}" created successfully in: ${featureDir}`);
      console.warn(`\n🔔 Action Required: Remember to create a route for ${names.pascal}ListComponent and declare it in a module!`);

    } catch (error) {
      console.error(`❌ An error occurred during Angular generation:`, error.message);
    }
  }

  private async generateModel(names: NamingConvention, featureDir: string) {
    const modelsDir = path.join(featureDir, 'models');
    const template = this.getModelTemplate(names);
    const filePath = path.join(modelsDir, `${names.singular}.model.ts`);
    await fsPromises.mkdir(modelsDir, { recursive: true });
    fs.writeFileSync(filePath, template);
  }

  private async generateService(names: NamingConvention, featureDir: string) {
    const servicesDir = path.join(featureDir, 'services');
    const template = this.getServiceTemplate(names);
    const filePath = path.join(servicesDir, `${names.singular}.service.ts`);
    await fsPromises.mkdir(servicesDir, { recursive: true });
    fs.writeFileSync(filePath, template);
  }

  private async generateFilterComponent(names: NamingConvention, featureDir: string) {
    const compDir = path.join(featureDir, 'components', `${names.singular}-filter`);
    await fsPromises.mkdir(compDir, { recursive: true });
    fs.writeFileSync(path.join(compDir, `${names.singular}-filter.component.ts`), this.getFilterComponentTsTemplate(names));
    fs.writeFileSync(path.join(compDir, `${names.singular}-filter.component.html`), this.getFilterComponentHtmlTemplate(names));
  }

  private async generateListComponent(names: NamingConvention, featureDir: string) {
    const compDir = path.join(featureDir, 'components', `${names.singular}-list`);
    await fsPromises.mkdir(compDir, { recursive: true });
    fs.writeFileSync(path.join(compDir, `${names.singular}-list.component.ts`), this.getListComponentTsTemplate(names));
    fs.writeFileSync(path.join(compDir, `${names.singular}-list.component.html`), this.getListComponentHtmlTemplate(names));
  }


  // --- TEMPLATE METHODS ---

  private getModelTemplate(names: NamingConvention): string {
    return `// Generated by the CLI
// This is a placeholder model. Adjust properties based on your actual entity.
export interface ${names.pascal} {
  id: number;
  name: string;
  // Add other properties from your NestJS entity here
}

export interface PaginatedResponse<T> {
  data: T[];
  meta: {
    totalItems: number;
    itemCount: number;
    itemsPerPage: number;
    totalPages: number;
    currentPage: number;
  };
}
`;
  }

  private getServiceTemplate(names: NamingConvention): string {
    return `// Generated by the CLI
import { Injectable } from '@angular/core';
import { HttpClient, HttpParams } from '@angular/common/http';
import { Observable } from 'rxjs';
import { ${names.pascal}, PaginatedResponse } from '../models/${names.singular}.model';
import { environment } from '../../../../environments/environment';

@Injectable({
  providedIn: 'root'
})
export class ${names.pascal}Service {
  private apiUrl = \`\${environment.apiUrl}/${names.plural}\`;

  constructor(private http: HttpClient) { }

  // A type for the filter parameters. Should match the QueryDto in NestJS.
  // For now, it's a flexible record.
  public find(filter: Record<string, any>): Observable<PaginatedResponse<${names.pascal}>> {
    const params = new HttpParams({ fromObject: filter });
    return this.http.get<PaginatedResponse<${names.pascal}>>(this.apiUrl, { params });
  }

  public findOne(id: number): Observable<${names.pascal}> {
    return this.http.get<${names.pascal}>(\`\${this.apiUrl}/\${id}\`);
  }

  public create(data: Omit<${names.pascal}, 'id'>): Observable<${names.pascal}> {
    return this.http.post<${names.pascal}>(this.apiUrl, data);
  }

  public update(id: number, data: Partial<${names.pascal}>>): Observable<${names.pascal}> {
    return this.http.patch<${names.pascal}>(\`\${this.apiUrl}/\${id}\`, data);
  }

  public remove(id: number): Observable<any> {
    return this.http.delete(\`\${this.apiUrl}/\${id}\`);
  }
}
`;
  }

  private getFilterComponentTsTemplate(names: NamingConvention): string {
    return `// Generated by the CLI
import { Component, EventEmitter, Output } from '@angular/core';
import { FormBuilder, FormGroup, ReactiveFormsModule } from '@angular/forms';
import { debounceTime, distinctUntilChanged } from 'rxjs/operators';

@Component({
  selector: 'app-${names.kebab}-filter',
  templateUrl: './${names.singular}-filter.component.html',
  standalone: true,
  imports: [ReactiveFormsModule]
})
export class ${names.pascal}FilterComponent {
  @Output() filterChanged = new EventEmitter<any>();
  filterForm: FormGroup;

  constructor(private fb: FormBuilder) {
    this.filterForm = this.fb.group({
      name: [''],
      // Add other filterable form controls here
    });

    this.filterForm.valueChanges.pipe(
      debounceTime(300),
      distinctUntilChanged()
    ).subscribe(values => {
      // Remove empty properties before emitting
      const cleanFilter = Object.fromEntries(
        Object.entries(values).filter(([_, v]) => v != null && v !== '')
      );
      this.filterChanged.emit(cleanFilter);
    });
  }

  reset() {
    this.filterForm.reset();
  }
}
`;
  }

  private getFilterComponentHtmlTemplate(names: NamingConvention): string {
    return `<!-- Generated by the CLI -->
<form [formGroup]="filterForm" class="p-4 bg-base-200 rounded-lg shadow">
  <div class="grid grid-cols-1 md:grid-cols-4 gap-4 items-end">
    
    <!-- Filter for 'name' -->
    <div class="form-control">
      <label class="label">
        <span class="label-text">Name</span>
      </label>
      <input type="text" formControlName="name" placeholder="Filter by name" class="input input-bordered w-full">
    </div>

    <!-- Add other filter inputs here -->

    <!-- Reset Button -->
    <div class="form-control">
      <button type="button" (click)="reset()" class="btn btn-secondary">Reset</button>
    </div>
  </div>
</form>
`;
  }

  private getListComponentTsTemplate(names: NamingConvention): string {
    return `// Generated by the CLI
import { Component, OnInit } from '@angular/core';
import { CommonModule } from '@angular/common';
import { BehaviorSubject, Observable, combineLatest } from 'rxjs';
import { switchMap, map, startWith } from 'rxjs/operators';
import { ${names.pascal}, PaginatedResponse } from '../../models/${names.singular}.model';
import { ${names.pascal}Service } from '../../services/${names.singular}.service';
import { ${names.pascal}FilterComponent } from '../${names.singular}-filter/${names.singular}-filter.component';

@Component({
  selector: 'app-${names.kebab}-list',
  templateUrl: './${names.singular}-list.component.html',
  standalone: true,
  imports: [CommonModule, ${names.pascal}FilterComponent],
})
export class ${names.pascal}ListComponent implements OnInit {
  
  private refresh$ = new BehaviorSubject<void>(undefined);
  private filter$ = new BehaviorSubject<any>({});
  private page$ = new BehaviorSubject<number>(1);
  
  paginatedResponse$!: Observable<PaginatedResponse<${names.pascal}>>;

  constructor(private ${names.camel}Service: ${names.pascal}Service) { }

  ngOnInit(): void {
    this.paginatedResponse$ = combineLatest([
      this.refresh$,
      this.filter$.pipe(startWith({})),
      this.page$.pipe(startWith(1))
    ]).pipe(
      switchMap(([_, filter, page]) => {
        const query = { ...filter, page, limit: 10 };
        return this.${names.camel}Service.find(query);
      })
    );
  }

  onFilterChanged(filter: any) {
    this.page$.next(1); // Reset to first page on filter change
    this.filter$.next(filter);
  }

  changePage(newPage: number) {
    if (newPage > 0) {
      this.page$.next(newPage);
    }
  }

  // Placeholder for delete action
  deleteItem(id: number) {
    if (confirm('Are you sure you want to delete this item?')) {
      this.${names.camel}Service.remove(id).subscribe(() => {
        console.log(\`Item \${id} deleted\`);
        this.refresh$.next(); // Trigger a data refresh
      });
    }
  }
}
`;
  }

  private getListComponentHtmlTemplate(names: NamingConvention): string {
    return `<!-- Generated by the CLI -->
<div class="p-4 md:p-8 space-y-6">
  <h1 class="text-3xl font-bold">${names.title}s</h1>

  <!-- Filter Component -->
  <app-${names.kebab}-filter (filterChanged)="onFilterChanged($event)"></app-${names.kebab}-filter>

  <!-- Data Table -->
  <ng-container *ngIf="paginatedResponse$ | async as response; else loading">
    <div class="overflow-x-auto bg-base-100 rounded-lg shadow">
      <table class="table w-full">
        <thead>
          <tr>
            <th>ID</th>
            <th>Name</th>
            <!-- Add other table headers here -->
            <th class="text-right">Actions</th>
          </tr>
        </thead>
        <tbody>
          <tr *ngFor="let item of response.data" class="hover">
            <td>{{ item.id }}</td>
            <td>{{ item.name }}</td>
            <!-- Add other table data cells here -->
            <td class="text-right space-x-2">
              <button class="btn btn-sm btn-ghost">View</button>
              <button class="btn btn-sm btn-ghost">Edit</button>
              <button (click)="deleteItem(item.id)" class="btn btn-sm btn-error btn-ghost">Delete</button>
            </td>
          </tr>
          <tr *ngIf="response.data.length === 0">
            <td colspan="3" class="text-center">No ${names.plural} found.</td>
          </tr>
        </tbody>
      </table>
    </div>

    <!-- Pagination Controls -->
    <div *ngIf="response.meta.totalPages > 1" class="flex justify-center mt-4">
      <div class="join">
        <button 
          class="join-item btn" 
          (click)="changePage(response.meta.currentPage - 1)" 
          [disabled]="response.meta.currentPage === 1">«</button>
        <button class="join-item btn">Page {{ response.meta.currentPage }} of {{ response.meta.totalPages }}</button>
        <button 
          class="join-item btn" 
          (click)="changePage(response.meta.currentPage + 1)" 
          [disabled]="response.meta.currentPage === response.meta.totalPages">»</button>
      </div>
    </div>
  </ng-container>

  <ng-template #loading>
    <div class="text-center p-8">
      <span class="loading loading-spinner loading-lg"></span>
    </div>
  </ng-template>
</div>
`;
  }

  // --- Naming Utilities ---
  private getNamingConvention(tableName: string): NamingConvention {
    const singular = this.toSingular(tableName);
    const pascal = this.toPascalCase(singular);
    return {
      singular: singular,
      plural: tableName,
      pascal: pascal,
      camel: this.toCamelCase(singular),
      title: pascal,
      kebab: singular,
    };
  }
  private toSingular(name: string): string {
    if (name.endsWith('ies')) return name.slice(0, -3) + 'y';
    return name.endsWith('s') ? name.slice(0, -1) : name;
  }
  private toPascalCase(text: string): string {
    return text.replace(/(^\w|-\w|_w)/g, (c) => c.replace(/[-_]/, '').toUpperCase());
  }
  private toCamelCase(text: string): string {
    const pascal = this.toPascalCase(text);
    return pascal.charAt(0).toLowerCase() + pascal.slice(1);
  }
}