import { HttpClient } from '@angular/common/http';
import { APP_INITIALIZER, InjectionToken } from '@angular/core';
import { lastValueFrom } from 'rxjs';

import { environment } from '../../environments/environment';

export interface AppConfig {
  apiBaseUrl: string;
}

export const APP_CONFIG = new InjectionToken<AppConfig>('appConfig');

// Default to the Angular environment value (http://localhost:8000 in dev, '' in prod).
// A runtime config.json can override this in production.
const _appConfig: AppConfig = {
  apiBaseUrl: environment.apiBaseUrl,
};

export function appConfigFactory(http: HttpClient) {
  return (): Promise<void> => {
    return lastValueFrom(http.get<AppConfig>('config.json')).then(
      (config) => { Object.assign(_appConfig, config); },
      () => {
        // Keep defaults if config.json is not available (dev mode).
      },
    );
  };
}

export const appConfigProvider = {
  provide: APP_CONFIG,
  useValue: _appConfig,
};

export const appConfigInitProvider = {
  provide: APP_INITIALIZER,
  useFactory: appConfigFactory,
  deps: [HttpClient],
  multi: true,
};

export function getAppConfig(): AppConfig {
  return _appConfig;
}

/** Resolve an image URL for rendering.
 * - Absolute HTTP(S) URLs are returned as-is.
 * - Static SVG assets (svg/…) are served by the Angular build — returned as-is.
 * - API paths (/api/storage/…) and legacy paths (uploads/…) are prefixed with apiBaseUrl.
 */
export function resolveImageUrl(url: string): string {
  if (!url) return '';
  if (url.startsWith('http://') || url.startsWith('https://')) return url;
  if (url.startsWith('svg/')) return url;
  if (url.startsWith('/')) return `${getAppConfig().apiBaseUrl}${url}`;
  return `${getAppConfig().apiBaseUrl}/${url}`;
}