import { Injectable, Type } from '@angular/core';
import { CxEvent } from '../../event/cx-event';
import { OccConfig } from '../config/occ-config';

@Injectable({
  providedIn: 'root',
})
export class LoadingScopesService {
  constructor(protected config: OccConfig) {}

  /**
   * Aims to expand scopes based on loading scopes config.
   *
   * I.e. if 'details' scope includes 'list' scope by configuration, it'll return ['details', 'list']
   *
   * If scope data overlaps with each other, the data should be merged in the order of scopes provided,
   * i.e. the last scope is merged last, overwriting parts of the data already provided by preceding scope.
   * It should apply also to implicit scopes (that are included by configuration).
   *
   * @param model
   * @param scopes
   */
  expand(model: string, scopes: string[]): string[] {
    const scopesConfig = this.config?.backend?.loadingScopes?.[model];

    if (scopesConfig) {
      const expandedScopes = [...scopes];
      let i = expandedScopes.length;

      while (i > 0) {
        i--;
        const includedScopes = scopesConfig[expandedScopes[i]]?.include;
        if (includedScopes) {
          for (const includedScope of includedScopes) {
            if (!expandedScopes.includes(includedScope)) {
              expandedScopes.splice(i, 0, includedScope);
              i++;
            }
          }
        }
      }

      return expandedScopes;
    }

    return scopes;
  }

  /**
   * Return maxAge for product scope in milliseconds
   *
   * @param model
   * @param scope
   */
  getMaxAge(model: string, scope: string): number {
    const configuredMaxAge =
      this.config.backend?.loadingScopes?.[model]?.[scope]?.maxAge ?? 0;
    return configuredMaxAge * 1000;
  }

  /**
   *
   * Returns the configured triggers for which to reload the product.
   *
   * @param model for which to look up the scopes (usually a 'product')
   * @param scope for which to look up the config
   * @returns the configured triggers, or an empty array if not configured
   */
  getReloadTriggers(model: string, scope: string): Type<CxEvent>[] {
    return this.config.backend?.loadingScopes?.[model]?.[scope]?.reloadOn ?? [];
  }
}