import { Injectable, Logger } from "@nestjs/common";
import {
  SystemSettingsResponseDto,
  UpdateSystemSettingsDto,
} from "./dto/system-settings.dto";
import { SystemSettingsDbService } from "./entities/db-service/system-settings.db.service";

@Injectable()
export class SystemSettingsService {
  private readonly logger = new Logger(SystemSettingsService.name);
  private cache: Record<string, unknown> | null = null;
  private cacheAt = 0;
  private readonly cacheTtlMs = 15_000;

  constructor(private readonly db: SystemSettingsDbService) {}

  private async loadGlobal(): Promise<Record<string, unknown>> {
    const now = Date.now();
    if (this.cache && now - this.cacheAt < this.cacheTtlMs) {
      return this.cache;
    }
    let doc = await this.db.findGlobal();
    if (!doc) {
      doc = await this.db.upsertGlobal({
        $set: { externalApis: { sandHubUseLiveApi: false } },
      });
      this.logger.log(
        "Created default system_settings document (sandHubUseLiveApi=false)",
      );
    }
    this.cache = doc;
    this.cacheAt = now;
    return doc;
  }

  private invalidateCache(): void {
    this.cache = null;
    this.cacheAt = 0;
  }

  /**
   * Whether SandHub/Tejarat live HTTP should run (`system_settings` collection).
   */
  async isSandHubLiveEnabled(): Promise<boolean> {
    const doc = await this.loadGlobal();
    const externalApis = doc.externalApis as
      | { sandHubUseLiveApi?: boolean }
      | undefined;
    return externalApis?.sandHubUseLiveApi === true;
  }

  async getSettingsView(): Promise<SystemSettingsResponseDto> {
    const doc = await this.loadGlobal();
    const externalApis = doc.externalApis as
      | { sandHubUseLiveApi?: boolean }
      | undefined;
    const sandHubUseLiveApi = externalApis?.sandHubUseLiveApi === true;
    return {
      key: String(doc.key ?? "global"),
      externalApis: { sandHubUseLiveApi },
      sandHubMode: sandHubUseLiveApi ? "live" : "mock",
    };
  }

  async updateSettings(
    body: UpdateSystemSettingsDto,
  ): Promise<SystemSettingsResponseDto> {
    const $set: Record<string, unknown> = {};
    if (body.externalApis?.sandHubUseLiveApi !== undefined) {
      $set["externalApis.sandHubUseLiveApi"] = body.externalApis.sandHubUseLiveApi;
    }
    if (Object.keys($set).length > 0) {
      await this.db.upsertGlobal({ $set });
      this.invalidateCache();
      this.logger.log(`System settings updated: ${JSON.stringify($set)}`);
    }
    return this.getSettingsView();
  }
}