import { Injectable } from "@nestjs/common";
import { Interval } from "@nestjs/schedule";
import { ConfigService } from "@nestjs/config";
import { AppConfig } from "../config/app.config";
import { TraceLogger } from "../common/trace-logger";
import { SessionService } from "./session.service";
import { SessionContextService } from "./session-context.service";

/**
 * Periodically:
 *  1. Closes sessions that have been idle for longer than SESSION_IDLE_TIMEOUT_MINUTES.
 *  2. Deletes closed sessions whose updatedAt is older than SESSION_DELETE_CLOSED_DAYS.
 */
@Injectable()
export class SessionSchedulerService {
  private readonly logger = new TraceLogger(SessionSchedulerService.name);

  constructor(
    private readonly sessionService: SessionService,
    private readonly sessionContextService: SessionContextService,
    private readonly config: ConfigService<AppConfig, true>,
  ) {}

  @Interval(60_000)
  async runScheduler(): Promise<void> {
    await this.closeExpired();
    await this.deleteOldClosed();
  }

  private async closeExpired(): Promise<void> {
    const idleMinutes = this.config.get("SESSION_IDLE_TIMEOUT_MINUTES");
    const cutoff = new Date(Date.now() - idleMinutes * 60_000);
    const expired = await this.sessionService.findExpiredOpen(cutoff);
    for (const session of expired) {
      await this.sessionContextService.close(session.sessionName);
      this.logger.log(
        `Session "${session.sessionName}" closed (idle > ${idleMinutes} min)`,
      );
    }
  }

  private async deleteOldClosed(): Promise<void> {
    const days = this.config.get("SESSION_DELETE_CLOSED_DAYS");
    const cutoff = new Date(Date.now() - days * 86_400_000);
    const old = await this.sessionService.findOldClosed(cutoff);
    for (const session of old) {
      await this.sessionService.remove(session.id);
      this.logger.log(
        `Session "${session.sessionName}" deleted (closed > ${days} days ago)`,
      );
    }
  }
}