import * as cron from "node-cron";
import { logger } from "../server.js";
import { S3Sync, createS3SyncFromEnv } from "./s3Sync.js";

export class DailyS3Scheduler {
  private s3Sync: S3Sync | null = null;
  private cronJob: cron.ScheduledTask | null = null;

  constructor() {
    this.s3Sync = createS3SyncFromEnv();
  }

  /**
   * Start the daily S3 sync scheduler
   * Runs at midnight PST (00:00 PST = 08:00 UTC during standard time, 07:00 UTC during daylight time)
   */
  async start(): Promise<void> {
    if (!this.s3Sync) {
      logger.warn("S3 sync not configured. Skipping scheduler setup.");
      return;
    }

    // Test S3 connection before starting scheduler
    const connectionTest = await this.s3Sync.testConnection();
    if (!connectionTest) {
      logger.error("S3 connection test failed. S3 sync scheduler will not be started.");
      return;
    }

    // Cron expression for midnight PST
    // Note: This uses PST timezone. During PDT (daylight time), it will still run at midnight local time
    const cronExpression = "0 0 * * *"; // Every day at midnight
    const timezone = "America/Los_Angeles"; // PST/PDT timezone

    this.cronJob = cron.schedule(
      cronExpression,
      async () => {
        await this.performDailySync();
      },
      {
        timezone: timezone,
      }
    );

    logger.info(`Daily S3 sync scheduler started. Will run at midnight PST/PDT.`);
    logger.info(`Next sync scheduled for: ${this.getNextRunTime()}`);
  }

  /**
   * Stop the scheduler
   */
  stop(): void {
    if (this.cronJob) {
      this.cronJob.stop();
      this.cronJob = null;
      logger.info("Daily S3 sync scheduler stopped.");
    }
  }

  /**
   * Perform the daily sync operation
   */
  private async performDailySync(): Promise<void> {
    if (!this.s3Sync) {
      logger.error("S3 sync not available for daily sync");
      return;
    }

    const startTime = new Date();
    logger.info(`Starting daily S3 sync at ${startTime.toISOString()}`);

    try {
      await this.s3Sync.syncJobsToS3();
      const endTime = new Date();
      const duration = endTime.getTime() - startTime.getTime();
      logger.info(`Daily S3 sync completed successfully in ${duration}ms`);
    } catch (error) {
      logger.error("Daily S3 sync failed:", error);
    }
  }

  /**
   * Manually trigger a sync (useful for testing)
   */
  async triggerManualSync(): Promise<void> {
    if (!this.s3Sync) {
      logger.error("S3 sync not configured");
      return;
    }

    logger.info("Triggering manual S3 sync...");
    await this.performDailySync();
  }

  /**
   * Get the next scheduled run time
   */
  private getNextRunTime(): string {
    if (!this.cronJob) {
      return "Not scheduled";
    }

    // Create a date object for midnight PST today
    const now = new Date();
    const pstNow = new Date(now.toLocaleString("en-US", { timeZone: "America/Los_Angeles" }));
    
    // If it's past midnight today, next run is tomorrow at midnight
    const nextRun = new Date(pstNow);
    if (pstNow.getHours() > 0 || pstNow.getMinutes() > 0 || pstNow.getSeconds() > 0) {
      nextRun.setDate(nextRun.getDate() + 1);
    }
    nextRun.setHours(0, 0, 0, 0);

    return nextRun.toLocaleString("en-US", { 
      timeZone: "America/Los_Angeles",
      weekday: "long",
      year: "numeric",
      month: "long",
      day: "numeric",
      hour: "2-digit",
      minute: "2-digit",
      timeZoneName: "short"
    });
  }

  /**
   * Get scheduler status
   */
  async getStatus(): Promise<{
    isConfigured: boolean;
    isRunning: boolean;
    nextRun: string;
    syncStats?: { bucketName: string; region: string; keyPrefix: string; available: boolean };
  }> {
    let syncStats;
    if (this.s3Sync) {
      try {
        syncStats = await this.s3Sync.getSyncStats();
      } catch (error) {
        logger.error("Failed to get sync stats:", error);
      }
    }

    return {
      isConfigured: this.s3Sync !== null,
      isRunning: this.cronJob !== null,
      nextRun: this.getNextRunTime(),
      syncStats,
    };
  }
}

// Export a singleton instance
export const dailyS3Scheduler = new DailyS3Scheduler();