package jobs

import (
	"context"
	"fmt"
	"log"
	"strconv"
	"strings"
	"time"

	"stock-user-system/internal/config"
	"stock-user-system/internal/services"
)

var chinaLoc, _ = time.LoadLocation("Asia/Shanghai")

// StartStockSyncScheduler 启动盘后数据同步调度器。
func StartStockSyncScheduler(cfg *config.Config, svc *services.StockSyncService) {
	if !cfg.DataSyncEnabled {
		log.Println("stock sync scheduler disabled")
		return
	}

	hour, minute, err := parseSyncTime(cfg.DataSyncTime)
	if err != nil {
		log.Printf("invalid DATA_SYNC_TIME %q, scheduler not started: %v", cfg.DataSyncTime, err)
		return
	}

	go func() {
		for {
			next := nextSyncTime(hour, minute, cfg.DataSyncWeekdays)
			wait := time.Until(next)
			log.Printf("next stock sync scheduled at %s (in %v)", next.Format(time.RFC3339), wait)
			time.Sleep(wait)

			if _, err := svc.Sync(context.Background(), "schedule"); err != nil {
				log.Printf("scheduled stock sync failed: %v", err)
			} else {
				log.Println("scheduled stock sync completed")
			}
		}
	}()
}

func parseSyncTime(s string) (int, int, error) {
	parts := strings.Split(s, ":")
	if len(parts) != 2 {
		return 0, 0, fmt.Errorf("expected HH:MM")
	}
	h, err := strconv.Atoi(parts[0])
	if err != nil {
		return 0, 0, err
	}
	m, err := strconv.Atoi(parts[1])
	if err != nil {
		return 0, 0, err
	}
	if h < 0 || h > 23 || m < 0 || m > 59 {
		return 0, 0, fmt.Errorf("invalid time")
	}
	return h, m, nil
}

func nextSyncTime(hour, minute int, weekdaysOnly bool) time.Time {
	now := time.Now().In(chinaLoc)
	today := time.Date(now.Year(), now.Month(), now.Day(), hour, minute, 0, 0, chinaLoc)

	candidate := today
	if now.Equal(candidate) || now.After(candidate) {
		candidate = candidate.Add(24 * time.Hour)
	}

	if weekdaysOnly {
		for candidate.Weekday() == time.Saturday || candidate.Weekday() == time.Sunday {
			candidate = candidate.Add(24 * time.Hour)
		}
	}

	return candidate
}