package user

import (
	"context"
	"log"
	"strings"
	"time"

	userdomain "hyapp/services/user-service/internal/domain/user"
)

const (
	defaultRegionRebuildPollInterval = 5 * time.Second
	defaultRegionRebuildLockTTL      = 30 * time.Second
	defaultRegionRebuildBatchSize    = 500
)

// RegionRebuildWorkerOptions 控制 user_region_rebuild_tasks 的后台消费节奏。
type RegionRebuildWorkerOptions struct {
	// WorkerID 写入 task locked_by，便于排查某个节点是否卡住任务。
	WorkerID string
	// PollInterval 是没有任务或单轮处理后下一次扫描的间隔。
	PollInterval time.Duration
	// LockTTL 是单个 task claim 后允许本节点持有的最长时间，过期可被其他节点接管。
	LockTTL time.Duration
	// BatchSize 是单次最多更新的 users 数量，避免大国家全量更新长事务。
	BatchSize int
}

func normalizeRegionRebuildWorkerOptions(options RegionRebuildWorkerOptions) RegionRebuildWorkerOptions {
	options.WorkerID = strings.TrimSpace(options.WorkerID)
	if options.WorkerID == "" {
		options.WorkerID = "user-region-rebuild"
	}
	if options.PollInterval <= 0 {
		options.PollInterval = defaultRegionRebuildPollInterval
	}
	if options.LockTTL <= 0 {
		options.LockTTL = defaultRegionRebuildLockTTL
	}
	if options.BatchSize <= 0 {
		options.BatchSize = defaultRegionRebuildBatchSize
	}

	return options
}

// RunRegionRebuildWorker 持续消费 user_region_rebuild_tasks，保证管理端映射变更最终刷新历史用户快照。
func (s *Service) RunRegionRebuildWorker(ctx context.Context, options RegionRebuildWorkerOptions) {
	options = normalizeRegionRebuildWorkerOptions(options)
	if s.regionRebuildRepository == nil {
		log.Printf("worker=user_region_rebuild status=stopped reason=%q", "repository is not configured")
		return
	}

	_, _ = s.ProcessNextRegionRebuildTask(ctx, options)
	ticker := time.NewTicker(options.PollInterval)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			_, _ = s.ProcessNextRegionRebuildTask(ctx, options)
		}
	}
}

// ProcessNextRegionRebuildTask 处理一个待重算任务；错误只影响本轮，worker 下一轮继续扫描。
func (s *Service) ProcessNextRegionRebuildTask(ctx context.Context, options RegionRebuildWorkerOptions) (userdomain.RegionRebuildProcessResult, error) {
	options = normalizeRegionRebuildWorkerOptions(options)
	if s.regionRebuildRepository == nil {
		return userdomain.RegionRebuildProcessResult{NoTask: true}, nil
	}

	result, err := s.regionRebuildRepository.ProcessNextRegionRebuildTask(ctx, options.WorkerID, s.now().UnixMilli(), options.LockTTL, options.BatchSize)
	if err != nil {
		log.Printf("worker=user_region_rebuild worker_id=%s status=failed error=%q", options.WorkerID, err.Error())
		return result, err
	}
	if result.NoTask {
		return result, nil
	}
	log.Printf("worker=user_region_rebuild worker_id=%s task_id=%d country=%s target_region_id=%d status=%s processed_users=%d cursor_user_id=%d", options.WorkerID, result.TaskID, result.CountryCode, result.TargetRegionID, result.Status, result.ProcessedUsers, result.CursorUserID)

	return result, nil
}