package polling

import (
	"context"
	"time"

	"github.com/redis/go-redis/v9"

	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
)

// ConcurrencyService 并发控制服务
type ConcurrencyService struct {
	store *postgres.PollingConcurrencyConfigStore
	redis *redis.Client
}

// NewConcurrencyService 创建并发控制服务实例
func NewConcurrencyService(store *postgres.PollingConcurrencyConfigStore, redis *redis.Client) *ConcurrencyService {
	return &ConcurrencyService{
		store: store,
		redis: redis,
	}
}

// ConcurrencyStatus 并发状态
type ConcurrencyStatus struct {
	TaskType       string  `json:"task_type"`
	TaskTypeName   string  `json:"task_type_name"`
	MaxConcurrency int     `json:"max_concurrency"`
	Current        int64   `json:"current"`
	Available      int64   `json:"available"`
	Utilization    float64 `json:"utilization"`
}

// List 获取所有并发控制配置及当前状态
func (s *ConcurrencyService) List(ctx context.Context) ([]*ConcurrencyStatus, error) {
	configs, err := s.store.List(ctx)
	if err != nil {
		return nil, errors.Wrap(errors.CodeInternalError, err, "获取并发配置列表失败")
	}

	result := make([]*ConcurrencyStatus, 0, len(configs))
	for _, cfg := range configs {
		status := &ConcurrencyStatus{
			TaskType:       cfg.TaskType,
			TaskTypeName:   s.getTaskTypeName(cfg.TaskType),
			MaxConcurrency: cfg.MaxConcurrency,
		}

		// 从 Redis 获取当前并发数
		currentKey := constants.RedisPollingConcurrencyCurrentKey(cfg.TaskType)
		current, err := s.redis.Get(ctx, currentKey).Int64()
		if err != nil && err != redis.Nil {
			current = 0
		}

		status.Current = current
		status.Available = int64(cfg.MaxConcurrency) - current
		if status.Available < 0 {
			status.Available = 0
		}
		if cfg.MaxConcurrency > 0 {
			status.Utilization = float64(current) / float64(cfg.MaxConcurrency) * 100
		}

		result = append(result, status)
	}

	return result, nil
}

// GetByTaskType 根据任务类型获取并发配置及状态
func (s *ConcurrencyService) GetByTaskType(ctx context.Context, taskType string) (*ConcurrencyStatus, error) {
	cfg, err := s.store.GetByTaskType(ctx, taskType)
	if err != nil {
		return nil, errors.Wrap(errors.CodeNotFound, err, "并发配置不存在")
	}

	status := &ConcurrencyStatus{
		TaskType:       cfg.TaskType,
		TaskTypeName:   s.getTaskTypeName(cfg.TaskType),
		MaxConcurrency: cfg.MaxConcurrency,
	}

	// 从 Redis 获取当前并发数
	currentKey := constants.RedisPollingConcurrencyCurrentKey(cfg.TaskType)
	current, err := s.redis.Get(ctx, currentKey).Int64()
	if err != nil && err != redis.Nil {
		current = 0
	}

	status.Current = current
	status.Available = int64(cfg.MaxConcurrency) - current
	if status.Available < 0 {
		status.Available = 0
	}
	if cfg.MaxConcurrency > 0 {
		status.Utilization = float64(current) / float64(cfg.MaxConcurrency) * 100
	}

	return status, nil
}

// UpdateMaxConcurrency 更新最大并发数
func (s *ConcurrencyService) UpdateMaxConcurrency(ctx context.Context, taskType string, maxConcurrency int, updatedBy uint) error {
	// 验证参数
	if maxConcurrency < 1 || maxConcurrency > 1000 {
		return errors.New(errors.CodeInvalidParam, "并发数必须在 1-1000 之间")
	}

	// 验证任务类型存在
	_, err := s.store.GetByTaskType(ctx, taskType)
	if err != nil {
		return errors.Wrap(errors.CodeNotFound, err, "任务类型不存在")
	}

	// 更新数据库
	if err := s.store.UpdateMaxConcurrency(ctx, taskType, maxConcurrency, updatedBy); err != nil {
		return errors.Wrap(errors.CodeInternalError, err, "更新并发配置失败")
	}

	// 同步更新 Redis 配置缓存
	configKey := constants.RedisPollingConcurrencyConfigKey(taskType)
	if err := s.redis.Set(ctx, configKey, maxConcurrency, 24*time.Hour).Err(); err != nil {
		// Redis 更新失败不影响主流程，下次读取会从数据库重新加载
	}

	return nil
}

// ResetConcurrency 重置并发计数（用于信号量修复）
func (s *ConcurrencyService) ResetConcurrency(ctx context.Context, taskType string) error {
	// 验证任务类型存在
	_, err := s.store.GetByTaskType(ctx, taskType)
	if err != nil {
		return errors.Wrap(errors.CodeNotFound, err, "任务类型不存在")
	}

	// 重置 Redis 当前计数为 0
	currentKey := constants.RedisPollingConcurrencyCurrentKey(taskType)
	if err := s.redis.Set(ctx, currentKey, 0, 24*time.Hour).Err(); err != nil {
		return errors.Wrap(errors.CodeInternalError, err, "重置并发计数失败")
	}

	return nil
}

// InitFromDB 从数据库初始化 Redis 并发配置
func (s *ConcurrencyService) InitFromDB(ctx context.Context) error {
	configs, err := s.store.List(ctx)
	if err != nil {
		return errors.Wrap(errors.CodeInternalError, err, "获取并发配置失败")
	}

	for _, cfg := range configs {
		configKey := constants.RedisPollingConcurrencyConfigKey(cfg.TaskType)
		if err := s.redis.Set(ctx, configKey, cfg.MaxConcurrency, 24*time.Hour).Err(); err != nil {
			// 忽略单个配置同步失败
			continue
		}
	}

	return nil
}

// SyncConfigToRedis 同步单个配置到 Redis
func (s *ConcurrencyService) SyncConfigToRedis(ctx context.Context, config *model.PollingConcurrencyConfig) error {
	configKey := constants.RedisPollingConcurrencyConfigKey(config.TaskType)
	return s.redis.Set(ctx, configKey, config.MaxConcurrency, 24*time.Hour).Err()
}

// getTaskTypeName 获取任务类型的中文名称
func (s *ConcurrencyService) getTaskTypeName(taskType string) string {
	switch taskType {
	case constants.TaskTypePollingRealname:
		return "实名检查"
	case constants.TaskTypePollingCarddata:
		return "流量检查"
	case constants.TaskTypePollingPackage:
		return "套餐检查"
	default:
		return taskType
	}
}