package saga

import (
	"context"
	"fmt"
	"sync"
	"time"

	"go.uber.org/zap"

	"tyapi-server/internal/shared/interfaces"
)

// SagaStatus Saga状态
type SagaStatus int

const (
	// StatusPending 等待中
	StatusPending SagaStatus = iota
	// StatusRunning 执行中
	StatusRunning
	// StatusCompleted 已完成
	StatusCompleted
	// StatusFailed 失败
	StatusFailed
	// StatusCompensating 补偿中
	StatusCompensating
	// StatusCompensated 已补偿
	StatusCompensated
	// StatusAborted 已中止
	StatusAborted
)

func (s SagaStatus) String() string {
	switch s {
	case StatusPending:
		return "PENDING"
	case StatusRunning:
		return "RUNNING"
	case StatusCompleted:
		return "COMPLETED"
	case StatusFailed:
		return "FAILED"
	case StatusCompensating:
		return "COMPENSATING"
	case StatusCompensated:
		return "COMPENSATED"
	case StatusAborted:
		return "ABORTED"
	default:
		return "UNKNOWN"
	}
}

// StepStatus 步骤状态
type StepStatus int

const (
	// StepPending 等待执行
	StepPending StepStatus = iota
	// StepRunning 执行中
	StepRunning
	// StepCompleted 完成
	StepCompleted
	// StepFailed 失败
	StepFailed
	// StepCompensated 已补偿
	StepCompensated
	// StepSkipped 跳过
	StepSkipped
)

func (s StepStatus) String() string {
	switch s {
	case StepPending:
		return "PENDING"
	case StepRunning:
		return "RUNNING"
	case StepCompleted:
		return "COMPLETED"
	case StepFailed:
		return "FAILED"
	case StepCompensated:
		return "COMPENSATED"
	case StepSkipped:
		return "SKIPPED"
	default:
		return "UNKNOWN"
	}
}

// SagaStep Saga步骤
type SagaStep struct {
	Name       string
	Action     func(ctx context.Context, data interface{}) error
	Compensate func(ctx context.Context, data interface{}) error
	Status     StepStatus
	Error      error
	StartTime  time.Time
	EndTime    time.Time
	RetryCount int
	MaxRetries int
	Timeout    time.Duration
}

// SagaConfig Saga配置
type SagaConfig struct {
	// 默认超时时间
	DefaultTimeout time.Duration
	// 默认重试次数
	DefaultMaxRetries int
	// 是否并行执行（当前只支持串行）
	Parallel bool
	// 事件发布器
	EventBus interfaces.EventBus
}

// DefaultSagaConfig 默认Saga配置
func DefaultSagaConfig() SagaConfig {
	return SagaConfig{
		DefaultTimeout:    30 * time.Second,
		DefaultMaxRetries: 3,
		Parallel:          false,
	}
}

// Saga 分布式事务
type Saga struct {
	ID          string
	Name        string
	Steps       []*SagaStep
	Status      SagaStatus
	Data        interface{}
	StartTime   time.Time
	EndTime     time.Time
	Error       error
	Config      SagaConfig
	logger      *zap.Logger
	mutex       sync.RWMutex
	currentStep int
	result      interface{}
}

// NewSaga 创建新的Saga
func NewSaga(id, name string, config SagaConfig, logger *zap.Logger) *Saga {
	return &Saga{
		ID:          id,
		Name:        name,
		Steps:       make([]*SagaStep, 0),
		Status:      StatusPending,
		Config:      config,
		logger:      logger,
		currentStep: -1,
	}
}

// AddStep 添加步骤
func (s *Saga) AddStep(name string, action, compensate func(ctx context.Context, data interface{}) error) *Saga {
	step := &SagaStep{
		Name:       name,
		Action:     action,
		Compensate: compensate,
		Status:     StepPending,
		MaxRetries: s.Config.DefaultMaxRetries,
		Timeout:    s.Config.DefaultTimeout,
	}

	s.mutex.Lock()
	s.Steps = append(s.Steps, step)
	s.mutex.Unlock()

	s.logger.Debug("Added step to saga",
		zap.String("saga_id", s.ID),
		zap.String("step_name", name))

	return s
}

// AddStepWithConfig 添加带配置的步骤
func (s *Saga) AddStepWithConfig(name string, action, compensate func(ctx context.Context, data interface{}) error, maxRetries int, timeout time.Duration) *Saga {
	step := &SagaStep{
		Name:       name,
		Action:     action,
		Compensate: compensate,
		Status:     StepPending,
		MaxRetries: maxRetries,
		Timeout:    timeout,
	}

	s.mutex.Lock()
	s.Steps = append(s.Steps, step)
	s.mutex.Unlock()

	s.logger.Debug("Added step with config to saga",
		zap.String("saga_id", s.ID),
		zap.String("step_name", name),
		zap.Int("max_retries", maxRetries),
		zap.Duration("timeout", timeout))

	return s
}

// Execute 执行Saga
func (s *Saga) Execute(ctx context.Context, data interface{}) error {
	s.mutex.Lock()
	if s.Status != StatusPending {
		s.mutex.Unlock()
		return fmt.Errorf("saga %s is not in pending status", s.ID)
	}

	s.Status = StatusRunning
	s.Data = data
	s.StartTime = time.Now()
	s.mutex.Unlock()

	s.logger.Info("Starting saga execution",
		zap.String("saga_id", s.ID),
		zap.String("saga_name", s.Name),
		zap.Int("total_steps", len(s.Steps)))

	// 发布Saga开始事件
	s.publishEvent(ctx, "saga.started")

	// 执行所有步骤
	for i, step := range s.Steps {
		s.mutex.Lock()
		s.currentStep = i
		s.mutex.Unlock()

		if err := s.executeStep(ctx, step, data); err != nil {
			s.logger.Error("Step execution failed",
				zap.String("saga_id", s.ID),
				zap.String("step_name", step.Name),
				zap.Error(err))

			// 执行补偿
			if compensateErr := s.compensate(ctx, i-1); compensateErr != nil {
				s.logger.Error("Compensation failed",
					zap.String("saga_id", s.ID),
					zap.Error(compensateErr))

				s.setStatus(StatusAborted)
				s.publishEvent(ctx, "saga.aborted")
				return fmt.Errorf("saga execution failed and compensation failed: %w", compensateErr)
			}

			s.setStatus(StatusCompensated)
			s.publishEvent(ctx, "saga.compensated")
			return fmt.Errorf("saga execution failed: %w", err)
		}
	}

	// 所有步骤成功完成
	s.setStatus(StatusCompleted)
	s.EndTime = time.Now()

	s.logger.Info("Saga completed successfully",
		zap.String("saga_id", s.ID),
		zap.Duration("duration", s.EndTime.Sub(s.StartTime)))

	s.publishEvent(ctx, "saga.completed")
	return nil
}

// executeStep 执行单个步骤
func (s *Saga) executeStep(ctx context.Context, step *SagaStep, data interface{}) error {
	step.Status = StepRunning
	step.StartTime = time.Now()

	s.logger.Debug("Executing step",
		zap.String("saga_id", s.ID),
		zap.String("step_name", step.Name))

	// 设置超时上下文
	stepCtx, cancel := context.WithTimeout(ctx, step.Timeout)
	defer cancel()

	// 重试逻辑
	var lastErr error
	for attempt := 0; attempt <= step.MaxRetries; attempt++ {
		if attempt > 0 {
			s.logger.Debug("Retrying step",
				zap.String("saga_id", s.ID),
				zap.String("step_name", step.Name),
				zap.Int("attempt", attempt))
		}

		err := step.Action(stepCtx, data)
		if err == nil {
			step.Status = StepCompleted
			step.EndTime = time.Now()

			s.logger.Debug("Step completed successfully",
				zap.String("saga_id", s.ID),
				zap.String("step_name", step.Name),
				zap.Duration("duration", step.EndTime.Sub(step.StartTime)))

			return nil
		}

		lastErr = err
		step.RetryCount = attempt

		// 检查是否应该重试
		if attempt < step.MaxRetries {
			select {
			case <-stepCtx.Done():
				// 上下文被取消，停止重试
				break
			case <-time.After(time.Duration(attempt+1) * 100 * time.Millisecond):
				// 等待一段时间后重试
			}
		}
	}

	// 所有重试都失败了
	step.Status = StepFailed
	step.Error = lastErr
	step.EndTime = time.Now()

	return lastErr
}

// compensate 执行补偿
func (s *Saga) compensate(ctx context.Context, fromStep int) error {
	s.setStatus(StatusCompensating)

	s.logger.Info("Starting compensation",
		zap.String("saga_id", s.ID),
		zap.Int("from_step", fromStep))

	// 逆序执行补偿
	for i := fromStep; i >= 0; i-- {
		step := s.Steps[i]

		// 只补偿已完成的步骤
		if step.Status != StepCompleted {
			step.Status = StepSkipped
			continue
		}

		if step.Compensate == nil {
			s.logger.Warn("No compensation function for step",
				zap.String("saga_id", s.ID),
				zap.String("step_name", step.Name))
			continue
		}

		s.logger.Debug("Compensating step",
			zap.String("saga_id", s.ID),
			zap.String("step_name", step.Name))

		// 设置超时上下文
		compensateCtx, cancel := context.WithTimeout(ctx, step.Timeout)

		err := step.Compensate(compensateCtx, s.Data)
		cancel()

		if err != nil {
			s.logger.Error("Compensation failed for step",
				zap.String("saga_id", s.ID),
				zap.String("step_name", step.Name),
				zap.Error(err))
			return err
		}

		step.Status = StepCompensated

		s.logger.Debug("Step compensated successfully",
			zap.String("saga_id", s.ID),
			zap.String("step_name", step.Name))
	}

	s.logger.Info("Compensation completed",
		zap.String("saga_id", s.ID))

	return nil
}

// setStatus 设置状态
func (s *Saga) setStatus(status SagaStatus) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.Status = status
}

// GetStatus 获取状态
func (s *Saga) GetStatus() SagaStatus {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.Status
}

// GetProgress 获取进度
func (s *Saga) GetProgress() SagaProgress {
	s.mutex.RLock()
	defer s.mutex.RUnlock()

	completed := 0
	for _, step := range s.Steps {
		if step.Status == StepCompleted {
			completed++
		}
	}

	var percentage float64
	if len(s.Steps) > 0 {
		percentage = float64(completed) / float64(len(s.Steps)) * 100
	}

	return SagaProgress{
		SagaID:          s.ID,
		Status:          s.Status.String(),
		TotalSteps:      len(s.Steps),
		CompletedSteps:  completed,
		CurrentStep:     s.currentStep + 1,
		PercentComplete: percentage,
		StartTime:       s.StartTime,
		Duration:        time.Since(s.StartTime),
	}
}

// GetStepStatus 获取所有步骤状态
func (s *Saga) GetStepStatus() []StepProgress {
	s.mutex.RLock()
	defer s.mutex.RUnlock()

	progress := make([]StepProgress, len(s.Steps))
	for i, step := range s.Steps {
		progress[i] = StepProgress{
			Name:       step.Name,
			Status:     step.Status.String(),
			RetryCount: step.RetryCount,
			StartTime:  step.StartTime,
			EndTime:    step.EndTime,
			Duration:   step.EndTime.Sub(step.StartTime),
			Error:      "",
		}

		if step.Error != nil {
			progress[i].Error = step.Error.Error()
		}
	}

	return progress
}

// publishEvent 发布事件
func (s *Saga) publishEvent(ctx context.Context, eventType string) {
	if s.Config.EventBus == nil {
		return
	}

	event := &SagaEvent{
		SagaID:    s.ID,
		SagaName:  s.Name,
		EventType: eventType,
		Status:    s.Status.String(),
		Timestamp: time.Now(),
		Data:      s.Data,
	}

	// 这里应该实现Event接口，简化处理
	_ = event
}

// SagaProgress Saga进度
type SagaProgress struct {
	SagaID          string        `json:"saga_id"`
	Status          string        `json:"status"`
	TotalSteps      int           `json:"total_steps"`
	CompletedSteps  int           `json:"completed_steps"`
	CurrentStep     int           `json:"current_step"`
	PercentComplete float64       `json:"percent_complete"`
	StartTime       time.Time     `json:"start_time"`
	Duration        time.Duration `json:"duration"`
}

// StepProgress 步骤进度
type StepProgress struct {
	Name       string        `json:"name"`
	Status     string        `json:"status"`
	RetryCount int           `json:"retry_count"`
	StartTime  time.Time     `json:"start_time"`
	EndTime    time.Time     `json:"end_time"`
	Duration   time.Duration `json:"duration"`
	Error      string        `json:"error,omitempty"`
}

// SagaEvent Saga事件
type SagaEvent struct {
	SagaID    string      `json:"saga_id"`
	SagaName  string      `json:"saga_name"`
	EventType string      `json:"event_type"`
	Status    string      `json:"status"`
	Timestamp time.Time   `json:"timestamp"`
	Data      interface{} `json:"data,omitempty"`
}

// SagaManager Saga管理器
type SagaManager struct {
	sagas  map[string]*Saga
	logger *zap.Logger
	mutex  sync.RWMutex
	config SagaConfig
}

// NewSagaManager 创建Saga管理器
func NewSagaManager(config SagaConfig, logger *zap.Logger) *SagaManager {
	return &SagaManager{
		sagas:  make(map[string]*Saga),
		logger: logger,
		config: config,
	}
}

// CreateSaga 创建Saga
func (sm *SagaManager) CreateSaga(id, name string) *Saga {
	saga := NewSaga(id, name, sm.config, sm.logger.Named("saga"))

	sm.mutex.Lock()
	sm.sagas[id] = saga
	sm.mutex.Unlock()

	sm.logger.Info("Created saga",
		zap.String("saga_id", id),
		zap.String("saga_name", name))

	return saga
}

// GetSaga 获取Saga
func (sm *SagaManager) GetSaga(id string) (*Saga, bool) {
	sm.mutex.RLock()
	defer sm.mutex.RUnlock()

	saga, exists := sm.sagas[id]
	return saga, exists
}

// ListSagas 列出所有Saga
func (sm *SagaManager) ListSagas() []*Saga {
	sm.mutex.RLock()
	defer sm.mutex.RUnlock()

	sagas := make([]*Saga, 0, len(sm.sagas))
	for _, saga := range sm.sagas {
		sagas = append(sagas, saga)
	}

	return sagas
}

// GetSagaProgress 获取Saga进度
func (sm *SagaManager) GetSagaProgress(id string) (SagaProgress, bool) {
	saga, exists := sm.GetSaga(id)
	if !exists {
		return SagaProgress{}, false
	}

	return saga.GetProgress(), true
}

// RemoveSaga 移除Saga
func (sm *SagaManager) RemoveSaga(id string) {
	sm.mutex.Lock()
	defer sm.mutex.Unlock()

	delete(sm.sagas, id)
	sm.logger.Debug("Removed saga", zap.String("saga_id", id))
}

// GetStats 获取统计信息
func (sm *SagaManager) GetStats() map[string]interface{} {
	sm.mutex.RLock()
	defer sm.mutex.RUnlock()

	statusCount := make(map[string]int)
	for _, saga := range sm.sagas {
		status := saga.GetStatus().String()
		statusCount[status]++
	}

	return map[string]interface{}{
		"total_sagas":  len(sm.sagas),
		"status_count": statusCount,
	}
}

// 实现Service接口

// Name 返回服务名称
func (sm *SagaManager) Name() string {
	return "saga-manager"
}

// Initialize 初始化服务
func (sm *SagaManager) Initialize(ctx context.Context) error {
	sm.logger.Info("Saga manager service initialized")
	return nil
}

// HealthCheck 健康检查
func (sm *SagaManager) HealthCheck(ctx context.Context) error {
	return nil
}

// Shutdown 关闭服务
func (sm *SagaManager) Shutdown(ctx context.Context) error {
	sm.logger.Info("Saga manager service shutdown")
	return nil
}