package engine

import (
	"bytes"
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/yourname/cyrene-ai/gateway/internal/store"
	"github.com/yourname/cyrene-ai/gateway/internal/ws"
)

// TriggerConfig 触发器配置
type TriggerConfig struct {
	Cron     string   `json:"cron,omitempty"`
	Time     string   `json:"time,omitempty"`
	Days     []string `json:"days,omitempty"`
	DeviceID string   `json:"device_id,omitempty"`
	Property string   `json:"property,omitempty"`
	Operator string   `json:"operator,omitempty"`
	Value    float64  `json:"value,omitempty"`
}

// Condition 条件定义
type Condition struct {
	Type     string  `json:"type"`
	Start    string  `json:"start,omitempty"`
	End      string  `json:"end,omitempty"`
	DeviceID string  `json:"device_id,omitempty"`
	Property string  `json:"property,omitempty"`
	Operator string  `json:"operator,omitempty"`
	Value    float64 `json:"value,omitempty"`
}

// Action 动作定义
type Action struct {
	Type     string      `json:"type"`
	DeviceID string      `json:"device_id,omitempty"`
	Property string      `json:"property,omitempty"`
	Value    interface{} `json:"value,omitempty"`
	Title    string      `json:"title,omitempty"`
	Body     string      `json:"body,omitempty"`
}

// RuleEngine 规则引擎
type RuleEngine struct {
	store        *store.AutomationStore
	hub          *ws.Hub
	iotServiceURL string
	httpClient   *http.Client
	lastTriggered map[string]time.Time
	mu           sync.RWMutex
	stopCh       chan struct{}
	running      bool
}

// NewRuleEngine 创建规则引擎
func NewRuleEngine(as *store.AutomationStore, hub *ws.Hub) *RuleEngine {
	iotServiceURL := os.Getenv("IOT_SERVICE_URL")
	if iotServiceURL == "" {
		iotServiceURL = "http://localhost:8083"
	}

	return &RuleEngine{
		store:         as,
		hub:           hub,
		iotServiceURL: iotServiceURL,
		httpClient: &http.Client{
			Timeout: 5 * time.Second,
		},
		lastTriggered: make(map[string]time.Time),
		stopCh:        make(chan struct{}),
	}
}

// Start 启动后台规则评估 goroutine
func (e *RuleEngine) Start() {
	e.mu.Lock()
	if e.running {
		e.mu.Unlock()
		return
	}
	e.running = true
	e.mu.Unlock()

	go e.loop()
	log.Printf("[RuleEngine] 规则引擎已启动 (IoT服务地址: %s)", e.iotServiceURL)
}

// Stop 停止规则引擎
func (e *RuleEngine) Stop() {
	e.mu.Lock()
	defer e.mu.Unlock()

	if !e.running {
		return
	}
	close(e.stopCh)
	e.running = false
	log.Println("[RuleEngine] 规则引擎已停止")
}

// loop 规则引擎主循环
func (e *RuleEngine) loop() {
	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	// 首次立即评估
	e.evaluateAllRules()

	for {
		select {
		case <-e.stopCh:
			return
		case <-ticker.C:
			e.evaluateAllRules()
		}
	}
}

// evaluateAllRules 评估所有启用的规则
func (e *RuleEngine) evaluateAllRules() {
	rules, err := e.store.GetEnabledRules()
	if err != nil {
		log.Printf("[RuleEngine] 获取启用的规则失败: %v", err)
		return
	}

	if len(rules) == 0 {
		return
	}

	for _, rule := range rules {
		if e.evaluateRule(&rule) {
			e.ExecuteRuleActions(&rule)
			e.store.MarkRuleTriggered(rule.ID)
			e.mu.Lock()
			e.lastTriggered[rule.ID] = time.Now()
			e.mu.Unlock()
		}
	}
}

// evaluateRule 评估单条规则是否应触发
func (e *RuleEngine) evaluateRule(rule *store.AutomationRule) bool {
	// 防重复触发：同一规则在 1 分钟内不重复触发
	e.mu.RLock()
	lastTime, exists := e.lastTriggered[rule.ID]
	e.mu.RUnlock()
	if exists && time.Since(lastTime) < 1*time.Minute {
		return false
	}

	// 解析 trigger_config
	var triggerCfg TriggerConfig
	if rule.TriggerConfig != nil {
		if err := json.Unmarshal(*rule.TriggerConfig, &triggerCfg); err != nil {
			log.Printf("[RuleEngine] 解析触发器配置失败: rule=%s err=%v", rule.ID, err)
			return false
		}
	}

	// 评估触发器
	triggered := false
	switch rule.TriggerType {
	case "schedule":
		triggered = e.evaluateScheduleTrigger(triggerCfg)
	case "device_state":
		triggered = e.evaluateDeviceStateTrigger(triggerCfg)
	case "manual":
		// 不自动触发
		return false
	default:
		return false
	}

	if !triggered {
		return false
	}

	// 评估 conditions
	var conditions []Condition
	if rule.Conditions != nil {
		if err := json.Unmarshal(*rule.Conditions, &conditions); err != nil {
			log.Printf("[RuleEngine] 解析条件失败: rule=%s err=%v", rule.ID, err)
			return false
		}
	}

	for _, cond := range conditions {
		if !e.evaluateCondition(cond) {
			return false
		}
	}

	return true
}

// evaluateScheduleTrigger 评估定时触发器
func (e *RuleEngine) evaluateScheduleTrigger(cfg TriggerConfig) bool {
	now := time.Now()

	// 检查 days (星期)
	if len(cfg.Days) > 0 {
		weekday := strings.ToLower(now.Weekday().String()[:3])
		found := false
		for _, d := range cfg.Days {
			if strings.ToLower(strings.TrimSpace(d)) == weekday {
				found = true
				break
			}
		}
		if !found {
			return false
		}
	}

	// 检查 time
	if cfg.Time != "" {
		currentTime := now.Format("15:04")
		return currentTime == cfg.Time
	}

	return false
}

// evaluateDeviceStateTrigger 评估设备状态触发器
func (e *RuleEngine) evaluateDeviceStateTrigger(cfg TriggerConfig) bool {
	if cfg.DeviceID == "" || cfg.Property == "" || cfg.Operator == "" {
		return false
	}

	// 从 IoT 服务获取设备状态
	devices, err := e.fetchIoTDevices()
	if err != nil {
		log.Printf("[RuleEngine] 获取设备状态失败: %v", err)
		return false
	}

	// 查找目标设备
	for _, d := range devices {
		if d.ID != cfg.DeviceID {
			continue
		}

		var actualValue float64
		switch cfg.Property {
		case "temperature":
			actualValue = d.Temperature
		case "value":
			actualValue = d.Value
		case "brightness":
			actualValue = float64(d.Brightness)
		case "position":
			actualValue = float64(d.Position)
		case "battery":
			actualValue = float64(d.Battery)
		default:
			// 尝试从 properties 中获取
			if props, ok := d.Properties[cfg.Property]; ok {
				if v, ok := props.(float64); ok {
					actualValue = v
				}
			} else {
				return false
			}
		}

		return compareValues(actualValue, cfg.Operator, cfg.Value)
	}

	return false
}

// evaluateCondition 评估单个条件
func (e *RuleEngine) evaluateCondition(cond Condition) bool {
	switch cond.Type {
	case "time_range":
		if cond.Start == "" || cond.End == "" {
			return true
		}
		now := time.Now()
		currentTime := now.Format("15:04")
		return currentTime >= cond.Start && currentTime <= cond.End

	case "device_state":
		if cond.DeviceID == "" || cond.Property == "" || cond.Operator == "" {
			return true
		}
		devices, err := e.fetchIoTDevices()
		if err != nil {
			return true // 无法获取设备状态时不阻塞
		}

		for _, d := range devices {
			if d.ID != cond.DeviceID {
				continue
			}

			var actualValue float64
			switch cond.Property {
			case "temperature":
				actualValue = d.Temperature
			case "value":
				actualValue = d.Value
			case "brightness":
				actualValue = float64(d.Brightness)
			case "position":
				actualValue = float64(d.Position)
			case "battery":
				actualValue = float64(d.Battery)
			default:
				if props, ok := d.Properties[cond.Property]; ok {
					if v, ok := props.(float64); ok {
						actualValue = v
					}
				} else {
					return true
				}
			}

			return compareValues(actualValue, cond.Operator, cond.Value)
		}

		return true
	}

	return true
}

// ExecuteRuleActions 执行规则的动作
func (e *RuleEngine) ExecuteRuleActions(rule *store.AutomationRule) {
	var actions []Action
	if rule.Actions != nil {
		if err := json.Unmarshal(*rule.Actions, &actions); err != nil {
			log.Printf("[RuleEngine] 解析动作失败: rule=%s err=%v", rule.ID, err)
			return
		}
	}

	log.Printf("[RuleEngine] 执行规则 %s (%s) 的 %d 个动作", rule.ID, rule.Name, len(actions))

	for _, action := range actions {
		switch action.Type {
		case "set_device":
			e.executeSetDevice(action)
		case "notify":
			e.executeNotify(action, rule.UserID)
		default:
			log.Printf("[RuleEngine] 未知动作类型: %s", action.Type)
		}
	}
}

// ExecuteScene 手动触发场景
func (e *RuleEngine) ExecuteScene(sceneID, userID string) error {
	rules, err := e.store.GetSceneRules(sceneID)
	if err != nil {
		return fmt.Errorf("获取场景规则失败: %w", err)
	}

	log.Printf("[RuleEngine] 执行场景 %s，共 %d 条关联规则", sceneID, len(rules))

	for _, rule := range rules {
		if rule.Enabled {
			e.ExecuteRuleActions(&rule)
			e.store.MarkRuleTriggered(rule.ID)
			e.mu.Lock()
			e.lastTriggered[rule.ID] = time.Now()
			e.mu.Unlock()
		}
	}

	return nil
}

// executeSetDevice 执行设备控制动作
func (e *RuleEngine) executeSetDevice(action Action) {
	url := fmt.Sprintf("%s/api/v1/devices/%s/set", e.iotServiceURL, action.DeviceID)

	body := map[string]interface{}{
		"property": action.Property,
		"value":    action.Value,
	}
	bodyBytes, _ := json.Marshal(body)

	resp, err := e.httpClient.Post(url, "application/json", bytes.NewReader(bodyBytes))
	if err != nil {
		log.Printf("[RuleEngine] 设备控制请求失败: device=%s property=%s err=%v",
			action.DeviceID, action.Property, err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
		log.Printf("[RuleEngine] 设备控制成功: device=%s property=%s value=%v",
			action.DeviceID, action.Property, action.Value)
	} else {
		log.Printf("[RuleEngine] 设备控制失败: device=%s property=%s status=%d",
			action.DeviceID, action.Property, resp.StatusCode)
	}
}

// executeNotify 执行通知动作
func (e *RuleEngine) executeNotify(action Action, userID string) {
	notif := ws.NotificationInfo{
		ID:        "notif_" + randomID(),
		Type:      "info",
		Title:     action.Title,
		Body:      action.Body,
		Timestamp: time.Now().UTC().Format(time.RFC3339),
	}

	msg := ws.ServerMessage{
		Type:         "notification",
		MessageID:    "notif_" + randomID(),
		Timestamp:    time.Now().UnixMilli(),
		Notification: &notif,
	}

	data, err := json.Marshal(msg)
	if err != nil {
		log.Printf("[RuleEngine] 序列化通知失败: %v", err)
		return
	}

	e.hub.SendToUser(userID, data)
	log.Printf("[RuleEngine] 通知已发送: user=%s title=%s", userID, action.Title)
}

// ========== 辅助方法 ==========

// IotDevice 设备信息（从 IoT 服务返回）
type IotDevice struct {
	ID          string                 `json:"id"`
	Name        string                 `json:"name"`
	Type        string                 `json:"type"`
	Status      string                 `json:"status"`
	Brightness  int                    `json:"brightness,omitempty"`
	Color       string                 `json:"color,omitempty"`
	Temperature float64                `json:"temperature,omitempty"`
	Mode        string                 `json:"mode,omitempty"`
	Position    int                    `json:"position,omitempty"`
	Value       float64                `json:"value,omitempty"`
	Unit        string                 `json:"unit,omitempty"`
	Battery     int                    `json:"battery,omitempty"`
	Properties  map[string]interface{} `json:"properties,omitempty"`
}

// fetchIoTDevices 从 IoT 调试服务获取设备列表
func (e *RuleEngine) fetchIoTDevices() ([]IotDevice, error) {
	resp, err := e.httpClient.Get(e.iotServiceURL + "/api/v1/devices")
	if err != nil {
		return nil, fmt.Errorf("请求IoT服务失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("IoT服务返回状态码 %d", resp.StatusCode)
	}

	var result struct {
		Devices []IotDevice `json:"devices"`
		Total   int         `json:"total"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("解析IoT设备列表失败: %w", err)
	}

	return result.Devices, nil
}

// compareValues 比较两个值
func compareValues(actual float64, operator string, expected float64) bool {
	switch operator {
	case "eq":
		return actual == expected
	case "neq":
		return actual != expected
	case "gt":
		return actual > expected
	case "gte":
		return actual >= expected
	case "lt":
		return actual < expected
	case "lte":
		return actual <= expected
	default:
		return false
	}
}

// randomID 使用 crypto/rand 生成随机 ID
func randomID() string {
	b := make([]byte, 8)
	rand.Read(b)
	return hex.EncodeToString(b)
}