package handlers

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"
	"tonav-go/database"
	"tonav-go/models"

	"github.com/gin-gonic/gin"
)

// ============ MCP (Model Context Protocol) v1 ============
// 传输: Streamable HTTP (POST /mcp, JSON-RPC 2.0)
// 鉴权: Authorization: Bearer <TONAV_MCP_TOKEN>

type mcpConfig struct {
	Token string
}

var mcpToken string

// LoadMCPConfig 读取 MCP 配置（环境变量 TONAV_MCP_TOKEN）
func LoadMCPConfig() {
	mcpToken = os.Getenv("TONAV_MCP_TOKEN")
	if mcpToken == "" {
		mcpToken = "tonav-mcp-default-token"
	}
}

// MCPAuthRequired MCP Bearer Token 鉴权
func MCPAuthRequired() gin.HandlerFunc {
	return func(c *gin.Context) {
		auth := c.GetHeader("Authorization")
		token := strings.TrimPrefix(auth, "Bearer ")
		if token == "" || token != mcpToken {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
				"jsonrpc": "2.0",
				"error": gin.H{
					"code":    -32001,
					"message": "unauthorized: invalid or missing bearer token",
				},
				"id": nil,
			})
			return
		}
		c.Next()
	}
}

// ============ JSON-RPC 结构 ============

type jsonRPCRequest struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      json.RawMessage `json:"id,omitempty"`
	Method  string          `json:"method"`
	Params  json.RawMessage `json:"params,omitempty"`
}

type jsonRPCResponse struct {
	JSONRPC string        `json:"jsonrpc"`
	ID      interface{}   `json:"id"`
	Result  interface{}   `json:"result,omitempty"`
	Error   *jsonRPCError `json:"error,omitempty"`
}

type jsonRPCError struct {
	Code    int         `json:"code"`
	Message string      `json:"message"`
	Data    interface{} `json:"data,omitempty"`
}

// ============ MCP 工具定义 ============

type mcpTool struct {
	Name        string                 `json:"name"`
	Description string                 `json:"description"`
	InputSchema map[string]interface{} `json:"inputSchema"`
}

func mcpToolDefs() []mcpTool {
	return []mcpTool{
		{
			Name: "tonav_add_service",
			Description: "向 ToNav 导航页添加一个服务网址。可指定名称、分类（不存在则自动创建）、标签、描述、是否开启健康检查。不传 name 时会尝试抓取目标网页的 <title> 自动命名。",
			InputSchema: map[string]interface{}{
				"type": "object",
				"properties": map[string]interface{}{
					"url":                   map[string]interface{}{"type": "string", "description": "服务网址，必填"},
					"name":                  map[string]interface{}{"type": "string", "description": "服务名称，不填自动抓取网页 title"},
					"category":              map[string]interface{}{"type": "string", "description": "分类名称，不存在时自动创建"},
					"tags":                  map[string]interface{}{"type": "array", "items": map[string]interface{}{"type": "string"}, "description": "标签列表，如 [\"监控\",\"告警\"]"},
					"description":           map[string]interface{}{"type": "string", "description": "服务描述，不填自动抓取网页 meta description"},
					"icon":                  map[string]interface{}{"type": "string", "description": "图标 URL，不填自动使用 /favicon.ico"},
					"health_check_enabled":  map[string]interface{}{"type": "boolean", "description": "是否开启健康检查，默认 true"},
					"health_check_url":      map[string]interface{}{"type": "string", "description": "健康检查地址，默认同 url"},
					"is_enabled":            map[string]interface{}{"type": "boolean", "description": "是否启用显示，默认 true"},
				},
				"required": []string{"url"},
			},
		},
		{
			Name:        "tonav_create_category",
			Description: "在 ToNav 中创建一个分类",
			InputSchema: map[string]interface{}{
				"type": "object",
				"properties": map[string]interface{}{
					"name":       map[string]interface{}{"type": "string", "description": "分类名称，必填"},
					"sort_order": map[string]interface{}{"type": "integer", "description": "排序权重，数字越大越靠前，默认 0"},
				},
				"required": []string{"name"},
			},
		},
		{
			Name:        "tonav_list_categories",
			Description: "列出 ToNav 所有分类（含每个分类下的服务数量）",
			InputSchema: map[string]interface{}{
				"type":       "object",
				"properties": map[string]interface{}{},
			},
		},
		{
			Name:        "tonav_list_services",
			Description: "列出 ToNav 服务，可按关键词/分类名/标签过滤",
			InputSchema: map[string]interface{}{
				"type": "object",
				"properties": map[string]interface{}{
					"keyword":  map[string]interface{}{"type": "string", "description": "按名称/URL/描述模糊匹配"},
					"category": map[string]interface{}{"type": "string", "description": "按分类名过滤"},
					"tag":      map[string]interface{}{"type": "string", "description": "按标签过滤"},
				},
			},
		},
		{
			Name:        "tonav_update_service",
			Description: "按名称或 ID 更新已有服务：可改名称/URL/分类/标签/描述/启用状态/健康检查开关",
			InputSchema: map[string]interface{}{
				"type": "object",
				"properties": map[string]interface{}{
					"id":                    map[string]interface{}{"type": "integer", "description": "服务 ID（与 name 二选一）"},
					"name":                  map[string]interface{}{"type": "string", "description": "现有服务名称（用于定位服务）"},
					"new_name":              map[string]interface{}{"type": "string", "description": "新名称"},
					"url":                   map[string]interface{}{"type": "string", "description": "新 URL"},
					"category":              map[string]interface{}{"type": "string", "description": "新分类名（不存在自动创建）"},
					"tags":                  map[string]interface{}{"type": "array", "items": map[string]interface{}{"type": "string"}, "description": "新标签列表（整体替换）"},
					"description":           map[string]interface{}{"type": "string", "description": "新描述"},
					"is_enabled":            map[string]interface{}{"type": "boolean"},
					"health_check_enabled":  map[string]interface{}{"type": "boolean"},
					"health_check_url":      map[string]interface{}{"type": "string"},
				},
			},
		},
		{
			Name:        "tonav_delete_service",
			Description: "按名称或 ID 删除一个服务",
			InputSchema: map[string]interface{}{
				"type": "object",
				"properties": map[string]interface{}{
					"id":   map[string]interface{}{"type": "integer", "description": "服务 ID（与 name 二选一）"},
					"name": map[string]interface{}{"type": "string", "description": "服务名称"},
				},
			},
		},
	}
}

// ============ 工具实现 ============

// fetchPageMeta 抓取网页 <title> 与 meta description
func fetchPageMeta(rawURL string) (title, desc string) {
	client := &http.Client{Timeout: 6 * time.Second}
	if !strings.HasPrefix(rawURL, "http") {
		rawURL = "https://" + rawURL
	}
	resp, err := client.Get(rawURL)
	if err != nil {
		return "", ""
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(io.LimitReader(resp.Body, 256*1024))
	if err != nil {
		return "", ""
	}
	html := string(body)

	// title
	if s := strings.Index(strings.ToLower(html), "<title"); s >= 0 {
		rest := html[s:]
		if e := strings.Index(strings.ToLower(rest), "</title>"); e >= 0 {
			inner := rest[len("<title"):e]
			if c := strings.Index(inner, ">"); c >= 0 {
				title = strings.TrimSpace(inner[c+1:])
			}
		}
	}
	// meta description
	lower := strings.ToLower(html)
	if idx := strings.Index(lower, "name=\"description\""); idx >= 0 {
		seg := html[idx:]
		if cIdx := strings.Index(strings.ToLower(seg), "content=\""); cIdx >= 0 {
			seg = seg[cIdx+len("content=\""):]
			if eIdx := strings.Index(seg, "\""); eIdx >= 0 {
				desc = strings.TrimSpace(seg[:eIdx])
			}
		}
	}
	if len(title) > 200 {
		title = title[:200]
	}
	if len(desc) > 500 {
		desc = desc[:500]
	}
	return title, desc
}

// normalizeURL 规范化 URL
func normalizeURL(u string) string {
	u = strings.TrimSpace(u)
	if u != "" && !strings.HasPrefix(u, "http://") && !strings.HasPrefix(u, "https://") {
		u = "https://" + u
	}
	return u
}

// ensureCategory 获取或创建分类，返回分类 ID
func ensureCategory(name string) (uint, error) {
	var cat models.Category
	if err := database.DB.Where("name = ?", name).First(&cat).Error; err == nil {
		return cat.ID, nil
	}
	cat = models.Category{Name: name, SortOrder: 50}
	if err := database.DB.Create(&cat).Error; err != nil {
		// 并发或重名冲突时再查一次
		if err2 := database.DB.Where("name = ?", name).First(&cat).Error; err2 == nil {
			return cat.ID, nil
		}
		return 0, err
	}
	return cat.ID, nil
}

// findService 按 ID 或名称定位服务
func findService(id float64, name string) (*models.Service, error) {
	var svc models.Service
	var err error
	if id > 0 {
		err = database.DB.First(&svc, uint(id)).Error
	} else if name != "" {
		err = database.DB.Where("name = ?", name).First(&svc).Error
	} else {
		err = fmt.Errorf("必须提供 id 或 name")
	}
	if err != nil {
		return nil, err
	}
	return &svc, nil
}

// tagsToString 标签数组转存储格式（逗号分隔）
func tagsToString(tags []interface{}) string {
	if len(tags) == 0 {
		return ""
	}
	parts := make([]string, 0, len(tags))
	for _, t := range tags {
		if s, ok := t.(string); ok && strings.TrimSpace(s) != "" {
			parts = append(parts, strings.TrimSpace(s))
		}
	}
	return strings.Join(parts, ",")
}

// toolAddService 添加服务
func toolAddService(args map[string]interface{}) (interface{}, error) {
	rawURL, _ := args["url"].(string)
	if strings.TrimSpace(rawURL) == "" {
		return nil, fmt.Errorf("url 不能为空")
	}
	url := normalizeURL(rawURL)

	name, _ := args["name"].(string)
	description, _ := args["description"].(string)
	category, _ := args["category"].(string)

	// 自动抓取 title / description
	autoTitle, autoDesc := "", ""
	if strings.TrimSpace(name) == "" || strings.TrimSpace(description) == "" {
		autoTitle, autoDesc = fetchPageMeta(url)
	}
	if strings.TrimSpace(name) == "" {
		name = autoTitle
	}
	if strings.TrimSpace(name) == "" {
		// 兜底用 host
		u := strings.TrimPrefix(strings.TrimPrefix(url, "https://"), "http://")
		name = strings.Split(u, "/")[0]
	}
	if strings.TrimSpace(description) == "" {
		description = autoDesc
	}

	healthEnabled := true
	if v, ok := args["health_check_enabled"].(bool); ok {
		healthEnabled = v
	}
	isEnabled := true
	if v, ok := args["is_enabled"].(bool); ok {
		isEnabled = v
	}
	healthURL, _ := args["health_check_url"].(string)

	var categoryID uint
	if strings.TrimSpace(category) != "" {
		cid, err := ensureCategory(strings.TrimSpace(category))
		if err != nil {
			return nil, fmt.Errorf("创建分类失败: %v", err)
		}
		categoryID = cid
	}

	icon, _ := args["icon"].(string)
	if strings.TrimSpace(icon) == "" {
		u := strings.TrimPrefix(strings.TrimPrefix(url, "https://"), "http://")
		host := strings.Split(u, "/")[0]
		icon = "https://" + host + "/favicon.ico"
	}

	// 查重：同名或同 URL 已存在则返回提示
	var existed models.Service
	if err := database.DB.Where("url = ?", url).First(&existed).Error; err == nil {
		return map[string]interface{}{
			"created":  false,
			"message":  fmt.Sprintf("已存在相同 URL 的服务「%s」(id=%d)，未重复创建。可使用 tonav_update_service 更新它。", existed.Name, existed.ID),
			"existing": existed,
		}, nil
	}

	svc := models.Service{
		Name:               strings.TrimSpace(name),
		URL:                url,
		Description:        strings.TrimSpace(description),
		Icon:               icon,
		CategoryID:         categoryID,
		Status:             "unknown",
		Tags:               tagsToString(args["tags"].([]interface{})),
		IsEnabled:          isEnabled,
		HealthCheckURL:     strings.TrimSpace(healthURL),
		HealthCheckEnabled: healthEnabled,
	}
	// tags 需要单独处理（args["tags"] 可能不存在）
	if rawTags, ok := args["tags"]; ok {
		if arr, ok := rawTags.([]interface{}); ok {
			svc.Tags = tagsToString(arr)
		}
	}
	if svc.Tags == "" {
		if arr, ok := args["tags"].([]interface{}); ok {
			svc.Tags = tagsToString(arr)
		}
	}

	if err := database.DB.Create(&svc).Error; err != nil {
		return nil, fmt.Errorf("创建失败: %v", err)
	}

	catName := category
	if catName == "" && categoryID > 0 {
		var cat models.Category
		if database.DB.First(&cat, categoryID).Error == nil {
			catName = cat.Name
		}
	}
	return map[string]interface{}{
		"created":     true,
		"message":     fmt.Sprintf("已添加服务「%s」%s", svc.Name, func() string { if catName != "" { return " 到分类「" + catName + "」" }; return "" }()),
		"service":     svc,
		"category_id": categoryID,
		"category":    catName,
		"tags":        svc.Tags,
	}, nil
}

// toolCreateCategory 创建分类
func toolCreateCategory(args map[string]interface{}) (interface{}, error) {
	name, _ := args["name"].(string)
	if strings.TrimSpace(name) == "" {
		return nil, fmt.Errorf("name 不能为空")
	}
	sortOrder := 0
	if v, ok := args["sort_order"].(float64); ok {
		sortOrder = int(v)
	}
	var existed models.Category
	if err := database.DB.Where("name = ?", name).First(&existed).Error; err == nil {
		return map[string]interface{}{
			"created":  false,
			"message":  fmt.Sprintf("分类「%s」已存在 (id=%d)", existed.Name, existed.ID),
			"category": existed,
		}, nil
	}
	cat := models.Category{Name: strings.TrimSpace(name), SortOrder: sortOrder}
	if err := database.DB.Create(&cat).Error; err != nil {
		return nil, fmt.Errorf("创建分类失败: %v", err)
	}
	return map[string]interface{}{
		"created":  true,
		"message":  fmt.Sprintf("已创建分类「%s」", cat.Name),
		"category": cat,
	}, nil
}

// toolListCategories 列出分类
func toolListCategories(_ map[string]interface{}) (interface{}, error) {
	var cats []models.Category
	database.DB.Order("sort_order desc").Find(&cats)
	type catWithCount struct {
		models.Category
		ServiceCount int64 `json:"service_count"`
	}
	result := make([]catWithCount, 0, len(cats))
	for _, c := range cats {
		var cnt int64
		database.DB.Model(&models.Service{}).Where("category_id = ?", c.ID).Count(&cnt)
		result = append(result, catWithCount{Category: c, ServiceCount: cnt})
	}
	return map[string]interface{}{"categories": result}, nil
}

// toolListServices 列出服务
func toolListServices(args map[string]interface{}) (interface{}, error) {
	var svcs []models.Service
	q := database.DB.Order("category_id asc, sort_order desc")
	keyword, _ := args["keyword"].(string)
	category, _ := args["category"].(string)
	tag, _ := args["tag"].(string)

	if category != "" {
		var cat models.Category
		if err := database.DB.Where("name = ?", category).First(&cat).Error; err != nil {
			return map[string]interface{}{"services": []models.Service{}, "message": "分类不存在: " + category}, nil
		}
		q = q.Where("category_id = ?", cat.ID)
	}
	if tag != "" {
		q = q.Where("tags LIKE ?", "%"+tag+"%")
	}
	if keyword != "" {
		like := "%" + keyword + "%"
		q = q.Where("name LIKE ? OR url LIKE ? OR description LIKE ?", like, like, like)
	}
	q.Find(&svcs)
	return map[string]interface{}{"count": len(svcs), "services": svcs}, nil
}

// toolUpdateService 更新服务
func toolUpdateService(args map[string]interface{}) (interface{}, error) {
	id, _ := args["id"].(float64)
	name, _ := args["name"].(string)
	svc, err := findService(id, name)
	if err != nil {
		return nil, fmt.Errorf("未找到服务: %v", err)
	}

	changes := map[string]interface{}{}
	if v, ok := args["new_name"].(string); ok && strings.TrimSpace(v) != "" {
		changes["name"] = strings.TrimSpace(v)
	}
	if v, ok := args["url"].(string); ok && strings.TrimSpace(v) != "" {
		changes["url"] = normalizeURL(v)
	}
	if v, ok := args["description"].(string); ok {
		changes["description"] = v
	}
	if v, ok := args["health_check_url"].(string); ok {
		changes["health_check_url"] = strings.TrimSpace(v)
	}
	if v, ok := args["is_enabled"].(bool); ok {
		changes["is_enabled"] = v
	}
	if v, ok := args["health_check_enabled"].(bool); ok {
		changes["health_check_enabled"] = v
	}
	if v, ok := args["tags"]; ok {
		if arr, ok := v.([]interface{}); ok {
			changes["tags"] = tagsToString(arr)
		}
	}
	if cat, ok := args["category"].(string); ok && strings.TrimSpace(cat) != "" {
		cid, err := ensureCategory(strings.TrimSpace(cat))
		if err != nil {
			return nil, fmt.Errorf("创建分类失败: %v", err)
		}
		changes["category_id"] = cid
	}

	if len(changes) == 0 {
		return nil, fmt.Errorf("未提供任何需要更新的字段")
	}
	if err := database.DB.Model(svc).Updates(changes).Error; err != nil {
		return nil, fmt.Errorf("更新失败: %v", err)
	}
	database.DB.First(svc, svc.ID)
	return map[string]interface{}{"updated": true, "message": fmt.Sprintf("已更新服务「%s」", svc.Name), "service": svc}, nil
}

// toolDeleteService 删除服务
func toolDeleteService(args map[string]interface{}) (interface{}, error) {
	id, _ := args["id"].(float64)
	name, _ := args["name"].(string)
	svc, err := findService(id, name)
	if err != nil {
		return nil, fmt.Errorf("未找到服务: %v", err)
	}
	if err := database.DB.Delete(svc).Error; err != nil {
		return nil, fmt.Errorf("删除失败: %v", err)
	}
	return map[string]interface{}{"deleted": true, "message": fmt.Sprintf("已删除服务「%s」(id=%d)", svc.Name, svc.ID)}, nil
}

// ============ JSON-RPC 处理 ============

func mcpResult(id json.RawMessage, result interface{}) gin.H {
	var idVal interface{}
	if len(id) > 0 {
		_ = json.Unmarshal(id, &idVal)
	}
	return gin.H{"jsonrpc": "2.0", "id": idVal, "result": result}
}

func mcpError(id json.RawMessage, code int, msg string) gin.H {
	var idVal interface{}
	if len(id) > 0 {
		_ = json.Unmarshal(id, &idVal)
	}
	return gin.H{"jsonrpc": "2.0", "id": idVal, "error": gin.H{"code": code, "message": msg}}
}

func callTool(name string, args map[string]interface{}) (interface{}, error) {
	switch name {
	case "tonav_add_service":
		return toolAddService(args)
	case "tonav_create_category":
		return toolCreateCategory(args)
	case "tonav_list_categories":
		return toolListCategories(args)
	case "tonav_list_services":
		return toolListServices(args)
	case "tonav_update_service":
		return toolUpdateService(args)
	case "tonav_delete_service":
		return toolDeleteService(args)
	default:
		return nil, fmt.Errorf("未知工具: %s", name)
	}
}

// MCPHandler 处理 POST /mcp (Streamable HTTP)
func MCPHandler(c *gin.Context) {
	body, err := io.ReadAll(io.LimitReader(c.Request.Body, 1024*1024))
	if err != nil {
		c.JSON(http.StatusBadRequest, mcpError(nil, -32700, "读取请求失败"))
		return
	}

	// 支持批量调用
	var batch []jsonRPCRequest
	var single jsonRPCRequest
	if err := json.Unmarshal(body, &batch); err == nil && len(batch) > 0 {
		responses := make([]gin.H, 0, len(batch))
		for _, req := range batch {
			if resp := handleMCPRequest(req); resp != nil {
				responses = append(responses, resp)
			}
		}
		if len(responses) == 0 {
			c.Status(http.StatusAccepted)
			return
		}
		c.JSON(http.StatusOK, responses)
		return
	}

	if err := json.Unmarshal(body, &single); err != nil {
		c.JSON(http.StatusBadRequest, mcpError(nil, -32700, "解析错误: "+err.Error()))
		return
	}

	resp := handleMCPRequest(single)
	if resp == nil {
		// notification -> 202 Accepted
		c.Status(http.StatusAccepted)
		return
	}
	c.JSON(http.StatusOK, resp)
}

// handleMCPRequest 处理单条 JSON-RPC 请求；notification 返回 nil
func handleMCPRequest(req jsonRPCRequest) gin.H {
	switch req.Method {
	case "initialize":
		proto, _ := strconv.Unquote(string(req.Params))
		_ = proto
		return mcpResult(req.ID, map[string]interface{}{
			"protocolVersion": "2025-03-26",
			"capabilities": map[string]interface{}{
				"tools": map[string]interface{}{"listChanged": false},
			},
			"serverInfo": map[string]interface{}{
				"name":    "tonav-mcp",
				"version": "1.0.0",
			},
		})

	case "notifications/initialized", "initialized":
		return nil // notification

	case "ping":
		return mcpResult(req.ID, map[string]interface{}{})

	case "tools/list":
		return mcpResult(req.ID, map[string]interface{}{"tools": mcpToolDefs()})

	case "tools/call":
		var params struct {
			Name      string                 `json:"name"`
			Arguments map[string]interface{} `json:"arguments"`
		}
		if err := json.Unmarshal(req.Params, &params); err != nil {
			return mcpError(req.ID, -32602, "参数解析失败: "+err.Error())
		}
		if params.Arguments == nil {
			params.Arguments = map[string]interface{}{}
		}
		result, err := callTool(params.Name, params.Arguments)
		if err != nil {
			return mcpResult(req.ID, map[string]interface{}{
				"content": []map[string]interface{}{{
					"type": "text",
					"text": "工具执行失败: " + err.Error(),
				}},
				"isError": true,
			})
		}
		data, _ := json.Marshal(result)
		return mcpResult(req.ID, map[string]interface{}{
			"content": []map[string]interface{}{{
				"type": "text",
				"text": string(data),
			}},
		})

	default:
		return mcpError(req.ID, -32601, "未知方法: "+req.Method)
	}
}

// GetMCPHeaderToken 供测试使用
func GetMCPHeaderToken() string {
	return mcpToken
}