package api

import (
	"net/http"

	"github.com/gin-gonic/gin"

	"github.com/hhs/camtalk/internal/logger"
	"github.com/hhs/camtalk/internal/models"
	"github.com/hhs/camtalk/internal/store"
)

const (
	MaxScenariosPerUser = 20   // 每个用户最多 20 个自建情景
	MaxPromptLength     = 2000 // Prompt 最大长度
)

// UserScenarioHandler 用户情景 API Handler。
type UserScenarioHandler struct {
	repo store.UserScenarioRepository
}

// NewUserScenarioHandler 创建用户情景 Handler。
func NewUserScenarioHandler(repo store.UserScenarioRepository) *UserScenarioHandler {
	return &UserScenarioHandler{repo: repo}
}

// List 获取用户的所有自建情景。
// GET /api/scenarios
func (h *UserScenarioHandler) List(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}

	scenarios, err := h.repo.FindByUserID(c.Request.Context(), userID.(string))
	if err != nil {
		logger.Log.Errorw("查询用户情景失败", "user_id", userID, "error", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "查询失败"})
		return
	}

	if scenarios == nil {
		scenarios = []*models.UserScenario{}
	}

	c.JSON(http.StatusOK, models.UserScenarioListResponse{
		Scenarios: scenarios,
		Total:     len(scenarios),
	})
}

// Create 创建用户情景。
// POST /api/scenarios
func (h *UserScenarioHandler) Create(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}

	var req models.CreateUserScenarioRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "参数错误: " + err.Error()})
		return
	}

	// 检查用户是否已达上限
	count, err := h.repo.CountByUserID(c.Request.Context(), userID.(string))
	if err != nil {
		logger.Log.Errorw("统计用户情景数量失败", "user_id", userID, "error", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "创建失败"})
		return
	}
	if count >= MaxScenariosPerUser {
		c.JSON(http.StatusBadRequest, gin.H{"error": "已达创建上限（最多 20 个）"})
		return
	}

	// 创建情景
	scenario := &models.UserScenario{
		UserID:      userID.(string),
		Name:        req.Name,
		Icon:        req.Icon,
		Description: req.Description,
		Prompt:      req.Prompt,
		Greeting:    req.Greeting,
		Language:    req.Language,
	}

	if err := h.repo.Create(c.Request.Context(), scenario); err != nil {
		logger.Log.Errorw("创建用户情景失败", "user_id", userID, "error", err)
		if err.Error() == "duplicate key value violates unique constraint" {
			c.JSON(http.StatusBadRequest, gin.H{"error": "情景名称已存在"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "创建失败"})
		return
	}

	logger.Log.Infow("创建用户情景成功", "user_id", userID, "scenario_id", scenario.ID)
	c.JSON(http.StatusCreated, scenario)
}

// Get 获取单个情景详情。
// GET /api/scenarios/:id
func (h *UserScenarioHandler) Get(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}

	scenarioID := c.Param("id")
	scenario, err := h.repo.FindByIDAndUserID(c.Request.Context(), scenarioID, userID.(string))
	if err != nil {
		logger.Log.Errorw("查询用户情景失败", "user_id", userID, "scenario_id", scenarioID, "error", err)
		c.JSON(http.StatusNotFound, gin.H{"error": "情景不存在或无权限"})
		return
	}

	c.JSON(http.StatusOK, scenario)
}

// Update 更新用户情景。
// PATCH /api/scenarios/:id
func (h *UserScenarioHandler) Update(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}

	scenarioID := c.Param("id")

	// 查询并校验所有权
	scenario, err := h.repo.FindByIDAndUserID(c.Request.Context(), scenarioID, userID.(string))
	if err != nil {
		logger.Log.Errorw("查询用户情景失败", "user_id", userID, "scenario_id", scenarioID, "error", err)
		c.JSON(http.StatusNotFound, gin.H{"error": "情景不存在或无权限"})
		return
	}

	var req models.UpdateUserScenarioRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "参数错误: " + err.Error()})
		return
	}

	// 更新字段
	if req.Name != nil {
		scenario.Name = *req.Name
	}
	if req.Icon != nil {
		scenario.Icon = *req.Icon
	}
	if req.Description != nil {
		scenario.Description = *req.Description
	}
	if req.Prompt != nil {
		scenario.Prompt = *req.Prompt
	}
	if req.Greeting != nil {
		scenario.Greeting = *req.Greeting
	}
	if req.Language != nil {
		scenario.Language = *req.Language
	}

	if err := h.repo.Update(c.Request.Context(), scenario); err != nil {
		logger.Log.Errorw("更新用户情景失败", "user_id", userID, "scenario_id", scenarioID, "error", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "更新失败"})
		return
	}

	logger.Log.Infow("更新用户情景成功", "user_id", userID, "scenario_id", scenarioID)
	c.JSON(http.StatusOK, scenario)
}

// Delete 删除用户情景。
// DELETE /api/scenarios/:id
func (h *UserScenarioHandler) Delete(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "未登录"})
		return
	}

	scenarioID := c.Param("id")

	// 查询并校验所有权
	_, err := h.repo.FindByIDAndUserID(c.Request.Context(), scenarioID, userID.(string))
	if err != nil {
		logger.Log.Errorw("查询用户情景失败", "user_id", userID, "scenario_id", scenarioID, "error", err)
		c.JSON(http.StatusNotFound, gin.H{"error": "情景不存在或无权限"})
		return
	}

	if err := h.repo.Delete(c.Request.Context(), scenarioID); err != nil {
		logger.Log.Errorw("删除用户情景失败", "user_id", userID, "scenario_id", scenarioID, "error", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "删除失败"})
		return
	}

	logger.Log.Infow("删除用户情景成功", "user_id", userID, "scenario_id", scenarioID)
	c.Status(http.StatusNoContent)
}