package api

import (
	"encoding/csv"
	"encoding/json"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"eaisalestrain/backend/internal/auth"
	"eaisalestrain/backend/internal/model"
	"eaisalestrain/backend/internal/store"
	"eaisalestrain/backend/internal/web"
)

// ============ 用户管理（管理员） ============

// ListUsers GET /api/system/users —— 含考试统计（考试次数/通过数/最近成绩）
func ListUsers(c *gin.Context) {
	var users []model.User
	if err := store.DB.Order("id ASC").Find(&users).Error; err != nil {
		web.Fail(c, web.NewBadRequest("查询用户失败"))
		return
	}
	var recs []model.ExamRecord
	store.DB.Order("submitted_at DESC").Find(&recs)

	type stat struct {
		ExamCount         int
		PassedCount       int
		LatestScore       *int
		LatestPassed      *bool
		LatestExamName    string
		LatestSubmittedAt *time.Time
	}
	stats := map[uint]*stat{}
	for _, r := range recs {
		s := stats[r.UserID]
		if s == nil {
			s = &stat{}
			stats[r.UserID] = s
		}
		s.ExamCount++
		if r.Passed {
			s.PassedCount++
		}
		if s.LatestSubmittedAt == nil {
			sc, ps := r.Score, r.Passed
			t := r.SubmittedAt
			s.LatestScore, s.LatestPassed = &sc, &ps
			s.LatestExamName = r.ExamName
			s.LatestSubmittedAt = &t
		}
	}

	out := make([]gin.H, 0, len(users))
	for _, u := range users {
		h := gin.H{
			"id": u.ID, "username": u.Username, "full_name": u.FullName,
			"role": u.Role, "status": u.Status, "ai_points": u.AiPoints,
			"department": u.Department, "position": u.Position, "hire_batch": u.HireBatch,
			"position_id": u.PositionID,
			"created_at": u.CreatedAt,
			"exam_count": 0, "passed_count": 0,
			"latest_score": nil, "latest_passed": nil, "latest_exam_name": "", "latest_submitted_at": nil,
		}
		if s := stats[u.ID]; s != nil {
			h["exam_count"] = s.ExamCount
			h["passed_count"] = s.PassedCount
			h["latest_score"] = s.LatestScore
			h["latest_passed"] = s.LatestPassed
			h["latest_exam_name"] = s.LatestExamName
			h["latest_submitted_at"] = s.LatestSubmittedAt
		}
		out = append(out, h)
	}
	web.OK(c, out)
}

// CreateUser POST /api/system/users —— {username,password,full_name,role,department,position,hire_batch}
func CreateUser(c *gin.Context) {
	var req struct {
		Username   string `json:"username"`
		Password   string `json:"password"`
		FullName   string `json:"full_name"`
		Role       string `json:"role"`
		Department string `json:"department"`
		Position   string `json:"position"`
		HireBatch  string `json:"hire_batch"`
	}
	if err := c.ShouldBindJSON(&req); err != nil || req.Username == "" || req.Password == "" || req.FullName == "" {
		web.Fail(c, web.NewBadRequest("username/password/full_name 必填"))
		return
	}
	if req.Role != "admin" && req.Role != "employee" {
		req.Role = "employee"
	}
	var count int64
	store.DB.Model(&model.User{}).Where("username = ?", req.Username).Count(&count)
	if count > 0 {
		web.Fail(c, web.NewConflictError("用户名已存在"))
		return
	}
	hash, err := auth.HashPassword(req.Password)
	if err != nil {
		web.Fail(c, web.NewBadRequest("密码加密失败"))
		return
	}
	u := model.User{
		Username: req.Username, PasswordHash: hash, FullName: req.FullName,
		Role: req.Role, Status: "active", AiPoints: defaultAiPoints(),
		Department: req.Department, Position: req.Position, HireBatch: req.HireBatch,
	}
	if req.Role == "admin" {
		u.AiPoints = 999999
	}
	if err := store.DB.Create(&u).Error; err != nil {
		web.Fail(c, web.NewBadRequest("创建用户失败"))
		return
	}
	web.OK(c, u)
}

// UpdateUser PUT /api/system/users/{id} —— 编辑（可选改密/禁用/改角色）
func UpdateUser(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var u model.User
	if err := store.DB.First(&u, id).Error; err != nil {
		web.Fail(c, web.NewNotFoundError("用户不存在"))
		return
	}
	var req struct {
		FullName   string `json:"full_name"`
		Role       string `json:"role"`
		Status     string `json:"status"`
		Password   string `json:"password"`
		AiPoints   *int   `json:"ai_points"`
		Department string `json:"department"`
		Position   string `json:"position"`
		HireBatch  string `json:"hire_batch"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		web.Fail(c, web.NewBadRequest("请求参数错误"))
		return
	}
	if req.FullName != "" {
		u.FullName = req.FullName
	}
	if req.Role == "admin" || req.Role == "employee" {
		u.Role = req.Role
	}
	if req.Status == "active" || req.Status == "disabled" {
		u.Status = req.Status
	}
	if req.Department != "" {
		u.Department = req.Department
	}
	if req.Position != "" {
		u.Position = req.Position
	}
	if req.HireBatch != "" {
		u.HireBatch = req.HireBatch
	}
	if req.Password != "" {
		hash, err := auth.HashPassword(req.Password)
		if err != nil {
			web.Fail(c, web.NewBadRequest("密码加密失败"))
			return
		}
		u.PasswordHash = hash
	}
	if req.AiPoints != nil {
		if *req.AiPoints < 0 {
			web.Fail(c, web.NewBadRequest("ai_points 不能为负"))
			return
		}
		u.AiPoints = *req.AiPoints
	}
	if err := store.DB.Save(&u).Error; err != nil {
		web.Fail(c, web.NewBadRequest("更新用户失败"))
		return
	}
	web.OK(c, u)
}

// defaultAiPoints 读取新用户默认 AI 算力点（system_config.ai_points_default，缺省 100）
func defaultAiPoints() int {
	var sc model.SystemConfig
	if err := store.DB.Where("config_key = ?", "ai_points_default").First(&sc).Error; err == nil {
		if v, err := strconv.Atoi(strings.TrimSpace(sc.ConfigValue)); err == nil {
			return v
		}
	}
	return 100
}

// ============ 成绩管理（管理员） ============

// ListExamRecords GET /api/system/exam-records?user_id=&paper_id=
func ListExamRecords(c *gin.Context) {
	q := store.DB.Model(&model.ExamRecord{})
	if uid := c.Query("user_id"); uid != "" {
		q = q.Where("user_id = ?", uid)
	}
	if pid := c.Query("paper_id"); pid != "" {
		q = q.Where("paper_id = ?", pid)
	}
	var items []model.ExamRecord
	if err := q.Order("submitted_at DESC").Find(&items).Error; err != nil {
		web.Fail(c, web.NewBadRequest("查询成绩失败"))
		return
	}
	web.OK(c, items)
}

// GetExamRecord GET /api/system/exam-records/{id} —— 详情
func GetExamRecord(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var rec model.ExamRecord
	if err := store.DB.First(&rec, id).Error; err != nil {
		web.Fail(c, web.NewNotFoundError("考试记录不存在"))
		return
	}
	var detail any
	_ = json.Unmarshal([]byte(rec.DetailJSON), &detail)
	web.OK(c, gin.H{
		"id": rec.ID, "user_id": rec.UserID, "paper_id": rec.PaperID, "exam_name": rec.ExamName,
		"score": rec.Score, "total_score": rec.TotalScore, "pass_score": rec.PassScore, "passed": rec.Passed,
		"correct_count": rec.CorrectCount, "wrong_count": rec.WrongCount,
		"detail": detail, "submitted_at": rec.SubmittedAt,
	})
}

// DeleteExamRecord DELETE /api/system/exam-records/{id} —— 删除成绩记录（用于重置正式考重考资格）
func DeleteExamRecord(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var rec model.ExamRecord
	if err := store.DB.First(&rec, id).Error; err != nil {
		web.Fail(c, web.NewNotFoundError("考试记录不存在"))
		return
	}
	if err := store.DB.Delete(&rec).Error; err != nil {
		web.Fail(c, web.NewBadRequest("删除考试记录失败"))
		return
	}
	web.OK(c, gin.H{"id": id, "deleted": true})
}

// ExportExamRecords GET /api/system/exam-records/export —— 导出 CSV（支持 user_id/paper_id 过滤）
func ExportExamRecords(c *gin.Context) {
	q := store.DB.Model(&model.ExamRecord{})
	if uid := c.Query("user_id"); uid != "" {
		q = q.Where("user_id = ?", uid)
	}
	if pid := c.Query("paper_id"); pid != "" {
		q = q.Where("paper_id = ?", pid)
	}
	var items []model.ExamRecord
	if err := q.Order("submitted_at DESC").Find(&items).Error; err != nil {
		web.Fail(c, web.NewBadRequest("查询成绩失败"))
		return
	}

	// 用户名映射
	var users []model.User
	store.DB.Find(&users)
	nameMap := map[uint]model.User{}
	for _, u := range users {
		nameMap[u.ID] = u
	}

	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", `attachment; filename="exam_records.csv"`)
	c.Writer.WriteString("\xEF\xBB\xBF") // UTF-8 BOM，兼容 Excel
	w := csv.NewWriter(c.Writer)
	_ = w.Write([]string{"编号", "用户名", "姓名", "部门", "考试名称", "得分", "总分", "结果", "答对", "答错", "提交时间"})
	for _, r := range items {
		u := nameMap[r.UserID]
		passed := "未通过"
		if r.Passed {
			passed = "通过"
		}
		_ = w.Write([]string{
			strconv.FormatUint(uint64(r.ID), 10),
			u.Username,
			u.FullName,
			u.Department,
			r.ExamName,
			strconv.Itoa(r.Score),
			strconv.Itoa(r.TotalScore),
			passed,
			strconv.Itoa(r.CorrectCount),
			strconv.Itoa(r.WrongCount),
			r.SubmittedAt.Format("2006-01-02 15:04:05"),
		})
	}
	w.Flush()
}

// ============ 系统参数配置（管理员） ============

// GetConfig GET /api/system/config —— 所有系统参数
func GetConfig(c *gin.Context) {
	var items []model.SystemConfig
	store.DB.Order("id ASC").Find(&items)
	type cfgItem struct {
		Key         string `json:"config_key"`
		Value       string `json:"config_value"`
		Description string `json:"description"`
	}
	out := make([]cfgItem, 0, len(items))
	for _, it := range items {
		out = append(out, cfgItem{Key: it.ConfigKey, Value: it.ConfigValue, Description: it.Description})
	}
	web.OK(c, gin.H{"configs": out})
}

// UpdateConfig PUT /api/system/config —— {configs: {key: value}}
func UpdateConfig(c *gin.Context) {
	var req struct {
		Configs map[string]string `json:"configs"`
	}
	if err := c.ShouldBindJSON(&req); err != nil || len(req.Configs) == 0 {
		web.Fail(c, web.NewBadRequest("configs 必填"))
		return
	}
	for k, v := range req.Configs {
		var sc model.SystemConfig
		if err := store.DB.Where("config_key = ?", k).First(&sc).Error; err == nil {
			sc.ConfigValue = v
			store.DB.Save(&sc)
		} else {
			store.DB.Create(&model.SystemConfig{ConfigKey: k, ConfigValue: v})
		}
	}
	web.OK(c, gin.H{"updated": len(req.Configs)})
}