package handlers

import (
	"database/sql"
	"encoding/json"
	"errors"
	"net/http"
	"strings"
	"time"

	"github.com/golang-jwt/jwt/v5"
	"golang.org/x/crypto/bcrypt"

	"mmgame/internal/config"
	"mmgame/internal/database"
	"mmgame/internal/models"
	"mmgame/internal/util"
)

var errUnauthorized = errors.New("unauthorized")

func createToken(userID string) (string, error) {
	exp := time.Now().Add(time.Duration(config.Cfg.AccessTokenExpireMinutes) * time.Minute)
	claims := jwt.MapClaims{
		"sub": userID,
		"exp": exp.Unix(),
		"v":   0,
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(config.Cfg.SecretKey))
}

func currentUser(r *http.Request) (*models.User, error) {
	auth := r.Header.Get("Authorization")
	if !strings.HasPrefix(auth, "Bearer ") {
		return nil, errUnauthorized
	}
	tokenStr := strings.TrimPrefix(auth, "Bearer ")
	claims := jwt.MapClaims{}
	token, err := jwt.ParseWithClaims(tokenStr, claims, func(t *jwt.Token) (interface{}, error) {
		return []byte(config.Cfg.SecretKey), nil
	}, jwt.WithValidMethods([]string{config.Cfg.Algorithm}))
	if err != nil || !token.Valid {
		return nil, errUnauthorized
	}
	userID, _ := claims["sub"].(string)
	if userID == "" {
		return nil, errUnauthorized
	}
	row := database.DB.QueryRow(
		`SELECT id, email, nickname, avatar_url, password_hash, role, is_guest, game_count, token_version, created_at
		 FROM users WHERE id = ?`, userID)
	var u models.User
	var email, nickname, avatarURL, passwordHash, createdAt sql.NullString
	if err := row.Scan(&u.ID, &email, &nickname, &avatarURL, &passwordHash, &u.Role,
		&u.IsGuest, &u.GameCount, &u.TokenVersion, &createdAt); err != nil {
		return nil, errUnauthorized
	}
	if email.Valid {
		u.Email = &email.String
	}
	if nickname.Valid {
		u.Nickname = &nickname.String
	}
	if avatarURL.Valid {
		u.AvatarURL = &avatarURL.String
	}
	if passwordHash.Valid {
		u.PasswordHash = &passwordHash.String
	}
	u.CreatedAt = util.ParseTime(createdAt.String)
	return &u, nil
}

func Register(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Email    string `json:"email"`
		Password string `json:"password"`
		Nickname string `json:"nickname"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, 422, "请求格式错误")
		return
	}
	var existingID string
	err := database.DB.QueryRow(`SELECT id FROM users WHERE email = ?`, req.Email).Scan(&existingID)
	if err == nil {
		writeError(w, 400, "邮箱已注册")
		return
	}
	if err != sql.ErrNoRows {
		writeError(w, 500, "服务器错误")
		return
	}
	hash, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
	if err != nil {
		writeError(w, 500, "服务器错误")
		return
	}
	userID := newID()
	_, err = database.DB.Exec(
		`INSERT INTO users (id, email, nickname, password_hash, role, is_guest, game_count, token_version, created_at)
		 VALUES (?, ?, ?, ?, ?, 0, 0, 0, ?)`,
		userID, req.Email, req.Nickname, string(hash), models.RolePlayer, util.NowStr())
	if err != nil {
		writeError(w, 500, "服务器错误")
		return
	}
	token, _ := createToken(userID)
	writeJSON(w, 200, map[string]interface{}{
		"token":    token,
		"user_id":  userID,
		"nickname": req.Nickname,
		"is_guest": false,
	})
}

func Login(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Email    string `json:"email"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, 422, "请求格式错误")
		return
	}
	var id, email, nickname, passwordHash string
	err := database.DB.QueryRow(
		`SELECT id, email, nickname, password_hash FROM users WHERE email = ?`, req.Email).
		Scan(&id, &email, &nickname, &passwordHash)
	if err == sql.ErrNoRows || passwordHash == "" {
		writeError(w, 401, "邮箱或密码错误")
		return
	}
	if err != nil {
		writeError(w, 500, "服务器错误")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(passwordHash), []byte(req.Password)) != nil {
		writeError(w, 401, "邮箱或密码错误")
		return
	}
	token, _ := createToken(id)
	writeJSON(w, 200, map[string]interface{}{
		"token":    token,
		"user_id":  id,
		"nickname": nickname,
		"is_guest": false,
	})
}

func GuestLogin(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Nickname string `json:"nickname"`
	}
	_ = json.NewDecoder(r.Body).Decode(&req)
	if req.Nickname == "" {
		req.Nickname = "游客"
	}
	userID := newID()
	_, err := database.DB.Exec(
		`INSERT INTO users (id, nickname, role, is_guest, game_count, token_version, created_at)
		 VALUES (?, ?, ?, 1, 0, 0, ?)`,
		userID, req.Nickname, models.RolePlayer, util.NowStr())
	if err != nil {
		writeError(w, 500, "服务器错误")
		return
	}
	token, _ := createToken(userID)
	writeJSON(w, 200, map[string]interface{}{
		"token":    token,
		"user_id":  userID,
		"nickname": req.Nickname,
		"is_guest": true,
	})
}

func Logout(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, 200, map[string]string{"status": "ok"})
}

func GetProfile(w http.ResponseWriter, r *http.Request) {
	user, err := currentUser(r)
	if err != nil {
		writeError(w, 401, "未登录")
		return
	}
	writeJSON(w, 200, map[string]interface{}{
		"user_id":    user.ID,
		"email":      nullStr(user.Email),
		"nickname":   nullStr(user.Nickname),
		"avatar_url": nullStr(user.AvatarURL),
		"is_guest":   user.IsGuest,
		"role":       user.Role,
		"game_count": user.GameCount,
		"created_at": util.TimeStr(user.CreatedAt),
	})
}

func UpdateProfile(w http.ResponseWriter, r *http.Request) {
	user, err := currentUser(r)
	if err != nil {
		writeError(w, 401, "未登录")
		return
	}
	var data map[string]interface{}
	_ = json.NewDecoder(r.Body).Decode(&data)

	var nickname, avatarURL *string
	if v, ok := data["nickname"].(string); ok {
		nickname = &v
	}
	if v, ok := data["avatar_url"].(string); ok {
		avatarURL = &v
	}
	if nickname != nil {
		if _, err := database.DB.Exec(`UPDATE users SET nickname = ? WHERE id = ?`, *nickname, user.ID); err != nil {
			writeError(w, 500, "服务器错误")
			return
		}
	}
	if avatarURL != nil {
		if _, err := database.DB.Exec(`UPDATE users SET avatar_url = ? WHERE id = ?`, *avatarURL, user.ID); err != nil {
			writeError(w, 500, "服务器错误")
			return
		}
	}
	writeJSON(w, 200, map[string]string{"status": "ok"})
}

func GetHistory(w http.ResponseWriter, r *http.Request) {
	if _, err := currentUser(r); err != nil {
		writeError(w, 401, "未登录")
		return
	}
	rows, err := database.DB.Query(
		`SELECT id, script_id, status, phase, phase_index, started_at, completed_at, created_at
		 FROM game_sessions ORDER BY created_at DESC LIMIT 50`)
	if err != nil {
		writeError(w, 500, "服务器错误")
		return
	}
	defer rows.Close()
	var items []map[string]interface{}
	for rows.Next() {
		var id, scriptID, status, phase, startedAt, completedAt, createdAt sql.NullString
		var phaseIndex int
		if err := rows.Scan(&id, &scriptID, &status, &phase, &phaseIndex, &startedAt, &completedAt, &createdAt); err != nil {
			continue
		}
		items = append(items, map[string]interface{}{
			"id":           id.String,
			"script_id":    scriptID.String,
			"status":       status.String,
			"phase":        phase.String,
			"phase_index":  phaseIndex,
			"started_at":   startedAt.String,
			"completed_at": completedAt.String,
			"created_at":   createdAt.String,
		})
	}
	writeJSON(w, 200, items)
}