package handlers

import (
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"github.com/toyffee/party-mix/internal/models"
	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"
)

type registerReq struct {
	Username string `json:"username" binding:"required,min=3,max=50"`
	Email    string `json:"email" binding:"required,email"`
	Password string `json:"password" binding:"required,min=6"`
}

func Register(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		var req registerReq
		if err := c.ShouldBindJSON(&req); err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}

		hash, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
			return
		}

		user := models.User{
			ID:           uuid.NewString(),
			Username:     req.Username,
			Email:        strings.ToLower(req.Email),
			PasswordHash: string(hash),
			CreatedAt:    time.Now(),
		}

		if err := db.Create(&user).Error; err != nil {
			if strings.Contains(err.Error(), "duplicate key") || strings.Contains(err.Error(), "unique") {
				c.JSON(http.StatusConflict, gin.H{"error": "username or email already taken"})
				return
			}
			c.JSON(http.StatusInternalServerError, gin.H{"error": "could not create user"})
			return
		}

		c.JSON(http.StatusCreated, user)
	}
}

type loginReq struct {
	Email    string `json:"email" binding:"required"`
	Password string `json:"password" binding:"required"`
}

func Login(db *gorm.DB, jwtSecret string) gin.HandlerFunc {
	return func(c *gin.Context) {
		var req loginReq
		if err := c.ShouldBindJSON(&req); err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}

		var user models.User
		if err := db.Where("email = ?", strings.ToLower(req.Email)).First(&user).Error; err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
			return
		}

		if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(req.Password)); err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
			return
		}

		token, err := generateToken(user.ID, jwtSecret)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "could not generate token"})
			return
		}

		c.JSON(http.StatusOK, gin.H{
			"token": token,
			"user":  user,
		})
	}
}

func Me(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		userID := currentUserID(c)
		var user models.User
		if err := db.First(&user, "id = ?", userID).Error; err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "user not found"})
			return
		}
		c.JSON(http.StatusOK, user)
	}
}