package handlers

import (
	"net/http"
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/nutcas3/telecom-platform/apps/api-server/internal/models"
	"github.com/nutcas3/telecom-platform/apps/api-server/internal/services"
)

// AuthHandler handles authentication endpoints
type AuthHandler struct {
	authService *services.AuthService
}

// NewAuthHandler creates a new auth handler
func NewAuthHandler(authService *services.AuthService) *AuthHandler {
	return &AuthHandler{
		authService: authService,
	}
}

// LoginRequest represents a login request
type LoginRequest struct {
	Username string `json:"username" binding:"required"`
	Password string `json:"password" binding:"required"`
}

// LoginResponse represents a login response
type LoginResponse struct {
	AccessToken  string       `json:"access_token"`
	RefreshToken string       `json:"refresh_token"`
	User         *models.User `json:"user"`
}

// RegisterRequest represents a registration request
type RegisterRequest struct {
	Username  string `json:"username" binding:"required"`
	Email     string `json:"email" binding:"required,email"`
	Password  string `json:"password" binding:"required,min=6"`
	FirstName string `json:"first_name" binding:"required"`
	LastName  string `json:"last_name" binding:"required"`
	Role      string `json:"role" binding:"required,oneof=admin operator viewer"`
}

// ChangePasswordRequest represents a password change request
type ChangePasswordRequest struct {
	OldPassword string `json:"old_password" binding:"required"`
	NewPassword string `json:"new_password" binding:"required,min=6"`
}

// Login handles user login
func (h *AuthHandler) Login(c *gin.Context) {
	var req LoginRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	accessToken, refreshToken, user, err := h.authService.Login(req.Username, req.Password)
	if err != nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": err.Error()})
		return
	}

	response := LoginResponse{
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
		User:         user,
	}

	c.JSON(http.StatusOK, response)
}

// Register handles user registration
func (h *AuthHandler) Register(c *gin.Context) {
	var req RegisterRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	user, err := h.authService.Register(req.Username, req.Email, req.Password, req.FirstName, req.LastName, req.Role)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Don't return password hash
	user.Password = ""

	c.JSON(http.StatusCreated, gin.H{
		"message": "User registered successfully",
		"user":    user,
	})
}

// RefreshToken handles token refresh
func (h *AuthHandler) RefreshToken(c *gin.Context) {
	var req struct {
		RefreshToken string `json:"refresh_token" binding:"required"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	accessToken, refreshToken, err := h.authService.GetJWTService().RefreshToken(req.RefreshToken)
	if err != nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"access_token":  accessToken,
		"refresh_token": refreshToken,
	})
}

// Logout handles user logout
func (h *AuthHandler) Logout(c *gin.Context) {
	authHeader := c.GetHeader("Authorization")
	if authHeader == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Authorization header required"})
		return
	}

	// Extract token from "Bearer <token>" format
	tokenParts := strings.Split(authHeader, " ")
	if len(tokenParts) != 2 || tokenParts[0] != "Bearer" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid authorization header format"})
		return
	}

	token := tokenParts[1]
	if err := h.authService.GetJWTService().InvalidateSession(token); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to logout"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "Logged out successfully"})
}

// GetProfile handles getting the current user's profile
func (h *AuthHandler) GetProfile(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "User not authenticated"})
		return
	}

	user, err := h.authService.GetUserByID(userID.(uint))
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "User not found"})
		return
	}

	// Don't return password hash
	user.Password = ""

	c.JSON(http.StatusOK, user)
}

// ChangePassword handles password change
func (h *AuthHandler) ChangePassword(c *gin.Context) {
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "User not authenticated"})
		return
	}

	var req ChangePasswordRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := h.authService.ChangePassword(userID.(uint), req.OldPassword, req.NewPassword); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "Password changed successfully"})
}

// GetUsers handles listing users (admin only)
func (h *AuthHandler) GetUsers(c *gin.Context) {
	// Parse pagination parameters
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	limit, _ := strconv.Atoi(c.DefaultQuery("limit", "20"))
	if page < 1 {
		page = 1
	}
	if limit < 1 || limit > 100 {
		limit = 20
	}

	offset := (page - 1) * limit

	var users []models.User
	var total int64

	// Get total count
	if err := h.authService.GetDB().Model(&models.User{}).Count(&total).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to count users"})
		return
	}

	// Get users with pagination
	if err := h.authService.GetDB().Offset(offset).Limit(limit).Find(&users).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch users"})
		return
	}

	// Remove password hashes
	for i := range users {
		users[i].Password = ""
	}

	c.JSON(http.StatusOK, gin.H{
		"users": users,
		"pagination": gin.H{
			"page":        page,
			"limit":       limit,
			"total":       total,
			"total_pages": (total + int64(limit) - 1) / int64(limit),
		},
	})
}

// CreateUser handles creating a new user (admin only)
func (h *AuthHandler) CreateUser(c *gin.Context) {
	var req RegisterRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	user, err := h.authService.Register(req.Username, req.Email, req.Password, req.FirstName, req.LastName, req.Role)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Don't return password hash
	user.Password = ""

	c.JSON(http.StatusCreated, gin.H{
		"message": "User created successfully",
		"user":    user,
	})
}

// UpdateUser handles updating a user (admin only)
func (h *AuthHandler) UpdateUser(c *gin.Context) {
	userIDStr := c.Param("id")
	userID, err := strconv.ParseUint(userIDStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid user ID"})
		return
	}

	var req struct {
		FirstName *string `json:"first_name"`
		LastName  *string `json:"last_name"`
		Email     *string `json:"email"`
		Role      *string `json:"role"`
		IsActive  *bool   `json:"is_active"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Get user
	var user models.User
	if err := h.authService.GetDB().First(&user, userID).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "User not found"})
		return
	}

	// Update fields if provided
	if req.FirstName != nil {
		user.FirstName = *req.FirstName
	}
	if req.LastName != nil {
		user.LastName = *req.LastName
	}
	if req.Email != nil {
		user.Email = *req.Email
	}
	if req.Role != nil {
		user.Role = *req.Role
	}
	if req.IsActive != nil {
		user.IsActive = *req.IsActive
	}

	if err := h.authService.GetDB().Save(&user).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to update user"})
		return
	}

	// Don't return password hash
	user.Password = ""

	c.JSON(http.StatusOK, user)
}

// DeleteUser handles deleting a user (admin only)
func (h *AuthHandler) DeleteUser(c *gin.Context) {
	userIDStr := c.Param("id")
	userID, err := strconv.ParseUint(userIDStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid user ID"})
		return
	}

	// Get current user
	currentUserID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "User not authenticated"})
		return
	}

	// Prevent self-deletion
	if currentUserID.(uint) == uint(userID) {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Cannot delete your own account"})
		return
	}

	// Delete user
	if err := h.authService.GetDB().Delete(&models.User{}, userID).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to delete user"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "User deleted successfully"})
}