package handler

import (
	"net/http"
	"strconv"

	"go-backend-template/internal/constants"
	"go-backend-template/internal/contract"
	"go-backend-template/internal/logger"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
)

type UserHandler struct {
	userService   UserService
	userValidator UserValidator
}

func NewUserHandler(userService UserService, userValidator UserValidator) *UserHandler {
	return &UserHandler{
		userService:   userService,
		userValidator: userValidator,
	}
}

func (h *UserHandler) CreateUser(c *gin.Context) {
	var req contract.CreateUserRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::CreateUser -> request binding failed")
		h.sendValidationErrorResponse(c, "Invalid request body", constants.MissingFieldErrorCode)
		return
	}

	validationError, validationErrorCode := h.userValidator.ValidateCreateUserRequest(&req)
	if validationError != nil {
		logger.FromContext(c).WithError(validationError).Error("UserHandler::CreateUser -> request validation failed")
		h.sendValidationErrorResponse(c, validationError.Error(), validationErrorCode)
		return
	}

	userResponse, err := h.userService.CreateUser(c.Request.Context(), &req)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::CreateUser -> Failed to create user from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	logger.FromContext(c).Infof("UserHandler::CreateUser -> Successfully created user = %+v", userResponse)
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(userResponse))
}

func (h *UserHandler) UpdateUser(c *gin.Context) {
	userIDStr := c.Param("id")
	userID, err := uuid.Parse(userIDStr)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::UpdateUser -> Invalid user ID")
		h.sendValidationErrorResponse(c, "Invalid user ID", constants.MalformedFieldErrorCode)
		return
	}

	validationError, validationErrorCode := h.userValidator.ValidateUserID(userID)
	if validationError != nil {
		logger.FromContext(c).WithError(validationError).Error("UserHandler::UpdateUser -> user ID validation failed")
		h.sendValidationErrorResponse(c, validationError.Error(), validationErrorCode)
		return
	}

	var req contract.UpdateUserRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::UpdateUser -> request binding failed")
		h.sendValidationErrorResponse(c, "Invalid request body", constants.MissingFieldErrorCode)
		return
	}

	validationError, validationErrorCode = h.userValidator.ValidateUpdateUserRequest(&req)
	if validationError != nil {
		logger.FromContext(c).WithError(validationError).Error("UserHandler::UpdateUser -> request validation failed")
		h.sendValidationErrorResponse(c, validationError.Error(), validationErrorCode)
		return
	}

	userResponse, err := h.userService.UpdateUser(c.Request.Context(), userID, &req)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::UpdateUser -> Failed to update user from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	logger.FromContext(c).Infof("UserHandler::UpdateUser -> Successfully updated user = %+v", userResponse)
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(userResponse))
}

func (h *UserHandler) DeleteUser(c *gin.Context) {
	userIDStr := c.Param("id")
	userID, err := uuid.Parse(userIDStr)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::DeleteUser -> Invalid user ID")
		h.sendValidationErrorResponse(c, "Invalid user ID", constants.MalformedFieldErrorCode)
		return
	}

	validationError, validationErrorCode := h.userValidator.ValidateUserID(userID)
	if validationError != nil {
		logger.FromContext(c).WithError(validationError).Error("UserHandler::DeleteUser -> user ID validation failed")
		h.sendValidationErrorResponse(c, validationError.Error(), validationErrorCode)
		return
	}

	err = h.userService.DeleteUser(c.Request.Context(), userID)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::DeleteUser -> Failed to delete user from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	logger.FromContext(c).Info("UserHandler::DeleteUser -> Successfully deleted user")
	c.JSON(http.StatusOK, &contract.SuccessResponse{Message: "User deleted successfully"})
}

func (h *UserHandler) GetUser(c *gin.Context) {
	userIDStr := c.Param("id")
	userID, err := uuid.Parse(userIDStr)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::GetUser -> Invalid user ID")
		h.sendValidationErrorResponse(c, "Invalid user ID", constants.MalformedFieldErrorCode)
		return
	}

	validationError, validationErrorCode := h.userValidator.ValidateUserID(userID)
	if validationError != nil {
		logger.FromContext(c).WithError(validationError).Error("UserHandler::GetUser -> user ID validation failed")
		h.sendValidationErrorResponse(c, validationError.Error(), validationErrorCode)
		return
	}

	userResponse, err := h.userService.GetUserByID(c.Request.Context(), userID)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::GetUser -> Failed to get user from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	logger.FromContext(c).Infof("UserHandler::GetUser -> Successfully retrieved user = %+v", userResponse)
	c.JSON(http.StatusOK, userResponse)
}

func (h *UserHandler) ListUsers(c *gin.Context) {
	ctx := c.Request.Context()

	page := 1
	limit := 10

	if pageStr := c.Query("page"); pageStr != "" {
		if p, err := strconv.Atoi(pageStr); err == nil {
			page = p
		}
	}

	if limitStr := c.Query("limit"); limitStr != "" {
		if l, err := strconv.Atoi(limitStr); err == nil {
			limit = l
		}
	}

	usersResponse, err := h.userService.GetUsers(ctx, page, limit)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::ListUsers -> Failed to list users from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	logger.FromContext(c).Infof("UserHandler::ListUsers -> Successfully listed users")
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(usersResponse))
}

func (h *UserHandler) sendErrorResponse(c *gin.Context, message string, statusCode int) {
	errorResponse := &contract.ErrorResponse{
		Error:   message,
		Code:    statusCode,
		Details: map[string]interface{}{},
	}
	c.JSON(statusCode, errorResponse)
}

func (h *UserHandler) sendValidationErrorResponse(c *gin.Context, message string, errorCode string) {
	statusCode := constants.HttpErrorMap[errorCode]
	if statusCode == 0 {
		statusCode = http.StatusBadRequest
	}

	errorResponse := &contract.ErrorResponse{
		Error: message,
		Code:  statusCode,
		Details: map[string]interface{}{
			"error_code": errorCode,
			"entity":     constants.UserValidatorEntity,
		},
	}
	c.JSON(statusCode, errorResponse)
}