package handler

import (
	"context"
	"net/http"
	"strconv"
	"time"

	"eslogad-be/internal/appcontext"
	"eslogad-be/internal/constants"
	"eslogad-be/internal/contract"
	"eslogad-be/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.StatusCreated, userResponse)
}

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

	if len(req.Users) == 0 {
		h.sendValidationErrorResponse(c, "Users list cannot be empty", constants.MissingFieldErrorCode)
		return
	}

	// Increased limit to handle 1000+ users
	if len(req.Users) > 5000 {
		h.sendValidationErrorResponse(c, "Cannot create more than 5000 users at once", constants.MissingFieldErrorCode)
		return
	}

	// Set a longer timeout for large bulk operations
	ctx := c.Request.Context()
	if len(req.Users) > 500 {
		// Create a context with extended timeout for large operations
		var cancel context.CancelFunc
		ctx, cancel = context.WithTimeout(ctx, 10*time.Minute)
		defer cancel()
	}

	logger.FromContext(c).Infof("UserHandler::BulkCreateUsers -> Starting bulk creation of %d users", len(req.Users))

	response, err := h.userService.BulkCreateUsers(ctx, &req)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::BulkCreateUsers -> Failed to bulk create users")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	statusCode := http.StatusCreated
	if response.Summary.Failed > 0 && response.Summary.Succeeded == 0 {
		statusCode = http.StatusBadRequest
	} else if response.Summary.Failed > 0 {
		statusCode = http.StatusMultiStatus
	}

	logger.FromContext(c).Infof("UserHandler::BulkCreateUsers -> Successfully processed bulk creation: %d succeeded, %d failed", 
		response.Summary.Succeeded, response.Summary.Failed)
	c.JSON(statusCode, contract.BuildSuccessResponse(response))
}

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, 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()

	req := &contract.ListUsersRequest{
		Page:  1,
		Limit: 10,
	}

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

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

	var roleParam *string
	if role := c.Query("role"); role != "" {
		roleParam = &role
		req.Role = &role
	}

	if roleCode := c.Query("role_code"); roleCode != "" {
		req.RoleCode = &roleCode
	}

	if req.RoleCode == nil && roleParam != nil {
		req.RoleCode = roleParam
	}

	if search := c.Query("search"); search != "" {
		req.Search = &search
	}

	if isActiveStr := c.Query("is_active"); isActiveStr != "" {
		if isActive, err := strconv.ParseBool(isActiveStr); err == nil {
			req.IsActive = &isActive
		}
	}

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

	usersResponse, err := h.userService.ListUsers(ctx, req)
	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 = %+v", usersResponse)
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(usersResponse))
}

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

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

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

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

	logger.FromContext(c).Info("UserHandler::ChangePassword -> Successfully changed password")
	c.JSON(http.StatusOK, &contract.SuccessResponse{Message: "Password changed successfully"})
}

func (h *UserHandler) GetProfile(c *gin.Context) {
	appCtx := appcontext.FromGinContext(c.Request.Context())
	if appCtx.UserID == uuid.Nil {
		h.sendErrorResponse(c, "Unauthorized", http.StatusUnauthorized)
		return
	}
	profile, err := h.userService.GetProfile(c.Request.Context(), appCtx.UserID)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::GetProfile -> Failed to get profile")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(profile))
}

func (h *UserHandler) UpdateProfile(c *gin.Context) {
	appCtx := appcontext.FromGinContext(c.Request.Context())
	if appCtx.UserID == uuid.Nil {
		h.sendErrorResponse(c, "Unauthorized", http.StatusUnauthorized)
		return
	}
	var req contract.UpdateUserProfileRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		h.sendValidationErrorResponse(c, "Invalid request body", constants.MissingFieldErrorCode)
		return
	}
	updated, err := h.userService.UpdateProfile(c.Request.Context(), appCtx.UserID, &req)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::UpdateProfile -> Failed to update profile")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}
	c.JSON(http.StatusOK, contract.BuildSuccessResponse(updated))
}

func (h *UserHandler) ListTitles(c *gin.Context) {
	titles, err := h.userService.ListTitles(c.Request.Context())
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::ListTitles -> Failed to get titles from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

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

func (h *UserHandler) GetActiveUsersForMention(c *gin.Context) {
	search := c.Query("search")
	limitStr := c.DefaultQuery("limit", "50")

	limit, err := strconv.Atoi(limitStr)
	if err != nil || limit <= 0 {
		limit = 50
	}
	if limit > 100 {
		limit = 100
	}
	
	var searchPtr *string
	if search != "" {
		searchPtr = &search
	}

	users, err := h.userService.GetActiveUsersForMention(c.Request.Context(), searchPtr, limit)
	if err != nil {
		logger.FromContext(c).WithError(err).Error("UserHandler::GetActiveUsersForMention -> Failed to get active users from service")
		h.sendErrorResponse(c, err.Error(), http.StatusInternalServerError)
		return
	}

	response := contract.MentionUsersResponse{
		Users: users,
		Count: len(users),
	}

	logger.FromContext(c).Infof("UserHandler::GetActiveUsersForMention -> Successfully retrieved %d active users", len(users))
	c.JSON(http.StatusOK, response)
}

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)
}