Backend/internal/api/services/friends/friend_cancel.go

/*
ScheduleTogether Backend
Copyright (C) 2024, Zervó Zadachin

DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License version 3 for more details.

This program incorporates external libraries for certain functionalities.
These libraries are covered by their respective licenses, and their usage
agreements are as outlined in their respective documentation or source
code.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package friends

import (
	"slices"

	"github.com/kataras/iris/v12"

	db "git.zervo.org/scheduletogether/backend/internal/database"
	"git.zervo.org/scheduletogether/backend/pkg/helpers/request"
	"git.zervo.org/scheduletogether/backend/pkg/types"
)

func FriendCancel_Service(ctx iris.Context, req types.FriendsAcceptRequest) {
	// Start a transaction
	tx := db.Db.Begin()

	// Get requesting user's ID from claims
	claims := request.GetUserClaims(ctx)
	id := claims.UserId

	// Make sure target user exists
	// Here target user refers to the user that *created* the friendrequest, opposite to friends_add
	var targetUser db.User
	err := tx.Where("uuid = ?", req.Uuid).First(&targetUser).Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusBadRequest)
		ctx.JSON(types.CommonErrorResponse{
			Error: "User does not exist",
		})
		return
	}

	// Get user from database
	// Here source user refers to the user *recieving* (accepting) the friendrequest, opposite to friends_add
	var sourceUser db.User
	err = tx.Where("id = ?", id).First(&sourceUser).Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusInternalServerError)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Something went wrong, please try again later",
		})
		logboi.Warn("Failed to retrieve user from the database: " + err.Error())
		return
	}

	// Make sure users are not already friends
	if slices.Contains(sourceUser.Friends, targetUser.Uuid) {
		tx.Rollback()
		ctx.StatusCode(iris.StatusBadRequest)
		ctx.JSON(types.CommonErrorResponse{
			Error: "You are already friends with this user",
		})
	}

	// Make sure friend request exists
	var friendRequest db.FriendRequest
	err = tx.Where("target = ? AND source = ?", sourceUser.Uuid, targetUser.Uuid).First(&friendRequest).Error
	if err == nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusBadRequest)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Friend request already sent",
		})
		return
	}

	// Add friend to source (receiving) user
	err = tx.Model(&db.User{}).Where("id = ?", id).Update("friends", append(sourceUser.Friends, targetUser.Uuid)).Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusInternalServerError)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Something went wrong, please try again later",
		})
		logboi.Warn("Failed to update user on the database: " + err.Error())
		return
	}

	// Add friend to target (accepting) user
	err = tx.Model(&db.User{}).Where("id = ?", targetUser.ID).Update("friends", append(targetUser.Friends, sourceUser.Uuid)).Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusInternalServerError)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Something went wrong, please try again later",
		})
		logboi.Warn("Failed to update user on the database: " + err.Error())
		return
	}

	// Remove friend request
	err = tx.Where("target = ? AND source = ?", targetUser.Uuid, sourceUser.Uuid).Delete(&db.FriendRequest{}).Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusInternalServerError)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Something went wrong, please try again later",
		})
		logboi.Warn("Failed to delete friend request from the database: " + err.Error())
		return
	}

	// Commit the transaction if everything is successful
	err = tx.Commit().Error
	if err != nil {
		tx.Rollback()
		ctx.StatusCode(iris.StatusInternalServerError)
		ctx.JSON(types.CommonErrorResponse{
			Error: "Something went wrong, please try again later",
		})
		return
	}

	ctx.JSON(types.CommonMessageResponse{
		Message: "Friend request accepted",
	})
}