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|
/*
* Handle the "N" message for unchoosing a course
*
* Copyright (C) 2024 Runxi Yu <https://runxiyu.org>
* SPDX-License-Identifier: AGPL-3.0-or-later
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* 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 for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package main
import (
"context"
"strconv"
"sync/atomic"
"github.com/coder/websocket"
)
func messageUnchooseCourse(
ctx context.Context,
c *websocket.Conn,
mar []string,
userID string,
userCourseGroups *userCourseGroupsT,
userCourseTypes *userCourseTypesT,
) error {
if atomic.LoadUint32(&state) != 2 {
err := writeText(ctx, c, "E :Course selections are not open")
if err != nil {
return wrapError(
errCannotSend,
err,
)
}
return nil
}
select {
case <-ctx.Done():
return wrapError(
errContextCanceled,
ctx.Err(),
)
default:
}
if len(mar) != 2 {
return errBadNumberOfArguments
}
_courseID, err := strconv.ParseInt(mar[1], 10, strconv.IntSize)
if err != nil {
return errNoSuchCourse
}
courseID := int(_courseID)
_course, ok := courses.Load(courseID)
if !ok {
return errNoSuchCourse
}
course, ok := _course.(*courseT)
if !ok {
panic("courses map has non-\"*courseT\" items")
}
if course == nil {
return errNoSuchCourse
}
ct, err := db.Exec(
ctx,
"DELETE FROM choices WHERE userid = $1 AND courseid = $2",
userID,
courseID,
)
if err != nil {
return wrapError(errUnexpectedDBError, err)
}
if ct.RowsAffected() != 0 {
err := course.decrementSelectedAndPropagate(ctx, c)
if err != nil {
return wrapError(
errCannotSend,
err,
)
}
_course, ok := courses.Load(courseID)
if !ok {
return errNoSuchCourse
}
course, ok := _course.(*courseT)
if !ok {
panic("courses map has non-\"*courseT\" items")
}
if course == nil {
return errNoSuchCourse
}
if _, ok := (*userCourseGroups)[course.Group]; !ok {
return errCourseGroupHandlingError
}
delete(*userCourseGroups, course.Group)
(*userCourseTypes)[course.Type]--
}
err = writeText(ctx, c, "N "+mar[1])
if err != nil {
return wrapError(
errCannotSend,
err,
)
}
return nil
}
|
