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/*
* WebSocket-based protocol auxiliary functions
*
* 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"
"fmt"
"sync/atomic"
"github.com/coder/websocket"
)
/*
* Split an IRC-style message of type []byte into type []string where each
* element is a complete argument. Generally, arguments are separated by
* spaces, and an argument that begins with a ':' causes the rest of the
* line to be treated as a single argument.
*/
func splitMsg(b *[]byte) []string {
mar := make([]string, 0, config.Perf.MessageArgumentsCap)
elem := make([]byte, 0, config.Perf.MessageBytesCap)
for i, c := range *b {
switch c {
case ' ':
if (*b)[i+1] == ':' {
mar = append(mar, string(elem))
mar = append(mar, string((*b)[i+2:]))
goto endl
}
mar = append(mar, string(elem))
elem = make([]byte, 0, config.Perf.MessageBytesCap)
default:
elem = append(elem, c)
}
}
mar = append(mar, string(elem))
endl:
return mar
}
func baseReportError(
ctx context.Context,
conn *websocket.Conn,
e string,
) error {
err := writeText(ctx, conn, "E :"+e)
if err != nil {
return fmt.Errorf("error reporting protocol violation: %w", err)
}
err = conn.Close(websocket.StatusProtocolError, e)
if err != nil {
return fmt.Errorf("error closing websocket: %w", err)
}
return nil
}
type reportErrorT func(e string) error
func makeReportError(ctx context.Context, conn *websocket.Conn) reportErrorT {
return func(e string) error {
return baseReportError(ctx, conn, e)
}
}
func propagateSelectedUpdate(course *courseT) {
course.Usems.Range(func(key, value interface{}) bool {
_ = key
usem, ok := value.(*usemT)
if !ok {
panic("Usems contains non-\"*usemT\" value")
}
usem.set()
return true
})
}
func sendSelectedUpdate(
ctx context.Context,
conn *websocket.Conn,
courseID int,
) error {
_course, ok := courses.Load(courseID)
if !ok {
return fmt.Errorf("%w: %d", errNoSuchCourse, courseID)
}
course, ok := _course.(*courseT)
if !ok {
panic("courses map has non-\"*courseT\" items")
}
if course == nil {
return fmt.Errorf("%w: %d", errNoSuchCourse, courseID)
}
selected := atomic.LoadUint32(&course.Selected)
err := writeText(ctx, conn, fmt.Sprintf("M %d %d", courseID, selected))
if err != nil {
return fmt.Errorf(
"error sending to websocket for course selected update: %w",
err,
)
}
return nil
}
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