1 files changed, 85 insertions, 0 deletions
diff --git a/backend/wsp.go b/backend/wsp.go
new file mode 100644
index 0000000..7a1f6ab
--- /dev/null
+++ b/backend/wsp.go
@@ -0,0 +1,85 @@
+/*
+ * 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"
+
+	"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(courseID int) {
+	course := courses[courseID]
+	course.UsemsLock.RLock()
+	defer course.UsemsLock.RUnlock()
+	for _, usem := range course.Usems {
+		usem.set()
+	}
+}