1 files changed, 78 insertions, 0 deletions
diff --git a/wsmsg_hello.go b/wsmsg_hello.go
new file mode 100644
index 0000000..b92dde9
--- /dev/null
+++ b/wsmsg_hello.go
@@ -0,0 +1,78 @@
+/*
+ * Handle the "HELLO" message
+ *
+ * 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"
+	"strings"
+	"sync/atomic"
+
+	"github.com/coder/websocket"
+	"github.com/jackc/pgx/v5"
+)
+
+func messageHello(
+	ctx context.Context,
+	c *websocket.Conn,
+	reportError reportErrorT,
+	mar []string,
+	userID string,
+	session string,
+) error {
+	_, _ = mar, session
+
+	select {
+	case <-ctx.Done():
+		return fmt.Errorf(
+			"%w: %w",
+			errContextCancelled,
+			ctx.Err(),
+		)
+	default:
+	}
+
+	rows, err := db.Query(
+		ctx,
+		"SELECT courseid FROM choices WHERE userid = $1",
+		userID,
+	)
+	if err != nil {
+		return reportError("error fetching choices")
+	}
+	courseIDs, err := pgx.CollectRows(rows, pgx.RowTo[string])
+	if err != nil {
+		return reportError("error collecting choices")
+	}
+
+	if atomic.LoadUint32(&state) == 2 {
+		err = writeText(ctx, c, "START")
+		if err != nil {
+			return fmt.Errorf("%w: %w", errCannotSend, err)
+		}
+	}
+	err = writeText(ctx, c, "HI :"+strings.Join(courseIDs, ","))
+	if err != nil {
+		return fmt.Errorf("%w: %w", errCannotSend, err)
+	}
+
+	return nil
+}