1 files changed, 118 insertions, 0 deletions
diff --git a/course_groups.go b/course_groups.go
new file mode 100644
index 0000000..c1541ce
--- /dev/null
+++ b/course_groups.go
@@ -0,0 +1,118 @@
+/*
+ * Course groups
+ *
+ * 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"
+)
+
+type userCourseGroupsT map[courseGroupT]struct{}
+
+type courseGroupT string
+
+func checkCourseGroup(cg courseGroupT) bool {
+	_, ok := courseGroups[cg]
+	return ok
+}
+
+const (
+	mw1 courseGroupT = "MW1"
+	mw2 courseGroupT = "MW2"
+	mw3 courseGroupT = "MW3"
+	tt1 courseGroupT = "TT1"
+	tt2 courseGroupT = "TT2"
+	tt3 courseGroupT = "TT3"
+)
+
+var courseGroups = map[courseGroupT]string{
+	mw1: "Monday/Wednesday CCA1",
+	mw2: "Monday/Wednesday CCA2",
+	mw3: "Monday/Wednesday CCA3",
+	tt1: "Tuesday/Thursday CCA1",
+	tt2: "Tuesday/Thursday CCA2",
+	tt3: "Tuesday/Thursday CCA3",
+}
+
+func populateUserCourseGroups(
+	ctx context.Context,
+	userCourseGroups *userCourseGroupsT,
+	userID string,
+) error {
+	rows, err := db.Query(
+		ctx,
+		"SELECT courseid FROM choices WHERE userid = $1",
+		userID,
+	)
+	if err != nil {
+		return fmt.Errorf(
+			"%w: %w",
+			errUnexpectedDBError,
+			err,
+		)
+	}
+	for {
+		if !rows.Next() {
+			err := rows.Err()
+			if err != nil {
+				return fmt.Errorf(
+					"%w: %w",
+					errUnexpectedDBError,
+					err,
+				)
+			}
+			break
+		}
+		var thisCourseID int
+		err := rows.Scan(&thisCourseID)
+		if err != nil {
+			return fmt.Errorf(
+				"%w: %w",
+				errUnexpectedDBError,
+				err,
+			)
+		}
+		var thisGroupName courseGroupT
+		_course, ok := courses.Load(thisCourseID)
+		if !ok {
+			return fmt.Errorf(
+				"%w: %d",
+				errNoSuchCourse,
+				thisCourseID,
+			)
+		}
+		course, ok := _course.(*courseT)
+		if !ok {
+			panic("courses map has non-\"*courseT\" items")
+		}
+		thisGroupName = course.Group
+		if _, ok := (*userCourseGroups)[thisGroupName]; ok {
+			return fmt.Errorf(
+				"%w: user %v, group %v",
+				errMultipleChoicesInOneGroup,
+				userID,
+				thisGroupName,
+			)
+		}
+		(*userCourseGroups)[thisGroupName] = struct{}{}
+	}
+	return nil
+}