1 files changed, 120 insertions, 0 deletions
diff --git a/backend/index.go b/backend/index.go
new file mode 100644
index 0000000..f446072
--- /dev/null
+++ b/backend/index.go
@@ -0,0 +1,120 @@
+/*
+ * Index page
+ *
+ * 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 (
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/jackc/pgx/v5"
+)
+
+/*
+ * Serve the index page. Also handles the login page in case the user doesn't
+ * have any valid login cookies.
+ */
+func handleIndex(w http.ResponseWriter, req *http.Request) {
+	sessionCookie, err := req.Cookie("session")
+	if errors.Is(err, http.ErrNoCookie) {
+		authURL, err := generateAuthorizationURL()
+		if err != nil {
+			wstr(w, http.StatusInternalServerError, "Cannot generate authorization URL")
+			return
+		}
+		err = tmpl.ExecuteTemplate(
+			w,
+			"login",
+			map[string]string{
+				"authURL": authURL,
+				"source":  config.Source,
+				/*
+				 * We directly generate the login URL here
+				 * instead of doing so in a redirect to save
+				 * requests.
+				 */
+			},
+		)
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		return
+	} else if err != nil {
+		wstr(w, http.StatusBadRequest, "Error: Unable to check cookie.")
+		return
+	}
+
+	var userID, userName, userDepartment string
+	err = db.QueryRow(
+		req.Context(),
+		"SELECT id, name, department FROM users WHERE session = $1",
+		sessionCookie.Value,
+	).Scan(&userID, &userName, &userDepartment)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			authURL, err := generateAuthorizationURL()
+			if err != nil {
+				wstr(w, http.StatusInternalServerError, "Cannot generate authorization URL")
+				return
+			}
+			err = tmpl.ExecuteTemplate(
+				w,
+				"login",
+				map[string]interface{}{
+					"authURL": authURL,
+					"notes":   "You sent an invalid session cookie.",
+					"source":  config.Source,
+				},
+			)
+			if err != nil {
+				log.Println(err)
+				return
+			}
+			return
+		}
+		wstr(w, http.StatusInternalServerError, fmt.Sprintf("Error: Unexpected database error: %s", err))
+		return
+	}
+
+	err = func() error {
+		coursesLock.RLock()
+		defer coursesLock.RUnlock()
+		return tmpl.ExecuteTemplate(
+			w,
+			"student",
+			map[string]interface{}{
+				"open": true,
+				"user": map[string]interface{}{
+					"Name":       userName,
+					"Department": userDepartment,
+				},
+				"courses": courses,
+				"source":  config.Source,
+			},
+		)
+	}()
+	if err != nil {
+		log.Println(err)
+		return
+	}
+}