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Diffstat (limited to '')
-rw-r--r-- | state.go | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/state.go b/state.go new file mode 100644 index 0000000..48b8907 --- /dev/null +++ b/state.go @@ -0,0 +1,160 @@ +/* + * Handle the unified global state + * + * 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" + "errors" + "fmt" + "net/http" + "strconv" + "sync/atomic" + + "github.com/jackc/pgx/v5" +) + +/* + * 0: Student access is disabled + * 1: Student have read-only access + * 2: Student can choose courses + */ +var state uint32 /* atomic */ + +func loadState() error { + var _state uint32 + err := db.QueryRow( + context.Background(), + "SELECT value FROM misc WHERE key = 'state'", + ).Scan(&_state) + if err != nil { + if errors.Is(err, pgx.ErrNoRows) { + _state = 0 + _, err := db.Exec( + context.Background(), + "INSERT INTO misc(key, value) VALUES ('state', $1)", + _state, + ) + if err != nil { + return fmt.Errorf("%w: %w", errUnexpectedDBError, err) + } + } else { + return fmt.Errorf("%w: %w", errUnexpectedDBError, err) + } + } + atomic.StoreUint32(&state, _state) + return nil +} + +func saveStateValue(ctx context.Context, newState uint32) error { + _, err := db.Exec( + ctx, + "UPDATE misc SET value = $1 WHERE key = 'state'", + newState, + ) + if err != nil { + return fmt.Errorf("%w: %w", errUnexpectedDBError, err) + } + return nil +} + +func setState(ctx context.Context, newState uint32) error { + if newState > 2 { + return fmt.Errorf("%w: %d", errInvalidState, newState) + } + err := saveStateValue(ctx, newState) + if err != nil { + return err + } + atomic.StoreUint32(&state, newState) + return nil +} + +func handleState(w http.ResponseWriter, req *http.Request) { + sessionCookie, err := req.Cookie("session") + if errors.Is(err, http.ErrNoCookie) { + wstr( + w, + http.StatusUnauthorized, + "No session cookie, which is required for this endpoint", + ) + 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) { + wstr( + w, + http.StatusForbidden, + "Invalid session cookie", + ) + return + } + wstr( + w, + http.StatusInternalServerError, + fmt.Sprintf( + "Error: Unexpected database error: %s", + err, + ), + ) + return + } + + if userDepartment != staffDepartment { + wstr( + w, + http.StatusForbidden, + "You are not authorized to view this page", + ) + return + } + + basePath := req.PathValue("s") + newState, err := strconv.ParseUint(basePath, 10, 32) + if err != nil { + wstr( + w, + http.StatusBadRequest, + "State must be an unsigned 32-bit integer", + ) + return + } + err = setState(req.Context(), uint32(newState)) + if err != nil { + wstr( + w, + http.StatusInternalServerError, + "Failed setting state, please return to previous page; are you sure it's within limits?", + ) + return + } + + http.Redirect(w, req, "/", http.StatusSeeOther) +} |