feat: add migrations to create database and add / change features down the line

src/backend/database.py

@@ -10,8 +10,6 @@ from string import ascii_lowercase as lower
 from string import digits, punctuation
 from typing import Any, List, Optional, Tuple, Union
 
-import loguru
-
 from src import DATABASE_DIR, settings
 from src.backend.db import (
     CREATE_ELSA_FILES_TABLE,
@@ -30,11 +28,9 @@ from src.errors import AppPresentError, NoResultError
 from src.logic import ELSA, Apparat, ApparatData, BookData, Prof
 from src.logic.constants import SEMAP_MEDIA_ACCOUNTS
 from src.logic.semester import Semester
+from src.shared.logging import log
 from src.utils.blob import create_blob
 
-log = loguru.logger
-
-
 ascii_lowercase = lower + digits + punctuation
 
 
@@ -123,6 +119,66 @@ class Database:
         if not self.db_initialized:
             self.checkDatabaseStatus()
             self.db_initialized = True
+            # run migrations after initial creation to bring schema up-to-date
+            try:
+                if self.db_path is not None:
+                    self.run_migrations()
+            except Exception as e:
+                log.error(f"Error while running migrations: {e}")
+
+    # --- Migration helpers integrated into Database ---
+    def _ensure_migrations_table(self, conn: sql.Connection) -> None:
+        cursor = conn.cursor()
+        cursor.execute(
+            """
+            CREATE TABLE IF NOT EXISTS schema_migrations (
+                id TEXT PRIMARY KEY,
+                applied_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+            )
+            """
+        )
+        conn.commit()
+
+    def _applied_migrations(self, conn: sql.Connection) -> List[str]:
+        cursor = conn.cursor()
+        cursor.execute("SELECT id FROM schema_migrations ORDER BY id")
+        rows = cursor.fetchall()
+        return [r[0] for r in rows]
+
+    def _apply_sql_file(self, conn: sql.Connection, path: Path) -> None:
+        log.info(f"Applying migration {path.name}")
+        sql_text = path.read_text(encoding="utf-8")
+        cursor = conn.cursor()
+        cursor.executescript(sql_text)
+        cursor.execute(
+            "INSERT OR REPLACE INTO schema_migrations (id) VALUES (?)", (path.name,)
+        )
+        conn.commit()
+
+    def run_migrations(self) -> None:
+        """Apply unapplied .sql migrations from src/backend/migrations using this Database's connection."""
+        migrations_dir = Path(__file__).parent / "migrations"
+        if not migrations_dir.exists():
+            log.debug("Migrations directory does not exist, skipping migrations")
+            return
+
+        conn = self.connect()
+        try:
+            self._ensure_migrations_table(conn)
+            applied = set(self._applied_migrations(conn))
+
+            migration_files = sorted(
+                [p for p in migrations_dir.iterdir() if p.suffix == ".sql"]
+            )
+            for m in migration_files:
+                if m.name in applied:
+                    log.debug(f"Skipping already applied migration {m.name}")
+                    continue
+                self._apply_sql_file(conn, m)
+        finally:
+            conn.close()
+
+    # --- end migration helpers ---
 
     def overwritePath(self, new_db_path: str):
         log.debug("got new path, overwriting")
@@ -204,39 +260,10 @@ class Database:
         """
         Create the tables in the database
         """
-        conn = self.connect()
-        cursor = conn.cursor()
-        cursor.execute(CREATE_TABLE_APPARAT)
-        cursor.execute(CREATE_TABLE_MESSAGES)
-        cursor.execute(CREATE_TABLE_MEDIA)
-        cursor.execute(CREATE_TABLE_FILES)
-        cursor.execute(CREATE_TABLE_PROF)
-        cursor.execute(CREATE_TABLE_USER)
-        cursor.execute(CREATE_TABLE_SUBJECTS)
-        cursor.execute(CREATE_ELSA_TABLE)
-        cursor.execute(CREATE_ELSA_FILES_TABLE)
-        cursor.execute(CREATE_ELSA_MEDIA_TABLE)
-        # Helpful indices to speed up frequent lookups and joins
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_media_app_prof ON media(app_id, prof_id);"
-        )
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_media_deleted ON media(deleted);"
-        )
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_media_available ON media(available);"
-        )
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_messages_remind_at ON messages(remind_at);"
-        )
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_semesterapparat_prof ON semesterapparat(prof_id);"
-        )
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_semesterapparat_appnr ON semesterapparat(appnr);"
-        )
-        conn.commit()
-        self.close_connection(conn)
+        # Bootstrapping of tables is handled via migrations. Run migrations instead
+        # of executing the hard-coded DDL here. Migrations are idempotent and
+        # contain the CREATE TABLE IF NOT EXISTS statements.
+        self.run_migrations()
 
     def insertInto(self, query: str, params: Tuple) -> None:
         """