query grade distributions working, and filtering by semesters working

src/views/lib/database/initializeDB.ts

@@ -0,0 +1,35 @@
+import initSqlJs from 'sql.js/dist/sql-wasm';
+
+const WASM_FILE_URL = chrome.runtime.getURL('database/sql-wasm.wasm');
+const DB_FILE_URL = chrome.runtime.getURL('database/grades.db');
+
+/**
+ * A utility type for the SQL.js Database type
+ */
+export type Database = initSqlJs.Database;
+
+/**
+ * We only want to load the database into memory once, so we store a reference to the database here.
+ */
+let db: Database;
+
+/**
+ * This function loads the database into memory and returns a reference to the sql.js Database object.
+ * @returns a reference to the sql.js Database object
+ */
+export async function initializeDB(): Promise<Database> {
+    if (!WASM_FILE_URL || !DB_FILE_URL) {
+        throw new Error('WASM_FILE_URL or DB_FILE_URL is undefined');
+    }
+    if (db) {
+        return db;
+    }
+    const { Database } = await initSqlJs({
+        locateFile: file => WASM_FILE_URL,
+    });
+
+    const dbBuffer = await fetch(DB_FILE_URL).then(res => res.arrayBuffer());
+    db = new Database(new Uint8Array(dbBuffer));
+
+    return db;
+}