Verify SQLite backups and restores

src/db/database-backup.ts

@@ -0,0 +1,78 @@
+import fs from "node:fs";
+import path from "node:path";
+import Database from "better-sqlite3";
+
+export interface DatabaseVerification {
+  integrityCheck: "ok";
+  foreignKeyViolations: number;
+}
+
+function resolveDatabasePath(filename: string): string {
+  return path.resolve(filename);
+}
+
+export function verifyDatabaseFile(filename: string): DatabaseVerification {
+  const databasePath = resolveDatabasePath(filename);
+  const sqlite = new Database(databasePath, {
+    readonly: true,
+    fileMustExist: true,
+  });
+
+  try {
+    const integrityCheck = sqlite.pragma("integrity_check", {
+      simple: true,
+    });
+    if (integrityCheck !== "ok") {
+      throw new Error(
+        `SQLite integrity check failed for ${databasePath}: ${String(integrityCheck)}`
+      );
+    }
+
+    const foreignKeyCheck = sqlite.pragma("foreign_key_check") as unknown[];
+    const foreignKeyViolations = foreignKeyCheck.length;
+    if (foreignKeyViolations > 0) {
+      throw new Error(
+        `SQLite foreign-key check failed for ${databasePath}: ${foreignKeyViolations} violation(s)`
+      );
+    }
+
+    return {
+      integrityCheck: "ok",
+      foreignKeyViolations,
+    };
+  } finally {
+    sqlite.close();
+  }
+}
+
+export async function createVerifiedDatabaseBackup(
+  sourceFilename: string,
+  destinationFilename: string
+): Promise<DatabaseVerification> {
+  const sourcePath = resolveDatabasePath(sourceFilename);
+  const destinationPath = resolveDatabasePath(destinationFilename);
+
+  if (sourcePath === destinationPath) {
+    throw new Error("Backup source and destination must be different files.");
+  }
+  if (!fs.existsSync(sourcePath)) {
+    throw new Error(`Database file not found: ${sourcePath}`);
+  }
+  if (fs.existsSync(destinationPath)) {
+    throw new Error(`Backup destination already exists: ${destinationPath}`);
+  }
+
+  fs.mkdirSync(path.dirname(destinationPath), { recursive: true });
+
+  const source = new Database(sourcePath, {
+    readonly: true,
+    fileMustExist: true,
+  });
+  try {
+    await source.backup(destinationPath);
+  } finally {
+    source.close();
+  }
+
+  return verifyDatabaseFile(destinationPath);
+}