import { BinaryReader } from "./binary";
import type { KdbxHeader } from "./types";

const KDBX_SIGNATURE_1 = 0x9aa2d903;
const KDBX_SIGNATURE_2 = 0xb54bfb67;

export function parseKdbxHeader(buffer: Uint8Array): { header: KdbxHeader; offset: number } {
	const reader = new BinaryReader(buffer);
	const signature1 = reader.readUint32LE();
	const signature2 = reader.readUint32LE();

	if (signature1 !== KDBX_SIGNATURE_1 || signature2 !== KDBX_SIGNATURE_2) {
		throw new Error("Invalid KDBX signature");
	}

	const versionMinor = reader.readUint16LE();
	const versionMajor = reader.readUint16LE();
	const version = { major: versionMajor, minor: versionMinor };

	return {
		header: { version },
		offset: buffer.length - reader.remaining(),
	};
}