import XCTest
@testable import Luma

final class CryptoKitAESGCMEngineTests: XCTestCase {
    func testRoundTrip() {
        let engine = CryptoKitAESGCMEngine()
        let key = Data(repeating: 0x31, count: 16)
        let iv = Data(repeating: 0x22, count: 12)
        let plaintext = Data("hello omemo".utf8)
        var ciphertext = Data()
        var tag = Data()

        XCTAssertTrue(engine.encrypt(iv: iv, key: key, message: plaintext, output: &ciphertext, tag: &tag))

        var decrypted = Data()
        XCTAssertTrue(engine.decrypt(iv: iv, key: key, encoded: ciphertext, auth: tag, output: &decrypted))
        XCTAssertEqual(decrypted, plaintext)
    }

    func testModifiedTagFails() {
        let engine = CryptoKitAESGCMEngine()
        let key = Data(repeating: 0x31, count: 16)
        let iv = Data(repeating: 0x22, count: 12)
        var ciphertext = Data()
        var tag = Data()
        XCTAssertTrue(engine.encrypt(iv: iv, key: key, message: Data("secret".utf8), output: &ciphertext, tag: &tag))
        tag[0] ^= 0x01

        var decrypted = Data()
        XCTAssertFalse(engine.decrypt(iv: iv, key: key, encoded: ciphertext, auth: tag, output: &decrypted))
    }
}