package com.dangerousthings.aliro;

import com.licel.jcardsim.smartcardio.CardSimulator;
import javacard.framework.AID;
import javax.smartcardio.CommandAPDU;
import javax.smartcardio.ResponseAPDU;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * Tests for {@link StepUpApplet} — scaffold for the Aliro step-up phase
 * (spec §8.4). This first pass only covers AID selection and
 * INS-not-supported handling; the mdoc DeviceRequest/DeviceResponse +
 * StepUpSK key derivation pipelines come in follow-up iterations.
 */
class StepUpAppletTest {

    private CardSimulator sim;

    @BeforeEach
    void setUp() {
        CredentialStore.get().resetForTesting();
        sim = new CardSimulator();
        AID aid = new AID(AliroAids.STEP_UP, (short) 0, (byte) AliroAids.STEP_UP.length);
        sim.installApplet(aid, StepUpApplet.class);
    }

    @Test
    void selectStepUpAidSucceeds() {
        CommandAPDU select = new CommandAPDU(0x00, 0xA4, 0x04, 0x00, AliroAids.STEP_UP, 256);
        ResponseAPDU r = sim.transmitCommand(select);
        assertEquals(0x9000, r.getSW(), "SELECT of step-up AID must succeed");
    }

    @Test
    void selectStepUpAidReturnsFciWithAid() {
        CommandAPDU select = new CommandAPDU(0x00, 0xA4, 0x04, 0x00, AliroAids.STEP_UP, 256);
        ResponseAPDU r = sim.transmitCommand(select);
        byte[] aidFromFci = TlvUtil.findTopLevel(unwrap6F(r.getData()), 0x84);
        org.junit.jupiter.api.Assertions.assertArrayEquals(AliroAids.STEP_UP, aidFromFci,
            "FCI 84 tag must echo the step-up AID");
    }

    @Test
    void unsupportedInsReturns6D00() {
        CommandAPDU select = new CommandAPDU(0x00, 0xA4, 0x04, 0x00, AliroAids.STEP_UP, 256);
        sim.transmitCommand(select);

        // Some arbitrary unsupported INS under the proprietary class.
        CommandAPDU bogus = new CommandAPDU(0x80, 0xFE, 0x00, 0x00, new byte[0], 256);
        assertEquals(0x6D00, sim.transmitCommand(bogus).getSW(),
            "unrecognized INS on step-up applet must return SW_INS_NOT_SUPPORTED");
    }

    @Test
    void wrongClaReturns6E00() {
        CommandAPDU select = new CommandAPDU(0x00, 0xA4, 0x04, 0x00, AliroAids.STEP_UP, 256);
        sim.transmitCommand(select);

        CommandAPDU wrongCla = new CommandAPDU(0x81, 0xC3, 0x00, 0x00, new byte[0], 256);
        assertEquals(0x6E00, sim.transmitCommand(wrongCla).getSW(),
            "wrong CLA must return SW_CLA_NOT_SUPPORTED");
    }

    /** Unwraps the outer 6F FCI template to expose its nested TLVs. */
    private static byte[] unwrap6F(byte[] fci) {
        if (fci.length < 2 || fci[0] != 0x6F) {
            throw new IllegalArgumentException("expected a 6F-wrapped FCI template");
        }
        int len = fci[1] & 0xFF;
        byte[] inner = new byte[len];
        System.arraycopy(fci, 2, inner, 0, len);
        return inner;
    }
}