package com.dangerousthings.aliro;

import com.licel.jcardsim.smartcardio.CardSimulator;
import javacard.framework.AID;
import javacard.framework.Applet;
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;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertSame;

/**
 * Tests for the PersonalizationApplet — our proprietary provisioning
 * channel that loads the Access Credential long-term private key and
 * reader public keys before the Aliro flow runs.
 */
class PersonalizationAppletTest {

    private static final byte CLA = (byte) 0x80;
    private static final byte INS_SET_CRED_PRIV = (byte) 0x20;
    private static final byte INS_SET_CRED_PUBK = (byte) 0x21;
    private static final byte INS_SET_READER_PUBK = (byte) 0x22;
    private static final byte INS_WRITE_ACCESS_DOC = (byte) 0x23;
    private static final byte INS_FINALIZE_ACCESS_DOC = (byte) 0x24;
    private static final byte INS_SET_CRED_ISSUER_PUBK = (byte) 0x25;
    private static final byte INS_COMMIT = (byte) 0x2C;

    /**
     * Canonical Aliro Access Document COSE_Sign1 bytes (272 B) — generated
     * by harness/aliro_harness.issuer.cose against the trustgen-issued
     * issuer.pem. Layout is the bare 4-element COSE_Sign1 array (no wrapper);
     * CoseVerifier.verifyCoseSign1 verifies these bytes verbatim against the
     * uncompressed issuer pubkey below.
     *
     * <p>Reproducibility: dump via
     * <pre>
     *   python - &lt;&lt;'EOF'
     *   from pathlib import Path
     *   from cryptography.hazmat.primitives import serialization
     *   ad = Path("/home/work/aliro-trust/access_document.bin").read_bytes()
     *   iss = serialization.load_pem_private_key(
     *       Path("/home/work/aliro-trust/issuer.pem").read_bytes(), password=None)
     *   pub = iss.public_key().public_bytes(
     *       serialization.Encoding.X962,
     *       serialization.PublicFormat.UncompressedPoint)
     *   print(ad.hex()); print(pub[1:].hex())
     *   EOF
     * </pre>
     */
    private static final byte[] AD_GOOD = hex(
        "8443a10126a104488dae9624eed9280c58bca7613163312e306132675348412d3235"
        + "366133a06134a16131a401022001215820aa3115ead5d1fecca289aef3598790a6"
        + "dba23edbe9b14e6818ac683e31a5af02225820839dcc32bcd32924a942c3b9999f"
        + "6cbf46960396e69606fe4295e83a0c7787a2613567616c69726f2d616136a36131"
        + "c074323032362d30342d31395432303a32393a31365a6132c074323032362d3034"
        + "2d31395432303a32393a31365a6133c074323032372d30342d31395432303a3239"
        + "3a31365a6137f458404927c33ec9c475768b269bb4ee2a098be8d64ac43644e92c"
        + "8106d9c537d6215dc00e131e4ecf00b37ebc6ac8c26210f939d38df6f1c5b1caf6"
        + "85c365b22a3f2a");

    /** Issuer pubkey x||y (64 B) corresponding to ISSUER_PEM at trustgen time.
     *  This is what the applet INS_SET_CRED_ISSUER_PUBK accepts (no 0x04 prefix). */
    private static final byte[] ISSUER_PUBK_XY = hex(
        "ebee35bacdfc585295da337b29b6f5e8b86d4056e22c793e4bf033e19e9ba31d"
        + "6b8679bb41a64c4f7f8a37972b6315b4fe91248527c1487caf3a6fe31f75bbc4");

    private CardSimulator sim;

    @BeforeEach
    void setUp() {
        // installApplet → PersonalizationApplet.<init> → CredentialStore.bootstrap()
        // gives us a fresh store for every test — no explicit reset needed any more.
        sim = new CardSimulator();
        AID aid = new AID(AliroAids.PROVISIONING, (short) 0, (byte) AliroAids.PROVISIONING.length);
        sim.installApplet(aid, PersonalizationApplet.class);
        selectProvisioning();
    }

    private void selectProvisioning() {
        CommandAPDU select = new CommandAPDU(0x00, 0xA4, 0x04, 0x00, AliroAids.PROVISIONING, 256);
        ResponseAPDU r = sim.transmitCommand(select);
        assertEquals(0x9000, r.getSW(), "SELECT provisioning AID must succeed");
    }

    private ResponseAPDU send(byte ins, byte[] data) {
        CommandAPDU c = new CommandAPDU(CLA & 0xFF, ins & 0xFF, 0x00, 0x00,
            data == null ? new byte[0] : data, 256);
        return sim.transmitCommand(c);
    }

    private ResponseAPDU sendWithP1P2(byte ins, int p1p2, byte[] data) {
        CommandAPDU c = new CommandAPDU(CLA & 0xFF, ins & 0xFF,
            (p1p2 >> 8) & 0xFF, p1p2 & 0xFF,
            data == null ? new byte[0] : data, 256);
        return sim.transmitCommand(c);
    }

    @Test
    void setCredentialPrivKeyWith32BytesSucceeds() {
        byte[] key = new byte[32];
        for (int i = 0; i < key.length; i++) key[i] = (byte) i;
        assertEquals(0x9000, send(INS_SET_CRED_PRIV, key).getSW());
    }

    @Test
    void setCredentialPrivKeyWithWrongLengthFails() {
        byte[] key = new byte[31];
        assertEquals(0x6A80, send(INS_SET_CRED_PRIV, key).getSW(),
            "credential private key length != 32 must be rejected");
    }

    @Test
    void setCredentialPubKeyWith64BytesSucceeds() {
        byte[] pub = new byte[64];
        for (int i = 0; i < pub.length; i++) pub[i] = (byte) (i * 3);
        assertEquals(0x9000, send(INS_SET_CRED_PUBK, pub).getSW());
    }

    @Test
    void setCredentialPubKeyWithWrongLengthFails() {
        byte[] pub = new byte[63];
        assertEquals(0x6A80, send(INS_SET_CRED_PUBK, pub).getSW(),
            "credential public key length != 64 must be rejected");
    }

    @Test
    void setCredentialPubKeyAfterCommitIsLocked() {
        assertEquals(0x9000, send(INS_COMMIT, null).getSW());
        byte[] pub = new byte[64];
        assertEquals(0x6985, send(INS_SET_CRED_PUBK, pub).getSW(),
            "writes after COMMIT must return SW_CONDITIONS_NOT_SATISFIED");
    }

    @Test
    void setReaderPubKeyWith64BytesSucceeds() {
        byte[] pub = new byte[64];
        for (int i = 0; i < pub.length; i++) pub[i] = (byte) (i * 7);
        assertEquals(0x9000, send(INS_SET_READER_PUBK, pub).getSW());
    }

    @Test
    void accessDocumentChunkedWriteAndFinalizeRoundTrip() {
        // Uses the canonical AD_GOOD vector because finalize now triggers
        // IssuerAuth verify — random bytes wouldn't verify. The shape under
        // test here is still the multi-chunk write path + final length.
        assertEquals(0x9000, send(INS_SET_CRED_ISSUER_PUBK, ISSUER_PUBK_XY).getSW());

        byte[] ad = AD_GOOD;
        byte[] chunk1 = java.util.Arrays.copyOfRange(ad, 0, 200);
        byte[] chunk2 = java.util.Arrays.copyOfRange(ad, 200, ad.length);
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk1).getSW());
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 200, chunk2).getSW());
        assertEquals(0x9000, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, ad.length, null).getSW());

        // Verify via the test-only hook: bytes must match.
        byte[] stored = new byte[ad.length];
        CredentialStore.get().copyAccessDocument(stored, (short) 0, (short) 0, (short) ad.length);
        org.junit.jupiter.api.Assertions.assertArrayEquals(ad, stored);
        assertEquals(ad.length, CredentialStore.get().getAccessDocumentLen());
        org.junit.jupiter.api.Assertions.assertTrue(CredentialStore.get().hasAccessDocument());
    }

    @Test
    void accessDocumentWriteBeyondMaxSizeFails() {
        byte[] payload = new byte[50];
        short maxOff = (short) (CredentialStore.ACCESS_DOC_MAX_LEN - 10);  // 10 bytes short of max
        assertEquals(0x6A80, sendWithP1P2(INS_WRITE_ACCESS_DOC, maxOff, payload).getSW(),
            "a 50-byte chunk at offset MAX-10 overruns and must be rejected");
    }

    @Test
    void accessDocumentFinalizeBeyondMaxSizeFails() {
        // Set issuer pubkey so the precondition check passes — we want to
        // test the length bound specifically, not the missing-pubkey path.
        assertEquals(0x9000, send(INS_SET_CRED_ISSUER_PUBK, ISSUER_PUBK_XY).getSW());
        byte[] chunk = new byte[10];
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk).getSW());
        int tooBig = CredentialStore.ACCESS_DOC_MAX_LEN + 1;
        assertEquals(0x6A80, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, tooBig, null).getSW(),
            "finalize length > ACCESS_DOC_MAX_LEN must be rejected");
    }

    @Test
    void accessDocumentWriteAfterCommitIsLocked() {
        assertEquals(0x9000, send(INS_COMMIT, null).getSW());
        byte[] chunk = new byte[8];
        assertEquals(0x6985, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk).getSW());
        assertEquals(0x6985, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, 8, null).getSW());
    }

    @Test
    void commitReturns9000() {
        assertEquals(0x9000, send(INS_COMMIT, null).getSW());
    }

    @Test
    void setAfterCommitIsLocked() {
        assertEquals(0x9000, send(INS_COMMIT, null).getSW());
        byte[] key = new byte[32];
        assertEquals(0x6985, send(INS_SET_CRED_PRIV, key).getSW(),
            "writes after COMMIT must return SW_CONDITIONS_NOT_SATISFIED");
    }

    @Test
    void secondCommitIsLocked() {
        assertEquals(0x9000, send(INS_COMMIT, null).getSW());
        assertEquals(0x6985, send(INS_COMMIT, null).getSW(),
            "a second COMMIT must also be refused");
    }

    @Test
    void personalizationAppletOwnsCredentialStoreInstance() throws Exception {
        // setUp() has already installed PersonalizationApplet via jcardsim.
        // Reach into the runtime and pull out the installed applet instance,
        // then assert it owns a non-null `store` instance field and that the
        // static publish-point in CredentialStore aliases the same object.
        Applet applet = getInstalledApplet(sim, AliroAids.PROVISIONING);
        org.junit.jupiter.api.Assertions.assertTrue(applet instanceof PersonalizationApplet,
            "installed applet at PROVISIONING AID must be a PersonalizationApplet");

        java.lang.reflect.Field storeField = PersonalizationApplet.class.getDeclaredField("store");
        storeField.setAccessible(true);
        Object instanceStore = storeField.get(applet);
        assertNotNull(instanceStore,
            "PersonalizationApplet must own a CredentialStore instance field");
        assertSame(instanceStore, CredentialStore.get(),
            "Static publish-point must alias the instance-owned store");
    }

    @Test
    void finalizeAccessDocument_validIssuerAuth_setsVerifiedFlag() {
        // Push the issuer pubkey, write the AD, then finalize with the exact
        // total length. The applet should run CoseVerifier internally, see
        // the signature verify, and atomically flip both the finalized and
        // verified flags.
        assertEquals(0x9000, send(INS_SET_CRED_ISSUER_PUBK, ISSUER_PUBK_XY).getSW());

        // Single chunk fits in a short-form APDU (255B max) — except AD is
        // 272B. Split into two chunks like the orchestrator does.
        byte[] chunk1 = java.util.Arrays.copyOfRange(AD_GOOD, 0, 200);
        byte[] chunk2 = java.util.Arrays.copyOfRange(AD_GOOD, 200, AD_GOOD.length);
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk1).getSW());
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 200, chunk2).getSW());

        assertEquals(0x9000, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, AD_GOOD.length, null).getSW(),
            "finalize with valid IssuerAuth must succeed");

        CredentialStore s = CredentialStore.get();
        org.junit.jupiter.api.Assertions.assertTrue(s.hasAccessDocument(),
            "finalized flag must be set after successful verify");
        org.junit.jupiter.api.Assertions.assertTrue(s.isAccessDocumentVerified(),
            "verified flag must be set after successful verify");
    }

    @Test
    void finalizeAccessDocument_tamperedIssuerAuth_returnsErrorAndLeavesUnverified() {
        assertEquals(0x9000, send(INS_SET_CRED_ISSUER_PUBK, ISSUER_PUBK_XY).getSW());

        // Flip one byte in the payload region (around offset 30 — well
        // inside the issuer-signed payload, away from outer CBOR headers).
        byte[] tampered = new byte[AD_GOOD.length];
        System.arraycopy(AD_GOOD, 0, tampered, 0, AD_GOOD.length);
        tampered[30] ^= (byte) 0x01;

        byte[] chunk1 = java.util.Arrays.copyOfRange(tampered, 0, 200);
        byte[] chunk2 = java.util.Arrays.copyOfRange(tampered, 200, tampered.length);
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk1).getSW());
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 200, chunk2).getSW());

        // Spec says verify failure → SW_DATA_INVALID (0x6984).
        assertEquals(0x6984, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, tampered.length, null).getSW(),
            "finalize with tampered IssuerAuth must return SW_DATA_INVALID");

        CredentialStore s = CredentialStore.get();
        org.junit.jupiter.api.Assertions.assertFalse(s.isAccessDocumentVerified(),
            "verified flag must stay false on tamper");
        org.junit.jupiter.api.Assertions.assertFalse(s.hasAccessDocument(),
            "finalized flag must stay false on tamper — atomic store guards both");
    }

    @Test
    void finalizeAccessDocument_missingIssuerPubkey_returnsConditionsNotSatisfied() {
        // Skip the SET_CRED_ISSUER_PUBK step entirely. Even with a valid AD
        // loaded, finalize cannot run verify without the trust anchor and
        // must refuse with SW_CONDITIONS_NOT_SATISFIED.
        byte[] chunk1 = java.util.Arrays.copyOfRange(AD_GOOD, 0, 200);
        byte[] chunk2 = java.util.Arrays.copyOfRange(AD_GOOD, 200, AD_GOOD.length);
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 0, chunk1).getSW());
        assertEquals(0x9000, sendWithP1P2(INS_WRITE_ACCESS_DOC, 200, chunk2).getSW());

        assertEquals(0x6985, sendWithP1P2(INS_FINALIZE_ACCESS_DOC, AD_GOOD.length, null).getSW(),
            "finalize without an issuer pubkey must return SW_CONDITIONS_NOT_SATISFIED");

        CredentialStore s = CredentialStore.get();
        org.junit.jupiter.api.Assertions.assertFalse(s.hasAccessDocument());
        org.junit.jupiter.api.Assertions.assertFalse(s.isAccessDocumentVerified());
    }

    private static byte[] hex(String s) {
        s = s.replaceAll("\\s+", "");
        byte[] out = new byte[s.length() / 2];
        for (int i = 0; i < out.length; i++) {
            out[i] = (byte) Integer.parseInt(s.substring(i * 2, i * 2 + 2), 16);
        }
        return out;
    }

    /** Reaches through jcardsim's protected runtime/applet APIs to fetch the
     *  installed Applet instance for a given AID. Reflection-only — this is
     *  test infrastructure, not production code. */
    private static Applet getInstalledApplet(CardSimulator sim, byte[] aidBytes) throws Exception {
        java.lang.reflect.Field runtimeField = null;
        for (Class<?> c = sim.getClass(); c != null && runtimeField == null; c = c.getSuperclass()) {
            try { runtimeField = c.getDeclaredField("runtime"); } catch (NoSuchFieldException ignore) {}
        }
        runtimeField.setAccessible(true);
        Object runtime = runtimeField.get(sim);
        java.lang.reflect.Method getApplet = runtime.getClass().getDeclaredMethod("getApplet", AID.class);
        getApplet.setAccessible(true);
        AID aid = new AID(aidBytes, (short) 0, (byte) aidBytes.length);
        return (Applet) getApplet.invoke(runtime, aid);
    }
}