import Foundation
import Security
import Testing
@testable import ClientTLS

// B4 · The device key factory. Two things must hold for the enrollment path to
// work at all: (1) a PERMANENT tagged key survives and is found again by tag —
// that is what lets the enrolled leaf bind to it and `kSecClassIdentity`
// assemble; (2) when the Secure Enclave is not usable (Simulator, missing
// entitlement) the failure is CLASSIFIED as `.secureEnclaveUnavailable`, because
// that is the signal callers use to fall back to a software key. A
// `.keyGenerationFailed` there would look like a bug instead of a platform
// limit and the fallback would never happen.
//
// Runs against the REAL keychain (no shim exists in this package): each test
// uses a UUID-scoped tag and deletes it again, so nothing leaks between runs.

/// A per-test keychain tag — never collides with another test or another run.
private func uniqueTag() -> Data {
    Data("com.yaojia.webterm.clienttls.test.key-\(UUID().uuidString)".utf8)
}

@Test("a software key exposes a 65-byte uncompressed X9.63 point and signs verifiably")
func softwareKeySignsVerifiably() throws {
    // Arrange
    let key = try SecureEnclaveKeyFactory.generateSoftware()

    // Act
    let point = try key.publicKeyX963()
    let message = Data("certificationRequestInfo".utf8)
    let signature = try key.sign(message)

    // Assert — X9.63 uncompressed form, and an X9.62 DER ECDSA signature that
    // verifies under the same algorithm the server's PoP check uses.
    #expect(point.count == 65)
    #expect(point.first == 0x04)
    let publicKey = try #require(
        SecKeyCreateWithData(
            point as CFData,
            [
                kSecAttrKeyType as String: kSecAttrKeyTypeECSECPrimeRandom,
                kSecAttrKeyClass as String: kSecAttrKeyClassPublic,
                kSecAttrKeySizeInBits as String: 256,
            ] as CFDictionary,
            nil
        )
    )
    #expect(
        SecKeyVerifySignature(
            publicKey, .ecdsaSignatureMessageX962SHA256,
            message as CFData, signature as CFData, nil
        )
    )
    #expect(signature.first == 0x30) // SEQUENCE { r, s }
}

@Test("a non-permanent key is NOT stored in the keychain", .keychainSerialized)
func nonPermanentKeyIsNotPersisted() async throws {
    // Arrange
    let tag = uniqueTag()
    defer { try? SecureEnclaveKeyFactory.delete(tag: tag) }

    // Act — tagged but permanent: false (the unit-test / Simulator shape).
    _ = try SecureEnclaveKeyFactory.generateSoftware(tag: tag, permanent: false)

    // Assert
    #expect(try SecureEnclaveKeyFactory.load(tag: tag) == nil)
}

@Test("a permanent tagged key is found again by tag and deleted idempotently", .keychainSerialized)
func permanentKeyRoundtripsByTag() async throws {
    // Arrange
    let tag = uniqueTag()
    defer { try? SecureEnclaveKeyFactory.delete(tag: tag) }
    #expect(try SecureEnclaveKeyFactory.load(tag: tag) == nil) // pre-enroll state

    // Act
    let generated = try SecureEnclaveKeyFactory.generateSoftware(tag: tag, permanent: true)
    let loaded = try SecureEnclaveKeyFactory.load(tag: tag)

    // Assert — the SAME key comes back (rotation must re-sign with it, never
    // mint a new one).
    let reloaded = try #require(loaded)
    #expect(try reloaded.publicKeyX963() == (try generated.publicKeyX963()))

    // Act — delete, then delete again.
    try SecureEnclaveKeyFactory.delete(tag: tag)

    // Assert — gone, and a second delete is a no-op (not a throw).
    #expect(try SecureEnclaveKeyFactory.load(tag: tag) == nil)
    #expect(throws: Never.self) { try SecureEnclaveKeyFactory.delete(tag: tag) }
}

@Test("two keys under different tags stay independent", .keychainSerialized)
func tagsScopeKeysIndependently() async throws {
    // Arrange
    let tagA = uniqueTag()
    let tagB = uniqueTag()
    defer {
        try? SecureEnclaveKeyFactory.delete(tag: tagA)
        try? SecureEnclaveKeyFactory.delete(tag: tagB)
    }

    // Act
    let keyA = try SecureEnclaveKeyFactory.generateSoftware(tag: tagA, permanent: true)
    let keyB = try SecureEnclaveKeyFactory.generateSoftware(tag: tagB, permanent: true)

    // Assert
    #expect(try keyA.publicKeyX963() != (try keyB.publicKeyX963()))
    #expect(try SecureEnclaveKeyFactory.load(tag: tagA)?.publicKeyX963()
        == (try keyA.publicKeyX963()))
    #expect(try SecureEnclaveKeyFactory.load(tag: tagB)?.publicKeyX963()
        == (try keyB.publicKeyX963()))

    // Deleting one leaves the other installed.
    try SecureEnclaveKeyFactory.delete(tag: tagA)
    #expect(try SecureEnclaveKeyFactory.load(tag: tagA) == nil)
    #expect(try SecureEnclaveKeyFactory.load(tag: tagB) != nil)
}

@Test("Secure-Enclave keygen without the entitlement fails as .secureEnclaveUnavailable", .keychainSerialized)
func secureEnclaveKeygenClassifiesUnavailability() async throws {
    // Arrange
    let tag = uniqueTag()
    defer { try? SecureEnclaveKeyFactory.delete(tag: tag) }

    // Act / Assert — an UNSIGNED test binary has no
    // `com.apple.developer.kernel...`/keychain-access-group entitlement, so
    // SecKeyCreateRandomKey over the SE token fails with -34018. What is under
    // test is the CLASSIFICATION: it must be `.secureEnclaveUnavailable`
    // (callers' fallback signal), never `.keyGenerationFailed`.
    //
    // On a host that CAN mint an SE key (entitled build on real hardware) the
    // call legitimately succeeds; then the key must be a usable signer. Both
    // outcomes are asserted so this test is honest on every machine.
    do {
        let key = try SecureEnclaveKeyFactory.generateSecureEnclave(tag: tag)
        let signature = try key.sign(Data("probe".utf8))
        #expect(signature.first == 0x30)
    } catch let error as SecureEnclaveKeyError {
        guard case let .secureEnclaveUnavailable(description) = error else {
            Issue.record("SE keygen failure must classify as .secureEnclaveUnavailable: \(error)")
            return
        }
        #expect(description.isEmpty == false) // the underlying CFError is kept for logs
    }
}

@Test("signing with a public-only key surfaces .signatureFailed instead of crashing")
func signingWithPublicKeyFails() throws {
    // Arrange — wrap a PUBLIC key in the signer (the shape a mis-wired
    // composition root could produce).
    let point = try SecureEnclaveKeyFactory.generateSoftware().publicKeyX963()
    let publicKey = try #require(
        SecKeyCreateWithData(
            point as CFData,
            [
                kSecAttrKeyType as String: kSecAttrKeyTypeECSECPrimeRandom,
                kSecAttrKeyClass as String: kSecAttrKeyClassPublic,
                kSecAttrKeySizeInBits as String: 256,
            ] as CFDictionary,
            nil
        )
    )
    let key = SecureEnclaveKey(privateKey: publicKey)

    // Act / Assert
    do {
        _ = try key.sign(Data("m".utf8))
        Issue.record("signing with a public key must throw")
    } catch let error as SecureEnclaveKeyError {
        guard case let .signatureFailed(description) = error else {
            Issue.record("expected .signatureFailed, got \(error)")
            return
        }
        #expect(description.isEmpty == false)
    }
}

@Test("a nil CFError is described as 'unknown' rather than crashing the error path")
func describeNilError() {
    #expect(SecureEnclaveKey.describe(nil) == "unknown")
}