// ===----------------------------------------------------------------------===
//
// This source file is part of the ASConnectService open source project
//
// Copyright (c) 2026 Röck+Cöde VoF. and the ASConnectService project authors
// Licensed under Apache license v2.0
//
// See LICENSE for license information
// See CONTRIBUTORS for the list of ASConnectService project authors
//
// SPDX-License-Identifier: Apache-2.0
//
// ===----------------------------------------------------------------------===

#if canImport(CryptoKit)
import CryptoKit
import Foundation
import Testing

// A non-testable import ensures that the provider can be created from outside the module.
import ASConnectService

@Suite("APIKeyTokenProvider")
struct APIKeyTokenProviderTests {
    // MARK: Properties

    private let key = P256.Signing.PrivateKey()
    private let clock = TestClock()

    // MARK: Tests

    @Test("Signs a token for a team key")
    func signsTeamKeyToken() async throws {
        let token = try await makeProvider(issuerID: .Sample.issuerID).token()
        let (header, payload) = try decode(token)

        #expect(header == ["alg": "ES256", "kid": String.Sample.keyID, "typ": "JWT"])
        #expect(payload["iss"] as? String == .Sample.issuerID)
        #expect(payload["sub"] == nil)
        #expect(payload["aud"] as? String == "appstoreconnect-v1")
        #expect(payload["iat"] as? Int == Int(clock.date.timeIntervalSince1970))
        #expect(payload["exp"] as? Int == Int(clock.date.timeIntervalSince1970) + 20 * 60)
    }

    @Test("Signs a token for an individual key")
    func signsIndividualKeyToken() async throws {
        let token = try await makeProvider(issuerID: nil).token()
        let (_, payload) = try decode(token)

        #expect(payload["iss"] == nil)
        #expect(payload["sub"] as? String == "user")
    }

    @Test("Signs the token with the private key")
    func signsWithPrivateKey() async throws {
        let token = try await makeProvider(issuerID: .Sample.issuerID).token()
        let parts = token.split(separator: ".").map(String.init)
        let signature = try P256.Signing.ECDSASignature(rawRepresentation: try #require(Data(base64URL: parts[2])))

        #expect(key.publicKey.isValidSignature(signature, for: Data("\(parts[0]).\(parts[1])".utf8)))
    }

    @Test("Returns the current token until it is about to expire")
    func returnsCurrentToken() async throws {
        let provider = try makeProvider(issuerID: .Sample.issuerID)
        let token = try await provider.token()

        clock.advance(by: 18 * 60)

        #expect(try await provider.token() == token)
    }

    @Test("Signs a new token when the current one is about to expire")
    func signsNewToken() async throws {
        let provider = try makeProvider(issuerID: .Sample.issuerID)
        let token = try await provider.token()

        clock.advance(by: 19 * 60 + 1)

        #expect(try await provider.token() != token)
    }

    @Test("Throws when the private key is not valid")
    func throwsWithInvalidPrivateKey() {
        #expect(throws: (any Error).self) {
            try APIKeyTokenProvider(
                issuerID: .Sample.issuerID,
                keyID: .Sample.keyID,
                privateKey: "not-a-private-key"
            )
        }
    }
}

// MARK: - Helpers

private extension APIKeyTokenProviderTests {
    func makeProvider(issuerID: String?) throws -> APIKeyTokenProvider {
        try APIKeyTokenProvider(
            issuerID: issuerID,
            keyID: .Sample.keyID,
            privateKey: key.pemRepresentation,
            now: { [clock] in clock.date }
        )
    }

    func decode(_ token: String) throws -> (header: [String: String], payload: [String: Any]) {
        let parts = token.split(separator: ".").map(String.init)

        try #require(parts.count == 3)

        let header = try JSONDecoder().decode([String: String].self, from: try #require(Data(base64URL: parts[0])))
        let payloadData = try #require(Data(base64URL: parts[1]))
        let payload = try #require(try JSONSerialization.jsonObject(with: payloadData) as? [String: Any])

        return (header, payload)
    }
}

/// A clock whose date only changes when it is advanced.
private final class TestClock: @unchecked Sendable {
    private(set) var date = Date(timeIntervalSince1970: 1_800_000_000)

    func advance(by interval: TimeInterval) {
        date = date.addingTimeInterval(interval)
    }
}

// MARK: - Data+Base64URL

private extension Data {
    init?(base64URL: String) {
        var base64 = base64URL
            .replacingOccurrences(of: "-", with: "+")
            .replacingOccurrences(of: "_", with: "/")

        base64 += String(repeating: "=", count: (4 - base64.count % 4) % 4)

        self.init(base64Encoded: base64)
    }
}

// MARK: - String+Samples

private extension String {
    enum Sample {
        static let issuerID: String = "57246542-96fe-1a63-e053-0824d011072a"
        static let keyID: String = "2X9R4HXF34"
    }
}
#endif