//===----------------------------------------------------------------------===//
// Copyright © 2025 Apple Inc. and the containerization project authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//===----------------------------------------------------------------------===//

#if os(macOS)
import Foundation

/// Holds the result of a query to the keychain.
public struct KeychainQueryResult {
    public var account: String
    public var data: String
    public var modifiedDate: Date
    public var createdDate: Date
}

/// Type that facilitates interacting with the macOS keychain.
public struct KeychainQuery {
    public init() {}

    /// Save a value to the keychain.
    public func save(id: String, host: String, user: String, token: String) throws {
        if try exists(id: id, host: host) {
            try delete(id: id, host: host)
        }

        guard let tokenEncoded = token.data(using: String.Encoding.utf8) else {
            throw Self.Error.invalidTokenConversion
        }
        let query: [String: Any] = [
            kSecClass as String: kSecClassInternetPassword,
            kSecAttrSecurityDomain as String: id,
            kSecAttrServer as String: host,
            kSecAttrAccount as String: user,
            kSecValueData as String: tokenEncoded,
            kSecAttrAccessible as String: kSecAttrAccessibleAfterFirstUnlock,
            kSecAttrSynchronizable as String: false,
        ]
        let status = SecItemAdd(query as CFDictionary, nil)
        guard status == errSecSuccess else { throw Self.Error.unhandledError(status: status) }
    }

    /// Delete a value from the keychain.
    public func delete(id: String, host: String) throws {
        let query: [String: Any] = [
            kSecClass as String: kSecClassInternetPassword,
            kSecAttrSecurityDomain as String: id,
            kSecAttrServer as String: host,
            kSecMatchLimit as String: kSecMatchLimitOne,
        ]
        let status = SecItemDelete(query as CFDictionary)
        guard status == errSecSuccess || status == errSecItemNotFound else {
            throw Self.Error.unhandledError(status: status)
        }
    }

    /// Retrieve a value from the keychain.
    public func get(id: String, host: String) throws -> KeychainQueryResult? {
        let query: [String: Any] = [
            kSecClass as String: kSecClassInternetPassword,
            kSecAttrSecurityDomain as String: id,
            kSecAttrServer as String: host,
            kSecReturnAttributes as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne,
            kSecReturnData as String: true,
        ]
        var item: CFTypeRef?
        let status = SecItemCopyMatching(query as CFDictionary, &item)
        let exists = try isQuerySuccessful(status)
        if !exists {
            return nil
        }

        guard let fetched = item as? [String: Any] else {
            throw Self.Error.unexpectedDataFetched
        }
        guard let data = fetched[kSecValueData as String] as? Data else {
            throw Self.Error.keyNotPresent(key: kSecValueData as String)
        }
        guard let decodedData = String(data: data, encoding: String.Encoding.utf8) else {
            throw Self.Error.unexpectedDataFetched
        }
        guard let account = fetched[kSecAttrAccount as String] as? String else {
            throw Self.Error.keyNotPresent(key: kSecAttrAccount as String)
        }
        guard let modifiedDate = fetched[kSecAttrModificationDate as String] as? Date else {
            throw Self.Error.keyNotPresent(key: kSecAttrModificationDate as String)
        }
        guard let createdDate = fetched[kSecAttrCreationDate as String] as? Date else {
            throw Self.Error.keyNotPresent(key: kSecAttrCreationDate as String)
        }
        return KeychainQueryResult(
            account: account,
            data: decodedData,
            modifiedDate: modifiedDate,
            createdDate: createdDate
        )
    }

    private func isQuerySuccessful(_ status: Int32) throws -> Bool {
        guard status != errSecItemNotFound else {
            return false
        }
        guard status == errSecSuccess else {
            throw Self.Error.unhandledError(status: status)
        }
        return true
    }

    /// Check if a value exists in the keychain.
    public func exists(id: String, host: String) throws -> Bool {
        let query: [String: Any] = [
            kSecClass as String: kSecClassInternetPassword,
            kSecAttrSecurityDomain as String: id,
            kSecAttrServer as String: host,
            kSecReturnAttributes as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne,
            kSecReturnData as String: false,
        ]

        let status = SecItemCopyMatching(query as CFDictionary, nil)
        return try isQuerySuccessful(status)
    }
}

extension KeychainQuery {
    enum Error: Swift.Error {
        case unhandledError(status: Int32)
        case unexpectedDataFetched
        case keyNotPresent(key: String)
        case invalidTokenConversion
    }
}
#endif