import Foundation

public protocol SimAdminClientProtocol: Sendable {
    func send(_ route: UpstreamRoute, baseURL: URL, cookie: String?) async throws -> UpstreamResponse
}

extension SimAdminClient: SimAdminClientProtocol {}

public enum ConnectionStatus: String, Equatable, Sendable {
    case online
    case offline
    case authRequired
    case degraded
    case unknown

    public var label: String {
        switch self {
        case .online: return "在线"
        case .offline: return "离线"
        case .authRequired: return "需登录"
        case .degraded: return "降级"
        case .unknown: return "未知"
        }
    }
}

public struct ConnectionResult: Equatable, Sendable {
    public let status: ConnectionStatus
    public let checkedAt: Date

    public init(status: ConnectionStatus, checkedAt: Date) {
        self.status = status
        self.checkedAt = checkedAt
    }
}

public struct ConnectionProbe: Sendable {
    private let client: any SimAdminClientProtocol

    public init(client: any SimAdminClientProtocol) {
        self.client = client
    }

    public func test(_ instance: Instance) async throws -> ConnectionResult {
        do {
            let response = try await client.send(.health, baseURL: instance.origin, cookie: nil)
            if response.status == 401 || response.status == 403 {
                return ConnectionResult(status: .authRequired, checkedAt: Date())
            }
            return ConnectionResult(status: .online, checkedAt: Date())
        } catch {
            switch error {
            case UpstreamError.unauthorized:
                return ConnectionResult(status: .authRequired, checkedAt: Date())
            case UpstreamError.timeout, is URLError:
                return ConnectionResult(status: .offline, checkedAt: Date())
            default:
                return ConnectionResult(status: .degraded, checkedAt: Date())
            }
        }
    }
}