/*

    Copyright (C) 2018 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A model-level object that describes how to make a TCP connection.

 */

import Foundation

/// A model-level object that describes how to make a TCP connection.  This

/// includes the transport to use, the name and port to connect to, and where

/// to use TLS.

///

/// This type is codable because the app uses it to save and restore the state

/// of the UI.  If you change this type you’re likely to invalidate that state,

/// which isn’t a big deal with certainly worth thinking about.

struct Endpoint : Codable {

    /// Describes all the known transports.

    ///

    /// - important: Before changing these values, see the comments associated

    ///   with `EndpointPicker`.

    ///

    /// - socketStream: Use `SocketStreamTransport`.

    /// - streamTask: Use `StreamTaskTransport`.

    /// - bsdSockets: Use `BSDSocketsTransport`.

    /// - nwTCPConnection: Use `NWTCPTransport`.

    enum Transport : Int, Codable {

        case socketStream

        case streamTask

        case bsdSockets

        case nwTCPConnection

    }

    /// The transport to use.

    var transport: Transport

    /// The host to connect to.  This can be a numeric IP address, either IPv4

    /// or IPv6.

    var hostName: String

    /// THe port on which to connect.

    var port: Int

    /// True if the connection should use TLS.

    var useTLS: Bool

    /// A reasonable ’nil’ value for situations where a default value is needed

    /// but `nil` is not allowed.

    static var empty: Endpoint = Endpoint(transport: .socketStream, hostName: Endpoint.defaultHostName, port: 12345, useTLS: false)

    /// The host name to use in the `empty` value.  This is here because I want

    /// to return different results on the simulator versus a real device.

    private static var defaultHostName: String = {

        #if arch(i386) || arch(x86_64)

            return "127.0.0.1"          // On the simulator it makes sense to default to localhost.

        #else

            return "guy-smiley.local"   // My machine!

        #endif

    }()

}

extension ConversationTransport {

    /// Creates an object that uses a transport configured by `endpoint`.

    ///

    /// - Parameter endpoint: Specifies the transport to use and various

    ///     parameters for that transport.

    /// - Throws: An error if the transport doesn’t support the configuration in

    ///     `endpoint`.

    convenience init(endpoint: Endpoint) throws {

        let transport = try ConversationTransport.transport(for: endpoint)

        self.init(localizedName: endpoint.hostName, transport: transport)

    }

    /// Creates a `TCPTransport` for the specified endpoint.

    ///

    /// This is exported for the benefit of our test code.  The app itself

    /// creates a `ConversationTransport` object directly via its initialiser.

    ///

    /// - Parameter endpoint: Specifies the transport to use and various

    ///     parameters for that transport.

    /// - Returns: The transport itself.

    /// - Throws: An error if the transport doesn’t support the configuration in

    ///     `endpoint`.

    static func transport(for endpoint: Endpoint) throws -> TCPTransport {

        let transport: TCPTransport

        switch endpoint.transport {

        case .socketStream:

            transport = SocketStreamTransport(hostName: endpoint.hostName, port: endpoint.port, useTLS: endpoint.useTLS, queue: .main)

        case .streamTask:

            transport = StreamTaskTransport(hostName: endpoint.hostName, port: endpoint.port, useTLS: endpoint.useTLS, queue: .main)

        case .bsdSockets:

            transport = try BSDSocketsTransport(numericAddress: endpoint.hostName, port: endpoint.port, useTLS: endpoint.useTLS, queue: .main)

        case .nwTCPConnection:

            transport = try NWTCPTransport(hostName: endpoint.hostName, port: endpoint.port, useTLS: endpoint.useTLS, queue: .main)

        }

        return transport

    }

}