using System.CommandLine;
using PCSC;
using PCSC.Monitoring;
using PCSC.Iso7816;

var rootCommand = new RootCommand("Fancy Test Machine for AfRApay");

var listReadersOption = new Option<bool>("--list-readers", "List card readers and exit");
rootCommand.Add(listReadersOption);

rootCommand.SetHandler((listReaders) => {
    using (var context = ContextFactory.Instance.Establish(SCardScope.System)) {
        // We need a card reader or this won't work!
        var readerNames = context.GetReaders();
        if (readerNames.Length == 0) {
            Console.Error.WriteLine("Error: no card reader detected");
            Environment.Exit(1);
        }

        // If --list-readers is passed, list readers and exit.
        if (listReaders) {
            Console.Error.WriteLine("---------- Connected Readers ----------");
            foreach (var name in readerNames) {
                Console.WriteLine(name);
            }
            Console.Error.WriteLine("---------------------------------------");
            Environment.Exit(0);
        }

        // Listen for events on all connected readers.
        using (var monitor = MonitorFactory.Instance.Create(SCardScope.System)) {
            monitor.Initialized += (_, args) => Console.WriteLine("[ Reader Initialized: {0} ]", args.ReaderName);
            monitor.MonitorException += (_, args) => {
                Console.Error.WriteLine("! ERROR: {0}", args);
                Environment.Exit(1);
            };
            monitor.StatusChanged += (_, args) => Console.WriteLine("~ {0} -> {1}", args.LastState, args.NewState);
            monitor.CardInserted += (_, args) => {
                Console.WriteLine("> TAP: {0}", Convert.ToHexString(args.Atr));
                var reader = new IsoReader(context, args.ReaderName, SCardShareMode.Shared, SCardProtocol.Any);
                HandleTap(reader);
            };
            monitor.CardRemoved += (_, args) => {
                Console.WriteLine("< OFF");
                Console.WriteLine(); // Write a blank line between card taps for readability.
            };

            Console.WriteLine("[ Starting... ]");
            monitor.Start(readerNames);
            while (true) {
                Console.Read();
            }
        }
    }
}, listReadersOption);

return await rootCommand.InvokeAsync(args);

// Queries a card for data when one is tapped.
static void HandleTap(IsoReader reader) {
    // Send a PCSC pseudo-APDU to query the ISO 14443 UID.
    var rsp = reader.Transmit(new CommandApdu(IsoCase.Case2Short, SCardProtocol.Any) {
        CLA = 0xFF,
        Instruction = InstructionCode.GetData,
        P1 = 0x00,
        P2 = 0x00,
    });
    if (!IsSucc(rsp)) {
        Console.Error.WriteLine("--> Card Error: SW1={0} SW2={1}", (SW1Code)rsp.SW1, rsp.SW2);
        return;
    }
    var uid = rsp.GetData();
    Console.WriteLine("  UID: {0}", Convert.ToHexString(uid));
}

// Was the command successful?
static bool IsSucc(Response rsp) {
    return rsp.SW1 == (byte)SW1Code.Normal && rsp.SW2 == 0x00;
}