using System.Runtime.InteropServices;
using System.Security.Cryptography;
using ChangeT50.Adapter;

return CommandLine.Run(args);

internal static class CommandLine
{
    public static int Run(string[] args)
    {
        if (args.Length == 0 || args[0] is "-h" or "--help" or "help")
        {
            PrintUsage();
            return args.Length == 0 ? 1 : 0;
        }

        var command = args[0];
        var dllPath = GetOption(args, "--dll") ?? "Change.dll";

        try
        {
            return command switch
            {
                "self-test" => SelfTest(dllPath),
                "load" => LoadOnly(dllPath),
                "probe-reader" => ProbeReader(dllPath),
                _ => UnknownCommand(command)
            };
        }
        catch (Exception exception)
        {
            Console.Error.WriteLine($"FAIL: {exception.GetType().Name}: {exception.Message}");
            return 2;
        }
    }

    private static int SelfTest(string dllPath)
    {
        var layoutErrors = ChangeAbi.ValidateManagedLayouts();
        if (layoutErrors.Count != 0)
        {
            foreach (var error in layoutErrors)
            {
                Console.Error.WriteLine($"ABI: {error}");
            }

            return 2;
        }

        var fullPath = Path.GetFullPath(dllPath);
        if (!File.Exists(fullPath))
        {
            throw new FileNotFoundException("Change.dll was not found.", fullPath);
        }

        var inspection = PortableExecutableInspector.Inspect(fullPath);
        var missingExports = ChangeAbi.RequiredExports
            .Except(inspection.ExportNames, StringComparer.Ordinal)
            .Order(StringComparer.Ordinal)
            .ToArray();

        Console.WriteLine("Managed ABI: PASS (Pack=8; CustomerInfo=68; UPLOADINFO=120; psamID offset=96).");
        Console.WriteLine($"DLL SHA-256: {ComputeSha256(fullPath)}");
        Console.WriteLine($"PE machine: 0x{inspection.Machine:x4} ({MachineName(inspection.Machine)}).");
        Console.WriteLine($"Exported module name: {inspection.ExportedModuleName}");
        Console.WriteLine($"Exports found: {inspection.ExportNames.Count}; required: {ChangeAbi.RequiredExports.Length}.");

        if (inspection.Machine != ChangeAbi.ImageFileMachineI386 || !inspection.IsPe32)
        {
            Console.Error.WriteLine("FAIL: The supplied Change.dll is not PE32/x86.");
            return 2;
        }

        if (missingExports.Length != 0)
        {
            Console.Error.WriteLine($"FAIL: Missing exports: {string.Join(", ", missingExports)}");
            return 2;
        }

        Console.WriteLine("PASS: Real Change.dll structure and all required exports match the .NET wrapper contract.");
        Console.WriteLine("Safe self-test only: the DLL was inspected, not loaded or executed.");
        return 0;
    }

    private static int LoadOnly(string dllPath)
    {
        using var library = new ChangeNativeLibrary(dllPath);
        Console.WriteLine("PASS: Change.dll loaded in a Windows x86 process and all 16 exports were bound.");
        Console.WriteLine("Safe load-only mode: no reader, card, WebService, debit or upload operation was invoked.");
        return 0;
    }

    private static int ProbeReader(string dllPath)
    {
        using var library = new ChangeNativeLibrary(dllPath);
        var openResult = library.OpenReader();
        Console.WriteLine($"OpenCom returned {openResult}.");
        if (openResult != 0)
        {
            Console.Error.WriteLine("BLOCKED: reader connection did not open; check driver, registration, reader and PSAM.");
            return 3;
        }

        try
        {
            var queryResult = library.QueryCard(out _);
            Console.WriteLine($"CapNBQueryCard returned {queryResult}.");
            if (queryResult != 0)
            {
                Console.Error.WriteLine("BLOCKED: no test card was detected, or the card query failed.");
                return 3;
            }

            var readResult = library.ReadCard(out _);
            Console.WriteLine($"CapGetNBCardInfo returned {readResult}.");
            if (readResult != 0)
            {
                Console.Error.WriteLine("FAIL: a card was detected but its information could not be read.");
                return 2;
            }

            Console.WriteLine("PASS: reader opened and test card read succeeded.");
            Console.WriteLine("Account, card, balance and identity values are intentionally not printed.");
            return 0;
        }
        finally
        {
            library.CloseReader();
            Console.WriteLine("Reader connection closed.");
        }
    }

    private static string? GetOption(IReadOnlyList<string> args, string option)
    {
        for (var index = 1; index < args.Count; index++)
        {
            if (args[index] != option)
            {
                continue;
            }

            if (index + 1 >= args.Count)
            {
                throw new ArgumentException($"Option {option} requires a value.");
            }

            return args[index + 1];
        }

        return null;
    }

    private static string ComputeSha256(string path)
    {
        using var stream = File.OpenRead(path);
        return Convert.ToHexString(SHA256.HashData(stream)).ToLowerInvariant();
    }

    private static string MachineName(ushort machine) => machine switch
    {
        ChangeAbi.ImageFileMachineI386 => "x86/i386",
        0x8664 => "x64",
        0xaa64 => "ARM64",
        _ => "unknown"
    };

    private static int UnknownCommand(string command)
    {
        Console.Error.WriteLine($"Unknown command: {command}");
        PrintUsage();
        return 1;
    }

    private static void PrintUsage()
    {
        Console.WriteLine("Change T5.0 .NET adapter test tool");
        Console.WriteLine();
        Console.WriteLine("  self-test    --dll <path>  Inspect the real DLL and verify ABI/exports on any OS.");
        Console.WriteLine("  load         --dll <path>  Load and bind the DLL in a Windows x86 process only.");
        Console.WriteLine("  probe-reader --dll <path>  Read-only reader/card probe; never debits or uploads.");
    }
}