// curl_global_init() with default flags.
var global = CurlNative.Init();

// curl_easy_init() to create easy handle.
var easy = CurlNative.Easy.Init();
try
{
    CurlNative.Easy.SetOpt(easy, CURLoption.URL, "http://httpbin.org/ip");

    var stream = new MemoryStream();
    CurlNative.Easy.SetOpt(easy, CURLoption.WRITEFUNCTION, (data, size, nmemb, user) =>
    {
        var length = (int) size * (int) nmemb;
        var buffer = new byte[length];
        Marshal.Copy(data, buffer, 0, length);
        stream.Write(buffer, 0, length);
        return (UIntPtr) length;
    });

    var result = CurlNative.Easy.Perform(easy);

    Console.WriteLine($"Result code: {result}.");
    Console.WriteLine();
    Console.WriteLine("Response body:");
    Console.WriteLine(Encoding.UTF8.GetString(stream.ToArray()));
}
finally
{
    easy.Dispose();

    if (global == CURLcode.OK)
    {
        CurlNative.Cleanup();
    }
}

// curl_global_init() with default flags.
var global = CurlNative.Init();

// curl_easy_init() to create easy handle.
var easy = CurlNative.Easy.Init();
try
{
    var postData = "fieldname1=fieldvalue1&fieldname2=fieldvalue2";

    CurlNative.Easy.SetOpt(easy, CURLoption.URL, "http://httpbin.org/post");

    // This one has to be called before setting COPYPOSTFIELDS.
    CurlNative.Easy.SetOpt(easy, CURLoption.POSTFIELDSIZE, Encoding.ASCII.GetByteCount(postData));
    CurlNative.Easy.SetOpt(easy, CURLoption.COPYPOSTFIELDS, postData);
    
    var stream = new MemoryStream();
    CurlNative.Easy.SetOpt(easy, CURLoption.WRITEFUNCTION, (data, size, nmemb, user) =>
    {
        var length = (int) size * (int) nmemb;
        var buffer = new byte[length];
        Marshal.Copy(data, buffer, 0, length);
        stream.Write(buffer, 0, length);
        return (UIntPtr) length;
    });

    var result = CurlNative.Easy.Perform(easy);

    Console.WriteLine($"Result code: {result}.");
    Console.WriteLine();
    Console.WriteLine("Response body:");
    Console.WriteLine(Encoding.UTF8.GetString(stream.ToArray()));
}
finally
{
    easy.Dispose();

    if (global == CURLcode.OK)
    {
        CurlNative.Cleanup();
    }
}

internal class HyperSample : ISample
{
    public void Run()
    {
        DllLoader.Init();
        if (CurlNative.Init() != CURLcode.OK)
        {
            throw new Exception("Could not init curl");
        }

        var reqProvider = new MyRequestProvider();
        var resConsumer = new MyResponseConsumer();

        using (var pipe = new HyperPipe<MyRequestContext>(6, reqProvider, resConsumer))
        {
            pipe.RunLoopWait();
        }
    }
}

/// <summary>
///     What exactly is request context? It can be any type (string, int, custom class, whatever) that will help pass some
///     data to method that will process response.
/// </summary>
public class MyRequestContext : IDisposable
{
    public string Label { get; set; }
    public MemoryStream HeaderStream { get; } = new MemoryStream();
    public MemoryStream ContentStream { get; } = new MemoryStream();

    public CurlNative.Easy.DataHandler HeaderFunction { get; set; }
    public CurlNative.Easy.DataHandler ContentFunction { get; set; }

    public void Dispose()
    {
        HeaderStream?.Dispose();
        ContentStream?.Dispose();
    }
}

/// <summary>
///     Request provider generates requests that you want to send to cURL.
///     This example shows how to web scrape StackOverflow questions (https://stackoverflow.com/)
///     beginning with ID 4400000 until ID 4400100.
/// </summary>
public class MyRequestProvider : IRequestProvider<MyRequestContext>
{
    private readonly int _maxQuestion = 4400100;
    private int _currentQuestion = 4400000;

    public bool TryNext(SafeEasyHandle easy, out MyRequestContext context)
    {
        // If question ID is higher than maximum, return false.
        if (_currentQuestion > _maxQuestion)
        {
            context = null;
            return false;
        }

        // Create request context. Assign it a label to easily recognize it later.
        var contextLocal = new MyRequestContext
        {
            Label = $"StackOverflow Question #{_currentQuestion}"
        };

        // Copy response header (it contains HTTP code and response headers, for example
        // "Content-Type") to MemoryStream in our RequestContext.
        context = contextLocal;
        context.HeaderFunction = (data, size, nmemb, userdata) =>
        {
            var length = (int) size * (int) nmemb;
            var buffer = new byte[length];
            Marshal.Copy(data, buffer, 0, length);
            contextLocal.HeaderStream.Write(buffer, 0, length);
            return (UIntPtr) length;
        };

        // Copy response body (it for example contains HTML source) to MemoryStream
        // in our RequestContext.
        context.ContentFunction = (data, size, nmemb, userdata) =>
        {
            var length = (int) size * (int) nmemb;
            var buffer = new byte[length];
            Marshal.Copy(data, buffer, 0, length);
            contextLocal.ContentStream.Write(buffer, 0, length);
            return (UIntPtr) length;
        };

        // Set request URL.
        CurlNative.Easy.SetOpt(easy, CURLoption.URL, $"http://stackoverflow.com/questions/{_currentQuestion}/");

        // Follow redirects.
        CurlNative.Easy.SetOpt(easy, CURLoption.FOLLOWLOCATION, 1);
        CurlNative.Easy.SetOpt(easy, CURLoption.HEADERFUNCTION, context.HeaderFunction);
        CurlNative.Easy.SetOpt(easy, CURLoption.WRITEFUNCTION, context.ContentFunction);

        _currentQuestion++;
        return true;
    }
}

/// <summary>
///     This class will process HTTP responses.
/// </summary>
public class MyResponseConsumer : IResponseConsumer<MyRequestContext>
{
    public HandleCompletedAction OnComplete(SafeEasyHandle easy, MyRequestContext context, CURLcode errorCode)
    {
        Console.WriteLine($"Request label: {context.Label}.");
        if (errorCode != CURLcode.OK)
        {
            Console.BackgroundColor = ConsoleColor.DarkRed;
            Console.ForegroundColor = ConsoleColor.White;

            Console.WriteLine($"cURL error code: {errorCode}");
            var pErrorMsg = CurlNative.Easy.StrError(errorCode);
            var errorMsg = Marshal.PtrToStringAnsi(pErrorMsg);
            Console.WriteLine($"cURL error message: {errorMsg}");

            Console.ResetColor();
            Console.WriteLine("--------");
            Console.WriteLine();

            context.Dispose();
            return HandleCompletedAction.ResetHandleAndNext;
        }

        // Get HTTP response code.
        CurlNative.Easy.GetInfo(easy, CURLINFO.RESPONSE_CODE, out int httpCode);
        if (httpCode != 200)
        {
            Console.BackgroundColor = ConsoleColor.DarkRed;
            Console.ForegroundColor = ConsoleColor.White;

            Console.WriteLine($"Invalid HTTP response code: {httpCode}");

            Console.ResetColor();
            Console.WriteLine("--------");
            Console.WriteLine();

            context.Dispose();
            return HandleCompletedAction.ResetHandleAndNext;
        }
        Console.WriteLine($"Response code: {httpCode}");

        // Get effective URL.
        IntPtr pDoneUrl;
        CurlNative.Easy.GetInfo(easy, CURLINFO.EFFECTIVE_URL, out pDoneUrl);
        var doneUrl = Marshal.PtrToStringAnsi(pDoneUrl);
        Console.WriteLine($"Effective URL: {doneUrl}");

        // Get response body as string.
        string html;
        context.ContentStream.Seek(0, SeekOrigin.Begin);
        using (var reader = new StreamReader(context.ContentStream))
        {
            html = reader.ReadToEnd();
        }

        // Scrape question from HTML source.
        var match = Regex.Match(html, "<title>(.+?)<\\/");

        Console.WriteLine($"Question: {match.Groups[1].Value.Trim()}");
        Console.WriteLine("--------");
        Console.WriteLine();

        context.Dispose();
        return HandleCompletedAction.ResetHandleAndNext;
    }
}