using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using System.Net.Http;

var builder = WebApplication.CreateBuilder(args);
// to build the binary dotnet publish -c Release -o ./publish
// Go backend
builder.Services.AddHttpClient("GoBackend", client =>
{
    client.BaseAddress = new Uri("http://localhost:8080");
    client.Timeout = TimeSpan.FromSeconds(30);
});

// Node frontend
builder.Services.AddHttpClient("NodeFrontend", client =>
{
    client.BaseAddress = new Uri("http://localhost:3000");
    client.Timeout = TimeSpan.FromSeconds(30);
});

var app = builder.Build();

app.UseStaticFiles();

app.Use((Func<HttpContext, Func<Task>, Task>)(async (context, next) =>
{
    var clientFactory = context.RequestServices.GetRequiredService<IHttpClientFactory>();

    var isApiRequest =
        context.Request.Path.StartsWithSegments("/api") ||
        context.Request.Path.StartsWithSegments("/graphql") ||
        context.Request.Path.StartsWithSegments("/auth") ||
        !context.Request.Method.Equals("GET", StringComparison.OrdinalIgnoreCase);

    var client = clientFactory.CreateClient(isApiRequest ? "GoBackend" : "NodeFrontend");

    try
    {
        var requestUri = context.Request.Path + context.Request.QueryString;

        var request = new HttpRequestMessage(
            new HttpMethod(context.Request.Method),
            requestUri);

        foreach (var header in context.Request.Headers)
        {
            if (!request.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray()))
            {
                request.Content ??= new StreamContent(context.Request.Body);
                request.Content.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray());
            }
        }

        if (context.Request.ContentLength > 0 || context.Request.Headers.ContainsKey("Transfer-Encoding"))
        {
            request.Content = new StreamContent(context.Request.Body);
        }

        var response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, context.RequestAborted);

        context.Response.StatusCode = (int)response.StatusCode;

        foreach (var header in response.Headers)
        {
            context.Response.Headers[header.Key] = header.Value.ToArray();
        }

        foreach (var header in response.Content.Headers)
        {
            context.Response.Headers[header.Key] = header.Value.ToArray();
        }

        context.Response.Headers.Remove("transfer-encoding");

        await response.Content.CopyToAsync(context.Response.Body);
    }
    catch (HttpRequestException ex)
    {
        context.Response.StatusCode = isApiRequest ? 503 : 502;
        await context.Response.WriteAsync($"{(isApiRequest ? "Go API" : "Frontend")} unavailable: {ex.Message}");
    }
}));

app.Run();