using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Owin;
using Microsoft.Owin.Mapping;

namespace Custom.Owin.Authentication.Infrastructure
{
  internal class MapMiddlewareEx
  {
    private readonly Func<IDictionary<string, object>, Task> _next;

    private readonly MapOptions _options;

    public MapMiddlewareEx(Func<IDictionary<string, object>, Task> next, MapOptions options)
    {
      if (next == null)
      {
        throw new ArgumentNullException(nameof(next));
      }

      if (options == null)
      {
        throw new ArgumentNullException(nameof(options));
      }

      _ = options.PathMatch;
      _next = next;
      _options = options;
    }

    public Task Invoke(IDictionary<string, object> environment)
    {
      OwinContext context = new OwinContext(environment);
      PathString path = context.Request.Path;
      if (path.StartsWithSegments(_options.PathMatch, out var remaining))
      {
        return InvokeCore(environment, context, remaining, path);
      }

      return _next(environment);
    }

    private async Task InvokeCore(IDictionary<string, object> environment, OwinContext context, PathString remaining, PathString path)
    {
      PathString pathBase = context.Request.PathBase;
      context.Request.PathBase = pathBase + _options.PathMatch;
      context.Request.Path = remaining;
      await _options.Branch(environment);
      context.Request.PathBase = pathBase;
      context.Request.Path = path;
    }
  }
}