using System.Collections.Generic;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.HttpOverrides;
using Microsoft.Extensions.DependencyInjection;
using xIdentityHelper;
using xCommons.Authorization;
using xCommons.Extensions;

namespace xApi.Extensions {
    public static class XStartupExtensions {
        /// <summary>
        /// Register Authorization Policies
        /// </summary>
        /// <param name="services"></param>
        /// <param name="policies"></param>
        public static void AddXAuthorization (
            this IServiceCollection services,
            IDictionary<string, AuthorizationPolicy> policies = null
        ) {
            //
            services.AddAuthorization (options => {
                //
                if (!policies.IsNull ()) {
                    //
                    // Fill Policies ...
                    using (var policiesEnumerator = policies.GetEnumerator ()) {
                        while (policiesEnumerator.MoveNext ()) {
                            var policyDescriptor = policiesEnumerator.Current;
                            options.AddPolicy (policyDescriptor.Key, policyDescriptor.Value);
                        }
                    }
                }

                //
                var xPolicies = XAuthorizationHelper.GetXAuthorizationPolicies ();
                if (!xPolicies.IsNull ()) {
                    //
                    // Fill Policies ...
                    using (var policiesEnumerator = xPolicies.GetEnumerator ()) {
                        while (policiesEnumerator.MoveNext ()) {
                            var policyDescriptor = policiesEnumerator.Current;
                            options.AddPolicy (policyDescriptor.Key, policyDescriptor.Value);
                        }
                    }
                }
            });

            //
            services.AddSingleton<IAuthorizationHandler, RequiredRolesHandler> ();
        }

        /// <summary>
        /// Use Forward Headers Options for resolving behind a proxy issues ...
        /// </summary>
        /// <param name="source"></param>
        /// <returns></returns>
        public static void UseXForwardOptions (this IApplicationBuilder source) {
            //
            var forwardOptions = new ForwardedHeadersOptions {
                ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto,
                RequireHeaderSymmetry = false
            };

            //
            forwardOptions.KnownNetworks.Clear ();
            forwardOptions.KnownProxies.Clear ();

            //
            // ref: https://github.com/aspnet/Docs/issues/2384
            source.UseForwardedHeaders (forwardOptions);
        }
    }
}