// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;

namespace Microsoft.AspNetCore.Mvc;

/// <summary>
/// An authorization filter that confirms requests are received over HTTPS.
/// </summary>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
public class RequireHttpsAttribute : Attribute, IAuthorizationFilter, IOrderedFilter
{
    private bool? _permanent;

    /// <summary>
    /// Specifies whether a permanent redirect, <c>301 Moved Permanently</c>,
    /// should be used instead of a temporary redirect, <c>302 Found</c>.
    /// </summary>
    public bool Permanent
    {
        get { return _permanent ?? false; }
        set { _permanent = value; }
    }

    /// <inheritdoc />
    /// <value>Default is <c>int.MinValue + 50</c> to run this <see cref="IAuthorizationFilter"/> early.</value>
    public int Order { get; set; } = int.MinValue + 50;

    /// <summary>
    /// Called early in the filter pipeline to confirm request is authorized. Confirms requests are received over
    /// HTTPS. Takes no action for HTTPS requests. Otherwise if it was a GET request, sets
    /// <see cref="AuthorizationFilterContext.Result"/> to a result which will redirect the client to the HTTPS
    /// version of the request URI. Otherwise, sets <see cref="AuthorizationFilterContext.Result"/> to a result
    /// which will set the status code to <c>403</c> (Forbidden).
    /// </summary>
    /// <inheritdoc />
    public virtual void OnAuthorization(AuthorizationFilterContext filterContext)
    {
        ArgumentNullException.ThrowIfNull(filterContext);

        if (!filterContext.HttpContext.Request.IsHttps)
        {
            HandleNonHttpsRequest(filterContext);
        }
    }

    /// <summary>
    /// Called from <see cref="OnAuthorization"/> if the request is not received over HTTPS. Expectation is
    /// <see cref="AuthorizationFilterContext.Result"/> will not be <c>null</c> after this method returns.
    /// </summary>
    /// <param name="filterContext">The <see cref="AuthorizationFilterContext"/> to update.</param>
    /// <remarks>
    /// If it was a GET request, default implementation sets <see cref="AuthorizationFilterContext.Result"/> to a
    /// result which will redirect the client to the HTTPS version of the request URI. Otherwise, default
    /// implementation sets <see cref="AuthorizationFilterContext.Result"/> to a result which will set the status
    /// code to <c>403</c> (Forbidden).
    /// </remarks>
    protected virtual void HandleNonHttpsRequest(AuthorizationFilterContext filterContext)
    {
        // only redirect for GET requests, otherwise the browser might not propagate the verb and request
        // body correctly.
        if (!HttpMethods.IsGet(filterContext.HttpContext.Request.Method))
        {
            filterContext.Result = new StatusCodeResult(StatusCodes.Status403Forbidden);
        }
        else
        {
            var optionsAccessor = filterContext.HttpContext.RequestServices.GetRequiredService<IOptions<MvcOptions>>();

            var request = filterContext.HttpContext.Request;

            var host = request.Host;
            if (optionsAccessor.Value.SslPort.HasValue && optionsAccessor.Value.SslPort > 0)
            {
                // a specific SSL port is specified
                host = new HostString(host.Host, optionsAccessor.Value.SslPort.Value);
            }
            else
            {
                // clear the port
                host = new HostString(host.Host);
            }

            var permanentValue = _permanent ?? optionsAccessor.Value.RequireHttpsPermanent;

            var newUrl = string.Concat(
                "https://",
                host.ToUriComponent(),
                request.PathBase.ToUriComponent(),
                request.Path.ToUriComponent(),
                request.QueryString.ToUriComponent());

            // redirect to HTTPS version of page
            filterContext.Result = new RedirectResult(newUrl, permanentValue);
        }
    }
}
