using System;
using System.Net;
using Microsoft.AspNetCore.Rewrite;

namespace StardewModdingAPI.Web.Framework.RedirectRules
{
    /// <summary>Redirect hostnames to a URL if they match a condition.</summary>
    internal class RedirectHostsToUrlsRule : RedirectMatchRule
    {
        /*********
        ** Fields
        *********/
        /// <summary>Maps a lowercase hostname to the resulting redirect URL.</summary>
        private readonly Func<string, string?> Map;


        /*********
        ** Public methods
        *********/
        /// <summary>Construct an instance.</summary>
        /// <param name="statusCode">The status code to use for redirects.</param>
        /// <param name="map">Hostnames mapped to the resulting redirect URL.</param>
        public RedirectHostsToUrlsRule(HttpStatusCode statusCode, Func<string, string?> map)
        {
            this.StatusCode = statusCode;
            this.Map = map ?? throw new ArgumentNullException(nameof(map));
        }


        /*********
        ** Private methods
        *********/
        /// <summary>Get the new redirect URL.</summary>
        /// <param name="context">The rewrite context.</param>
        /// <returns>Returns the redirect URL, or <c>null</c> if the redirect doesn't apply.</returns>
        protected override string? GetNewUrl(RewriteContext context)
        {
            // get requested host
            string? host = context.HttpContext.Request.Host.Host;

            // get new host
            host = this.Map(host);
            if (host == null)
                return null;

            // rewrite URL
            UriBuilder uri = this.GetUrl(context.HttpContext.Request);
            uri.Host = host;
            return uri.ToString();
        }
    }
}