// OpenTween - Client of Twitter
// Copyright (c) 2012 kim_upsilon (@kim_upsilon) <https://upsilo.net/~upsilon/>
// All rights reserved.
//
// This file is part of OpenTween.
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>, or write to
// the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
// Boston, MA 02110-1301, USA.

#nullable enable

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Net.Http;
using System.Runtime.Serialization.Json;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Xml;
using System.Xml.Linq;
using System.Xml.XPath;
using OpenTween.Connection;
using OpenTween.Models;

namespace OpenTween.Thumbnail.Services
{
    class FoursquareCheckin : IThumbnailService
    {
        public static readonly Regex UrlPatternRegex =
            new Regex(@"^https?://www\.swarmapp\.com/c/(?<checkin_id>[0-9a-zA-Z]+)");

        public static readonly Regex LegacyUrlPatternRegex =
            new Regex(@"^https?://(?:foursquare\.com|www\.swarmapp\.com)/.+?/checkin/(?<checkin_id>[0-9a-z]+)(?:\?s=(?<signature>[^&]+))?");

        public static readonly string ApiBase = "https://api.foursquare.com/v2";

        protected HttpClient http
            => this.localHttpClient ?? Networking.Http;

        private readonly HttpClient? localHttpClient;
        private readonly ApiKey clientId;
        private readonly ApiKey clientSecret;

        public FoursquareCheckin()
            : this(null, ApplicationSettings.FoursquareClientId, ApplicationSettings.FoursquareClientSecret)
        {
        }

        public FoursquareCheckin(HttpClient? http, ApiKey clientId, ApiKey clientSecret)
        {
            this.localHttpClient = http;
            this.clientId = clientId;
            this.clientSecret = clientSecret;
        }

        public override async Task<ThumbnailInfo?> GetThumbnailInfoAsync(string url, PostClass post, CancellationToken token)
        {
            // ツイートに位置情報が付与されている場合は何もしない
            if (post.PostGeo != null)
                return null;

            var location = await this.FetchCheckinLocation(url, token)
                .ConfigureAwait(false);

            if (location == null)
            {
                location = await this.FetchCheckinLocationLegacy(url, token)
                    .ConfigureAwait(false);
            }

            if (location != null)
            {
                var map = MapThumb.GetDefaultInstance();

                return await map.GetThumbnailInfoAsync(new PostClass.StatusGeo(location.Longitude, location.Latitude))
                    .ConfigureAwait(false);
            }

            return null;
        }

        /// <summary>
        /// Foursquare のチェックイン URL から位置情報を取得します
        /// </summary>
        public async Task<GlobalLocation?> FetchCheckinLocation(string url, CancellationToken token)
        {
            var match = UrlPatternRegex.Match(url);
            if (!match.Success)
                return null;

            if (!(this.clientId, this.clientSecret).TryGetValue(out var keyPair))
                return null;

            var (clientId, clientSecret) = keyPair;
            var checkinIdGroup = match.Groups["checkin_id"];

            try
            {
                // Foursquare のチェックイン情報を取得
                // 参照: https://developer.foursquare.com/docs/checkins/resolve

                var query = new Dictionary<string, string>
                {
                    ["client_id"] = clientId,
                    ["client_secret"] = clientSecret,
                    ["v"] = "20140419", // https://developer.foursquare.com/overview/versioning

                    ["shortId"] = checkinIdGroup.Value,
                };

                var apiUrl = new Uri(ApiBase + "/checkins/resolve?" + MyCommon.BuildQueryString(query));

                using var response = await this.http.GetAsync(apiUrl, token)
                    .ConfigureAwait(false);

                response.EnsureSuccessStatusCode();

                var jsonBytes = await response.Content.ReadAsByteArrayAsync()
                    .ConfigureAwait(false);

                return ParseIntoLocation(jsonBytes);
            }
            catch (HttpRequestException)
            {
                return null;
            }
        }

        /// <summary>
        /// Foursquare のチェックイン URL から位置情報を取得します (古い形式の URL)
        /// </summary>
        public async Task<GlobalLocation?> FetchCheckinLocationLegacy(string url, CancellationToken token)
        {
            var match = LegacyUrlPatternRegex.Match(url);

            if (!match.Success)
                return null;

            if (!(this.clientId, this.clientSecret).TryGetValue(out var keyPair))
                return null;

            var (clientId, clientSecret) = keyPair;
            var checkinIdGroup = match.Groups["checkin_id"];
            var signatureGroup = match.Groups["signature"];

            try
            {
                // Foursquare のベニュー情報を取得
                // 参照: https://developer.foursquare.com/docs/venues/venues

                var query = new Dictionary<string, string>
                {
                    ["client_id"] = clientId,
                    ["client_secret"] = clientSecret,
                    ["v"] = "20140419", // https://developer.foursquare.com/overview/versioning
                };

                if (signatureGroup.Success)
                    query["signature"] = signatureGroup.Value;

                var apiUrl = new Uri(ApiBase + "/checkins/" + checkinIdGroup.Value + "?" + MyCommon.BuildQueryString(query));

                using var response = await this.http.GetAsync(apiUrl, token)
                    .ConfigureAwait(false);

                response.EnsureSuccessStatusCode();

                var jsonBytes = await response.Content.ReadAsByteArrayAsync()
                    .ConfigureAwait(false);

                return ParseIntoLocation(jsonBytes);
            }
            catch (HttpRequestException)
            {
                return null;
            }
        }

        internal static GlobalLocation? ParseIntoLocation(byte[] jsonBytes)
        {
            using var jsonReader = JsonReaderWriterFactory.CreateJsonReader(jsonBytes, XmlDictionaryReaderQuotas.Max);
            var xElm = XElement.Load(jsonReader);

            var locationElm = xElm.XPathSelectElement("/response/checkin/venue/location");

            // 座標が得られなかった場合
            if (locationElm == null)
                return null;

            // 月など、地球以外の星の座標である場合
            var planetElm = locationElm.Element("planet");
            if (planetElm != null && planetElm.Value != "earth")
                return null;

            return new GlobalLocation
            {
                Latitude = double.Parse(locationElm.Element("lat").Value, CultureInfo.InvariantCulture),
                Longitude = double.Parse(locationElm.Element("lng").Value, CultureInfo.InvariantCulture),
            };
        }
    }
}
