using System;
using System.IO;
using System.Threading.Tasks;
using System.Xml;
using System.ServiceModel.Syndication;
using System.Linq;
using System.Collections.Generic;
using System.Net.Http;
using Newtonsoft.Json;
using Discord;

namespace rssberg
{
    class Program
    {
        private const string archivePath = "doneIDs.txt";
        private const string configPath = "config.json";
        static readonly HttpClient client = new HttpClient();
        static List<string> doneIDs;

        static void Main(string[] args)
        {
            if (!File.Exists(configPath)){
                File.CreateText(configPath);
                var sampleCfg = new Config();
                sampleCfg.FeedPairs.Add("rss", "webhook");
                File.WriteAllText(configPath, JsonConvert.SerializeObject(sampleCfg));
            }
            var cfg = JsonConvert.DeserializeObject<Config>(File.ReadAllText(configPath));

            Console.WriteLine("rss reader alive");

            if (!File.Exists(archivePath))
            {
                File.CreateText(archivePath);
            }
            doneIDs = File.ReadAllLines(archivePath).ToList();

            var postMetaTasks = new List<Task>();
            foreach (var kvp in cfg.FeedPairs.ToList())
            {
                postMetaTasks.Add(rss2webhook(kvp.Key, kvp.Value));
            }

            Console.WriteLine($"rss reader collected {postMetaTasks.Count} post metatasks");
            Task.WaitAll(postMetaTasks.ToArray());
            while(doneIDs.Count > 5000){
                doneIDs.RemoveAt(0);
            }
            File.WriteAllLines(archivePath, doneIDs);

            Console.WriteLine("rss reader actually done");
        }

        private static async Task rss2webhook(string key, string value)
        {
            var postTasks = new List<Task<ulong>>();
            postTasks.Add(Task.Run<ulong>(() => {return (ulong)1;})); //dummy task for debugging
            var responseStream = await client.GetStreamAsync(key);
            var wh = new Discord.Webhook.DiscordWebhookClient(value);

            using (XmlReader xr = XmlReader.Create(responseStream))
            {
                var feed = SyndicationFeed.Load(xr);
                foreach (var item in feed.Items)
                {
                    var date = item.PublishDate;
                    if(item.LastUpdatedTime > item.PublishDate)
                    {
                        date = item.LastUpdatedTime; //imo the library should automatically set last updated to created, in this case
                        //but I think that would break with tradition in a painful way, so meh
                    }
                    if(!doneIDs.Contains(item.Id) && DateTime.UtcNow - date < TimeSpan.FromDays(5))
                    {
                        // var sb = new StringBuilder();
                        // using(XmlWriter xw = XmlWriter.Create(sb)){
                        //     item.Content.WriteTo(xw, "html", null);
                        // }
                        Console.WriteLine($"to post! {item.Id} {item.Title?.Text}");
                        doneIDs.Add(item.Id);
                        postTasks.Add(wh.SendMessageAsync(item.Title?.Text + ' ' + item.Links?.ToList().FirstOrDefault()?.Uri.ToString()));
                    }
                }
            }
            Task.WaitAll(postTasks.ToArray());
        }
        static async Task<List<SyndicationItem>> rssArticles(string rssURL)
        {
            var toReturn = new List<SyndicationItem>();
            var responseStream = await client.GetStreamAsync(rssURL);
            using (XmlReader xr = XmlReader.Create(responseStream))
            {
                var feed = SyndicationFeed.Load(xr);
                foreach (var item in feed.Items)
                {
                    if(!doneIDs.Contains(item.Id))
                    {
                        toReturn.Add(item);
                    }
                }
            }
            return toReturn;
        }
    }
}