using System;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

using Myriad.Extensions;
using Myriad.Rest.Exceptions;
using Myriad.Rest.Types;
using Myriad.Rest.Types.Requests;
using Myriad.Types;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using PluralKit.Core;

namespace PluralKit.Bot
{
    public class ImportExport
    {
        private readonly DataFileService _dataFiles;
        private readonly HttpClient _client;
        private readonly JsonSerializerSettings _settings = new()
        {
            // Otherwise it'll mess up/reformat the ISO strings for ???some??? reason >.>
            DateParseHandling = DateParseHandling.None
        };

        public ImportExport(DataFileService dataFiles, HttpClient client)
        {
            _dataFiles = dataFiles;
            _client = client;
        }

        public async Task Import(Context ctx)
        {
            var url = ctx.RemainderOrNull() ?? ctx.Message.Attachments.FirstOrDefault()?.Url;
            if (url == null) throw Errors.NoImportFilePassed;

            await ctx.BusyIndicator(async () =>
            {
                JObject data;
                try
                {
                    var response = await _client.GetAsync(url);
                    if (!response.IsSuccessStatusCode)
                        throw Errors.InvalidImportFile;
                    data = JsonConvert.DeserializeObject<JObject>(await response.Content.ReadAsStringAsync(), _settings);
                    if (data == null)
                        throw Errors.InvalidImportFile;
                }
                catch (InvalidOperationException)
                {
                    // Invalid URL throws this, we just error back out
                    throw Errors.InvalidImportFile;
                }
                catch (JsonException)
                {
                    throw Errors.InvalidImportFile;
                }

                async Task ConfirmImport(string message)
                {
                    var msg = $"{message}\n\nDo you want to proceed with the import?";
                    if (!await ctx.PromptYesNo(msg, "Proceed"))
                        throw Errors.ImportCancelled;
                }

                if (data.ContainsKey("accounts")
                    && data.Value<JArray>("accounts").Type != JTokenType.Null
                    && data.Value<JArray>("accounts").Contains((JToken)ctx.Author.Id.ToString()))
                {
                    var msg = $"{Emojis.Warn} You seem to importing a system profile belonging to another account. Are you sure you want to proceed?";
                    if (!await ctx.PromptYesNo(msg, "Import")) throw Errors.ImportCancelled;
                }

                var result = await _dataFiles.ImportSystem(ctx.Author.Id, ctx.System, data, ConfirmImport);
                if (!result.Success)
                    if (result.Message == null)
                        throw Errors.InvalidImportFile;
                    else
                        await ctx.Reply($"{Emojis.Error} The provided system profile could not be imported: {result.Message}");
                else if (ctx.System == null)
                    // We didn't have a system prior to importing, so give them the new system's ID
                    await ctx.Reply($"{Emojis.Success} PluralKit has created a system for you based on the given file. Your system ID is `{result.CreatedSystem}`. Type `pk;system` for more information.");
                else
                    // We already had a system, so show them what changed
                    await ctx.Reply($"{Emojis.Success} Updated {result.Modified} members, created {result.Added} members. Type `pk;system list` to check!");
            });
        }

        public async Task Export(Context ctx)
        {
            ctx.CheckSystem();

            var json = await ctx.BusyIndicator(async () =>
            {
                // Make the actual data file
                var data = await _dataFiles.ExportSystem(ctx.System);
                return JsonConvert.SerializeObject(data, Formatting.None);
            });


            // Send it as a Discord attachment *in DMs*
            var stream = new MemoryStream(Encoding.UTF8.GetBytes(json));

            try
            {
                var dm = await ctx.Cache.GetOrCreateDmChannel(ctx.Rest, ctx.Author.Id);

                var msg = await ctx.Rest.CreateMessage(dm.Id,
                    new MessageRequest { Content = $"{Emojis.Success} Here you go!" },
                    new[] { new MultipartFile("system.json", stream, null) });
                await ctx.Rest.CreateMessage(dm.Id, new MessageRequest { Content = $"<{msg.Attachments[0].Url}>" });

                // If the original message wasn't posted in DMs, send a public reminder
                if (ctx.Channel.Type != Channel.ChannelType.Dm)
                    await ctx.Reply($"{Emojis.Success} Check your DMs!");
            }
            catch (ForbiddenException)
            {
                // If user has DMs closed, tell 'em to open them
                await ctx.Reply(
                    $"{Emojis.Error} Could not send the data file in your DMs. Do you have DMs closed?");
            }
        }
    }
}