Add command line interface and change solution structure (#26)

DiscordChatExporter.Cli/ViewModels/MainViewModel.cs

@@ -0,0 +1,53 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using DiscordChatExporter.Core.Models;
+using DiscordChatExporter.Core.Services;
+using Tyrrrz.Extensions;
+
+namespace DiscordChatExporter.Cli.ViewModels
+{
+    public class MainViewModel : IMainViewModel
+    {
+        private readonly IDataService _dataService;
+        private readonly IMessageGroupService _messageGroupService;
+        private readonly IExportService _exportService;
+
+        public MainViewModel(IDataService dataService, IMessageGroupService messageGroupService,
+            IExportService exportService)
+        {
+            _dataService = dataService;
+            _messageGroupService = messageGroupService;
+            _exportService = exportService;
+        }
+
+        public async Task ExportAsync(string token, string channelId, string filePath, ExportFormat format, DateTime? from,
+            DateTime? to)
+        {
+            // Get channel and guild
+            var channel = await _dataService.GetChannelAsync(token, channelId);
+            var guild = channel.GuildId == Guild.DirectMessages.Id
+                ? Guild.DirectMessages
+                : await _dataService.GetGuildAsync(token, channel.GuildId);
+
+            // Generate file path if not set
+            if (filePath.IsBlank())
+            {
+                filePath = $"{guild} - {channel}.{format.GetFileExtension()}"
+                    .Replace(Path.GetInvalidFileNameChars(), '_');
+            }
+
+            // Get messages
+            var messages = await _dataService.GetChannelMessagesAsync(token, channelId, from, to);
+
+            // Group them
+            var messageGroups = _messageGroupService.GroupMessages(messages);
+
+            // Create log
+            var log = new ChannelChatLog(guild, channel, messageGroups, messages.Count);
+
+            // Export
+            await _exportService.ExportAsync(format, filePath, log);
+        }
+    }
+}