/*
buypeeb - a program to track yahoo jp auctions of peebus.
Copyright (C) 2020 lynnesbian

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 <https://www.gnu.org/licenses/>.
*/

using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using System.Net;
using System.Linq;
using System.Diagnostics;
using CsvHelper;
using Gtk;

namespace Buypeeb {
	class MainWindow : Window {

		private string location;
		private JsonSerializerOptions jsonOptions;

		private ListStore items;
		private Settings settings;
		private TreeView itemTreeView;
		private Builder builder;

		// TODO: whenever we get something from the builder, cache it for later
		// that way we don't need to constantly do "builder.GetObject"s
		// when that is done, you can use the cache array to replace everything from here...

		private Box selectionViewBox;
		private Label endingLabel;
		private bool queueActive;
		private SearchEntry searchEntry;
		private Dictionary<string, CheckButton> filterChecks = new Dictionary<string, CheckButton>();

		// ...to here.

		static SemaphoreSlim taskLimit = new SemaphoreSlim(6);
		private Queue<string> updateQueue = new Queue<string>();
		private IEnumerable<YahooAuctionsItem> filterQuery {
			get {
				// father forgive me for i have lynned
				return
					from item in this.settings.watchlist.Values.ToList()
					where (item.favourite != this.filterChecks["Favourites"].Active ||
					item.favourite == this.filterChecks["NonFavourites"].Active) &&
					(item.available != this.filterChecks["Active"].Active ||
					item.available == this.filterChecks["Ended"].Active) &&
					(item.endingToday != this.filterChecks["EndingToday"].Active ||
					item.endingToday == this.filterChecks["EndingAfterToday"].Active) &&
					(item.hasWinPrice != this.filterChecks["WithWinPrice"].Active ||
					item.hasWinPrice == this.filterChecks["WithNoWinPrice"].Active) &&
					(String.IsNullOrWhiteSpace(this.searchEntry.Text) ||
					item.name.ToLower().Contains(this.searchEntry.Text.ToLower()) ||
					item.originalName.ToLower().Contains(this.searchEntry.Text.ToLower()))
					select item;
			}
		}
		private IEnumerable<YahooAuctionsItem> outdatedItemQuery {
			get {
				// only returns items that meet all of the following:
				// - marked as "ready", as in, they aren't in the process of updating
				// - not updated since the interval
				return
				from item in this.settings.watchlist.Values.ToList()
				where item.ready && this.settings.ItemNotUpdatedSinceInterval(item)
				select item;
			}
		}

		private YahooAuctionsItem selectedItem {
			get {
				if (this.itemTreeView.Selection.CountSelectedRows() == 0) {
					// avoids incurring the wrath of Gtk-CRITICAL **
					return null;
				}

				this.itemTreeView.Selection.GetSelected(out TreeIter iter);
				return (YahooAuctionsItem)this.itemTreeView.Model.GetValue(iter, 0);
			}
		}

		public MainWindow() : this(new Builder("main.glade")) { }

		private MainWindow(Builder builder) : base(builder.GetObject("wndMain").Handle) {
			this.jsonOptions = new JsonSerializerOptions {
				Encoder = System.Text.Encodings.Web.JavaScriptEncoder.Create(System.Text.Unicode.UnicodeRanges.All)
			};

			if (Environment.OSVersion.Platform == PlatformID.Win32NT) {
				// C:\Users\Beebus\AppData\Roaming\Lynnear Software\buypeeb
				this.location = System.IO.Path.Combine(Environment.ExpandEnvironmentVariables("%APPDATA%"), "Lynnear Software", "buypeeb");
			}
			else {
				// ~/.config/Lynnear Software/buypeeb
				this.location = System.IO.Path.Combine(Environment.GetEnvironmentVariable("HOME"), ".config", "Lynnear Software", "buypeeb");
			}

			string userdata = System.IO.Path.Combine(location, "userdata.json");
			if (File.Exists(userdata)) {
				try {
					string j = File.ReadAllText(userdata);
					this.settings = JsonSerializer.Deserialize<Settings>(j);
				}
				catch {
					// ???
					Console.WriteLine("oops");
					Application.Quit();
				}

			}
			else {
				this.settings = new Settings();
			}
			this.SaveSettings();
			this.Title = "Buypeeb";

			this.builder = builder;
			builder.Autoconnect(this);

			var menuButtonFilter = (MenuButton)builder.GetObject("MenuButtonFilter");
			var menuButtonSort = (MenuButton)builder.GetObject("MenuButtonSort");
			menuButtonFilter.Child = (Image)builder.GetObject("ImageFilter");
			menuButtonSort.Child = (Image)builder.GetObject("ImageSort");

			this.selectionViewBox = (Box)builder.GetObject("SelectionViewBox");
			this.endingLabel = (Label)builder.GetObject("LabelSelectedEnding");
			this.searchEntry = (SearchEntry)builder.GetObject("FilterSearchEntry");
			foreach (var name in new List<string> { "Favourites", "NonFavourites", "Active", "Ended", "EndingToday", "EndingAfterToday", "WithWinPrice", "WithNoWinPrice" }) {
				this.filterChecks.Add(name, (CheckButton)builder.GetObject($"CheckButtonFilter{name}"));
				this.filterChecks[name].Active = false;
			}

			// bind treeview columns to watchlist instead of needing to manually sync its liststore
			this.itemTreeView = (TreeView)builder.GetObject("TreeViewItems");
			this.items = new ListStore(typeof(YahooAuctionsItem));
			var filteredItems = new TreeModelFilter(this.items, null);
			filteredItems.VisibleFunc = this.ItemFilter;

			this.itemTreeView.Model = filteredItems;
			TreeCellDataFunc[] funcs = {
				new TreeCellDataFunc(this.RenderColumnFavourite),
				new TreeCellDataFunc(this.RenderColumnName),
				new TreeCellDataFunc(this.RenderColumnPriceYen),
				new TreeCellDataFunc(this.RenderColumnPriceAUD),
				new TreeCellDataFunc(this.RenderColumnEnding)
			};

			for (int i = 0; i < this.itemTreeView.Columns.Length; i++) {
				var c = this.itemTreeView.Columns[i];
				c.SetCellDataFunc(c.Cells[0], funcs[i]);
			}

			this.RenderList();
			this.UpdateItems();
			GLib.Timeout.Add(1000, new GLib.TimeoutHandler(UpdateSelectionEndTime));
			GLib.Timeout.Add(10000, new GLib.TimeoutHandler(AutoUpdateItems));

			DeleteEvent += WindowShutdown;
		}

		private void WindowShutdown(object sender, DeleteEventArgs args) {
			SaveSettings();
			Application.Quit();
		}

		// general behaviour

		/// <summary>
		/// gets the path and iter for a given item id.
		/// </summary>
		/// <param name="id">the item id to find in the treeview</param>
		/// <returns>a tuple of (TreePath, TreeIter)</returns>
		private (TreePath path, TreeIter iter) GetRow(string id) {
			// TODO: surely there's a better way to do this
			TreeIter iter;
			this.itemTreeView.Model.GetIterFirst(out iter);
			var m = (TreeModelFilter)this.itemTreeView.Model;

			for (int i = 0; i < this.itemTreeView.Model.IterNChildren(); i++) {
				var x = (YahooAuctionsItem)this.itemTreeView.Model.GetValue(iter, 0);
				if (x.id == id) {
					return (m.ConvertPathToChildPath(m.GetPath(iter)), m.ConvertIterToChildIter(iter));
				}
				else {
					this.itemTreeView.Model.IterNext(ref iter);
				}
			}

			Console.WriteLine($"Couldn't find {id}!");
			return (null, iter);
		}

		/// <summary>
		/// saves the settings to userdata.json.
		/// </summary>
		private void SaveSettings() {
			string j = JsonSerializer.Serialize(this.settings, this.jsonOptions);
			string p = System.IO.Path.Combine(this.location, "userdata.json");
			Console.WriteLine(j);
			if (!Directory.Exists(this.location)) {
				Directory.CreateDirectory(this.location);
			}

			using (StreamWriter fs = File.CreateText(p)) {
				fs.Write(j);
			}

		}

		/// <summary>
		/// updates the item with the given id. this method blocks and is intended to be run from a task.
		/// </summary>
		/// <param name="id">the id of the item to update</param>
		private void UpdateThread(string id) {
			var item = this.settings.watchlist[id];
			// Console.WriteLine($"Updating {id}...");
			// set item.ready to false to show that it's still being updated
			// this changes a few behaviours, such as displaying the price as "..." instead of whatever's currently stored
			item.ready = false;

			Gtk.Application.Invoke(delegate {
				// TODO: find a way to not have to do this. i think we need to avoid actually modifying the items outside of the main thread :/
				var pathAndIter = this.GetRow(id);
				if (pathAndIter.path != null) {
					this.items.EmitRowChanged(pathAndIter.path, pathAndIter.iter);
				}
			});

			using (WebClient client = new WebClient()) {
				// TODO: download should have timeout
				item.Update(client.DownloadString(item.url));
				// Thread.Sleep(5000);
				// item.Update(File.ReadAllText("yahoo.html"));
			}

			Gtk.Application.Invoke(delegate {
				var pathAndIter = this.GetRow(id);
				if (pathAndIter.path != null) {
					this.items.EmitRowChanged(pathAndIter.path, pathAndIter.iter);
				}
				if (item == this.selectedItem) {
					// if the user has this item selected and it just became ready, enable the selection box and redraw the info
					this.selectionViewBox.Sensitive = true;
					this.UpdateSelectionView();
				}
			});

			item.ready = true;
			// Console.WriteLine($"{id} updated.");
		}

		/// <summary>
		/// recursively processes the update queue. this is a blocking function.
		/// </summary>
		private void ProcessUpdateQueue() {
			this.queueActive = true;
			this.UpdateItem(this.updateQueue.Dequeue());
			if (this.updateQueue.TryPeek(out string _)) {
				this.ProcessUpdateQueue();
			}
			else {
				this.queueActive = false;
			}
		}

		/// <summary>
		/// updates an item with the given id with a new task.
		/// </summary>
		/// <param name="id">the id of the task to update</param>
		/// <param name="renderListWhenDone">whether or not to call this.RenderList() after updating the item</param>
		private void UpdateItem(string id, bool renderListWhenDone = false) {
			var item = this.settings.watchlist[id];
			if (item.updatedRecently) {
				// the item has been updated recently, and force is not true
				return;
			}

			// don't start a new task if there are more than `tasklimit` tasks currently running
			// this makes sure we don't make 1000 simultaneous requests to yahoo auctions if there are 1000 items on the watchlist
			taskLimit.Wait();
			var t = Task.Factory.StartNew(() => {
				this.UpdateThread(id);
			}).ContinueWith(task => {
				taskLimit.Release();
				if (renderListWhenDone) {
					Gtk.Application.Invoke(delegate {
						this.RenderList();
					});
				}
			});
		}

		/// <summary>
		/// add every item in the watchlist to the update queue. if the update queue is already being processed (this.queueActive), this will do nothing.
		/// </summary>
		private void UpdateItems() {
			if (this.queueActive) {
				return;
			}

			this.selectionViewBox.Sensitive = false;
			foreach (var item in this.settings.watchlist) {
				if (!this.updateQueue.Contains(item.Key)) {
					// set everything to not ready first
					// ensures other actions don't attempt to display the items even if UpdateItem hasn't started yet
					item.Value.ready = false;
					this.updateQueue.Enqueue(item.Key);
				}
			}

			if (!this.updateQueue.TryPeek(out string _)) {
				// queue is empty
				return;
			}

			this.itemTreeView.QueueDraw();
			var t = Task.Factory.StartNew(() => {
				this.ProcessUpdateQueue();
			});

		}

		/// <summary>
		/// updates the selection view, displaying the id, name, etc. for the currently selected item.
		/// </summary>
		private void UpdateSelectionView() {
			// get the currently selected item
			var item = this.selectedItem;
			var infobox = (Box)this.builder.GetObject("SelectionInfoBox");

			if (item == null) {
				this.selectionViewBox.Sensitive = false;
				infobox.Visible = false;
				(this.builder.GetObject("LabelSelectedName") as Label).Text = "buypeeb";
				return;
			}

			this.selectionViewBox.Sensitive = item.ready;
			infobox.Visible = true;

			var info = new Dictionary<string, string> {
				{ "Name", item.name },
				{ "YahooName", item.originalName },
				{ "Price", item.priceJPY },
				{ "PriceAUD", item.priceAUD },
				{ "Ending", "Please wait..." },
				{ "Bids", $"{item.bids}" },
				{ "BuyItNow", item.winPrice == 0 ? "No" : $"{item.winPriceJPY} ({item.winPriceAUD})" },
				{ "AutoExtension", item.autoExtension ? "Yes" : "No" },
				{ "LastUpdated", $"Last updated: {(item.ready ? item.lastUpdated.ToString("MMM dd, HH:mm:ss") : "Right now!")}" }
			};

			foreach (var row in info) {
				(this.builder.GetObject($"LabelSelected{row.Key}") as Label).Text = row.Value;
			}
			this.UpdateSelectionEndTime();

			var noteBuffer = (TextBuffer)this.builder.GetObject("TextBufferSelectedNotes");
			noteBuffer.Clear();
			if (!String.IsNullOrWhiteSpace(item.notes)) {
				noteBuffer.Text = item.notes;
			}

			(this.builder.GetObject("ButtonSelectedFavourite") as ToggleButton).Active = item.favourite;

		}

		/// <summary>
		/// opens a URL in the user's browser.
		/// </summary>
		/// <param name="url">the url to open</param>
		private void OpenUrl(string url) {
			// https://github.com/dotnet/runtime/issues/17938
			if (Environment.OSVersion.Platform == PlatformID.Win32NT) {
				ProcessStartInfo psi = new ProcessStartInfo {
					FileName = url,
					UseShellExecute = true
				};
				Process.Start(psi);
			}
			else {
				// let's hope you have xdg-open installed
				Process.Start("xdg-open", url);
			}
		}

		/// <summary>
		/// a simple MessageDialog constructor.
		/// </summary>
		/// <param name="message">the MessageDialog's format</param>
		/// <param name="buttonsType">the MessageDialog's bt</param>
		/// <returns></returns>
		private MessageDialog MsgBox(string message, ButtonsType buttonsType = ButtonsType.OkCancel) {
			var md = new MessageDialog(
				parent_window: this,
				flags: DialogFlags.DestroyWithParent | DialogFlags.Modal,
				type: MessageType.Question,
				bt: buttonsType,
				format: message
			);
			md.KeepAbove = true;
			md.Resizable = false;
			md.FocusOnMap = true;
			md.Title = "Buypeeb";

			return md;
		}

		/// <summary>
		/// show a simple entry dialogue that allows the user to enter text and either cancel or submit it.
		/// </summary>
		/// <param name="title">the title of the entry dialogue</param>
		/// <param name="message">the prompt that should be presented to the user</param>
		/// <param name="prefill">a string to prefill the input box with</param>
		/// <returns></returns>
		private (Boolean accepted, string response) EntryDialogue(string title = "Buypeeb", string message = "Hi there!", string prefill = null) {
			Dialog ed = new Dialog(
				title: title,
				parent: this,
				flags: DialogFlags.DestroyWithParent | DialogFlags.Modal,
				/* button_data: */ "Cancel", ResponseType.Cancel, "OK", ResponseType.Ok
			);

			ed.DefaultResponse = ResponseType.Ok;
			ed.KeepAbove = true;

			Label edLabel = new Label(message);
			Entry edEntry = new Entry();
			if (!String.IsNullOrWhiteSpace(prefill)) {
				edEntry.Text = prefill;
			}
			edEntry.ActivatesDefault = true;

			ed.ContentArea.PackStart(edLabel, true, true, 2);
			edLabel.Show();
			ed.ContentArea.PackStart(edEntry, true, true, 10);
			edEntry.Show();

			ed.ContentArea.MarginBottom = 5;
			ed.ContentArea.MarginTop = 5;
			ed.ContentArea.MarginStart = 5;
			ed.ContentArea.MarginEnd = 5;
			ed.MarginBottom = 5;

			ResponseType accepted = (ResponseType)ed.Run();
			string response = edEntry.Text;
			ed.Dispose();
			return (accepted == ResponseType.Ok, response);
		}

		/// <summary>
		/// gets the sort type selected by the user - "NameDescending", "EndingAscending", etc.
		/// </summary>
		/// <returns>the id of the radiobutton without the "Sort" prefix</returns>
		private string GetSortType() {
			foreach (var name in new List<string> { "NameDescending", "NameAscending", "PriceDescending", "PriceAscending", "EndingDescending", "EndingAscending" }) {
				var radio = (RadioMenuItem)this.builder.GetObject($"Sort{name}");
				if (radio.Active) {
					return name;
				}
			}

			return "NameAscending";
		}

		/// <summary>
		/// clears the treeview's liststore and adds everything in the watchlist to it, obeying sort order. tries to reselect the item that the user had selected, if possible.
		/// </summary>
		private void RenderList() {
			string id = null;
			if (this.selectedItem != null) {
				id = this.selectedItem.id;
			}

			this.items.Clear();
			var values = this.settings.watchlist.Values;
			IOrderedEnumerable<YahooAuctionsItem> sorted;
			var type = this.GetSortType();
			if (type == "NameDescending") {
				sorted = values.OrderByDescending(item => item.name);
			}
			else if (type == "NameAscending") {
				sorted = values.OrderBy(item => item.name);
			}
			else if (type == "PriceDescending") {
				sorted = values.OrderByDescending(item => item.price);
			}
			else if (type == "PriceAscending") {
				sorted = values.OrderBy(item => item.price);
			}
			else if (type == "EndingDescending") {
				sorted = values.OrderByDescending(item => item.endDate);
			}
			else {
				sorted = values.OrderBy(item => item.endDate);
			}

			if (settings.showFavouritesAtTopOfList) {
				foreach (var item in sorted.Where(item => item.favourite)) {
					items.AppendValues(item);
				}

				foreach (var item in sorted.Where(item => !item.favourite)) {
					items.AppendValues(item);
				}
			}
			else {
				foreach (var item in sorted) {
					items.AppendValues(item);
				}
			}

			(this.itemTreeView.Model as TreeModelFilter).Refilter();

			if (id != null) {
				// attempt to reselect the item we were just looking at
				var pathAndIter = this.GetRow(id);
				if (pathAndIter.path != null) {
					this.itemTreeView.Selection.SelectPath(pathAndIter.path);
				}
			}
		}

		// event handlers

		private void ButtonAddClicked(object sender, EventArgs a) {
			// Console.WriteLine("ButtonAddClicked");
			AddItemDialogue aid = new AddItemDialogue();
			aid.Title = "Buypeeb";
			ResponseType accepted = (ResponseType)aid.Run();
			string url = aid.GetURL();
			string name = aid.GetName();
			aid.Dispose();

			// vry simpl url validation for simpol creachers
			// TODO: better. do better.
			Regex rx = new Regex(@"^http.+yahoo.+");
			if (rx.IsMatch(url)) {
				this.UpdateItem(this.settings.Watch(url, name).id, true);
				this.RenderList();
			}
			else {
				var md = this.MsgBox($"\"{url}\" is not a valid Buyee or Yahoo! Auctions Japan URL.", ButtonsType.Ok);
				md.Run();
				md.Dispose();
			}
		}

		private void ButtonUpdateAllClicked(object sender, EventArgs a) {
			this.UpdateItems();
		}

		private void ButtonClearEndedClicked(object sender, EventArgs a) {
			var md = this.MsgBox("Are you sure you want to remove all ended auctions from the list?");
			var r = (ResponseType)md.Run();
			md.Dispose();
			if (r != ResponseType.Ok) {
				return;
			}

			var removeMe = new List<string>();
			foreach (var item in this.settings.watchlist) {
				if (!item.Value.available) {
					removeMe.Add(item.Key);
				}
			}

			foreach (var id in removeMe) {
				this.settings.watchlist.Remove(id);
			}

			this.RenderList();
		}

		private void ButtonClearAllClicked(object sender, EventArgs a) {
			var md = this.MsgBox("Are you sure you want to clear ALL items?");
			if (md.Run() == (int)ResponseType.Ok) {
				this.settings.watchlist.Clear();
				this.RenderList();
			}
			md.Dispose();
		}

		private void ButtonOpenClicked(object sender, EventArgs a) {
			var od = new FileChooserDialog(
				title: "Open userdata.json",
				parent: this,
				action: FileChooserAction.Open,
				"Cancel", ResponseType.Cancel, "Open", ResponseType.Accept
			);

			var odf = new FileFilter();
			odf.Name = "JSON files";
			odf.AddMimeType("application/json");
			odf.AddPattern("*.json");
			od.AddFilter(odf);

			if (od.Run() == (int)ResponseType.Accept) {
				try {
					string j = File.ReadAllText(od.Filename);
					this.settings = JsonSerializer.Deserialize<Settings>(j);
					this.RenderList();
					this.UpdateItems();
				}
				catch (Exception e) {
					Console.WriteLine(e);
					var md = MsgBox($"Failed to load {od.Filename}!\n{e.Message}", ButtonsType.Ok);
					md.Run();
					md.Dispose();
				}
			}
			od.Dispose();
		}

		private void ButtonSaveClicked(object sender, EventArgs a) {
			this.SaveSettings();
		}

		private void ButtonSaveAsClicked(object sender, EventArgs a) {
			var sd = new FileChooserDialog(
				title: "Save userdata.json",
				parent: this,
				action: FileChooserAction.Save,
				"Cancel", ResponseType.Cancel, "Save", ResponseType.Accept
			);
			sd.CurrentName = "userdata.json";

			var sdf = new FileFilter();
			sdf.Name = "JSON files";
			sdf.AddMimeType("application/json");
			sdf.AddPattern("*.json");
			sd.AddFilter(sdf);

			if (sd.Run() == (int)ResponseType.Accept) {
				try {
					if (!File.Exists(sd.Filename)) {
						using (StreamWriter fs = File.CreateText(sd.Filename)) {
							fs.Write(JsonSerializer.Serialize(this.settings, jsonOptions));
						}
					}
				}
				catch (Exception e) {
					Console.WriteLine(e);
					var md = MsgBox($"Failed to write {sd.Filename}!\n{e.Message}.", ButtonsType.Ok);
					md.Run();
					md.Dispose();
				}
			}

			sd.Dispose();
		}

		private void ButtonExportClicked(object sender, EventArgs a) {
			var readyQuery = from item in this.settings.watchlist.Values.ToList() where !item.ready select item;

			if (readyQuery.Count() != 0) {
				var md = MsgBox("Please wait for all items to update before exporting a CSV.", ButtonsType.Ok);
				md.Run();
				md.Dispose();
				return;
			}

			var sd = new FileChooserDialog(
				title: "Export watchlist as CSV",
				parent: this,
				action: FileChooserAction.Save,
				"Cancel", ResponseType.Cancel, "Save", ResponseType.Accept
			);
			sd.CurrentName = "buypeeb.csv";

			var sdf = new FileFilter();
			sdf.Name = "CSV files";
			sdf.AddMimeType("text/csv");
			sdf.AddPattern("*.csv");
			sd.AddFilter(sdf);

			if (sd.Run() == (int)ResponseType.Accept) {
				try {
					using (var writer = new StreamWriter(sd.Filename))
					using (var csv = new CsvWriter(writer, System.Globalization.CultureInfo.InvariantCulture)) {

						csv.WriteRecords(this.settings.watchlist);
					}
				}
				catch (Exception e) {
					Console.WriteLine(e);
					var md = MsgBox($"Failed to write {sd.Filename}!\n{e.Message}.", ButtonsType.Ok);
					md.Run();
					md.Dispose();
				}
			}

			sd.Dispose();
		}

		private void ButtonHelpClicked(object sender, EventArgs args) {
			Console.WriteLine("Watchlist:");
			foreach (var item in this.settings.watchlist) {
				Console.WriteLine(item);
			}
			Console.WriteLine("---\nFilter results:");
			foreach (var item in this.filterQuery) {
				Console.WriteLine(item);
			}
			Console.WriteLine("---\nListstore contents:");
			foreach (object[] item in this.items) {
				Console.WriteLine(item[0]);
			}
		}

		private void ButtonQuitClicked(object sender, EventArgs a) {
			var md = this.MsgBox("Are you sure you want to quit?");

			ResponseType response = (ResponseType)md.Run();
			md.Dispose();
			if (response == ResponseType.Ok) {
				this.SaveSettings();
				Application.Quit();
			}
		}

		private void ButtonSettingsClicked(object sender, EventArgs args) {
			var win = new SettingsWindow(this.settings);
			Application.AddWindow(win);
			win.DeleteEvent += this.WindowSettingsClosed;
			win.Show();
		}

		private void TreeViewItemsSelectionChanged(object sender, EventArgs a) {
			this.UpdateSelectionView();
		}

		private void ButtonViewBuyeeClicked(object sender, EventArgs a) {
			this.OpenUrl(this.selectedItem.buyeeUrl);
		}

		private void ButtonViewYahooClicked(object sender, EventArgs a) {
			this.OpenUrl(this.selectedItem.url);
		}

		private void ButtonSelectedRemoveClicked(object sender, EventArgs a) {
			var item = this.selectedItem;

			var md = this.MsgBox($"Are you sure you want to remove the item \"{item.name}\"?"); // TODO: this looks bad being all on one line

			ResponseType response = (ResponseType)md.Run();
			md.Dispose();
			if (response == ResponseType.Ok) {
				this.settings.watchlist.Remove(item.id);
				this.RenderList();
			}
		}

		private void ButtonSelectedRenameClicked(object sender, EventArgs a) {
			var item = this.selectedItem;
			(bool accepted, string response) = this.EntryDialogue("Rename item", $"Enter a new name for the item \"{item.name}\".", item.name);
			if (accepted) {
				item.name = response;
				this.UpdateSelectionView();
			}
		}

		private void ButtonSelectedUpdateClicked(object sender, EventArgs args) {
			this.selectionViewBox.Sensitive = false;
			if (this.updateQueue.Contains(this.selectedItem.id)) {
				// the item is already waiting to be updated
				return;
			}
			this.UpdateItem(this.selectedItem.id);
		}

		private void ButtonSelectedFavouriteToggled(object sender, EventArgs args) {
			ToggleButton s = (ToggleButton)sender;
			this.selectedItem.favourite = s.Active;

			if (this.settings.showFavouritesAtTopOfList) {
				var id = this.selectedItem.id;
				this.RenderList();
			}
			else {
				// i don't know why this is necessary
				var pathAndIter = this.GetRow(this.selectedItem.id);
				if (pathAndIter.path != null) {
					this.items.EmitRowChanged(pathAndIter.path, pathAndIter.iter);
				}
			}
		}

		private void ButtonSelectedNotesClearClicked(object sender, EventArgs args) {
			var item = this.selectedItem;
			var md = this.MsgBox($"Are you sure you want to clear the notes for \"{item.name}\"?");
			if (md.Run() == (int)ResponseType.Ok) {
				var noteBuffer = (TextBuffer)this.builder.GetObject("TextBufferSelectedNotes");
				noteBuffer.Clear();
				this.selectedItem.notes = null;
			}
			md.Dispose();
		}

		private void TextViewSelectedNotesFocusOut(object sender, FocusOutEventArgs args) {
			// the "save" button does nothing, however, when you click the save button, you transfer focus to it, firing this event!
			// how very sneaky
			var noteBuffer = (TextBuffer)this.builder.GetObject("TextBufferSelectedNotes");
			if (this.selectedItem != null) {
				this.selectedItem.notes = String.IsNullOrWhiteSpace(noteBuffer.Text) ? null : noteBuffer.Text;
			}
		}

		private void SortMenuClosed(object sender, EventArgs args) {
			this.RenderList();
		}

		private void WindowSettingsClosed(object sender, EventArgs args) {
			this.RenderList();
		}

		// timers

		/// <summary>
		/// updates the end time displayed in the selection box. runs every second to update the countdown timer.
		/// </summary>
		/// <returns>true</returns>
		private bool UpdateSelectionEndTime() {
			if (!this.selectionViewBox.IsSensitive) {
				return true;
			}

			var item = this.selectedItem;
			if (!item.ready) {
				return true;
			}

			string ending = "";
			if (item.available) {
				var now = DateTime.Now;
				var end = item.endDate.ToLocalTime();
				var span = end.Subtract(now);

				if (span.Days > 0) {
					ending += span.ToString("dd' days, '"); // will format twelve days as "12 days, "
				}
				// timespan objects don't contain definitions for the time or date separators, so the colons need to be escaped
				// `HH` doesn't exist, but `hh` behaves identically
				// see https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-timespan-format-strings
				ending += span.ToString(@"hh\:mm\:ss");
			}
			else {
				ending = "Auction has ended";
			}

			this.endingLabel.Text = ending;
			return true;
		}

		/// <summary>
		/// updates all items that need updating. runs every ten seconds.
		/// </summary>
		/// <returns>true</returns>
		private bool AutoUpdateItems() {
			if (this.queueActive) {
				// don't autoupdate if the queue is active
				return true;
			}

			foreach (var item in this.outdatedItemQuery) {
				updateQueue.Enqueue(item.id);
			}

			if (updateQueue.TryPeek(out string _)) {
				// there's at least one item in the queue
				this.ProcessUpdateQueue();
			}

			return true;
		}

		// column renderers

		private void RenderColumnFavourite(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
			(cell as Gtk.CellRendererText).Text = item.favourite ? "♥" : "";
		}

		private void RenderColumnName(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
			(cell as Gtk.CellRendererText).Text = item.name ?? "Loading...";
		}

		private void RenderColumnPriceYen(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
			(cell as Gtk.CellRendererText).Text = item.ready ? item.priceJPY : "...";
		}

		private void RenderColumnPriceAUD(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
			(cell as Gtk.CellRendererText).Text = item.ready ? item.priceAUD : "...";
		}

		private void RenderColumnEnding(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
			string ending = "";
			if (item.ready) {
				if (!item.available) {
					ending = "Ended";
				}
				else {
					var now = DateTime.Now;
					var end = item.endDate.ToLocalTime();
					// TODO: should we show the year if the auction ends next year? 0uo
					if (end.DayOfYear != now.DayOfYear) {
						// the auction isn't ending today, so we should show the day it's ending on for clarity
						ending += end.ToString("MMM d ");
					}
					ending += end.ToString("HH:mm");
					if (this.settings.showSecondsInListView) {
						// add the seconds on to the end
						ending += end.ToString(":ss");
					}
				}
			}
			(cell as Gtk.CellRendererText).Text = item.ready ? ending : "...";
		}

		// tree filter

		private bool ItemFilter(ITreeModel model, TreeIter iter) {
			var item = (YahooAuctionsItem)model.GetValue(iter, 0);
			if (item == null) {
				return true;
			}
			if (item.price == 0) {
				// the item has only just been added, so we can't compare it against the filters, since it's missing most of its data
				return true;
			}

			bool Filtered(string name) {
				return this.filterChecks[name].Active;
			}

			// first, check to see if any filters are set that would exclude everything, such as hiding both active and ended auctions
			// if so, there's no need to run the more expensive linq query
			if (
				(Filtered("Favourites") && Filtered("NonFavourites")) ||
				(Filtered("Active") && Filtered("Ended")) ||
				(Filtered("EndingToday") && Filtered("EndingAfterToday")) ||
				(Filtered("WithWinPrice") && Filtered("WithNoWinPrice"))
			) {
				return false;
			}

			return this.filterQuery.Contains(item);
		}

		private void RunFilter(object sender, EventArgs a) {
			(this.itemTreeView.Model as TreeModelFilter).Refilter();
		}
	}
}