using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Windows;
using dnlib.DotNet.Emit;
using dnSpy.Contracts.App;
using dnSpy.Contracts.Documents.TreeView;
using dnSpy.Contracts.Menus;
using dnSpy.Contracts.TreeView;

// Adds a couple of commands to the file treeview context menu.
// Since there are several commands using the same state, MenuItemBase<TContext> is used
// as the base class so the context is created once and shared by all commands.

namespace Example1.Extension {
	sealed class TVContext {
		public bool SomeValue { get; }
		public DocumentTreeNodeData[] Nodes { get; }

		public TVContext(bool someValue, IEnumerable<DocumentTreeNodeData> nodes) {
			SomeValue = someValue;
			Nodes = nodes.ToArray();
		}
	}

	abstract class TVCtxMenuCommand : MenuItemBase<TVContext> {
		protected sealed override object CachedContextKey => ContextKey;
		static readonly object ContextKey = new object();

		protected sealed override TVContext? CreateContext(IMenuItemContext context) {
			// Make sure it's the file treeview
			if (context.CreatorObject.Guid != new Guid(MenuConstants.GUIDOBJ_DOCUMENTS_TREEVIEW_GUID))
				return null;

			// Extract the data needed by the context
			var nodes = context.Find<TreeNodeData[]>();
			if (nodes is null)
				return null;
			var newNodes = nodes.OfType<DocumentTreeNodeData>();

			bool someValue = true;
			return new TVContext(someValue, newNodes);
		}
	}

	[ExportMenuItem(Header = "Command #1", Group = Constants.GROUP_TREEVIEW, Order = 0)]
	sealed class TVCommand1 : TVCtxMenuCommand {
		public override void Execute(TVContext context) => MsgBox.Instance.Show("Command #1");
		public override bool IsEnabled(TVContext context) => context.Nodes.Length > 1;
	}

	[ExportMenuItem(Header = "Command #2", Group = Constants.GROUP_TREEVIEW, Order = 10)]
	sealed class TVCommand2 : TVCtxMenuCommand {
		public override void Execute(TVContext context) => MsgBox.Instance.Show("Command #2");
		public override bool IsVisible(TVContext context) => context.Nodes.Length > 0;
	}

	[ExportMenuItem(Header = "Command #3", Group = Constants.GROUP_TREEVIEW, Order = 20)]
	sealed class TVCommand3 : TVCtxMenuCommand {
		public override void Execute(TVContext context) {
			int secretNum = new Random().Next() % 10;
			MsgBox.Instance.Ask<int?>("Number", null, "Guess a number", null, s => {
				if (string.IsNullOrWhiteSpace(s))
					return "Enter a number";
				if (!int.TryParse(s, out int num))
					return "Not an integer";
				if (num == 42)
					return "Nope!";
				if (num != secretNum)
					return "WRONG!!!";
				return string.Empty;
			});
		}
	}

	[ExportMenuItem(Header = "Command #4", Group = Constants.GROUP_TREEVIEW, Order = 30)]
	sealed class TVCommand4 : TVCtxMenuCommand {
		public override void Execute(TVContext context) => MsgBox.Instance.Show("Command #4");
		public override bool IsEnabled(TVContext context) => context.Nodes.Length == 1 && context.Nodes[0] is ModuleDocumentNode;
	}

	[ExportMenuItem(Group = Constants.GROUP_TREEVIEW, Order = 40)]
	sealed class TVCommand5 : TVCtxMenuCommand {
		public override void Execute(TVContext context) {
			var node = GetTokenNode(context);
			if (node is not null) {
				try {
					Clipboard.SetText($"{node.Reference!.MDToken.Raw:X8}");
				}
				catch (ExternalException) { }
			}
		}

		IMDTokenNode? GetTokenNode(TVContext context) {
			if (context.Nodes.Length == 0)
				return null;
			return context.Nodes[0] as IMDTokenNode;
		}

		public override string? GetHeader(TVContext context) {
			var node = GetTokenNode(context);
			if (node is null)
				return string.Empty;
			return $"Copy token {node.Reference!.MDToken.Raw:X8}";
		}

		public override bool IsVisible(TVContext context) => GetTokenNode(context) is not null;
	}

	[ExportMenuItem(Header = "Copy Second Instruction", Group = Constants.GROUP_TREEVIEW, Order = 50)]
	sealed class TVCommand6 : TVCtxMenuCommand {
		public override void Execute(TVContext context) {
			var instr = GetSecondInstruction(context);
			if (instr is not null) {
				try {
					Clipboard.SetText($"Second instruction: {instr}");
				}
				catch (ExternalException) { }
			}
		}

		Instruction? GetSecondInstruction(TVContext context) {
			if (context.Nodes.Length == 0)
				return null;
			var methNode = context.Nodes[0] as MethodNode;
			if (methNode is null)
				return null;
			var body = methNode.MethodDef.Body;
			if (body is null || body.Instructions.Count < 2)
				return null;
			return body.Instructions[1];
		}

		public override bool IsEnabled(TVContext context) => GetSecondInstruction(context) is not null;
	}
}