using System;
using System.Collections.Generic;
using System.Linq;
using OpenRa.GameRules;
using OpenRa.Graphics;
using OpenRa.Orders;
using OpenRa.Traits;
using OpenRa.FileFormats;

namespace OpenRa
{
	public class Controller : IHandleInput
	{
		public IOrderGenerator orderGenerator;
		public Selection selection = new Selection();

		readonly Func<Modifiers> GetModifierKeys;

		public Controller(Func<Modifiers> getModifierKeys)
		{
			GetModifierKeys = getModifierKeys;
			CancelInputMode();
		}

		public void CancelInputMode() { orderGenerator = new UnitOrderGenerator(); }

		public bool ToggleInputMode<T>() where T : IOrderGenerator, new()
		{
			if (orderGenerator is T)
			{
				CancelInputMode();
				return false;
			}
			else
			{
				orderGenerator = new T();
				return true;
			}
		}

		void ApplyOrders(World world, float2 xy, MouseInput mi)
		{
			if (orderGenerator == null) return;

			var orders = orderGenerator.Order(world, xy.ToInt2(), mi).ToArray();
			Game.orderManager.IssueOrders( orders );

			var voicedActor = orders.Select(o => o.Subject)
				.FirstOrDefault(a => a.Owner == world.LocalPlayer && a.traits.Contains<Unit>());

			var isMove = orders.Any(o => o.OrderString == "Move");
			var isAttack = orders.Any( o => o.OrderString == "Attack" );

			if (voicedActor != null)
			{
				Sound.PlayVoice(isAttack ? "Attack" : "Move", voicedActor);

				if (isMove)
					world.Add(new Effects.MoveFlash(world, Game.CellSize * xy));
			}
		}

		float2 dragStart, dragEnd;
		public bool HandleInput(World world, MouseInput mi)
		{
			var xy = Game.viewport.ViewToWorld(mi);

			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Down)
			{
				if (!(orderGenerator is PlaceBuildingOrderGenerator))
					dragStart = dragEnd = xy;
				ApplyOrders(world, xy, mi);
			}

			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Move)
				dragEnd = xy;

			if (mi.Button == MouseButton.Left && mi.Event == MouseInputEvent.Up)
			{
				if (orderGenerator is UnitOrderGenerator)
				{
					var newSelection = world.SelectActorsInBox(Game.CellSize * dragStart, Game.CellSize * xy);
					selection.Combine(world, newSelection, mi.Modifiers.HasModifier(Modifiers.Shift), dragStart == xy);
				}

				dragStart = dragEnd = xy;
			}

			if (mi.Button == MouseButton.None && mi.Event == MouseInputEvent.Move)
				dragStart = dragEnd = xy;

			if (mi.Button == MouseButton.Right && mi.Event == MouseInputEvent.Down)
				ApplyOrders(world, xy, mi);

			return true;
		}

		public Pair<float2, float2>? SelectionBox
		{
			get
			{
				if (dragStart == dragEnd) return null;
				return Pair.New(Game.CellSize * dragStart, Game.CellSize * dragEnd);
			}
		}

		public float2 MousePosition { get { return dragEnd; } }

		public string ChooseCursor( World world )
		{
			int sync = world.SyncHash();

			try
			{
				var mi = new MouseInput
				{
					Location = ( Game.CellSize * MousePosition - Game.viewport.Location ).ToInt2(),
					Button = MouseButton.Right,
					Modifiers = GetModifierKeys(),
				};

				return orderGenerator.GetCursor( world, MousePosition.ToInt2(), mi );
			}
			finally
			{
				if( sync != world.SyncHash() )
					throw new InvalidOperationException( "Desync in Controller.ChooseCursor" );
			}
		}
	}
}