module( "undo", package.seeall )

-- undo.Create("Wheel")
-- undo.AddEntity( axis )
-- undo.AddEntity( constraint )
-- undo.SetPlayer( self.Owner )
-- undo.Finish()

if ( CLIENT ) then

	local ClientUndos = {}
	local bIsDirty = true

	--[[---------------------------------------------------------
		GetTable
		Returns the undo table for whatever reason
	-----------------------------------------------------------]]
	function GetTable()
		return ClientUndos
	end


	--[[---------------------------------------------------------
		UpdateUI
		Actually updates the UI. Removes old controls and
		re-creates them using the new data.
	-----------------------------------------------------------]]
	local function UpdateUI()

		local Panel = controlpanel.Get( "Undo" )
		if ( !IsValid( Panel ) ) then return end

		Panel:ClearControls()
		Panel:AddControl( "Header", { Description = "#spawnmenu.utilities.undo.help" } )

		local ComboBox = Panel:ListBox()
		ComboBox:SetTall( 500 )

		local Limit = 100
		local Count = 0
		for k, v in ipairs( ClientUndos ) do

			local Item = ComboBox:AddItem( tostring( v.Name ) )
			Item.DoClick = function() RunConsoleCommand( "gmod_undonum", tostring( v.Key ) ) end

			Count = Count + 1
			if ( Count > Limit ) then break end

		end

	end

	--[[---------------------------------------------------------
		AddUndo
		Called from server. Adds a new undo to our UI
	-----------------------------------------------------------]]
	local function AddUndo()

		local k	= net.ReadInt( 16 )
		local v	= net.ReadString()

		table.insert( ClientUndos, 1, { Key = k, Name = v } )

		MakeUIDirty()

	end
	net.Receive( "Undo_AddUndo", AddUndo )


	--[[---------------------------------------------------------
		Undone
		Called from server. Notifies us that one of our undos
		has been undone or made redundant. We act by updating
		out data (We wait until the UI is viewed until updating)
	-----------------------------------------------------------]]
	local function Undone()

		local key = net.ReadInt( 16 )

		local NewUndo = {}
		local i = 1
		for k, v in ipairs( ClientUndos ) do

			if ( v.Key != key ) then
				NewUndo [ i ] = v
				i = i + 1
			end
		end

		ClientUndos = NewUndo
		NewUndo = nil

		MakeUIDirty()

	end
	net.Receive( "Undo_Undone", Undone )

	--[[---------------------------------------------------------
		MakeUIDirty
		Makes the UI dirty - it will re-create the controls
		the next time it is viewed. We also take this opportun
	-----------------------------------------------------------]]
	function MakeUIDirty()

		bIsDirty = true

	end

	--[[---------------------------------------------------------
		CPanelPaint
		Called when the inner panel of the undo CPanel is painted
		We hook onto this to determine when the panel is viewed.
		When it's viewed we update the UI if it's marked as dirty
	-----------------------------------------------------------]]
	local function CPanelUpdate( panel )

		-- This is kind of a shitty way of doing it - but we only want
		-- to update the UI when it's visible.
		if ( bIsDirty ) then

			-- Doing this in a timer so it calls it in a sensible place
			-- Calling in the paint function could cause all kinds of problems
			-- It's a hack but hey welcome to GMod!
			timer.Simple( 0, UpdateUI )
			bIsDirty = false

		end

	end

	--[[---------------------------------------------------------
		SetupUI
		Adds a hook (CPanelPaint) to the control panel paint
		function so we can determine when it is being drawn.
	-----------------------------------------------------------]]
	function SetupUI()

		local UndoPanel = controlpanel.Get( "Undo" )
		if ( !IsValid( UndoPanel ) ) then return end

		-- Panels only think when they're visible
		UndoPanel.Think = CPanelUpdate

	end

	hook.Add( "PostReloadToolsMenu", "BuildUndoUI", SetupUI )

end


if ( !SERVER ) then return end

local PlayerUndo = {}
-- PlayerUndo
--	- Player UniqueID
--		- Undo Table
--			- Name
--			- Entities (table of ents)
--			- Owner (player)

local Current_Undo = nil

util.AddNetworkString( "Undo_Undone" )
util.AddNetworkString( "Undo_AddUndo" )

--[[---------------------------------------------------------
	GetTable
	Returns the undo table for whatever reason
-----------------------------------------------------------]]
function GetTable()
	return PlayerUndo
end

--[[---------------------------------------------------------
	GetTable
	Save/Restore the undo tavles
-----------------------------------------------------------]]
local function Save( save )

	saverestore.WriteTable( PlayerUndo, save )

end

local function Restore( restore )

	PlayerUndo = saverestore.ReadTable( restore )

end

saverestore.AddSaveHook( "UndoTable", Save )
saverestore.AddRestoreHook( "UndoTable", Restore )

--[[---------------------------------------------------------
	Start a new undo
-----------------------------------------------------------]]
function Create( text )

	Current_Undo = {}
	Current_Undo.Name			= text
	Current_Undo.Entities		= {}
	Current_Undo.Owner			= nil
	Current_Undo.Functions		= {}

end

--[[---------------------------------------------------------
	Adds an entity to this undo (The entity is removed on undo)
-----------------------------------------------------------]]
function SetCustomUndoText( CustomUndoText )

	if ( !Current_Undo ) then return end

	Current_Undo.CustomUndoText = CustomUndoText

end

--[[---------------------------------------------------------
	Adds an entity to this undo (The entity is removed on undo)
-----------------------------------------------------------]]
function AddEntity( ent )

	if ( !Current_Undo ) then return end
	if ( !IsValid( ent ) ) then return end

	table.insert( Current_Undo.Entities, ent )

end

--[[---------------------------------------------------------
	Add a function to call to this undo
-----------------------------------------------------------]]
function AddFunction( func, ... )

	if ( !Current_Undo ) then return end
	if ( !func ) then return end

	table.insert( Current_Undo.Functions, { func, {...} } )

end

--[[---------------------------------------------------------
	Replace Entity
-----------------------------------------------------------]]
function ReplaceEntity( from, to )

	local ActionTaken = false

	for _, PlayerTable in pairs( PlayerUndo ) do
		for _, UndoTable in pairs( PlayerTable ) do
			if ( UndoTable.Entities ) then

				for key, ent in pairs( UndoTable.Entities ) do
					if ( ent == from ) then
						UndoTable.Entities[ key ] = to
						ActionTaken = true
					end
				end

			end
		end
	end

	return ActionTaken

end


--[[---------------------------------------------------------
	Sets who's undo this is
-----------------------------------------------------------]]
function SetPlayer( ply )

	if ( !Current_Undo ) then return end
	if ( !IsValid( ply ) ) then return end

	Current_Undo.Owner = ply

end

--[[---------------------------------------------------------
	SendUndoneMessage
	Sends a message to notify the client that one of their
	undos has been removed. They can then update their GUI.
-----------------------------------------------------------]]
local function SendUndoneMessage( ent, id, ply )

	if ( !IsValid( ply ) ) then return end

	-- For further optimization we could queue up the ids and send them
	-- in one batch every 0.5 seconds or something along those lines.

	net.Start( "Undo_Undone" )
		net.WriteInt( id, 16 )
	net.Send( ply )

end

--[[---------------------------------------------------------
	Finish
-----------------------------------------------------------]]
function Finish( NiceText )

	if ( !Current_Undo ) then return end

	-- Do not add undos that have no owner or anything to undo
	if ( !IsValid( Current_Undo.Owner ) || ( table.IsEmpty( Current_Undo.Entities ) && table.IsEmpty( Current_Undo.Functions ) ) ) then 
		Current_Undo = nil
		return
	end

	local index = Current_Undo.Owner:UniqueID()
	PlayerUndo[ index ] = PlayerUndo[ index ] or {}

	local id = table.insert( PlayerUndo[ index ], Current_Undo )

	NiceText = NiceText or Current_Undo.Name

	net.Start( "Undo_AddUndo" )
		net.WriteInt( id, 16 )
		net.WriteString( NiceText )
	net.Send( Current_Undo.Owner )

	-- Have one of the entities in the undo tell us when it gets undone.
	if ( IsValid( Current_Undo.Entities[ 1 ] ) ) then

		local ent = Current_Undo.Entities[ 1 ]
		ent:CallOnRemove( "undo" .. id, SendUndoneMessage, id, Current_Undo.Owner )

	end

	Current_Undo = nil

end

--[[---------------------------------------------------------
	Undos an undo
-----------------------------------------------------------]]
function Do_Undo( undo )

	if ( !undo ) then return false end

	local count = 0

	-- Call each function
	if ( undo.Functions ) then
		for index, func in pairs( undo.Functions ) do

			func[ 1 ]( undo, unpack( func[ 2 ] ) )
			count = count + 1

		end
	end

	-- Remove each entity in this undo
	if ( undo.Entities ) then
		for index, entity in pairs( undo.Entities ) do

			if ( IsValid( entity ) ) then
				entity:Remove()
				count = count + 1
			end

		end
	end

	if ( count > 0 ) then
		if ( undo.CustomUndoText ) then
			undo.Owner:SendLua( 'hook.Run("OnUndo","' .. undo.Name .. '","' .. undo.CustomUndoText .. '")' )
		else
			undo.Owner:SendLua( 'hook.Run("OnUndo","' .. undo.Name .. '")' )
		end
	end

	return count

end

--[[---------------------------------------------------------
	Console command
-----------------------------------------------------------]]
local function CC_UndoLast( pl, command, args )

	local index = pl:UniqueID()
	PlayerUndo[ index ] = PlayerUndo[ index ] or {}

	local last = nil
	local lastk = nil

	for k, v in pairs( PlayerUndo[ index ] ) do

		lastk = k
		last = v

	end

	-- No undos
	if ( !last ) then return end

	-- This is quite messy, but if the player rejoined the server
	-- 'Owner' might no longer be a valid entity. So replace the Owner
	-- with the player that is doing the undoing
	last.Owner = pl

	local count = Do_Undo( last )

	net.Start( "Undo_Undone" )
		net.WriteInt( lastk, 16 )
	net.Send( pl )

	PlayerUndo[ index ][ lastk ] = nil

	-- If our last undo object is already deleted then compact
	-- the undos until we hit one that does something
	if ( count == 0 ) then
		CC_UndoLast( pl )
	end

end

--[[---------------------------------------------------------
	Console command
-----------------------------------------------------------]]
local function CC_UndoNum( ply, command, args )

	if ( !args[ 1 ] ) then return end

	local index = ply:UniqueID()
	PlayerUndo[ index ] = PlayerUndo[ index ] or {}

	local UndoNum = tonumber( args[ 1 ] )
	if ( !PlayerUndo[ index ][ UndoNum ] ) then return end

	-- Undo!
	Do_Undo( PlayerUndo[ index ][ UndoNum ] )

	-- Notify the client UI that the undo happened
	-- This is normally called by the deleted entity via SendUndoneMessage
	-- But in cases where the undo only has functions that will not do
	net.Start( "Undo_Undone" )
		net.WriteInt( UndoNum, 16 )
	net.Send( ply )

	-- Don't delete the entry completely so nothing new takes its place and ruin CC_UndoLast's logic (expecting newest entry be at highest index)
	PlayerUndo[ index ][ UndoNum ] = {}

end

concommand.Add( "undo",			CC_UndoLast, nil, "", { FCVAR_DONTRECORD } )
concommand.Add( "gmod_undo",	CC_UndoLast, nil, "", { FCVAR_DONTRECORD } )
concommand.Add( "gmod_undonum",	CC_UndoNum, nil, "", { FCVAR_DONTRECORD } )