Multitasker v1.0 PR1

local oldevent = os.pullEventRaw
local x,y = term.getSize()
tabbing = false;
isMultitasking = false
screenMemory = {}
multiMemory = {
	"CraftOS vM.1",
}

local cPrint = function(text)
	local x2,y2 = term.getCursorPos()
	term.setCursorPos(math.ceil((x / 2) - (text:len() / 2)), y2)

	print(text)
end

function mRead( _sReplaceChar, _tHistory )
	term.setCursorBlink( true )

    local sLine = ""
	local nHistoryPos = nil
	local nPos = 0
    if _sReplaceChar then
		_sReplaceChar = string.sub( _sReplaceChar, 1, 1 )
	end

	local w, h = term.getSize()
	local sx, sy = term.getCursorPos()
	local function redraw()
		local nScroll = 0
		if sx + nPos >= w then
			nScroll = (sx + nPos) - w
		end

		term.setCursorPos( sx, sy )
		mWrite( "> " ..string.rep(" ", 14) )
		term.setCursorPos( sx, sy )
		if _sReplaceChar then
			mWrite( "> " ..string.rep(_sReplaceChar, string.len(sLine) - nScroll) )
		else
			mWrite( "> " ..string.sub( sLine, nScroll + 1 ) )
		end
		term.setCursorPos( sx + nPos - nScroll, sy )
	end

	while true do
		local sEvent, param = os.pullEvent()
		if sEvent == "char" then
			if nPos < 14 then
				sLine = string.sub( sLine, 1, nPos ) .. param .. string.sub( sLine, nPos + 1 )
				nPos = nPos + 1
			end
			redraw()

		elseif sEvent == "key" then
		    if param == keys.enter then
				-- Enter
				break

			elseif param == keys.left then
				-- Left
				if nPos > 0 then
					nPos = nPos - 1
					redraw()
				end

			elseif param == keys.right then
				-- Right
				if nPos < string.len(sLine) then
					nPos = nPos + 1
					redraw()
				end

			elseif param == keys.up or param == keys.down then
                -- Up or down
				if _tHistory then
					if param == keys.up then
						-- Up
						if nHistoryPos == nil then
							if #_tHistory > 0 then
								nHistoryPos = #_tHistory
							end
						elseif nHistoryPos > 1 then
							nHistoryPos = nHistoryPos - 1
						end
					else
						-- Down
						if nHistoryPos == #_tHistory then
							nHistoryPos = nil
						elseif nHistoryPos ~= nil then
							nHistoryPos = nHistoryPos + 1
						end
					end

					if nHistoryPos then
                    	sLine = _tHistory[nHistoryPos]
                    	nPos = string.len( sLine )
                    else
						sLine = ""
						nPos = 0
					end
					redraw()
                end
			elseif param == keys.backspace then
				-- Backspace
				if nPos > 0 then
					sLine = string.sub( sLine, 1, nPos - 1 ) .. string.sub( sLine, nPos + 1 )
					nPos = nPos - 1
					redraw()
				end
			end
		end
	end

	term.setCursorBlink( false )
	term.setCursorPos( w + 1, sy )
	print()

	return sLine
end

mWrite = function(text)
	length1 = #("|                           |")
	length2 = math.ceil((x /2) - (length1 / 2))
	local x2,y2 = term.getCursorPos()
	term.setCursorPos(length2+2, y2)

	write(text)
end

local _write = function(text)
	multiMemory[#multiMemory+1] = text
end

function newevent( _sFilter )
	local event, p1, p2, p3, p4, p5 = oldevent( _sFilter )
	if event == "key" then
		if p1 == 15 then
			if tabbing == false then
				tabbing = true
				thattimer = os.startTimer(0.7)
			else
				tabbing = false
				isMultitasking = true
				while isMultitasking do
					term.setCursorPos(1,3)
					cPrint("+------Simulated_Shell------+")
					cPrint("|                           |")
					cPrint("|                           |")
					cPrint("|                           |")
					cPrint("|                           |")
					cPrint("|                           |")
					cPrint("|                           |")
					cPrint("+---------------------------+")
					local testPos1 = 1
					if #multiMemory < 5 then
						for i=1,5 do
							if multiMemory[i] then
								term.setCursorPos(1, 3+i)
								mWrite(string.sub(multiMemory[i], 1, 26))
								testPos1 = testPos1+1
							end
						end
					else
						for i=#multiMemory-4,#multiMemory do
							if multiMemory[i] then
								term.setCursorPos(1, 3+testPos1)
								mWrite(string.sub(multiMemory[i], 1, 26))
								testPos1 = testPos1+1
							end
						end
					end
					term.setCursorPos(1, 3+testPos1)
					mWrite("> ")
					local request = mRead()
					_write("> " ..request)
					if request ~= "" then
						_write("Not yet implemented")
					end
				end
			end
		else
			tabbing = false
		end
	elseif event == "timer" and p1 == thattimer then
		tabbing = false
	end
	return event, p1, p2, p3, p4, p5
end

print("Loading multitasker... ")
textutils.slowPrint("Creating new events...")
sleep(0)
textutils.slowPrint("Generating event function...")
sleep(0)
textutils.slowPrint("Overwriting old events...")
sleep(0)
textutils.slowPrint("Done!")
print("Multitasker loaded. Version: 1.0 PR1")
print("Run a program and double press Tab to multitask.")

os.pullEventRaw = newevent