-- pain2

local scr_x, scr_y = term.getSize()
local mx, my = scr_x/2, scr_y/2		-- midpoint of screen
local keysDown = {}					-- list of all pushed keys
local miceDown = {}					-- list of all clicked mice buttons
local dragPoses = {{{},{}}, {{},{}}, {{},{}}}	-- records initial and current mouse position per button while scrolling

local TICKNO = 0				-- iterates every time main() loops
local flashPaletteOnBar = false	-- whether or not to flash the dot palette numbers on the bottom bar

-- debug renderer is slower, but the normal one isn't functional yet
local useDebugRenderer = false

local canvas = {
	{{},{},{}}
}
local frame = 1
local dot = 1

local pain = {
	screenWidth = scr_x,
	screenHeight = scr_y,
	scrollX = 0,
	scrollY = 0,
	brushSize = 2,
	barmsg = "Started PAIN.",
	barlife = 12,
	showBar = true,
	doRender = true,
	size = {
		x = 1,
		y = 1,
		width = scr_x,
		height = scr_y
	},
	dots = {
		[0] = {
			" ",
			" ",
			" "
		},
		[1] = {
			" ",
			"f",
			"0"
		},
		[2] = {
			" ",
			"f",
			"e"
		},
	},
	tool = "pencil"
}

local setBarMsg = function(message)
	pain.barmsg = message
	pain.barlife = 16
	pain.doRender = true
end

local controlHoldCheck = {}	-- used to prevent repeated inputs on non-repeating controls
local control = {
	quit = {
		key = keys.q,
		holdDown = false,
		modifiers = {
			[keys.leftCtrl] = true
		},
	},
	scrollUp = { -- decrease scrollY
		key = keys.up,
		holdDown = true,
		modifiers = {},
	},
	scrollDown = {
		key = keys.down,
		holdDown = true,
		modifiers = {},
	},
	scrollLeft = {
		key = keys.left,
		holdDown = true,
		modifiers = {},
	},
	scrollRight = {
		key = keys.right,
		holdDown = true,
		modifiers = {},
	},
	resetScroll = {
		key = keys.a,
		holdDown = false,
		modifiers = {},
	},
	switchNextFrame = {
		key = keys.rightBracket,
		holdDown = false,
		modifiers = {},
	},
	switchPrevFrame = {
		key = keys.leftBracket,
		holdDown = false,
		modifiers = {},
	},
	increaseBrushSize = {
		key = keys.equals,
		holdDown = false,
		modifiers = {},
	},
	increaseBrushSize_Alt = {
		key = keys.numPadAdd,
		holdDown = false,
		modifiers = {},
	},
	decreaseBrushSize = {
		key = keys.minus,
		holdDown = false,
		modifiers = {},
	},
	decreaseBrushSize_Alt = {
		key = keys.numPadSubtract,
		holdDown = false,
		modifiers = {},
	},
	moveMod = {
		key = keys.leftShift,
		holdDown = true,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	creepMod = {
		key = keys.leftAlt,
		holdDown = true,
		modifiers = {
			[keys.leftAlt] = true
		},
	},
	toolMod = {
		key = keys.leftShift,
		holdDown = true,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	pencilTool = {
		key = keys.p,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	brushTool = {
		key = keys.b,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	textTool = {
		key = keys.t,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	lineTool = {
		key = keys.l,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_0 = {
		key = keys.zero,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_1 = {
		key = keys.one,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_2 = {
		key = keys.two,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_3 = {
		key = keys.three,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_4 = {
		key = keys.four,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_5 = {
		key = keys.five,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_6 = {
		key = keys.six,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_7 = {
		key = keys.seven,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_8 = {
		key = keys.eight,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
	selectPalette_9 = {
		key = keys.nine,
		holdDown = false,
		modifiers = {
			[keys.leftShift] = true
		},
	},
}

local checkControl = function(name)
	local modlist = {
		keys.leftCtrl,
		keys.rightCtrl,
		keys.leftShift,
		keys.rightShift,
		keys.leftAlt,
		keys.rightAlt,
	}
	for i = 1, #modlist do
		if control[name].modifiers[modlist[i]] then
			if not keysDown[modlist[i]] then
				return false
			end
		else
			if keysDown[modlist[i]] then
				return false
			end
		end
	end
	if keysDown[control[name].key] then
		if control[name].holdDown then
			return true
		else
			if not controlHoldCheck[name] then
				controlHoldCheck[name] = true
				return true
			end
		end
	else
		controlHoldCheck[name] = false
		return false
	end
end

-- converts hex colors to colors api, and back
local to_colors, to_blit = {
	[' '] = 0,
	['0'] = 1,
	['1'] = 2,
	['2'] = 4,
	['3'] = 8,
	['4'] = 16,
	['5'] = 32,
	['6'] = 64,
	['7'] = 128,
	['8'] = 256,
	['9'] = 512,
	['a'] = 1024,
	['b'] = 2048,
	['c'] = 4096,
	['d'] = 8192,
	['e'] = 16384,
	['f'] = 32768,
}, {}
for k,v in pairs(to_colors) do
	to_blit[v] = k
end

-- takes two coordinates, and returns every point between the two
local getDotsInLine = function( startX, startY, endX, endY )
	local out = {}
	startX = math.floor(startX)
	startY = math.floor(startY)
	endX = math.floor(endX)
	endY = math.floor(endY)
	if startX == endX and startY == endY then
		out = {{x=startX,y=startY}}
		return out
	end
    local minX = math.min( startX, endX )
	if minX == startX then
		minY = startY
		maxX = endX
		maxY = endY
	else
		minY = endY
		maxX = startX
		maxY = startY
	end
	local xDiff = maxX - minX
	local yDiff = maxY - minY
	if xDiff > math.abs(yDiff) then
        local y = minY
        local dy = yDiff / xDiff
        for x=minX,maxX do
            out[#out+1] = {x=x,y=math.floor(y+0.5)}
            y = y + dy
        end
    else
        local x = minX
        local dx = xDiff / yDiff
        if maxY >= minY then
            for y=minY,maxY do
                out[#out+1] = {x=math.floor(x+0.5),y=y}
                x = x + dx
            end
        else
            for y=minY,maxY,-1 do
                out[#out+1] = {x=math.floor(x+0.5),y=y}
                x = x - dx
            end
        end
    end
    return out
end

-- deletes a dot on the canvas, fool
local deleteDot = function(x, y, frame)
	x, y = 1 + x - pain.size.x, 1 + y - pain.size.y
	if canvas[frame][1][y] then
		if canvas[frame][1][y][x] then
			canvas[frame][1][y][x] = nil
			canvas[frame][2][y][x] = nil
			canvas[frame][3][y][x] = nil
		end
	end
end

-- places a dot on the canvas, predictably enough
local placeDot = function(x, y, frame, dot)
	x, y = 1 - pain.size.x + x, 1 - pain.size.y + y
	if not canvas[frame][1][y] then
		canvas[frame][1][y] = {}
		canvas[frame][2][y] = {}
		canvas[frame][3][y] = {}
	end
	canvas[frame][1][y][x] = dot[1]
	canvas[frame][2][y][x] = dot[2]
	canvas[frame][3][y][x] = dot[3]
end

-- used for tools that involve dragging
local dragPos = {}

local getGridAtPos = function(x, y)
	local grid = {
		"..%%",
		"..%%",
		"..%%",
		"%%..",
		"%%..",
		"%%..",
	}
	if x < 1 or y < 1 then
		return "/", "7", "f"
	else
		local sx, sy = 1 + (1 + x) % #grid[1], 1 + (2 + y) % #grid
		return grid[sy]:sub(sx,sx), "7", "f"
	end
end

-- shows everything on screen
local render = function(x, y, width, height)
	local buffer = {{},{},{}}
	local cx, cy
	x = x or pain.size.x
	y = y or pain.size.y
	width = width or pain.size.width
	height = height or pain.size.height
	-- see, it wouldn't do if I just individually set the cursor position for every dot
	if useDebugRenderer then

		term.clear()
		local cx, cy
		for yy, line in pairs(canvas[frame][1]) do
			for xx, dot in pairs(canvas[frame][1][yy]) do
				cx = xx - pain.scrollX
				cy = yy - pain.scrollY
				if cx >= x and cx <= (x + width - 1) and cy >= y and cy <= (x + width - 1) then
					term.setCursorPos(cx, cy)
					term.blit(
						canvas[frame][1][yy][xx],
						canvas[frame][2][yy][xx],
						canvas[frame][3][yy][xx]
					)
				end
			end
		end

	else

		local gChar, gText, gBack
		for yy = 1, -1 + height + y do
			buffer[1][yy] = ""
			buffer[2][yy] = ""
			buffer[3][yy] = ""
			if pain.showBar and yy == height then
				term.setTextColor(colors.black)
				term.setBackgroundColor(colors.lightGray)
				term.setCursorPos(pain.size.x, -1 + pain.size.y + pain.size.height)
				term.write("[" .. pain.scrollX .. "," .. pain.scrollY .. "] ")
				for i = 1, #pain.dots do
					if flashPaletteOnBar then
						term.blit(table.unpack(pain.dots[i]))
					else
						term.blit(tostring(i), "7", pain.dots[i][3])
					end
				end
				if pain.barlife > 0 then
					term.write(" " .. pain.barmsg)
				end
				term.write((" "):rep(x + width - term.getCursorPos()))
			else
				for xx = 1, width do
					cx = xx + pain.scrollX
					cy = yy + pain.scrollY
					if canvas[frame][1][cy] then
						if canvas[frame][1][cy][cx] then
							for c = 1, 3 do
								buffer[c][yy] = buffer[c][yy] .. canvas[frame][c][cy][cx]
							end
						else
							gChar, gText, gBack = getGridAtPos(cx, cy)
							buffer[1][yy] = buffer[1][yy] .. gChar
							buffer[2][yy] = buffer[2][yy] .. gText
							buffer[3][yy] = buffer[3][yy] .. gBack
						end
					else
						gChar, gText, gBack = getGridAtPos(cx, cy)
						buffer[1][yy] = buffer[1][yy] .. gChar
						buffer[2][yy] = buffer[2][yy] .. gText
						buffer[3][yy] = buffer[3][yy] .. gBack
					end
				end
			end
		end
		for yy = 0, height - 1 do
			term.setCursorPos(x, y + yy)
			term.blit(buffer[1][yy+1], buffer[2][yy+1], buffer[3][yy+1])
		end

	end
end

-- every tool at your disposal
local tools = {
	pencil = {
		info = {
			name = "Pencil",
			swapTool = "line",	-- if swap button is held, will turn into this tool
			swapArg = {			-- any values in this table will overwrite those in 'arg'
				size = 1
			},
		},
		run = function(arg)
			if arg.event == "mouse_click" then
				if arg.button == 1 then
					placeDot(arg.sx, arg.sy, frame, arg.dot)
				elseif arg.button == 2 then
					deleteDot(arg.sx, arg.sy, frame)
				end
				dragPos = {arg.sx, arg.sy}
			else
				if #dragPos == 0 then
					dragPos = {arg.sx, arg.sy}
				end
				local poses = getDotsInLine(arg.sx, arg.sy, dragPos[1], dragPos[2])
				for i = 1, #poses do
					if arg.button == 1 then
						placeDot(poses[i].x, poses[i].y, frame, arg.dot)
					elseif arg.button == 2 then
						deleteDot(poses[i].x, poses[i].y, frame)
					end
				end
				dragPos = {arg.sx, arg.sy}
			end
		end
	},
	brush = {
		info = {
			name = "Brush",
			swapTool = "line",
			swapArg = {},
		},
		run = function(arg)
			if arg.event == "mouse_click" then
				for y = -arg.size, arg.size do
					for x = -arg.size, arg.size do
						if math.sqrt(x^2 + y^2) <= arg.size / 2 then
							if arg.button == 1 then
								placeDot(arg.sx + x, arg.sy + y, frame, arg.dot)
							elseif arg.button == 2 then
								deleteDot(arg.sx + x, arg.sy + y, frame)
							end
						end
					end
				end
				dragPos = {arg.sx, arg.sy}
			else
				if #dragPos == 0 then
					dragPos = {arg.sx, arg.sy}
				end
				local poses = getDotsInLine(arg.sx, arg.sy, dragPos[1], dragPos[2])
				for i = 1, #poses do
					for y = -arg.size, arg.size do
						for x = -arg.size, arg.size do
							if math.sqrt(x^2 + y^2) <= arg.size / 2 then
								if arg.button == 1 then
									placeDot(poses[i].x + x, poses[i].y + y, frame, arg.dot)
								elseif arg.button == 2 then
									deleteDot(poses[i].x + x, poses[i].y + y, frame)
								end
							end
						end
					end
				end
				dragPos = {arg.sx, arg.sy}
			end
		end
	},
	text = function(arg)
		pain.paused = true
		pain.barmsg = "Type text to add to canvas."
		pain.barlife = 1
		render()
		term.setCursorPos(arg.x, arg.y)
		term.setTextColor(to_colors[arg.dot[2]])
		term.setBackgroundColor(to_colors[arg.dot[3]])
		local text = read()
		-- re-render every keypress, requires custom read function
		for i = 1, #text do
			placeDot(arg.sx + i - 1, arg.sy, frame, {text:sub(i,i), pain.dots[dot][2], pain.dots[dot][3]})
		end
		pain.paused = false
		keysDown = {}
		miceDown = {}
	end,
	line = {
		info = {
			name = "Line",
			swapTool = "pencil",
		},
		run = function(arg)
			local dots
			while miceDown[arg.button] do
				dots = getDotsInLine(
					dragPoses[arg.button][1].x + (arg.scrollX - pain.scrollX),
					dragPoses[arg.button][1].y + (arg.scrollY - pain.scrollY),
					dragPoses[arg.button][2].x,
					dragPoses[arg.button][2].y
				)
				render()
				for i = 1, #dots do
					if dots[i].x >= pain.size.x and dots[i].x < pain.size.x + pain.size.width then
						for y = -arg.size, arg.size do
							for x = -arg.size, arg.size do
								if math.sqrt(x^2 + y^2) <= arg.size / 2 then
									if (not pain.showBar) or dots[i].y + y < -1 + pain.size.y + pain.size.height then
										term.setCursorPos(dots[i].x + x, dots[i].y + y)
										if arg.button == 1 then
											term.blit(table.unpack(arg.dot))
										elseif arg.button == 2 then
											term.blit(getGridAtPos(dots[i].x + pain.scrollX, dots[i].y + pain.scrollY))
										end
									end
								end
							end
						end
					end
				end

				os.pullEvent()
			end
			-- write dots to canvas
			for i = 1, #dots do
				for y = -arg.size, arg.size do
					for x = -arg.size, arg.size do
						if math.sqrt(x^2 + y^2) <= arg.size / 2 then
							if arg.button == 1 then
								placeDot(dots[i].x + x + pain.scrollX, dots[i].y + y + pain.scrollY, frame, arg.dot)
							elseif arg.button == 2 then
								deleteDot(dots[i].x + x + pain.scrollX, dots[i].y + y + pain.scrollY, frame)
							end
						end
					end
				end
			end
		end
	},
}

local tryTool = function()
	local swapArg, t = {}
	if checkControl("toolMod") then
		t = tools[tools[pain.tool].info.swapTool]
		swapArg = tools[pain.tool].info.swapArg or {}
	else
		t = tools[pain.tool]
	end
	for butt = 1, 3 do
		if miceDown[butt] and t then
			t.run({
				x 		= swapArg.x or miceDown[butt].x,
				y 		= swapArg.y or miceDown[butt].y,
				sx 		= swapArg.sx or ((swapArg.x or miceDown[butt].x) + pain.scrollX),
				sy 		= swapArg.sy or ((swapArg.y or miceDown[butt].y) + pain.scrollY),
				scrollX = swapArg.scrollX or pain.scrollX,
				scrollY = swapArg.scrollY or pain.scrollY,
				frame 	= swapArg.frame or frame,
				dot 	= swapArg.dot or pain.dots[dot],
				size 	= swapArg.size or pain.brushSize,
				button 	= swapArg.button or butt,
				event 	= swapArg.event or miceDown[butt].event
			})
			pain.doRender = true
			break
		end
	end
end

local getInput = function()
	local evt
	while true do
		evt = {os.pullEvent()}
		if evt[1] == "mouse_click" or evt[1] == "mouse_drag" then
			if evt[3] >= pain.size.x and evt[3] <= -1 + pain.size.x + pain.size.width and evt[4] >= pain.size.y and evt[4] <= -1 + pain.size.y + pain.size.height then
				if evt[4] == -1 + pain.size.y + pain.size.height then
					-- openBarMenu()
				else
					dragPoses[evt[2]] = {
						{
							x = dragPoses[evt[2]][1].x or evt[3],
							y = dragPoses[evt[2]][1].y or evt[4]
						},
						{
							x = evt[3],
							y = evt[4]
						}
					}
					miceDown[evt[2]] = {
						event = evt[1],
						button = evt[2],
						x = evt[3],
						y = evt[4],
					}
				end
			end
		elseif evt[1] == "key" then
			keysDown[evt[2]] = true
		elseif evt[1] == "mouse_up" then
			dragPoses[evt[2]] = {{},{}}, {{},{}}, {{},{}}
			miceDown[evt[2]] = false
		elseif evt[1] == "key_up" then
			keysDown[evt[2]] = false
		end
	end
end

-- executes everything that doesn't run asynchronously
main = function()
	while true do

		if not pain.paused then

			if TICKNO % 30 <= 20 then
				flashPaletteOnBar = true
				pain.doRender = true
			elseif (TICKNO + 3) % 30 <= 20 then
				flashPaletteOnBar = false
				pain.doRender = true
			end

			if pain.doRender then
				render()
				pain.doRender = false
			end

			if checkControl("quit") then
				return true
			end

			-- handle scrolling
			if checkControl("resetScroll") then
				pain.scrollX = 0
				pain.scrollY = 0
				pain.doRender = true
			else
				if checkControl("increaseBrushSize") or checkControl("increaseBrushSize_Alt") then
					pain.brushSize = math.min(pain.brushSize + 1, 16)
					setBarMsg("Increased brush size to " .. pain.brushSize .. ".")
				elseif checkControl("decreaseBrushSize") or checkControl("decreaseBrushSize_Alt") then
					pain.brushSize = math.max(pain.brushSize - 1, 1)
					setBarMsg("Decreased brush size to " .. pain.brushSize .. ".")
				elseif checkControl("scrollLeft") then
					pain.scrollX = pain.scrollX - 1
					pain.doRender = true
				end
				if checkControl("scrollRight") then
					pain.scrollX = pain.scrollX + 1
					pain.doRender = true
				end
				if checkControl("scrollUp") then
					pain.scrollY = pain.scrollY - 1
					pain.doRender = true
				end
				if checkControl("scrollDown") then
					pain.scrollY = pain.scrollY + 1
					pain.doRender = true
				end
			end
			for i = 0, 9 do
				if checkControl("selectPalette_" .. i) then
					if pain.dots[i] then
						dot = i
						setBarMsg("Selected palette " .. dot .. ".")
						break
					else
						setBarMsg("There is no palette " .. i .. ".")
						break
					end
				end
			end
			if checkControl("pencilTool") then
				pain.tool = "pencil"
				setBarMsg("Selected pencil tool.")
			elseif checkControl("textTool") then
				pain.tool = "text"
				setBarMsg("Selected text tool.")
			elseif checkControl("brushTool") then
				pain.tool = "brush"
				setBarMsg("Selected brush tool.")
			elseif checkControl("lineTool") then
				pain.tool = "line"
				setBarMsg("Selected line tool.")
			end

			pain.barlife = math.max(pain.barlife - 1, 0)
			if pain.barlife == 0 and pain.barmsg ~= "" then
				pain.barmsg = ""
				pain.doRender = true
			end

		end

		TICKNO = TICKNO + 1
		sleep(0.05)

	end
end

local keepTryingTools = function()
	while true do
		os.pullEvent()
		tryTool()
	end
end

term.clear()

parallel.waitForAny( main, getInput, keepTryingTools )

-- exit cleanly

term.setCursorPos(1, scr_y)
term.setBackgroundColor(colors.black)
term.setTextColor(colors.white)
term.clearLine()