local function HSVtoRGB(h, s, v)

    local r,g,b = 0,0,0
    local tempS = s / 100
    local tempV = v / 100

	local calc = h / 60
	local calc_floor = math.floor(calc)

	local hi = calc_floor % 6
    local f = calc - calc_floor
    local p = (tempV * (1 - tempS))

	if(hi==0) then
		r = tempV
		g = (tempV * (1 - (1 - f) * tempS))
		b = p
	elseif(hi==1) then
		 r = (tempV * (1 - f * tempS))
		 g = tempV
		 b = p
	elseif(hi==2) then
		r = p
		g = tempV
		b = (tempV * (1 - (1 - f) * tempS))
	elseif(hi==3) then
		r = p
		g = (tempV * (1 - f * tempS))
		b = tempV
	elseif(hi==4) then
		r = (tempV * (1 - (1 - f) * tempS))
		g = p
		b = tempV
	elseif(hi==5) then
		r = tempV
		g = p
		b = (tempV * (1 - f * tempS))
	end

	return r * 255, g * 255, b * 255

end

local function HUEtoRGB( h )

    local r,g,b = 0,0,0

	local z = math.floor(h / 60)
	local hi = z % 6
    local f = h / 60 - z

	if(hi==0) then
		r = 1
		g = f
		b = 0
	elseif(hi==1) then
		 r = (1 - f)
		 g = 1
		 b = 0
	elseif(hi==2) then
		r = 0
		g = 1
		b = f
	elseif(hi==3) then
		r = 0
		g = (1 - f)
		b = 1
	elseif(hi==4) then
		r = f
		g = 0
		b = 1
	elseif(hi==5) then
		r = 1
		g = 0
		b = (1 - f)
	end

	return r * 255, g * 255, b * 255

end

local function RGBToHSV( red, green, blue )

	local hue, saturation, value

	local min_value = math.min( red, green, blue )
	local max_value = math.max( red, green, blue )

	value = max_value

	local value_delta = max_value - min_value

	if max_value ~= 0 then
		saturation = value_delta / max_value

	else
		saturation = 0
		hue = -1
		return hue, saturation, value
	end

	if red == max_value then
		hue = ( green - blue ) / value_delta
	elseif green == max_value then
		hue = 2 + ( blue - red ) / value_delta
	else
		hue = 4 + ( red - green ) / value_delta
	end

	hue = hue * 60
	if hue < 0 then
		hue = hue + 360
	end

	if(hue ~= hue) then
		hue = 0
	end

	return hue, saturation*100, value/2.55
end

local function in_boundary(x1,y1,x2,y2)
    local mouse_x, mouse_y = input.GetMousePos()

    if(mouse_x >= x1 and mouse_y >= y1 and mouse_x <= x1+x2 and mouse_y <= y1+y2) then
        return true
    end

    return false
end

local image = file.Open( "transparent.png", "r" )
local data = image:Read()
image:Close()

local img_rgba, img_width, img_height = common.DecodePNG( data )
local texture = draw.CreateTexture( img_rgba, img_width, img_height )

local picker_x, picker_y, picker_width, picker_height =  400, 700, 200, 200
local hue_x, hue_y, hue_width = ( picker_x + picker_width ) + 20, picker_y, 20
local preview_x, preview_y, preview_width, preview_height = picker_x, ( picker_y + picker_height ) + 20, picker_x + picker_width, ( picker_y + picker_height + 20 ) + 40

local lmouse_hue_x, lmouse_hue_y = 0,0
local lmouse_picker_x, lmouse_picker_y = 0,0
local mouse_down_hue, mouse_down_picker = false, false

local hue, saturation, value = 50, 20, 70
local r, g, b = HSVtoRGB( hue, saturation, value )

local function color_picker()

    local screen_width, screen_height = draw.GetScreenSize()
    local mouse_x, mouse_y = input.GetMousePos()

    draw.SetTexture(0, 0, 0, 0)
    draw.Color( HUEtoRGB( hue ) )
    draw.FilledRect( picker_x, picker_y, picker_x + picker_width, picker_y + picker_height )

    draw.Color(255, 255, 255, 255)
    draw.SetTexture( texture )
    draw.FilledRect( picker_x, picker_y, picker_x + picker_width, picker_y + picker_height )

    draw.SetTexture(0, 0, 0, 0)
    for i=0, 360, 1 do

        draw.Color( HUEtoRGB( i * 360 / picker_height ) )
        draw.FilledRect( hue_x, hue_y + i, hue_x + hue_width, hue_y + picker_height )

    end

    if( input.IsButtonDown( "mouse1" ) and in_boundary( picker_x, picker_y, picker_width, picker_height ) ) then
        saturation = ( mouse_x - picker_x ) / picker_width * 100

        value = ( (picker_y - mouse_y) / picker_height * 100 ) + 100

		r,g,b = HSVtoRGB( hue, saturation, value )

        lmouse_hue_x = mouse_x
        lmouse_hue_y = mouse_y

		mouse_down_hue = true
	end

    if( input.IsButtonDown( "mouse1" ) and in_boundary( hue_x, picker_y, hue_width, picker_height ) ) then

        hue = math.floor( ( ( mouse_y - picker_y ) / picker_height ) * 360 )
        r,g,b = HSVtoRGB( hue, saturation, value )

        lmouse_picker_x = mouse_x
        lmouse_picker_y = mouse_y

		mouse_down_picker = true
	end

	draw.Color( 54, 0, 0, 255 )
	if( mouse_down_hue ) then
		draw.OutlinedRect( lmouse_hue_x - 2, lmouse_hue_y - 2, lmouse_hue_x + 2, lmouse_hue_y + 2 )
	else
		draw.OutlinedRect( picker_x + ( saturation * ( picker_width / 100 ) ) - 2, picker_y - ( value * ( picker_height / 100 ) ) + picker_height - 2, picker_x + (saturation * ( picker_width / 100 ) ) + 2, ( picker_y-value * ( picker_height / 100 ) ) + picker_height + 2 )
    end

	if( mouse_down_picker ) then
		draw.OutlinedRect( hue_x - 2, lmouse_picker_y - 2, hue_x + hue_width + 2, lmouse_picker_y + 2 )
	else
		draw.OutlinedRect( hue_x - 2, picker_y + ( ( picker_height / 360 ) * hue) - 2, hue_x + hue_width + 2, picker_y + ( ( picker_height / 360 ) * hue) + 2 )
    end

	draw.Color( r, g , b , 255 )
	draw.FilledRect( preview_x, preview_y, preview_width, preview_height )

end


callbacks.Register("Draw", "color_picker", color_picker)