local chainLabel = gfx.CreateSkinImage("gameplay/chain/label.png", 0)

local desw = 1080;
local desh = 1920;

local transitionShakeScale = 0;
local transitionShakePosOffset = 0;
local shakeTimer = 0;

function load_number_image(path)
    local images = {}
    for i = 0, 9 do
        images[i + 1] = gfx.CreateSkinImage(string.format("%s/%d.png", path, i), 0)
    end
    return images
end

local chainNumbersReg = load_number_image('gameplay/chain/reg')
local chainNumbersUC = load_number_image('gameplay/chain/uc')
local chainNumbersPUC = load_number_image('gameplay/chain/puc')

function draw_number(x, y, alpha, num, digits, images, is_dim, scale, kern)
    scale = scale or 1;
	kern = kern or 1;
	local tw, th = gfx.ImageSize(images[1])
	tw = tw * scale;
	th = th * scale;
    x = x + (tw * (digits - 1)) / 2
    y = y - th / 2
    for i = 1, digits do
        local mul = 10 ^ (i - 1)
        local digit = math.floor(num / mul) % 10
        local a = alpha
        if is_dim and num < mul then
            a = 0.4
        end
        gfx.BeginPath()
        gfx.ImageRect(x, y, tw, th, images[digit + 1], a, 0)
        x = x - (tw * kern)
    end
end

local tickTransitions = function (deltaTime)
    
    if transitionShakeScale < 1 then
        transitionShakeScale = transitionShakeScale + deltaTime / 0.075 -- transition should last for that time in seconds
    else
        transitionShakeScale = 0
    end

    if (transitionShakeScale < 1/3) then
        transitionShakePosOffset = 0;
    elseif (transitionShakeScale > 2/3) then
        transitionShakePosOffset = -1;
    else
        transitionShakePosOffset = 1;
    end
end

local onNewCombo = function ()
    shakeTimer = 0.25;
end

local render = function (deltaTime, comboState, combo, critLineCenterX, critLineCenterY)
    tickTransitions(deltaTime)

    if shakeTimer > 0 then
        shakeTimer = shakeTimer - deltaTime;
    else
        transitionShakePosOffset = 0;
    end

    if combo == 0 then return end

    local posx = desw / 2 + transitionShakePosOffset;
    local posy = desh - 640 + transitionShakePosOffset;

    local chainNumbers = chainNumbersReg --regular
    if comboState == 2 then
        chainNumbers = chainNumbersPUC --puc
    elseif comboState == 1 then
        chainNumbers = chainNumbersUC --uc

        if (not game.GetSkinSetting('gameplay_ucDifferentColor')) then
            chainNumbers = chainNumbersPUC -- force the PUC numbers in case the setting is turned off
        end
    end

    -- \_ chain _/
    local tw, th
    tw, th = gfx.ImageSize(chainLabel)
    gfx.BeginPath()
    gfx.ImageRect(posx - tw * 0.85 / 2, posy - 220, tw * 0.85, th * 0.85, chainLabel, 1, 0)

    tw, th = gfx.ImageSize(chainNumbers[1])
    posy = posy - th + 32

    local comboScale = 0.45;
    draw_number(posx - (tw*4*comboScale)/2+(tw*comboScale*1.5)+10, posy - th / 2, 1.0, combo, 4, chainNumbers, true, comboScale, 1.12)
end

return {
    onNewCombo=onNewCombo,
    render=render
}