os_gfx

local utils = require("utils")

HasSomethingChanged = false
RenderBuffer = {}
Width, Height = term.getSize()



-- Helper functions
function getWidth()
    return Width
end

function getHeight()
    return Height
end

function clear()
    term.clear()
end



-- Text
function addCentralXText(message, posY)
    -- y goes unused here
    local x, y = utils.midpoint(Width, Height)
    local newX = utils.getXPosOfString(message, x)
    return addText(message, newX, posY)
end

function addCentralText(message)
    -- x goes unused here
    local x, y = utils.midpoint(Width, Height)
    return addCentralXText(message, y)
end

function addText(message, posX, posY)
    data = {}

    data["message"] = message
    data["posX"] = posX
    data["posY"] = posY

    RenderBuffer[(#RenderBuffer) + 1] = data
    HasSomethingChanged = true
    return #RenderBuffer
end

function updateText(handle, newText)
    RenderBuffer[handle]["message"] = newText
end



-- Display
function flush()
    local count = #RenderBuffer
    for i = 1, count do
        RenderBuffer[i] = nil
    end
end

function writeText(message, startX, startY)
    term.setCursorPos(startX, startY)
    term.write(message)
end

function display()
    if HasSomethingChanged then
        clear()
        for i = 1, #RenderBuffer do
            local current = RenderBuffer[i]
            local x, y, message = current["posX"], current["posY"], current["message"]
            writeText(message, x, y)
        end
        HasSomethingChanged = false
    end
end



return {
    clear = clear,
    addText = addText,
    addCentralText = addCentralText,
    addCentralXText = addCentralXText,
    updateText = updateText,
    flush = flush,
    display = display,
    getWidth = getWidth,
    getHeight = getHeight
}