Simple UI API v4

--[[ Computercraft UI API by ThePH]]

-- functions comonly used, suing targets (being a monitor or term)
function cur(target, x, y) target.setCursorPos(x, y) end
function color(target,fg,bg) if fg > -1 then    target.setTextColor(fg) end if bg > -1 then target.setBackgroundColor(bg) end end
function drawPixel(target, x, y, nColour) if nColour then term.setBackgroundColor( nColour ) end cur(target, x, y) v.write(' ') end

--Function to check if item is contained in tbl and return en key or 0 if not in tbl
function inTable(tbl, item)
    if type(item) == 'table' then
        for i, v in pairs(item) do
            for key,value in pairs(tbl) do
                if value == v then return key end
            end
        end
    elseif type(item) == 'string' then
        for key,value in pairs(tbl) do
            if value == item then return key end
        end
    end
    return 0
end

-- Reset the the UI list to make it fit the 'format'
function reset(list)
    list.ui = {}
    list.shape = {}
    return list
end


-- Function to create and edit the lists

-- Adding a UI element
function addUI(uiList, keyName, x, y, text, fg, bg, action, pages, output, enabled, visible)
    if enabled == nil then enabled = true end
    if visible == nil then visible = true end
    uiList.ui[keyName] = {x, y, text, fg, bg, action, pages, output, enabled, visible}
    return uiList
end

-- Adding a shape (p3 is not used yet, but its here just in case)
function addShape(uiList, keyName, shape, x, y, p1, p2, p3, color, pages, output, enabled)
    if enabled == nil then enabled = true end
    uiList.shape[keyName] = {shape, x, y, p1, p2, p3, color, pages, output, enabled}
    return uiList
end

-- Editing a UI element
function editUI(uiList, key, id, value)
    local ids = {'x','y','text','fg','bg','action','pages','output', 'enabled', 'visible'}
    local index = inTable(ids, id)
    uiList.ui[key][index] = value
    return uiList
end

-- Draws the UI and shapes (shapes  before)
function draw(uiList, pageList, dFG, dBG)
    for index, value in pairs(uiList.shape) do
        local shape, x, y, p1, p2, p3, color, pagesIn, output, enabled = unpack(value)
        local pageOk = false
        if inTable(pagesIn, pageList) > 0 then
            pageOk = true
        end
        if pageOk and enabled then
            if shape == 'line' then
                drawLine(x, y, p1, p2, output, color)
            elseif shape == 'outline' then
                drawOutline(x, y, p1, p2, output, color)
            elseif shape == 'box' then
                drawBox(x, y, p1, p2, output, color)
            end
        end
    end
    for index, value in pairs(uiList.ui) do
        local x, y, text, fg, bg, action, pagesIn, output, enabled, visible = unpack(value)
        local pageOk = false
        if inTable(pagesIn, pageList) > 0 then
            pageOk = true
        end
        if pageOk and visible and enabled then
            for i,v in pairs(output) do
                color(v, dFG, dBG)
                cur(v, x, y)
                color(v, fg, bg)
                v.write(text)
            end
        end
    end
end

-- Function to draw something not used for interaction (captions etc)
function drawSingle(x, y, text, fg, bg, output)
    for i, v in pairs(output) do
        cur(v, x, y)
        color(v, fg, bg)
        v.write(text)
    end
end

-- Checks mouse function (using the ui list, x, y pages and (optional, the targets))
-- returns the action, the key in the ui list and the position on the string
function mouse(uiList, mx, my, pageList, target)
    for index, value in pairs(uiList.ui) do
        local x, y, text, fg, bg, action, pagesIn, output, enabled, visible = unpack(value)
        pageOk = false
        if inTable(pagesIn, pageList) > 0 then pageOk = true end
        if (not(target) or inTable(output, target) > 0) and not(action == 'nil') and pageOk and enabled then
            for i, v in pairs(pagesIn) do
                if inTable(pageList, v) then
                    if my == y then
                        if mx >= x and mx <= (x + text:len() - 1) then
                            return action, index, (mx - x + 1)
                        end
                    end
                    break
                end
            end
        end
    end
    return nil, nil, nil
end

-- function the draw an empty box on target
function drawOutline(x1,y1, x2, y2, target, c)
    drawLine(x1,y1, x1, y2, target, c)
    drawLine(x1,y2, x2, y2, target, c)
    drawLine(x2,y1, x2, y2, target, c)
    drawLine(x1,y1, x2, y1, target, c)
end

-- function from paintutils ported for using targets
local function drawPixelInternal( xPos, yPos, target )
    target.setCursorPos(xPos, yPos)
    target.write(" ")
end

-- function to draw line using targets
function drawLine(startX, startY, endX, endY, target, nColour)
    for i, v in pairs(target) do
        line( startX, startY, endX, endY, v, nColour )
    end
end

-- function to draw a filled box on target
function drawBox(startX, startY, endX, endY, target, nColour)
    if startY <= endY then s = 1 else s= -1 end
    for index=startY, endY, s do
        drawLine( startX, index, endX, index, target, nColour )
    end
end

-- function from paintutils ported for using targets
function line( startX, startY, endX, endY, v, nColour )
    if nColour then
        v.setBackgroundColor( nColour )
    end

    startX = math.floor(startX)
    startY = math.floor(startY)
    endX = math.floor(endX)
    endY = math.floor(endY)

    if startX == endX and startY == endY then
        drawPixelInternal( startX, startY, v )
        return
    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
            drawPixelInternal( x, math.floor( y + 0.5 ), v )
            y = y + dy
        end
    else
        local x = minX
        local dx = xDiff / yDiff
        if maxY >= minY then
            for y=minY,maxY do
                drawPixelInternal( math.floor( x + 0.5 ), y, v )
                x = x + dx
            end
        else
            for y=minY,maxY,-1 do
                drawPixelInternal( math.floor( x + 0.5 ), y, v )
                x = x - dx
            end
        end
    end
end