GUI API 1.2

-- Basic Functions --

local mSel = 1
local l = 1
local flag = false
local rsType,rtData
local w,h = term.getSize()

local defaultColourSet = {
    overlayHF = colours.grey;
    overlayBack = colours.black;
    overlayText = colours.white;
    menuItem = colours.white;
    msgBoxText = colours.white;
    msgBoxBack = colours.grey;
    inpBoxText = colours.white;
    inpBoxBack  = colours.grey;
    inpBoxInput = colours.orange;
}
local defaultTextSet ={
    overlayHeaderText = {"Menu"};
    overlayFooterText = {"GUIAPI by KyleRGS"};
    itemName = "Default";
}

function defineDefaultColour(overlayHF,overlayBack,overlayText,menuItem,msgBoxText,msgBoxBack,inpBoxText,inpBoxBack,inpBoxInput)
    defaultColourSet.overlayHF = overlayHF
    defaultColourSet.overlayBack = overlayBack
    defaultColourSet.overlayText = overlayText
    defaultColourSet.menuItem = menuItem
    defaultColourSet.msgBoxText = msgBoxText
    defaultColourSet.msgBoxBack = msgBoxBack
    defaultColourSet.inpBoxText = inpBoxText
    defaultColourSet.inpBoxBack = inpBoxBack
    defaultColourSet.inpBoxInput = inpBoxInput
end
function defineDefaultColourTable(tColours)
    defaultColourSet = tColours
end
function defineDefaultValues(HeaderText, FooterText, MenuItem)
    defaultTextSet.overlayHeaderText = HeaderText
    defaultTextSet.overlayFooterText = FooterText
    defaultTextSet.itemName = MenuItem
end

function isInteger(nIn)
    if math.floor(nIn) == nIn then return true
    else return false end
end
function printCentred(str , h)
  term.setCursorPos(w/2 - #str/2, h)
  term.write(str)
end
function printRight(str , h)
  term.setCursorPos(w - #str, h)
  term.write(str)
end
function printLeft(str , h)
  term.setCursorPos(1, h)
  term.write(str)
end

function reduceMenu(height, head, foot)
    return math.floor(math.floor(height - head - foot -1)/2)
end

--Presenting the Menu--

function drawMenu(tMenu)
    l = 0
    if #tMenu.tItems > tMenu.iMenuLen then l = tMenu.iMenuLen
    else l = #tMenu.tItems end
    local j = 4
    term.setBackgroundColour(tMenu.tOverlay.cOverlayBackground)
    for i = tMenu.iFItem, l+tMenu.iFItem-1 do
        if tMenu.tItems[i] then
            term.setTextColour(tMenu.tItems[i].nColour)
            printCentred(tMenu.tItems[i].sDisp, j)
            j = j +2
        end
    end

  term.setTextColour(tMenu.tItems[tMenu.iCursorPos].nColour)
  local selpos = tMenu.iRSel*2 + 2
  printCentred("[  "..tMenu.tItems[tMenu.iCursorPos].sDisp.."  ]", selpos)
  term.setBackgroundColour(tMenu.tOverlay.cOverlayColour)



end

function reDraw(tMenu)
    tMenu:draw()
end

-- Display functions --


function msgBox(tMsg)
    term.setTextColour(defaultColourSet.msgBoxText)
    term.setBackgroundColour(defaultColourSet.msgBoxBack)
    assert(type(tMsg)=="table", "Message Box must contain a table")
    local tStrLen = {}
    for i,v in ipairs(tMsg) do
        tStrLen[i] = #v
    end
    local boxHeight = #tMsg
    local boxWidth = math.max(unpack(tStrLen)) +2
    printCentred("+"..string.rep("-",boxWidth).."+", math.floor(h/2 -boxHeight/2))
    for i = math.floor(h/2 -boxHeight/2)+1, math.floor(h/2 +boxHeight/2) do
        printCentred("I"..string.rep(" ",boxWidth).."I", i)
    end
    printCentred("+"..string.rep("-",boxWidth).."+", math.floor(h/2 +boxHeight/2)+1)
    printCentred("{[ENTER]}", math.floor(h/2 +boxHeight/2)+1)
    local j = 1
    for i = math.floor(h/2 -boxHeight/2)+1, math.floor(h/2 +boxHeight/2) do
        printCentred(tMsg[j], i)
        j = j+1
    end
        do sleep(0.1); event, id, param2 = os.pullEvent() repeat until (event =="key" and id==28) or (event=="mouse_click") end
end


function inpBox(tMsg)
    term.setTextColour(defaultColourSet.inpBoxText)
    term.setBackgroundColour(defaultColourSet.inpBoxBack)
    assert(type(tMsg)=="table", "Message Box must contain a table")
    local tStrLen = {}
    for i,v in ipairs(tMsg) do
        tStrLen[i] = #v
    end
    local boxHeight = #tMsg
    local boxWidth = math.max(unpack(tStrLen)) +2
    printCentred("+"..string.rep("-",boxWidth).."+", math.floor(h/2 -boxHeight/2))
    for i = math.floor(h/2 -boxHeight/2)+1, math.floor(h/2 +boxHeight/2)+1 do
        printCentred("I"..string.rep(" ",boxWidth).."I", i)
    end
    printCentred("+"..string.rep("-",boxWidth).."+", math.floor(h/2 +boxHeight/2)+2)
    printCentred("{[ENTER]}", math.floor(h/2 +boxHeight/2)+2)
    local j = 1
    for i = math.floor(h/2 -boxHeight/2)+1, math.floor(h/2 +boxHeight/2) do
        printCentred(tMsg[j], i)
        j = j+1
    end
    term.setCursorPos((w-boxWidth)/2+1, (h+boxHeight)/2+1)
    term.setTextColour(defaultColourSet.inpBoxInput)
    return read()
end

-- The API functions --

function newOverlay()
    local tOverlay = {
        nHeadLen = 2;
        nFootLen = 2;
        cOverlayColour = defaultColourSet.overlayText;
        cOverlayBackground = defaultColourSet.overlayBack;
        cOverlayHF = defaultColourSet.overlayHF;
        tTitle = defaultTextSet.overlayHeaderText;
        tFoot = defaultTextSet.overlayFooterText;
        setHeaderTitle = function(self,...)
            if arg.n < h then
                self.tTitle = {}
                for i,v in ipairs(arg) do
                    table.insert(self.tTitle, v)
                end
                self.nHeadLen = arg.n+1
            else error("Too Many Lines to set Header Title") end
        end;
        setFooterText = function(self,...)
            if arg.n < h then
                self.tFoot = {}
                for i,v in ipairs(arg) do
                    table.insert(self.tFoot, v)
                end
            self.nFootLen = arg.n +1
            else error("Too Many Lines to set Footer text") end
        end;
        setOverlayColour = function(self, colour)
            self.cOverlayColour = colour
        end;
        setBackgroundColour = function(self, colour)
            self.cOverlayBackground = colour
        end;
        setBackgroundHF = function(self, colour)
            self.cOverlayHF = colour
        end;
        draw = function(self)
            term.setBackgroundColour(self.cOverlayBackground)
            term.clear()
            term.setBackgroundColour(self.cOverlayHF)
            term.setTextColour(self.cOverlayColour)

            for i,v in ipairs(self.tTitle) do
                term.setCursorPos(1,i)
                term.clearLine()
                printCentred(v, i)
            end
            printLeft(string.rep("-",w),self.nHeadLen)
            printLeft(string.rep("-",w),h-self.nFootLen+1)
            for i,v in ipairs(self.tFoot) do
                term.setCursorPos(1,h-i+1)
                term.clearLine()
                printRight(v, h - i +1)
            end
            term.setTextColour(1)
            term.setBackgroundColour(colours.black)
        end;
    }
    return tOverlay
end

function newItem()
    local tItem = {
        sDisp = defaultTextSet.itemName;
        sType = "text";
        nColour = defaultColourSet.menuItem;
        tData = {};
        newName = function(self, sName)
            self.sDisp = sName
        end;
        newType = function(self, sType)
            self.sType = sType
        end;
        newColour = function(self, nColour)
            self.nColour = nColour
        end;
        newColor = function(self, nColour)
            self.nColour = nColour
        end;
        setData = function(self, tData)
            self.tData = tData
        end;
        addData = function(self, aData)
            table.insert(self.tData, aData)
        end;
    }
    return tItem
end

function newMenu()
    local tMenu = {
        tOverlay = newOverlay();
        tItems = {};
        iCursorPos = 1;
        iFItem = 1;
        iRSel = 1;
        iMenuLen = 0;
        newOverlay = function(self, tOver)
            self.tOverlay = tOver
        end;
        resetItems = function(self) self.tItems = {} end;
        newItem = function(self, tItem) table.insert(self.tItems, tItem) end;
        checkSel = function(self)
            if self.iRSel > self.iMenuLen -1 and self.iCursorPos<#self.tItems then
                self.iRSel = self.iRSel -1
                self.iFItem = self.iFItem+1
            elseif self.iRSel == 1 and self.iCursorPos > 1 then
                self.iRSel = self.iRSel +1
                self.iFItem = self.iFItem -1
            end
        end;
        draw = function(self)
            local id
            local key
            local param2
            local param3
            flag = false
            while true do
                if not flag then
                    self.tOverlay:draw()
                    drawMenu(self)
                    do sleep(0.02); id, key, param2, param3 = os.pullEvent(); repeat until id == "key" or id =="mouse_click" or id == "mouse_scroll" end
                    if id == "key" then
                        if key == 200 and self.iCursorPos > 1 then self.iCursorPos = self.iCursorPos-1 ; self.iRSel=self.iRSel-1 ; self:checkSel();
                        elseif key == 208 and self.iCursorPos < #self.tItems then self.iCursorPos = self.iCursorPos + 1 ; self.iRSel = self.iRSel +1 ; self:checkSel();
                        elseif key == 28 then
                            if self.tItems[self.iCursorPos].sType == "menu" then reDraw(self.tItems[self.iCursorPos].tData[1])
                            elseif self.tItems[self.iCursorPos].sType == "text" then
                            elseif self.tItems[self.iCursorPos].sType == "msgbox" then msgBox(self.tItems[self.iCursorPos].tData);
                            else rsType,rtData = self.tItems[self.iCursorPos].sType,self.tItems[self.iCursorPos].tData flag = true; break end
                        end
                    elseif id =="mouse_click" then
                        local mSel = param3/2 -1
                        if isInteger(mSel) and key == 1 and mSel <= l then  self.iCursorPos = mSel+self.iFItem -1; self.iRSel=mSel;
                            if self.tItems[self.iCursorPos].sType == "menu" then reDraw(self.tItems[self.iCursorPos].tData[1])
                            elseif self.tItems[self.iCursorPos].sType == "text" then
                            elseif self.tItems[self.iCursorPos].sType == "msgbox" then msgBox(self.tItems[self.iCursorPos].tData);
                            else rsType,rtData = self.tItems[self.iCursorPos].sType,self.tItems[self.iCursorPos].tData flag = true; break end
                        end
                    elseif id =="mouse_scroll" then
                        if key == -1 and self.iFItem > 1 then self.iFItem = self.iFItem-1 ; self.iCursorPos=self.iCursorPos-1 ; self:checkSel() ;
                        elseif key == -1 and self.iFItem == 1 and self.iCursorPos > 1 then self.iCursorPos = self.iCursorPos - 1 ; self.iRSel = self.iRSel -1 ;
                        elseif key == 1 and self.iFItem +l -1< #self.tItems then self.iCursorPos = self.iCursorPos + 1 ; self.iFItem = self.iFItem+1 ; self:checkSel() ;
                        elseif key == 1 and self.iFItem +l-1 >= #self.tItems and self.iCursorPos < #self.tItems then self.iCursorPos = self.iCursorPos + 1 ; self.iRSel = self.iRSel +1;
                        end
                    end
                else break end
            end
            return rsType, rtData
        end;
    }
    tMenu.iMenuLen = reduceMenu(h, tMenu.tOverlay.nHeadLen, tMenu.tOverlay.nFootLen)
    return tMenu
end