Sample OS

--[[
     This program was made by solely by remiX for users
     that are wanting to make/design their own 'OS'. This
     can be used as an example/sample for themselves.
     This program is freeware and credits is required if
     used in anyway.
--]]

--[[ Variables ]] --
screenX, screenY = term.getSize()
mainProg = true
showTime = true

-- Tables
-- t_osStuff table contains the stuff that will appear on the desktop
t_osStuff = {
    {text = "-------", option = "startMenu", x = 1, y = screenY - 1, textCol = colours.black, bgCol = colours.blue},
    {text = "|Start|", option = "startMenu", x = 1, y = screenY, textCol = colours.black, bgCol = colours.blue}
}
-- t_startMenu is the stuff that will appear for when start is clicked,
-- Also contains the other stuff within it, like the help and programs menu.
t_startMenu = {
    ["main"] = {
        {text = "Programs", option = "programsMenu", x = 2, y = 11, textCol = colours.black, bgCol = colours.white},
        {text = "Help", option = "helpMenu", x = 2, y = 12, textCol = colours.black, bgCol = colours.white},
        {text = "Reboot", option = function() os.reboot() end, x = 13, y = 17, textCol = colours.white, bgCol = colours.black}
    },
    ["helpMenu"] = {
        textCol = colours.black,
        bgCol = colours.white,
        mainText = "Help",
        text = {
            "first",
            "Second line of help",
            "Third line of help",
            "Third line of help",
            "First line of help",
            "Second line of help",
            "Third line of help",
            "Third line of help",
            "First line of help",
            "Second line of help",
            "Third line of help",
            "Third line of help",
            "First line of help",
            "Second line of help",
            "Third line of help",
            "Third line of help",
            "First line of help",
            "Second line of help",
            "Third line of help",
            "Third line of help",
            "First line of help",
            "Second line of help",
            "3rd last",
            "2nd last",
            "last"
        }
    },
    ["programsMenu"] = {
        textCol = colours.black,
        bgCol = colours.white,
        mainText = "Programs",
        startX = 3,
        startY = 3,
        programs = {
            {text = "MineSweeper", path = "progs/minesweeper"},
            {text = "Thunderbird", path = "progs/thunderbird"},
            {text = "Lightshot", path = "progs/lightshot"},
            {text = "CCiri", path = "games/cciri"},
        }
    }
}

--[[ Functions ]] --

--[[ isValidMouseClick function:
    Takes: table, which key to return within that table, x value
           and y value.
    Returns: true if valid click for that table with the key,
             false and nil if not.
    Basically, it loops through a specified table and checks to see
    if the specified x and y values match up with the ones with the
    table plus the length of the text for precision.
--]]
function isValidMouseClick(_table, _returnKey, mx, my)
    for _, v in pairs(_table) do
        if mx >= v.x and mx < v.x + #v.text
        and my == v.y then
            return true, v[_returnKey]
        end
    end
    return false, nil
end

--[[ popupMenu function is used when you rightclick
     while at the desktop for a list of options to
     pop up.
     Takes: x and y values, background colour, text
            colour and the arguments (which are the
            options)
     Returns: the selected option
--]]

function popupMenu(x, y, _bgColour, _textColour, ...)
    bgCol = _bgColour or colours.black
    textCol = _textColour or colours.white
    local args = {...}
    l = 0
    for i = 1, #args do
        if l < #args[i] then
            l = (#args[i] + 4)
        end
    end
    local objects = {}
    local bMenuDown = (y + 3 + #args) <= screenY
    local bMenuRight = (x + l - 2) <= screenX
    startX = bMenuRight and x or (x - l + 2)
    startY = bMenuDown and y or (y - (#args + 1))
    for i,v in pairs(args) do
        objects[i] = {
            x = startX + 1;
            y = i + startY;
            text = v;
            }
    end
    term.setBackgroundColour(bgCol)
    term.setCursorPos(startX-1, startY)
    write(string.rep(" ", l))
    term.setCursorPos(startX-1, startY+#objects+1)
    write(string.rep(" ", l))
    term.setTextColour(textCol)
    for _, option in pairs(objects) do
        term.setCursorPos(startX - 1, option.y)
        write(string.rep(" ", l))
        term.setCursorPos(option.x, option.y)
        term.write(option.text)
    end
    local _, button, mx, my = os.pullEvent('mouse_click')
    return isValidMouseClick(objects, "text", mx, my)
end

--[[ drawMainOS function is for drawing the desktop
     of the program with all the colours etc.
--]]

function drawMainOS()
    term.setBackgroundColour(colours.grey)
    term.clear()
    sTime = textutils.formatTime(os.time(), false)
        term.setCursorPos(screenX - #sTime - 2, 1)
    term.setTextColour(colours.white)
    write(sTime)
    term.setCursorPos(3, 1)
    term.setTextColour(colours.lightBlue)
    write("Sample OS")
    term.setBackgroundColour(colours.red)
    term.setCursorPos(1, 2)
    write(string.rep(" ", screenX))
    term.setCursorPos(1, screenY - 1)
    write(string.rep(" ", screenX))
    term.setCursorPos(1, screenY)
    write(string.rep(" ", screenX))
    for _, tab in pairs(t_osStuff) do
        term.setCursorPos(tab.x, tab.y)
        term.setTextColour(tab.textCol)
        term.setBackgroundColour(tab.bgCol)
        write(tab.text)
    end
end

--[[ MC_time function for the time at the
     top right
--]]
function MC_time()
    while true do
        if showTime then
            sTime = textutils.formatTime(os.time(), false)
            term.setCursorPos(screenX - #sTime - 2, 1)
            term.setTextColour(colours.white)
            term.setBackgroundColour(colours.grey)
            write(sTime)
            sleep(1)
        else sleep(5) end
    end
end

local function cWrite(...)
  local curColor
  for i=1, #arg do -- arg is ...
    if type(arg[i]) == 'number' then
      curColor = arg[i]
    else
      if curColor then
        term.setTextColor(curColor)
      end
      write(arg[i])
    end
  end
end

--[[ startMenu function is for when the bottom
     left is clicked (the start button). This
     displays various things, such as 'Programs',
     'Help', and 'Reboot' and all do their own thing.
--]]

function startMenu()
    for y = 10, screenY - 2 do
        for x = 1, 20 do
            term.setBackgroundColour( (x >= 1 and x <= 10) and colours.white or colours.black)
            term.setCursorPos(x, y)
            write(" ")
        end
    end
    term.setBackgroundColour(colours.white)
    for _, tab in pairs(t_startMenu["main"]) do -- prints all text for the start menu
        term.setCursorPos(tab.x, tab.y)
        term.setTextColour(tab.textCol)
        term.setBackgroundColour(tab.bgCol)
        write(tab.text)
    end
    --[[ This loop waits for a click within the start-up
        menu. It waits until a click is performed on one
        of the options or if the click is outside the menu,
        which it thens returns to the main OS screen.
        If an option is clicked, it then performs that
        option
    --]]
    local running = true
    while running do
        local _, button, x, y = os.pullEventRaw("mouse_click")
        bValidClick, option = isValidMouseClick(t_startMenu["main"], "option", x, y)
        if bValidClick then
            if type(option) == "function" then
                option()
            else
                term.setBackgroundColour(t_startMenu[option].bgCol)
                term.clear()
                term.setBackgroundColour(colours.red)
                term.setCursorPos(screenX, 1)
                write("X")
                term.setBackgroundColour(colours.grey)
                term.setCursorPos(1, 1)
                write(string.rep(" ", screenX-1))
                term.setTextColour(colours.lightBlue)
                term.setCursorPos(2, 1)
                write(t_startMenu[option].mainText)
                if option == "programsMenu" then
                    local yPos = 1
                    while true do
                        for i = 3, screenY do
                            term.setBackgroundColour(t_startMenu["programsMenu"].bgCol)
                            term.setCursorPos(t_startMenu["programsMenu"].startX, i)
                            if t_startMenu["programsMenu"].programs[yPos + i - 3] then
                                term.clearLine()
                                cWrite(colours.red, "[", colours.yellow, "RUN", colours.red, "]  ", t_startMenu["programsMenu"].textCol, t_startMenu["programsMenu"].programs[yPos + i - 3].text)
                            else break end
                        end
                        ev, button, x, y = os.pullEvent()
                        if ev == "mouse_scroll" then
                            if button == -1 and yPos > 1 then
                                yPos = yPos - 1
                            elseif button == 1 and yPos < (#t_startMenu["programsMenu"].programs - (screenY - 3)) then
                                yPos = yPos + 1
                            end
                        elseif ev == "mouse_click" then
                            if button == 1 and x == screenX and y == 1 then
                                running = false
                                break
                            elseif button == 1 and x >= 3 and x <= 7 and y >= 3 then
                                showTime = false
                                term.setBackgroundColour(colours.black) term.setTextColour(colours.white) term.clear()
                                sleep(1)
                                if fs.exists(t_startMenu["programsMenu"].programs[y + yPos - 3].path) then
                                    shell.run(t_startMenu["programsMenu"].programs[y + yPos - 3].path)
                                else
                                    error("Invalid file: " .. t_startMenu["programsMenu"].programs[y + yPos - 3].path)
                                end
                                running = false
                                showTime = true
                                break
                            end
                        end
                    end
                else
                    local scroll = option == "helpMenu"
                    if scroll then
                        local yPos = 1
                        while true do
                            term.setTextColour(t_startMenu[option].textCol)
                            term.setBackgroundColour(t_startMenu[option].bgCol)
                            for i = 2, screenY do
                                term.setCursorPos(1, i)
                                term.clearLine()
                                if not t_startMenu[option].text[yPos + i - 2] then break
                                else write(t_startMenu[option].text[yPos + i - 2]) end
                            end
                            local ev, button, x, y = os.pullEvent()
                            if ev == "mouse_scroll" then
                                if button == -1 and yPos > 1 then
                                    yPos = yPos - 1
                                elseif button == 1 and yPos <= (#t_startMenu[option].text - (screenY - 4)) then
                                    yPos = yPos + 1
                                end
                            elseif ev == "mouse_click" then
                                if button == 1 and x == screenX and y == 1 then
                                    running = false
                                    break
                                end
                            end
                        end
                    end
                end
            end
        else
            if not (x >= 1 and x <= 20 and y >= 10 and y <= screenY - 2) then
                running = false
            end
        end
    end
end

function main()
    while mainProg do
        drawMainOS()
        e = {os.pullEventRaw()}
        if e[1] == "mouse_click" then
            if e[2] == 2 and e[4] >= 3 and e[4] <= screenY - 2 then -- brings up Popup menu
                bValidClick, option = popupMenu(e[3], e[4], colours.black, colours.lightBlue, "Option1", "Option2", "Option3")
                --[[ Add an if, elseif, end statement here for
                     each option and what it must do
                --]]
            elseif e[2] == 1 then
                bMouseClick, option = isValidMouseClick(t_osStuff, "option", e[3], e[4]) -- checks to see if the position clicked is a valid area
                if bMouseClick then
                    if option == "startMenu" then
                        startMenu()
                    end
                end
            end
        elseif e[1] == "terminate" then
            term.setCursorPos(1, 1)
            term.setBackgroundColour(colours.black)
            term.clear()
            term.setTextColour(colours.red)
            print("Terminated\n")
            term.setTextColour(colours.white)
            mainProg = false
        end
    end
end

if not term.isColor() then
    print("This program requires an advanced computer.")
    return
end

parallel.waitForAny(main, MC_time)