Googol Installer

local runningApp = "search"

local alreadyUpdated = {}

local pinwheel = {[0] = "|", "/", "-", "\\"}
local pinwheel_index = 0
function checkForUpdates(app, path, onlyIfAbsent)
    local w, h = term.getSize()
    if not alreadyUpdated[app] then
        if fs.exists(path) and onlyIfAbsent then
            return false
        end
        term.setBackgroundColor(colors.white)
        term.setTextColor(colors.blue)
        term.clear()
        http.request("http://www.googol.comli.com/data/"..app)
        pinwheel_timer = os.startTimer(0.1)
        while true do
            local event = { os.pullEvent() }
            if event[1] == "http_success" then
                newdata = event[3]:readAll()
                break
            elseif event[1] == "http_failure" then
                error("Error updating "..app, 0)
            elseif event[1] == "timer" and event[2] == pinwheel_timer then
                str = "Updating "..app
                term.setCursorPos(w/2-str:len()/2, h/2-1)
                print(str)
                term.setCursorPos(w/2, h/2+1)
                print(pinwheel[pinwheel_index])
                pinwheel_index = (pinwheel_index + 1) % (#pinwheel+1)
                pinwheel_timer = os.startTimer(0.1)
            end
        end

        local file = io.open(path or "/.googol/apps/"..app, "r")
        local currentdata
        if file then
            currentdata = file:read("*a")
            file:close()
        else
            currentdata = ""
        end

        if newdata ~= currentdata then
            local file = io.open(path or "/.googol/apps/"..app, "w")
            file:write(newdata)
            file:close()

            alreadyUpdated[app] = true
            return true
        end

        alreadyUpdated[app] = true
        return false
    end
end

if not fs.exists("/.googol") then fs.makeDir("/.googol") end
if not fs.exists("/.googol/media") then fs.makeDir("/.googol/media") end
if not fs.exists("/.googol/apps") then fs.makeDir("/.googol/apps") end
local updated = checkForUpdates("googol", shell.getRunningProgram())
checkForUpdates("api.lua", "/.googol/api.lua")
checkForUpdates("LibCompress.lua", "/.googol/LibCompress.lua", true)
checkForUpdates("logo.nfp", "/.googol/media/logo.nfp", true)
checkForUpdates("gamelogo.nfp", "/.googol/media/gamelogo.nfp", true)

if updated then
    local w, h = term.getSize()
    local str = "Googol has been updated"
    term.clear()
    term.setCursorPos(w/2-str:len()/2, h/2)
    term.setTextColor(colors.blue)
    print(str)
    sleep(3)

    shell.run(shell.getRunningProgram())

    error("", 0)
end

shell.run("/.googol/api.lua")

while true do
    checkForUpdates(runningApp, "/.googol/apps/"..runningApp)

    googol.clearButtons()
    shell.run("/.googol/apps/"..runningApp)
    local timeout = os.startTimer(0.5)

    while true do
        local event = { os.pullEvent() }
        if event[1] == "GOOGOL_APP_CHANGE" then
            runningApp = event[2]
            break
        elseif event[1] == "GOOGOL_EXIT" then
            term.clear()
            term.setCursorPos(1, 1)
            term.setTextColor(colors.yellow)
            print(os.version())
            error("", 0)
        elseif event[1] == "timer" and event[2] == timeout then
            runningApp = "search"
            break
        end
    end
end