MineOS installer

local component = require("component")
local computer = require("computer")
local os = require("os")

local gpu = component.gpu

-- Checking if computer is tough enough for such a S T Y L I S H product as MineOS
do
    local potatoes = {}

    -- GPU/screen
    if gpu.getDepth() < 8 or gpu.maxResolution() < 160 then
        table.insert(potatoes, "Tier 3 graphics card and screen");
    end

    -- RAM
    if computer.totalMemory() < 2 * 1024 * 1024 then
        table.insert(potatoes, "At least 2x tier 3.5 RAM modules");
    end

    -- HDD
    do
        local filesystemFound = false

        for address in component.list("filesystem") do
            if component.invoke(address, "spaceTotal") >= 2 * 1024 * 1024 then
                filesystemFound = true
                break
            end
        end

        if not filesystemFound then
            table.insert(potatoes, "At least tier 2 hard disk drive");
        end
    end

    -- Internet
    if not component.isAvailable("internet") then
        table.insert(potatoes, "Internet card");
    end

    -- EEPROM
    if not component.isAvailable("eeprom") then
        table.insert(potatoes, "EEPROM");
    end

    -- SORRY BRO NOT TODAY
    if #potatoes > 0 then
        print("Your computer does not meet the minimum system requirements:")

        for i = 1, #potatoes do
            print("  ⨯ " .. potatoes[i])
        end

        return
    end
end

-- Checking if installer can be downloaded from GitHub, because of PKIX errors, server blacklists, etc
do
    local success, result = pcall(component.internet.request, "https://raw.githubusercontent.com/IgorTimofeev/MineOS/master/Installer/Main.lua")

    if not success then
        if result then
            print("Download servers are unavailable: " .. tostring(result))
        else
            print("Download servers are unavailable for unknown reasons")
        end
    end

    local deadline = computer.uptime() + 5
    local message

    while computer.uptime() < deadline do
        success, message = result.finishConnect()

        if success then
            break
        else
            if message then
                break
            else
                os.sleep(0.1)
            end
        end
    end

    result.close()

    if not success then
        if message then
            if message:match("PKIX") then
                local foreground = gpu.getForeground()
                gpu.setForeground(0x00AAFF)

                print [[  __  _____  ___  ___ __________     _____ _   _____ ]]
                print [[ / / / / _ \/ _ \/ _ /_  __/ __/ __ / / _ | | / / _ |]]
                print [[/ /_/ / ___/ // / __ |/ / / _/  / // / __ | |/ / __ |]]
                print [[\____/_/  /____/_/ |_/_/ /___/  \___/_/ |_|___/_/ |_|]]
                print ""

                gpu.setForeground(foreground)
                print "The Java version you are using is VERY outdated. It won't allow you to download any files over HTTPS due to outdated SSL certificates. Here are some steps to solve this problem:"
                print "• If you're in single player mode, just get latest Java 8 release from java.com/download"
                print "• If you're using an \"unofficial\" launcher, check its settings and make sure that it uses the latest Java 8 release"
                print "• If you're seeing this on a public server, the only thing you can do is to tell server owner to update Java on his side"
            else
                print("Download servers are unavailable: " .. tostring(result))
            end
        else
            print("Download servers are unavailable for unknown reasons")
        end

        return
    end
end

-- Flashing EEPROM with tiny script that will run installer itself after reboot.
-- It's necessary, because we need clean computer without OpenOS hooks to computer.pullSignal()
component.eeprom.set([[
    local connection, data, chunk = component.proxy(component.list("internet")()).request("https://raw.githubusercontent.com/IgorTimofeev/MineOS/master/Installer/Main.lua"), ""

    while true do
        chunk = connection.read(math.huge)

        if chunk then
            data = data .. chunk
        else
            break
        end
    end

    connection.close()

    load(data)()
]])

computer.shutdown(true)