[GraviBank] PayATM

-- Variables
local diskDrive = peripheral.wrap("bottom")

rednet.open("back")

local w, h = term.getSize()
local select = 1
local payAmount
local menustate = "select"

-- Functions

function printCentered(str, ypos)
    term.setCursorPos(w/2 - #str/2, ypos)
    term.write(str)
end

function printRight(str, ypos)
    term.setCursorPos(w - #str, ypos)
    term.write(str)
end

function printLeft(str, ypos)
    term.setCursorPos(#str, ypos)
    term.write(str)
end

function readTable(dir)
    local file = fs.open(dir, "r")
    local data = file.readAll()
    file.close()
    return textutils.unserialize(data)
end

function checkPassword(password)
    if password == nil then
        return "false"
    end
    local data = readTable("disk/userData.txt")
    local username = data.username
    rednet.broadcast({"request", {"checkPassword", username, password}}, "graviBank")
    local senderID, message = rednet.receive("graviBank")
    return message[1]
end

function hasEnoughMoney(amount)
    local data = readTable("disk/userData.txt")
    local username = data.username
    rednet.broadcast({"request", {"getBalance", username}}, "graviBank")
    local senderID, message = rednet.receive("graviBank")
    if message[1] >= amount then
        return true
    else
        return false
    end
end

-- Menus

---- Drawing menus

function drawSelect()
    printCentered("PAYMENT", h/2 - 1)

    if payAmount == nil then
        printCentered("Amount: ", h/2)
        term.setCursorPos(w/2, h/2+1)
        payAmount = read()
    else
        printCentered("Amount: ", h/2)
        printCentered(payAmount, h/2+1)
    end


    if select == 1 then
        printCentered(">CONFIRM<  CANCEL", h - 2)
    elseif  select ==2 then
        printCentered("CONFIRM  >CANCEL<", h - 2)
    end
end

function drawPassword()
    if not diskDrive.isDiskPresent() then
        printCentered("No card in the system.", h/2-1)
        printCentered("Returning to start menu.", h/2)
        os.sleep(0.5)
        os.reboot()
        return
    end

    if not hasEnoughMoney(tonumber(payAmount)) then
        printCentered("Not enough balance.", h/2)
        os.sleep(0.5)
        os.reboot()
    end

    printCentered("Password:", h/2-1)
    printCentered("__________", h/2+1)

    term.setCursorPos(w/2 - 10/2, h/2)
    local password = read("*")
    local isCorrect = checkPassword(password)

    if isCorrect[1] == "false" then
        return
    else
        menustate = "pay"
    end
end

function drawPay()
    printCentered("PAID", h/2)
end

function drawCancel()
    printCentered("CANCELLED", h/2)
end

function drawHeader()
    printCentered("GRAVIBANK ATM", 1)
    printCentered(string.rep("-", w + 1), 2)
    printRight("GraviBank system made by gravitowl.", h)
end

---- Menu state

local mopt = {
    ["select"] = {
        options = {"password", "cancel"},
        draw = drawSelect
    },
    ["cancel"] = {
        options = {"start"},
        draw = drawCancel
    },
    ["password"] = {
        options = {},
        draw = drawPassword
    },
    ["pay"] = {
        options = {"start"},
        draw = drawPay
    }
}

---- Run functions

function runMenu()
    while true do
        term.clear()
        drawHeader()
        mopt[menustate].draw()
        if #mopt[menustate].options > 0 then
            local id, key = os.pullEvent("key")
            if key == keys.up and select > 1 then select = select-1
            elseif key == keys.down and select < #mopt[menustate].options then select = select + 1
            elseif key == keys.enter then
                if mopt[menustate].options[select] == "quit" then break end
                menustate = mopt[menustate].options[select]
                select = 1
            end
        end
    end
end

runMenu()