NSP Banking system

local accounts = textutils.unserializeJSON(fs.open("bank_accounts/accounts.json", "r").readAll())
local tanks = {peripheral.wrap("left"), peripheral.wrap("right")}
local modem = peripheral.wrap("back")

modem.callRemote("redrouter_2", "setOutput", "right", false)
modem.callRemote("redrouter_2", "setOutput", "top", false)

local function find_user(user)
    for ID, account in pairs(accounts) do
        if account.username == user then
            return ID
        end
    end

    return false
end

local function reset()
    term.clear()
    term.setCursorPos(1,1)
end

local function search(str,substr)
    return string.find(string.lower(str), substr)
end

local function get_tank()
    local exp = 0

    for _, tank in pairs(tanks) do
        if tank.tanks()[1] == nil then
            break;
        end

        exp = exp + tank.tanks()[1].amount

    end

    return exp
end

local function get_big_tank()
    local tank = modem.callRemote("create:fluid_tank_0", "tanks")

    if tank[1] == nil then
        return 0
    end

    return tank[1].amount
end

local function empty()
    modem.callRemote("redrouter_2", "setOutput", "right", true)

    reset()

    write("Emptying..")

    repeat
        os.sleep(1)
    until get_tank() == 0

    modem.callRemote("redrouter_2", "setOutput", "right", false)

    write("\nEmpty!")

    os.sleep(2)
end

local function shower(amount)
    modem.callRemote("redrouter_2", "setOutput", "top", true)

    local current = get_big_tank()
    local goal = get_big_tank() - amount

    repeat
        current = get_big_tank()
        print(current, goal)
        os.sleep(1)
    until current <= goal

    modem.callRemote("redrouter_2", "setOutput", "top", false)
end

local function select_action(account)
    reset()

    local username = accounts[account].username
    local experience = accounts[account].amount

    write("LOGGED IN AS: \""..username.."\"\nPlease input one of the following letters to select an action:\nW: Withdraw Experience\nD: Deposit Experience\nI: See account information\nC: Cancel\n")

    local input = read()

    if search(input,"i") then
        reset()
        write("THE ACCOUNT \""..username.."\" HAS "..experience.." EXPERIENCE POINTS.")

        os.sleep(5)
    elseif search(input,"d") then
        reset()

        local function update_screen()
            local last = get_tank()

            reset()
            write("Press enter to deposit\nCurrent amount: "..last.." experience points")

            while true do
                local current = get_tank()

                if current ~= last then
                    reset()
                    write("Press enter to deposit\nCurrent amount: "..current.." experience points")
                end

                os.sleep(0.05)
            end
        end

        local function wait_for_enter()
            repeat
                local _, key = os.pullEvent("key")
            until key == keys.enter
        end

        parallel.waitForAny(update_screen, wait_for_enter)

        local to_add = get_tank()

        empty()

        reset()
        write(to_add.." experience points successfully deposited to \""..username.."\"")

        accounts[account].amount = accounts[account].amount + to_add

        os.sleep(5)
    elseif search(input, "w") then
        reset()
        write("Please Input how much experience you\'d like to withdraw: ")

        local amount = tonumber(io.read())

        if accounts[account].amount - amount < 0 then
            write("Nice try, you do not have the funds for such a withdrawal.")
            os.sleep(5)
            return
        end

        shower(amount)

        accounts[account].amount = accounts[account].amount - amount

        reset()
        write(amount.." experience points successfully withdrawn from \""..username.."\"")

        os.sleep(5)
    elseif search(input, "c") then
    else
        select_action(account)
    end
end

local function login(input, account, attempt)

    if input == accounts[account].password then
        select_action(account)
    elseif attempt ~= 3 then

        write("\nINCORRECT PASSWORD, TRY AGAIN ("..attempt.."/3): ")

        login(read("*"), account, attempt + 1)
    end

end

local function create(user)
    reset()
    write("Create a password: ")
    local pwd = read("*")

    table.insert(accounts, {username = user, password = pwd, amount = 0})

    reset()
    write("Account successfully created!")

    os.sleep(3)
end

local function main_loop()

    reset()

    write("NPS EXP BANKING SYSTEM.\n\n\nUSERNAME: ")

    local username = read("*")
    local account = find_user(username)

    if account then
        write("\nPASSWORD: ")

        login(read("*"), account, 1)
    else
        reset()
        write("There is no account with the username \""..username.."\" would you like to create an account with that username? (Y/N): ")

        local input = read()

        if search(input, "y") then
            create(username)
        elseif not search(input, "n") then
            reset()
            write("There is no account with the username \""..username.."\" would you like to create an account with that username? (Y/N)")
        end

    end

    local t = fs.open("bank_accounts/accounts.json", "w+")
    t.write(textutils.serialiseJSON(accounts))
    t.close()

    main_loop()

end

main_loop()