messager.lua

local basalt = require("modules/basalt")
basalt.setTheme("LabelText", colors.red)

local player = require("player")

local main = basalt.createFrame()
    :setBackground(colors.lightBlue)

local tx, ty = term.current().getSize()

local title = main
    :addLabel()
    :setText("Message receiver")

local titleX, titleY = title.getSize()
title:setPosition(
    math.floor(tx / 2 - titleX / 2) + 1,
    math.floor(2)
):setForeground(colors.black)

local chatFrame = main:addScrollableFrame()
    :setPosition(2, 3)
    :setSize("parent.w - 2", "parent.h - 4")
    :setBackground(colors.black)

local chatFrameX, chatFrameY = chatFrame:getSize()

local noMessagesText = chatFrame
    :addLabel()
    :setText("No messages found")
    :setBackground(colors.black)
    :setForeground(colors.red)

local noMessageX, noMessageY = noMessagesText
    :getSize()

noMessagesText:setPosition(
    math.floor(chatFrameX / 2 - noMessageX / 2) + 1,
    math.floor(chatFrameY / 2 + 1)
)

local current = 1
local CFWidth, CFHeight = chatFrame.getSize()

function showMessage(id, message)
    noMessagesText:hide()
    local from = ""
    local textColor = colors.red
    if not id then
        from = "You: "
        textColor = colors.blue
    else
        from = "ID_" .. id .. ": "
        textColor = colors.green
        player.playNotice()
    end
    chatFrame
        :addLabel()
        :setPosition(1, current)
        :setBackground(colors.black)
        :setForeground(textColor)
        :setText(from .. message)
    if current > CFHeight then
        chatFrame:setOffset(0, current - CFHeight)
    end
    current = current + 1
end
basalt.onEvent(function(event, client, message)
    if event == "rednet_message" then
        showMessage(client, message)
    end
end)

local input = main
    :addInput()
    :setBackground(colors.gray)
    :setForeground(colors.lightBlue)
    :setDefaultText("Send message")
    :setPosition(2, ty - 1)
    :setSize("parent.w - 2", 1)
    :onLoseFocus(function(self)
        local message = self:getValue()
        if message and message ~= "" then
            showMessage(nil, message)
            rednet.broadcast(message)
        end
        self:setValue("")
    end)

basalt.autoUpdate()