groovy_monitor.lua

os.loadAPI("nbs") -- load the API

local function endsWith(input, endPattern)
    if input == nil or (not type(string) == string) then
        return false
    else
        local length = string.len(input)
        if endPattern == nil or (not type(endPattern) == string) then
            return false
        else
            local patternLength = string.len(endPattern)
            local inputEnd = string.sub(input, 0 - string.len(endPattern))

            if inputEnd == endPattern then
                return true
            else
                return false
            end
        end
    end
end

local function getSongNames(dirPath)
    if fs.isDir(dirPath) then
        files = fs.list(dirPath)
        songFiles = {}
        local i = 1

        for key, value in pairs(files) do
            if endsWith(value, ".nbs") then
                songFiles[i] = value
                i = i + 1
            end
        end

        return songFiles
    else
        return nil
    end
end

local function printSongLabel(monitor, text, maxLength, x, y)
    text = string.sub(text, 1, maxLength)

    for j = 0, 2, 1 do
        monitor.setCursorPos(x, y + j)
        for i = 1, maxLength + 2, 1 do
            monitor.write(" ")
        end
    end

    local shiftX = math.floor((maxLength - string.len(text)) / 2)

    monitor.setCursorPos(x + 1 + shiftX, y + 1)
    monitor.write(text)
end

local function getSelectedIdx(monitor, maxFileNameLength, pageNumber, x, y)
    if x == nil or y == nil then
        return nil
    end

    local sizeX, sizeY = monitor.getSize()
    local songsPerRow = math.floor(sizeX / (maxFileNameLength + 4))
    local songsPerColumn = math.floor(sizeY / 5)
    local songsPerPage = songsPerRow * songsPerColumn
    local shiftX = math.floor((sizeX - songsPerRow * (maxFileNameLength + 4)) / 2)
    local shiftY = math.floor((sizeY - songsPerColumn * 5) / 2)

    local col = nil
    local row = nil

    local xStart = nil
    for k = 1, songsPerRow, 1 do
        xStart = 2 + shiftX + (k-1) * (maxFileNameLength + 4)
        if x >= xStart and x <= xStart + maxFileNameLength + 2 then
            col = k
        end
    end

    local yStart = nil
    for k = 1, songsPerColumn, 1 do
        yStart = 2 + shiftY + (k - 1) * 5
        if y >= yStart and y <= yStart + 2 then
            row = k
        end
    end

    if col and row then
        local selectedIdx = (pageNumber - 1) * songsPerPage + (col - 1) * songsPerColumn + row
        return selectedIdx
    end
    return nil
end

local function updateMonitor(monitor, songFiles, maxFileNameLength, pageNumber, selectedIdx)
    monitor.clear()
    local sizeX, sizeY = monitor.getSize()
    local songsPerRow = math.floor(sizeX / (maxFileNameLength + 4))
    local songsPerColumn = math.floor(sizeY / 5)
    local songsPerPage = songsPerRow * songsPerColumn
    local firstSongIdx = 1

    if selectedIdx then
        firstSongIdx = math.floor(selectedIdx / songsPerPage) + 1
    end

    local x = 1
    local y = 1
    local shiftX = math.floor((sizeX - songsPerRow * (maxFileNameLength + 4)) / 2)
    local shiftY = math.floor((sizeY - songsPerColumn * 5) / 2)

    local defaultBgColor = colors.lightGray
    local selectedBgColor = colors.lime

    local k = 1
    for i = firstSongIdx, firstSongIdx + songsPerPage - 1, 1 do
        if i == selectedIdx then
            monitor.setBackgroundColor(selectedBgColor)
        else
            monitor.setBackgroundColor(defaultBgColor)
        end

        x = 2 + shiftX + math.floor((k - 1) / songsPerColumn) * (maxFileNameLength + 4)
        y = 2 + shiftY + ((k - 1) % songsPerColumn) * 5

        if songFiles[i] then
            printSongLabel(monitor, songFiles[i], maxFileNameLength, x, y)
        end

        k = k + 1
    end

    monitor.setBackgroundColor(colors.black)
end

local modemSide, monitorSide = ...

rednet.open(modemSide)
local monitor = peripheral.wrap(monitorSide)
monitor.setTextScale(1)
monitor.clear()

local maxFileNameLength = 16
local pageNumber = 1
local selectedIdx = nil
local selectedSong = nil

local songFiles = getSongNames("music")

updateMonitor(monitor, songFiles, maxFileNameLength, pageNumber)

while true do
    event, par1, x, y = os.pullEvent("monitor_touch")
    selectedIdx = getSelectedIdx(monitor, maxFileNameLength, pageNumber, x, y)

    if selectedIdx then
        selectedSong = songFiles[selectedIdx]
        if selectedSong then
            updateMonitor(monitor, songFiles, maxFileNameLength, pageNumber, selectedIdx)
            nbs.play("music/"..selectedSong, modemSide, 3, true)
            updateMonitor(monitor, songFiles, maxFileNameLength, pageNumber)
        end
    end
end