Memdia player

local songBpm = 240
local songLength = 1
local songCursor = 1
local songBeats = 0

local sp = {}
local _i = 0
for i=0, 50 do
	local p = peripheral.wrap("speaker_"..i)
	if (p ~= nil) then
	    sp[_i] = p
	    _i = _i+1
    end
end

local nextSpeaker = 0
local speakerCount = table.getn(sp)

local instrumentCount = 11
local instruments = {
    -- musical
    {["name"] = "piano", ["file"] = "block.note.harp"},
    {["name"] = "bass", ["file"] = "block.note.bass"},
    {["name"] = "bell", ["file"] = "block.note.bell"},
    {["name"] = "chime", ["file"] = "block.note.chime"},
    {["name"] = "xhylophone", ["file"] = "block.note.xylophone"},
    {["name"] = "flute", ["file"] = "block.note.flute"},
    {["name"] = "guitar", ["file"] = "block.note.guitar"},
    {["name"] = "kick", ["file"] = "block.note.basedrum"},
    {["name"] = "hat", ["file"] = "block.note.hat"},
    {["name"] = "cimbal", ["file"] = "block.sand.break"},
    {["name"] = "snare", ["file"] = "block.note.snare"},
    -- sfx
    {["name"] = "levelup", ["file"] ="entity.player.levelup"}
}

local song = {}
local patterns = {}

local currentPattern = 1
local currentSongPattern = 1
local cursor = 1
local playing = false

local playingTimer = nil
local delayedNoteTimer = nil
local delayedAllChannels = false
local delayTime = 1

local progressTimer = nil

-- Data of the current pattern
local function getCurrentNotes(time)
	local notes = patterns[currentPattern].channels[currentChannel].notes[time]
	if (notes == nil) then
		return ""
    else
    	return notes
    end
end

-- Data of the pattern for the specified channel
local function getChannelNotes(channel, time)
	local notes = patterns[currentPattern].channels[channel].notes[time]
	if (notes == nil) then
		return ""
    else
    	return notes
    end
end

-- Get an instrument by name
local function getInstrumentByName(name)
	for k, v in pairs(instruments) do
		if (v.name == name) then
			return v
		end
	end
	error("Invalid instrument name")
end

-- Get an instrument ID by name
local function getInstrumentIDByName(name)
	for i=1, instrumentCount do
		if (instruments[i].name == name) then
			return i
		end
	end
	error("Invalid instrument name")
end

-- Note character to note number
local function characterToNote(c)
    local delayed = true
    if (string.byte(c) >= 97) then
        delayed = false
    end

    if (delayed) then
        return string.byte(c)-65, delayed
    else
        return string.byte(c)-97, delayed
    end
end

-- Note number to note character
local function noteToCharacter(n, delayed)
    if (delayed) then
        return string.char(tonumber(n)+65) --Mayuscula
    else
        return string.char(tonumber(n)+97) --minuscula
    end
end

-- Pitch of a note number
local function notePitch(n)
    return math.pow(2, (n-12)/12)
end

-- Pitch of a note character
local function charPitch(c)
    return notePitch(characterToNote(c))
end

local function playSoundEffect(soundname, vol, pitch)
	sp[nextSpeaker].playSound(getInstrumentByName(soundname).file, vol, pitch)
    nextSpeaker = nextSpeaker+1
    if (nextSpeaker > speakerCount) then
        nextSpeaker = 0
    end
end

-- Play a single note number
local function playNote(inst, vol, note)
    sp[nextSpeaker].playSound(instruments[inst].file, vol, note)
    nextSpeaker = nextSpeaker+1
    if (nextSpeaker > speakerCount) then
        nextSpeaker = 0
    end
end

-- Play a string of notes
local function playBar(inst, vol, notes, delayed)
    for n=1, string.len(notes) do
        local note = string.sub(notes, n, n)
        if (delayed and string.byte(note) < 97) then -- If its delayed, play only uppercases
        	playNote(inst, vol, charPitch(note))
        elseif (not delayed and string.byte(note) >= 97) then -- If not, play only lowercases
        	playNote(inst, vol, charPitch(note))
        end
    end
end

-- Play the delayed bar
local function playCurrentBarDelayed()
	if (delayedAllChannels) then
		for i=1, instrumentCount do
			playBar(i, 1, getChannelNotes(i, delayTime), true)
		end
	else
		playBar(currentChannel, 1, getCurrentNotes(delayTime), true)
	end
end

-- Play the bar at a specified time
local function playSpecificBar(time, allChannels)
	delayTime = time
	if (allChannels) then
		for i=1, instrumentCount do
			playBar(i, 1, getChannelNotes(i, time), false)
		end
	else
		playBar(currentChannel, 1, getCurrentNotes(time), false)
	end
	delayedNoteTimer = os.startTimer(30/(songBpm*patterns[currentPattern].speed)-0.001)
	delayedAllChannels = allChannels
end

-- Play the current channel's bar currently indicated by the cursor
local function playCurrentChannelBar()
	playSpecificBar(cursor, false)
end

-- Play the every bar currently indicated by the cursor
local function playCurrentBar()
	playSpecificBar(cursor, true)
end

local function updateProgress()
    term.setCursorPos(6, 13)
    local percent = songCursor/songBeats
    local characters = math.ceil(percent*40)
    term.setBackgroundColor(colors.orange)
    term.write(string.rep(" ", characters))
    term.setBackgroundColor(colors.brown)
    term.write(string.rep(" ", 40-characters))
    term.setBackgroundColor(colors.black)
end

-- StartPlaying
local function playFromCursor()
    if (songBeats > 0) then
        playing = true
        playingTimer = os.startTimer(60/(songBpm*patterns[currentPattern].speed))
        progressTimer = os.startTimer(1)
        updateProgress()
        playCurrentBar()
        term.setCursorPos(5, 12)
        term.setTextColor(colors.lime)
        term.write(" > Play        ")
    end
end

-- StartPlaying
local function playFromStart()
    loadSong()
	cursor = 1
    songCursor = 1
	currentXOffset = 0
    playing = true
    playingTimer = os.startTimer(60/(songBpm*patterns[currentPattern].speed))
    progressTimer = os.startTimer(1)
    updateProgress()
    playCurrentBar()
    term.setCursorPos(5, 12)
    term.setTextColor(colors.lime)
    term.write("|> Play         ")
end

-- Pause
local function stop()
    playing = false
    cursor = 1
    songCursor = 1
    term.setCursorPos(5, 12)
    term.setTextColor(colors.red)
    term.write("[] Stop     ")
end

-- Pause
local function pause()
    playing = false
    term.setCursorPos(5, 12)
    term.setTextColor(colors.red)
    term.write("|| Pause    ")
end

local function newPattern()
	local p = {
    	["channels"] = {},
    	["length"] = defaultPatternLength,
    	["speed"] = 1,
    	["measure"] = defaultMeasure
	}
    for i=1, instrumentCount do
    	p.channels[i] = {
    		["notes"] = {}
		}
    end
    return p
end

local function newSong()
	song = {
		["patterns"] = {}
	}
	currentPattern = 1
	patterns[currentPattern] = newPattern()
end

-- Load song from disk
function loadSong()
	local f = fs.open("disk/memsong.txt", "r")

	local fileTitle = "unknown"
	local fileBpm = 240
	local fileSong = {}

	newSong()
	patterns = {}
    songBeats = 0

	local line = f.readLine()
	repeat
		if (line == "title") then
			fileTitle = f.readLine()
		elseif (line == "bpm") then
			fileBpm = tonumber(f.readLine())
		elseif (line == "structure") then
			local songPart = f.readLine()
			local i=1
			repeat
				fileSong[i] = tonumber(songPart)
				i = i+1
				songPart = f.readLine()
			until songPart == ""
		elseif (line == "pattern") then
			local currentPattern = tonumber(f.readLine())
			if (currentPattern ~= nil) then
				patterns[currentPattern] = newPattern()
				local pLine = f.readLine()
				repeat
					local broken = false
					if (pLine == "length") then
						patterns[currentPattern].length = tonumber(f.readLine())
					elseif (pLine == "measure") then
						patterns[currentPattern].measure = tonumber(f.readLine())
					elseif (pLine == "speed") then
						patterns[currentPattern].speed = tonumber(f.readLine())
					elseif (pLine == "notes") then
						local instrument = f.readLine()
						if (instrument ~= "") then
							repeat
								local noteString = f.readLine()
								local notes = {}
								local pointer = 1
								local spaces = 0

								for i=1, string.len(noteString) do

									local char = string.sub(noteString, i, i)

									if (tonumber(char)) then -- If the character is a number, count spaces
										spaces = spaces*10
										spaces = spaces+tonumber(char)
									else
										pointer = pointer+spaces
										if (notes[pointer] == nil) then
											notes[pointer] = ""
										end
										notes[pointer] = notes[pointer]..char
										spaces = 0
									end
								end

								patterns[currentPattern].channels[getInstrumentIDByName(instrument)].notes = notes
                                songBeats = songBeats + patterns[currentPattern].length

								instrument = f.readLine()
							until instrument == ""
							broken = true
						end
					end
					if (broken) then
						pLine = nil
					else
						pLine = f.readLine()
					end
				until pLine == "" or pLine == nil
			end
		end
		line = f.readLine()
	until line == "" or line == nil
	f.close()

	song.patterns = fileSong
	songLength = #song.patterns
	songBpm = fileBpm
	currentSongPattern = 1
	currentPattern = song.patterns[1]

    term.setCursorPos(1, 8)
    term.setTextColor(colors.yellow)
    term.write("Cancion: "..fileTitle)
end

term.clear()
term.setCursorPos(1,1)
term.setBackgroundColor(colors.black)
term.setTextColor(colors.orange)
print("~ Memdia Player ~")
print("")
print("Enter: Cargar canción / Iniciar desde el principio / Pausa")
print("Espacio: Pausa / Play")

-- Update
while true do
    local event, a, b, c = os.pullEvent()
    if (event == "timer") then
    	local completed = a
    	if (completed == playingTimer) then
	        if (playing) then
	        	local patternLength = patterns[currentPattern].length
                cursor = cursor+1
                songCursor = songCursor+1
                if (cursor > patternLength) then
                	currentSongPattern = currentSongPattern+1
                	if (currentSongPattern > songLength) then
	                	currentSongPattern = 1
                        songCursor = 1
                        updateProgress()
	                end
	                currentPattern = song.patterns[currentSongPattern]
	                cursor = 1
	                currentXOffset = 0
                end
                playCurrentBar()
                playingTimer = os.startTimer(60/(songBpm*patterns[currentPattern].speed))
	        end
	    elseif (completed == delayedNoteTimer) then
	    	playCurrentBarDelayed()
        elseif (completed == progressTimer) then
            if (playing) then
                updateProgress()
                progressTimer = os.startTimer(1)
            end
	    end
    elseif (event == "key") then
        local key = a
        if (key == keys.space) then
        	if (playing) then
        		pause()
        	else
        		playFromCursor()
        	end

        elseif (key == keys.enter) then
        	if (playing) then
        		pause()
        	else
        		playFromStart()
        	end

        end
    end
end