memusic

local patternLength = 16
local beatLength = 4

local sp = peripheral.find("speaker")

local function pitch(note)
    return math.pow(2, (note-12)/12)
end

instruments = {
    -- musical
    ["bass"] = "block.note.bass",
    ["bassdrum"] = "block.note.bassdrum",
    ["bell"] = "block.note.bell",
    ["chime"] = "block.note.chime",
    ["flute"] = "block.note.flute",
    ["guitar"] = "block.note.guitar",
    ["hat"] = "block.note.hat",
    ["snare"] = "block.note.snare",
    ["harp"] = "block.note.harp",
    ["xylophone"] = "block.noteblock.xylophone",
    -- sfx
    ["levelup"] ="entity.player.levelup"
}

local function playNote(inst, vol, note)
    sp.playSound(instruments[inst], vol, note)
end

local notes = {
    "F#", "G ", "G#", "A ", "A#", "B ",
    "C ", "C#", "D ", "D#", "E ", "F "
}

local song = {}
local patterns = {}
local instruments = {}

local currentPattern = 0
local currentPatternData = {}
local currentChannel = 0
local currentYOffset = 0
local currentXOffset = 0
local pressingShift = false

local beatsOnScreen = math.floor(36/beatLength)
local scrW, scrH = term.getSize()

local function addCharAt(str, char, pos)
    local prev = string.sub(str, 1, pos)
    local post = string.sub(str, pos+1, string.len(str))
    return prev..char..post
end

local function replaceCharAt(str, char, pos)
    local prev = string.sub(str, 1, pos)
    local post = string.sub(str, pos+2, string.len(str))
    return prev..char..post
end

local function DrawPattern()
    local channel = currentChannel
    local pattern = currentPattern
    local xoffset = currentXOffset
    local yoffset = currentYOffset
    for _y=1, scrH-1 do
        local y = scrH-_y
        local octave = math.floor((_y+yoffset-7)/12)+1
        local n = (_y+yoffset)%12
        local c = xoffset
        term.setCursorPos(1,y+1)

        term.setBackgroundColor(colors.black)
        if (n==1 or n==3 or n==5 or n==8 or n==10) then
            term.setTextColor(colors.blue)
        else
            term.setTextColor(colors.cyan)
        end
        term.write(notes[(n-1)%12+1]..tostring(octave))

        if (n==1 or n==3 or n==5 or n==8 or n==10) then
            term.setBackgroundColor(colors.lightGray)
            term.setTextColor(colors.gray)
        else
            term.setBackgroundColor(colors.white)
            term.setTextColor(colors.lightGray)
        end
        for c=currentXOffset, math.min(patternLength-1, currentXOffset+beatsOnScreen-1) do
            if (c%4 == 0) then
                term.write("|")
            else
                term.write(",")
            end
            term.write(string.rep("_",beatLength-1))
        end
    end
    term.setCursorPos(1,1)
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.yellow)
    term.write("   ")
    local i = 1
    for c=xoffset, math.min(xoffset+beatsOnScreen-1, patternLength-1) do
        term.setCursorPos(3+i, 1)
        term.write(tonumber(c+1))
        term.write(" ")
        i = i+beatLength
    end

    term.setBackgroundColor(colors.blue)
    term.setTextColor(colors.black)
    for c=xoffset*beatLength+1, math.min(xoffset+beatsOnScreen-1, patternLength-1)*beatLength+beatLength do
        local n = currentPatternData[c]
        if (n ~= ".") then
            local x, y = musicToPixel(c, n)
            term.setCursorPos(x, y)
            term.write(" ")
        end
    end
end

local function DrawScreen()
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.white)
    DrawPattern()
end

local function scrollRight()
    if (currentXOffset < patternLength-beatsOnScreen) then
        currentXOffset = currentXOffset+1
        DrawPattern()
    end
end

local function scrollLeft()
    if (currentXOffset > 0) then
        currentXOffset = currentXOffset-1
        DrawPattern()
    end
end

local function scrollUp()
    if (currentYOffset < 26-scrH) then
        currentYOffset = currentYOffset+1
        DrawPattern()
    end
end

local function scrollDown()
    if (currentYOffset > 0) then
        currentYOffset = currentYOffset-1
        DrawPattern()
    end
end

local function loadPattern(str)
    if (str == nil) then
        for i=1, patternLength*beatLength do
            currentPatternData[i] = "."
        end
    end
end

function pixelToMusic(x, y)
    local time = x-3+currentXOffset*beatLength
    local note = scrH-y+currentYOffset
    return time, note
end

function musicToPixel(time, note)
    local x = time+3-currentXOffset*beatLength
    local y = -note+currentYOffset+scrH
    return x, y
end

local function characterToNote(c, chord)
    if (chord) then
        return string.byte(c)-65
    else
        return string.byte(c)-97
    end
end

local function noteToCharacter(n, chord)
    if (chord) then
        return string.char(n+65) --Mayuscula
    else
        return string.char(n+97) --minuscula
    end
end

local function placeNote(x, y)
    local time, note = pixelToMusic(x,y)
    playNote("harp", 1, pitch(note))

    currentPatternData[time] = note

    DrawPattern()
end

loadPattern()
playNote("levelup", 0.5, 3)
DrawScreen()

while true do
    local event, a, b, c = os.pullEvent()
    if (event == "key") then
        local key = a
        if (key == keys.up) then
            scrollUp()
        elseif (key == keys.down) then
            scrollDown()
        elseif (key == keys.left) then
            scrollLeft()
        elseif (key == keys.right) then
            scrollRight()
        elseif (key == keys.leftShift) then
            pressingShift = true
        end
    end
    if (event == "key_up") then
        local key = a
        if (key == keys.leftShift) then
            pressingShift = false
        end
    end
    if (event == "mouse_scroll") then
        local scrollDirection = a
        if (scrollDirection == 1) then
            if (not pressingShift) then
                scrollDown()
            else
                scrollRight()
            end
        else
            if (not pressingShift) then
                scrollUp()
            else
                scrollLeft()
            end
        end
    end
    if (event == "mouse_click") then
        local button = a
        local x = b
        local y = c
        if (x > 3 and x < 4+4*math.min(9, patternLength) and y > 1) then
            placeNote(x,y)
        end
    end
end