local computer=require("computer")

local note={}

local notes={}

local reverseNotes={}

do

local tempNotes={
"c",
"c#",
"d",
"d#",
"e",
"f",
"f#",
"g",
"g#",
"a",
"a#",
"b"
}

local sNotes={}

local bNotes={}


do
table.insert(sNotes,"a0")
table.insert(sNotes,"a#0")
table.insert(bNotes,"bb0")
table.insert(sNotes,"b0")
for i=1,6 do
for _,v in ipairs(tempNotes)do
table.insert(sNotes,v..tostring(i))
if#v==1 and v~="c"and v~="f"then
table.insert(bNotes,v.."b"..tostring(i))
end
end
end
end
for i=21,95 do
notes[sNotes[i-20]]=tostring(i)
end


do
for k,v in pairs(notes)do
reverseNotes[tonumber(v)]=k
end
end


for k,v in ipairs(bNotes)do
notes[v]=tostring(notes[string.gsub(v,"(.)b(.)","%1%2")]-1)
end
end


function note.midi(n)
if type(n)=="string"then
n=string.lower(n)
if tonumber(notes[n])~=nil then
return tonumber(notes[n])
else
error("Wrong input "..tostring(n).." given to note.midi, needs to be <note>[semitone sign]<octave>, e.g. A#0 or Gb4")
end
elseif type(n)=="number"then
return math.floor((12*math.log(n/440,2))+69)
else
error("Wrong input "..tostring(n).." given to note.midi, needs to be a number or a string")
end
end


function note.freq(n)
if type(n)=="string"then
n=string.lower(n)
if tonumber(notes[n])~=nil then
return math.pow(2,(tonumber(notes[n])-69)/12)*440
else
error("Wrong input "..tostring(n).." given to note.freq, needs to be <note>[semitone sign]<octave>, e.g. A#0 or Gb4",2)
end
elseif type(n)=="number"then
return math.pow(2,(n-69)/12)*440
else
error("Wrong input "..tostring(n).." given to note.freq, needs to be a number or a string",2)
end
end


function note.name(n)
n=tonumber(n)
if reverseNotes[n]then
return string.upper(string.match(reverseNotes[n],"^(.)"))..string.gsub(reverseNotes[n],"^.(.*)","%1")
else
error("Attempt to get a note for a non-exsisting MIDI code",2)
end
end


function note.ticks(n)
if type(n)=="number"then
if n>=0 and n<=24 then
return n+34
elseif n>=34 and n<=58 then
return n-34
else
error("Wrong input "..tostring(n).." given to note.ticks, needs to be a number [0-24 or 34-58]",2)
end
else
error("Wrong input "..tostring(n).." given to note.ticks, needs to be a number",2)
end
end


function note.play(tone,duration)
computer.beep(note.freq(tone),duration)
end

return note