# Thanks to Jiahao Chen for this great example!

using AudioIO
import AudioIO.play

type note{S<:Real, T<:Real}
    pitch::S
    duration::T
    sustained::Bool
end

function play(A::note, samplingfreq::Real=44100, shape::Function=t->0.6sin(t)+0.2sin(2t)+.05*sin(8t))
    timesamples=0:1/samplingfreq:(A.duration*(A.sustained ? 0.98 : 0.9))
    v = Float64[shape(2π*A.pitch*t) for t in timesamples]
    if !A.sustained
        decay_length = int(length(timesamples) * 0.2)
        v[end-decay_length:end-1] = v[end-decay_length:end-1] .* linspace(1, 0, decay_length)
    end
    play(v)
    sleep(A.duration)
end

function parsevoice(melody::String; tempo=132, beatunit=4, lyrics=nothing)
    play([0]) #Force AudioIO to initialize
    lyrics_syllables = lyrics==nothing? nothing : split(lyrics)

    note_idx = 1
    oldduration = 4
    for line in split(melody, '\n')
        percent_idx = findfirst(line, '%') #Trim comment
        percent_idx == 0 || (line = line[1:percent_idx-1])
        for token in split(line)
            pitch, duration, dotted, sustained =parsetoken(token)
            duration==nothing && (duration = oldduration)
            oldduration = duration
            dotted && (duration *= 1.5)
            if lyrics_syllables!=nothing && 1<=note_idx<=length(lyrics_syllables) #Print the lyrics, omitting hyphens
                if lyrics_syllables[note_idx][end]=='-'
                    print(lyrics_syllables[note_idx][1:end-1])
                else
                    print(lyrics_syllables[note_idx], ' ')
                end
            end
            play(note(pitch, (beatunit/duration)*(60/tempo), sustained))
            note_idx += 1
        end
        println()
    end
end

function parsetoken(token::String, Atuning::Real=220)
    state = :findpitch
    pitch = 0.0
    sustain = dotted = false
    lengthbuf = Char[]
    for char in token
        if state == :findpitch
            scale_idx = findfirst('a':'g', char) + findfirst('A':'G', char)
            if scale_idx!=0
                const halfsteps = [12, 14, 3, 5, 7, 8, 10]
                pitch = Atuning*2^(halfsteps[scale_idx]/12)
                state = :findlength
            elseif char=='r'
                pitch, state = 0, :findlength
            else
                error("unknown pitch: $char")
            end
        elseif state == :findlength
            if     char == '#' ; pitch *= 2^(1/12) #sharp
            elseif char == 'b' ; pitch /= 2^(1/12) #flat
            elseif char == '\''; pitch *= 2        #higher octave
            elseif char == ',' ; pitch /= 2        #lower octave
            elseif char == '.' ; dotted = true     #dotted note
            elseif char == '~' ; sustain = true    #tied note
            else
                push!(lengthbuf, char)
                #Check for "is" and "es" suffixes for sharps and flats
                if length(lengthbuf) >= 2
                    if lengthbuf[end-1:end] == "is"
                        pitch *= 2^(1/12)
                        lengthbuf = lengthbuf[1:end-2]
                    elseif lengthbuf[end-1:end] == "es"
                        pitch /= 2^(1/12)
                        lengthbuf = lengthbuf[1:end-2]
                    end
                end
            end
        end
    end
    #finalize length
    lengthstr = convert(String, lengthbuf)
    duration = isempty(lengthstr) ? nothing : parseint(lengthstr)
    return (pitch, duration, sustain, dotted)
end

parsevoice("""
f# f# g a a g f# e d d e f# f#~ f#8 e e2
f#4 f# g a a g f# e d d e f# e~ e8 d d2
e4 e f# d e f#8~ g8 f#4 d e f#8~ g f#4 e d e a,
f#2 f#4 g a a g f# e d d e f# e~ e8 d8 d2""",
lyrics="""
Freu- de, schö- ner Göt- ter- fun- ken, Toch- ter aus E- li- - si- um!
Wir be- tre- ten feu- er- trun- ken, Himm- li- sche, dein Hei- - lig- thum!
Dei- ne Zau- ber bin den - wie- der, was die - Mo- de streng ge- theilt,
al- le mensch- en wer- den Brü- der wo dein sanf- ter Flü- - gel weilt.
""")