import math, wave, struct
SR=48000
# Proporcoes medidas nas referencias: fundamental, oitava, 3o, 4o
HARM=(1.00, 0.85, 0.10, 0.02)
TAU=0.19          # decaimento a 1/e medido
ATTACK=0.004

def note(f, dur):
    n=int(SR*dur); o=[]
    for i in range(n):
        t=i/SR
        s=sum(a*math.sin(2*math.pi*f*(k+1)*t) for k,a in enumerate(HARM))
        o.append(s*min(1.0,t/ATTACK)*math.exp(-t/TAU))
    return o

def mix(layers,total):
    b=[0.0]*total
    for off,s in layers:
        for i,v in enumerate(s):
            if off+i<total: b[off+i]+=v
    return b

def peak_rms(x, win=int(SR*0.01)):
    best=0.0
    for i in range(0,len(x)-win,win):
        seg=x[i:i+win]
        best=max(best, math.sqrt(sum(v*v for v in seg)/len(seg)))
    return best

def write(name, buf, target_rms):
    cur=peak_rms(buf)
    g=target_rms/max(1e-9,cur)
    # nao deixa estourar mesmo casando o volume da referencia
    pk=max(abs(s*g) for s in buf)
    if pk>0.97: g*=0.97/pk
    with wave.open(name,'w') as w:
        w.setnchannels(1); w.setsampwidth(2); w.setframerate(SR)
        w.writeframes(b''.join(struct.pack('<h',int(max(-1,min(1,s*g))*32767)) for s in buf))
    print(f"{name}: pico RMS {peak_rms([s*g for s in buf]):.3f}, {len(buf)/SR:.2f}s")

C4,D4,G3,G4 = 261.63, 293.66, 196.00, 392.00
GAP=int(SR*0.10)   # 100ms entre as notas, medido

# join: quinta subindo — mesmas notas da referencia
write('user_join.wav',  mix([(0,note(C4,0.55)),(GAP,note(G4,0.55))], int(SR*0.62)), 0.365)
# leave: quinta descendo
write('user_leave.wav', mix([(0,note(D4,0.55)),(GAP,note(G3,0.55))], int(SR*0.62)), 0.440)