import math
import sys
def to_littleEndian(zahl,byte):
	return zahl.to_bytes(byte, 'little', signed=True)


def riff_header(samples, channels):
	header = b"RIFF"
	header += to_littleEndian(samples*2*channels+44-8, 4)
	header += b"WAVE"
	header += b"fmt " # Achtung Leerschlag
	header += to_littleEndian(16, 4)  # restlicher Header
	header += to_littleEndian(1, 2)  # PCM-Format
	header += to_littleEndian(channels, 2)  # 2 Kanal (stereo)
	header += to_littleEndian(44100, 4)  # Samplerate
	header += to_littleEndian(2*44100*channels, 4)  # Bytes/s
	header += to_littleEndian(2*channels, 2)  # Blocksize
	header += to_littleEndian(16, 2)  # Bits/sample
	header += b'data'
	header += to_littleEndian(samples*2*channels, 4)  # Datenblock
	return header


def sinus(t,f,a):
	return a*math.sin(math.pi*2*f*t)


if len(sys.argv)<3:
	print("Bitte zwei Frequenzen angegeben!")
	exit(-1)
f1 = float(sys.argv[1])
f2 = float(sys.argv[2])

# Rechts, Links, Links und Rechts zusammen, Beide Frequenzen überlagert und kombiniert.
zeiten = [2,2,4,4]

dauer = sum(zeiten)
with open(f"sinus_{f1}Hz_und_{f2}Hz.wav", "wb") as wav:  # b fuer binary file
	# Header ausgeben
	wav.write(riff_header(dauer*44100,2))

	# i zaehlt die Samples
	for i in range(dauer*44100):
		# reale Zeit in Sekunden
		t = i/44100.0
		sample1 = int(sinus(t,f1,15000)) if (t<zeiten[0] or t>sum(zeiten[0:2])) else 0
		sample2 = int(sinus(t,f2,15000)) if (t>zeiten[0]) else 0
		if (t>sum(zeiten[0:3])):
			sample1 = (sample1+sample2)//2
			sample2 = sample1
		wav.write(to_littleEndian(sample1, 2))
		wav.write(to_littleEndian(sample2, 2))