osu! beatmap speed scaler

beatmapScaler.py

#change this
path='C:\\Users\\pavlukivan\\AppData\\Local\\osu!\\Songs\\328117 Kurokotei - Galaxy Collapse\\Kurokotei - Galaxy Collapse (Sayaka-) [Oni].osu'
outPath='C:\\Users\\pavlukivan\\AppData\\Local\\osu!\\Songs\\Custom Collapse\\Kurokotei - Galaxy Collapse (Sayaka-) [Oni].osu'
newSpeed = 0.5

class OsuFile:
	SECTION_DICT = 0
	SECTION_DICT_NO_SPACE = 1
	SECTION_TUPLES = 2
	SECTION_OBJECTS = 3
	SECTION_TIMINGS = 4
	SECTION_RAW = 5
	
	SECTION_TYPES = {
		'General': SECTION_DICT,
		'Editor': SECTION_DICT,
		'Metadata': SECTION_DICT_NO_SPACE,
		'Difficulty': SECTION_DICT_NO_SPACE,
		'Events': SECTION_TUPLES,
		'TimingPoints': SECTION_TIMINGS,
		'HitObjects': SECTION_OBJECTS
	}
	
	def __init__(self, path):
		self.path = path
		with open(path, 'rb') as f:
			d = f.read().decode('utf-8')
		
		self.lines = [l.strip() for l in d.split('\n') if not l.startswith('//')]
		self.data = {}
		
		n = -1
		i = 0
		while n != 0:
			n = self.loadSectionAtPos(i)
			i += n
	
	def loadSectionAtPos(self, i):
		if i >= len(self.lines):
			return 0
		if len(self.lines[i]) == 0:
			return 1
		if not self.lines[i].startswith('['):
			if self.lines[i].startswith('osu file format v'):
				self.data['Version'] = self.lines[i][17:]
				return 2
			else:
				raise ValueError(f'Invalid section at index {i}')
		name = self.lines[i][1:-1]
		self.data[name] = {}
		values = []
		i += 1
		while len(self.lines[i]) > 0:
			values.append(self.lines[i])
			i += 1
		type = self.SECTION_TYPES[name] if name in self.SECTION_TYPES.keys() else self.SECTION_RAW
		if type in [self.SECTION_DICT, self.SECTION_DICT_NO_SPACE]:
			sep = (': ' if type is self.SECTION_DICT else ':')
			values = [v.split(sep, 1) for v in values]
			for k,v in values:
				self.data[name][k] = v
			return len(values)+2
		elif type in [self.SECTION_TUPLES, self.SECTION_OBJECTS, self.SECTION_TIMINGS]:
			values = [v.split(',') for v in values]
			if type is self.SECTION_OBJECTS:
				for i in range(len(values)):
					values[i][-1] = values[i][-1].split(':')
			self.data[name] = [tuple(v) for v in values]
			return len(values)+2
		elif type == self.SECTION_RAW:
			self.data[name] = values
			return len(values)
	
	def save(self):
		d = ['osu file format v', self.data['Version'], '\n']
		
		d.append('\n[General]\n')
		for k,v in self.data['General'].items():
			d.append(k)
			d.append(': ')
			d.append(v)
			d.append('\n')
		
		d.append('\n[Editor]\n')
		for k,v in self.data['Editor'].items():
			d.append(k)
			d.append(': ')
			d.append(v)
			d.append('\n')
		
		d.append('\n[Metadata]\n')
		for k,v in self.data['Metadata'].items():
			d.append(k)
			d.append(':')
			d.append(v)
			d.append('\n')
		
		d.append('\n[Difficulty]\n')
		for k,v in self.data['Difficulty'].items():
			d.append(k)
			d.append(':')
			d.append(v)
			d.append('\n')
		
		d.append('\n[Events]\n')
		for v in self.data['Events']:
			d.append(','.join(v))
			d.append('\n')
		
		d.append('\n[TimingPoints]\n')
		for v in self.data['TimingPoints']:
			d.append(','.join(v))
			d.append('\n')
		
		if 'Colours' in self.data.keys():
			d.append('\n[Colours]\n')
			for v in self.data['Colours']:
				d.append(v)
				d.append('\n')
		
		d.append('\n[HitObjects]\n')
		for v in self.data['HitObjects']:
			v = (*v[:-1], ':'.join(v[-1]))
			d.append(','.join(v))
			d.append('\n')
		
		d.append('\n')
		d = ''.join(d).encode('utf-8')
		
		with open(self.path, 'wb') as f:
			f.write(d)

#increase song speed by n times
def scaleFile(o, n):
	m = 1 / n
	def scaleByKey(d, k, n, t=int):
		d[k] = str(t(t(d[k]) * n))
	def scaleIfExists(d, k, n, t=int):
		if k in d.keys():
			d[k] = str(t(t(d[k]) * n))
	scaleIfExists(o.data['General'], 'AudioLeadIn', m)
	scaleIfExists(o.data['General'], 'PreviewTime', m)
	#todo editor stuff. Not really useful tho
	
	#OD cant be scaled perfectly, so 300 notes are use to determine hit windows
	
	scaleIfExists(o.data['Difficulty'], 'SliderMultiplier', n, float)
	OD = float(o.data['Difficulty']['OverallDifficulty'])
	
	if OD >= 13.33333333333333333333:
		pass #300s cant even be done so it would only get worse, do nothing
	else:
		OD = max((-40+6*OD)/3, 0)
	
	o.data['Difficulty']['OverallDifficulty'] = str(OD)
	
	for i in range(len(o.data['Events'])):
		e=list(o.data['Events'][i])
		if e[0] == 2: #break
			scaleByKey(e, 1, m)
			scaleByKey(e, 2, m)
			o.data['Events'][i] = tuple(e)
	
	for i in range(len(o.data['TimingPoints'])):
		t = list(o.data['TimingPoints'][i])
		scaleByKey(t, 0, m)
		#if float(t[1]) >= 0.0: # SV
		#	scaleByKey(t, 1, m, float)
		o.data['TimingPoints'][i] = tuple(t)
	
	for i in range(len(o.data['HitObjects'])): 
		h = list(o.data['HitObjects'][i])
		
		scaleByKey(h, 2, m) #time
		if int(h[3]) & 8: #spinner
			scaleByKey(h, 5, m) #end time
		
		o.data['HitObjects'][i] = tuple(h)
	
	o.data['Metadata']['Title'] += f' {n}x speed'
	o.data['Metadata']['TitleUnicode'] += f' {n}x speed'
	del o.data['Metadata']['BeatmapID']
	del o.data['Metadata']['BeatmapSetID']
	
	pathEnd = '['+o.path.split('[')[-1]
	pathBeginning = o.path[:-len(pathEnd)]
	o.path = f'{pathBeginning} {n}x speed {pathEnd}'
	
	afn = o.data['General']['AudioFilename']
	aExt = afn[::-1].split('.', 1)[0][::-1]
	aBeginning = afn[:-len(aExt)-1]
	o.data['General']['AudioFilename'] = f'{aBeginning} {n}.{aExt}'

o=OsuFile(path)
o.path = outPath
scaleFile(o, newSpeed)
o.save()