VienDesu! VNTools compressor implementation hint

compress.py

import typing as t
import dataclasses as dtc

from functools import reduce
from pathlib import Path

class FileIsNotSupportedError(Exception):
	def __init__(self, path: Path) -> None:
		self.path = path
		super().__init__(f"files of that kind are not supported by this compressor (path: {path})")

@dtc.dataclass(frozen=True)
class Diff:
	before: int
	now: int

	# Compression ratio
	@property
	def ratio(self) -> float:
		return self.before / self.now

class Compressor(t.Protocol):
	def __call__(self, source: Path, dest: Path) -> Diff:
		...

class Or(Compressor):
	def __init__(self, lhs: Compressor, rhs: Compressor) -> None:
		self.lhs = lhs
		self.rhs = rhs

	def __call__(self, source: Path, dest: Path) -> Diff:
		try:
			return self.lhs(source, dest)
		except FileIsNotSupportedError as lhs_exc:
			try:
				return self.rhs(source, dest)
			except FileIsNotSupportedError as rhs_exc:
				raise rhs_exc from lhs_exc

# Creates one compressor from many compressors
def alt(first: Compressor, *others: Compressor) -> Compressor:
	return reduce(Or, others, first)

compress = alt(images, videos, audio)