helper.py

"""
Helper functions.
"""

from __future__ import annotations

import logging
import os
import shutil
import sys
import tempfile
from functools import lru_cache
from io import BytesIO

import pytest
from packaging.version import parse as parse_version

from PIL import Image, ImageFile, ImageMath, features

TYPE_CHECKING = False
if TYPE_CHECKING:
    from collections.abc import Callable, Sequence
    from pathlib import Path
    from typing import Any

logger = logging.getLogger(__name__)

uploader = None
if os.environ.get("SHOW_ERRORS"):
    uploader = "show"
elif "GITHUB_ACTIONS" in os.environ:
    uploader = "github_actions"


def upload(a: Image.Image, b: Image.Image) -> str | None:
    if uploader == "show":
        # local img.show for errors.
        a.show()
        b.show()
    elif uploader == "github_actions":
        dir_errors = os.path.join(os.path.dirname(__file__), "errors")
        os.makedirs(dir_errors, exist_ok=True)
        tmpdir = tempfile.mkdtemp(dir=dir_errors)
        a.save(os.path.join(tmpdir, "a.png"))
        b.save(os.path.join(tmpdir, "b.png"))
        return tmpdir
    return None


def convert_to_comparable(
    a: Image.Image, b: Image.Image
) -> tuple[Image.Image, Image.Image]:
    new_a, new_b = a, b
    if a.mode == "P":
        new_a = Image.new("L", a.size)
        new_b = Image.new("L", b.size)
        new_a.putdata(a.get_flattened_data())
        new_b.putdata(b.get_flattened_data())
    elif a.mode == "I;16":
        new_a = a.convert("I")
        new_b = b.convert("I")
    return new_a, new_b


def assert_deep_equal(a: Any, b: Any, msg: str | None = None) -> None:
    try:
        assert len(a) == len(b), msg or f"got length {len(a)}, expected {len(b)}"
    except Exception:
        assert a == b, msg


def assert_image(
    im: Image.Image, mode: str, size: tuple[int, int], msg: str | None = None
) -> None:
    if mode is not None:
        assert im.mode == mode, (
            msg or f"got mode {repr(im.mode)}, expected {repr(mode)}"
        )

    if size is not None:
        assert im.size == size, (
            msg or f"got size {repr(im.size)}, expected {repr(size)}"
        )


def assert_image_equal(a: Image.Image, b: Image.Image, msg: str | None = None) -> None:
    assert a.mode == b.mode, msg or f"got mode {repr(a.mode)}, expected {repr(b.mode)}"
    assert a.size == b.size, msg or f"got size {repr(a.size)}, expected {repr(b.size)}"
    if a.tobytes() != b.tobytes():
        try:
            url = upload(a, b)
            if url:
                logger.error("URL for test images: %s", url)
        except Exception:
            pass

        pytest.fail(msg or "got different content")


def assert_image_equal_tofile(
    a: Image.Image,
    filename: str | Path,
    msg: str | None = None,
    mode: str | None = None,
) -> None:
    with Image.open(filename) as im:
        converted_im = im.convert(mode) if mode else im
        assert_image_equal(a, converted_im, msg)


def assert_image_similar(
    a: Image.Image, b: Image.Image, epsilon: float, msg: str | None = None
) -> None:
    assert a.mode == b.mode, msg or f"got mode {repr(a.mode)}, expected {repr(b.mode)}"
    assert a.size == b.size, msg or f"got size {repr(a.size)}, expected {repr(b.size)}"

    a, b = convert_to_comparable(a, b)

    diff = 0
    for ach, bch in zip(a.split(), b.split()):
        chdiff = ImageMath.lambda_eval(
            lambda args: abs(args["a"] - args["b"]), a=ach, b=bch
        ).convert("L")
        diff += sum(i * num for i, num in enumerate(chdiff.histogram()))

    ave_diff = diff / (a.size[0] * a.size[1])
    try:
        assert epsilon >= ave_diff, (
            (msg or "")
            + f" average pixel value difference {ave_diff:.4f} > epsilon {epsilon:.4f}"
        )
    except Exception as e:
        try:
            url = upload(a, b)
            if url:
                logger.exception("URL for test images: %s", url)
        except Exception:
            pass
        raise e


def assert_image_similar_tofile(
    a: Image.Image,
    filename: str | Path,
    epsilon: float,
    msg: str | None = None,
) -> None:
    with Image.open(filename) as img:
        assert_image_similar(a, img, epsilon, msg)


def assert_not_all_same(items: Sequence[Any], msg: str | None = None) -> None:
    assert items.count(items[0]) != len(items), msg


def timeout_unless_slower_valgrind(timeout: float) -> pytest.MarkDecorator:
    if "PILLOW_VALGRIND_TEST" in os.environ:
        return pytest.mark.pil_noop_mark()
    return pytest.mark.timeout(timeout)


def skip_unless_feature(feature: str) -> pytest.MarkDecorator:
    reason = f"{feature} not available"
    return pytest.mark.skipif(not features.check(feature), reason=reason)


def has_feature_version(feature: str, required: str) -> bool:
    version = features.version(feature)
    assert version is not None
    version_required = parse_version(required)
    version_available = parse_version(version)
    return version_available >= version_required


def skip_unless_feature_version(
    feature: str, required: str, reason: str | None = None
) -> pytest.MarkDecorator:
    version = features.version(feature)
    if version is None:
        return pytest.mark.skip(f"{feature} not available")
    if reason is None:
        reason = f"{feature} is older than {required}"
    version_required = parse_version(required)
    version_available = parse_version(version)
    return pytest.mark.skipif(version_available < version_required, reason=reason)


def mark_if_feature_version(
    mark: pytest.MarkDecorator,
    feature: str,
    version_blacklist: str,
    reason: str | None = None,
) -> pytest.MarkDecorator:
    version = features.version(feature)
    if version is None:
        return pytest.mark.pil_noop_mark()
    if reason is None:
        reason = f"{feature} is {version_blacklist}"
    version_required = parse_version(version_blacklist)
    version_available = parse_version(version)
    if (
        version_available.major == version_required.major
        and version_available.minor == version_required.minor
    ):
        return mark(reason=reason)
    return pytest.mark.pil_noop_mark()


@pytest.mark.skipif(sys.platform.startswith("win32"), reason="Requires Unix or macOS")
class PillowLeakTestCase:
    # requires unix/macOS
    iterations = 100  # count
    mem_limit = 512  # k

    def _get_mem_usage(self) -> float:
        """
        Gets the RUSAGE memory usage, returns in K. Encapsulates the difference
        between macOS and Linux rss reporting

        :returns: memory usage in kilobytes
        """

        from resource import RUSAGE_SELF, getrusage

        mem = getrusage(RUSAGE_SELF).ru_maxrss
        # man 2 getrusage:
        #     ru_maxrss
        # This is the maximum resident set size utilized
        # in bytes on macOS, in kilobytes on Linux
        return mem / 1024 if sys.platform == "darwin" else mem

    def _test_leak(self, core: Callable[[], None]) -> None:
        start_mem = self._get_mem_usage()
        for cycle in range(self.iterations):
            core()
            mem = self._get_mem_usage() - start_mem
            msg = f"memory usage limit exceeded in iteration {cycle}"
            assert mem < self.mem_limit, msg


# helpers


def fromstring(data: bytes) -> ImageFile.ImageFile:
    return Image.open(BytesIO(data))


def tostring(im: Image.Image, string_format: str, **options: Any) -> bytes:
    out = BytesIO()
    im.save(out, string_format, **options)
    return out.getvalue()


def hopper(mode: str | None = None) -> Image.Image:
    # Use caching to reduce reading from disk, but return a copy
    # so that the cached image isn't modified by the tests
    # (for fast, isolated, repeatable tests).

    if mode is None:
        # Always return fresh not-yet-loaded version of image.
        # Operations on not-yet-loaded images are a separate class of errors
        # that we should catch.
        return Image.open("Tests/images/hopper.ppm")

    return _cached_hopper(mode).copy()


@lru_cache
def _cached_hopper(mode: str) -> Image.Image:
    if mode == "F":
        im = hopper("L")
    else:
        im = hopper()
    try:
        im = im.convert(mode)
    except ImportError:
        if mode == "LAB":
            im = Image.open("Tests/images/hopper.Lab.tif")
        else:
            raise
    return im


def netpbm_available() -> bool:
    return bool(shutil.which("ppmquant") and shutil.which("ppmtogif"))


def magick_command() -> list[str] | None:
    if sys.platform == "win32":
        magickhome = os.environ.get("MAGICK_HOME")
        if magickhome:
            imagemagick = [os.path.join(magickhome, "convert.exe")]
            graphicsmagick = [os.path.join(magickhome, "gm.exe"), "convert"]
        else:
            imagemagick = None
            graphicsmagick = None
    else:
        imagemagick = ["convert"]
        graphicsmagick = ["gm", "convert"]

    if imagemagick and shutil.which(imagemagick[0]):
        return imagemagick
    if graphicsmagick and shutil.which(graphicsmagick[0]):
        return graphicsmagick
    return None


def on_ci() -> bool:
    return "CI" in os.environ


def is_big_endian() -> bool:
    return sys.byteorder == "big"


def is_ppc64le() -> bool:
    import platform

    return platform.machine() == "ppc64le"


def is_win32() -> bool:
    return sys.platform.startswith("win32")


def is_pypy() -> bool:
    return sys.implementation.name == "pypy"