#!/usr/bin/env python
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"""Compares the image output of a test to the expected image output using
fuzzy matching.
"""

import errno
import logging
import os
import shutil

from layout_package import test_failures
from test_types import test_type_base

_log = logging.getLogger("webkitpy.layout_tests.test_types.fuzzy_image_diff")


class FuzzyImageDiff(test_type_base.TestTypeBase):

    def compare_output(self, filename, output, test_args, target):
        """Implementation of CompareOutput that checks the output image and
        checksum against the expected files from the LayoutTest directory.
        """
        failures = []

        # If we didn't produce a hash file, this test must be text-only.
        if test_args.hash is None:
            return failures

        expected_png_file = self._port.expected_filename(filename, '.png')

        if test_args.show_sources:
            _log.debug('Using %s' % expected_png_file)

        # Also report a missing expected PNG file.
        if not os.path.isfile(expected_png_file):
            failures.append(test_failures.FailureMissingImage(self))

        # Run the fuzzymatcher
        r = self._port.fuzzy_diff(test_args.png_path, expected_png_file)
        if r != 0:
            failures.append(test_failures.FailureFuzzyFailure(self))

        return failures
