#!/usr/bin/env python
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"""Defines the interface TestTypeBase which other test types inherit from.

Also defines the TestArguments "struct" to pass them additional arguments.
"""

from __future__ import with_statement

import codecs
import cgi
import errno
import logging
import os.path

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


class TestArguments(object):
    """Struct-like wrapper for additional arguments needed by
    specific tests."""
    # Whether to save new baseline results.
    new_baseline = False

    # Path to the actual PNG file generated by pixel tests
    png_path = None

    # Value of checksum generated by pixel tests.
    hash = None

    # Whether to use wdiff to generate by-word diffs.
    wdiff = False

# Python bug workaround.  See the wdiff code in WriteOutputFiles for an
# explanation.
_wdiff_available = True


class TestTypeBase(object):

    # Filename pieces when writing failures to the test results directory.
    FILENAME_SUFFIX_ACTUAL = "-actual"
    FILENAME_SUFFIX_EXPECTED = "-expected"
    FILENAME_SUFFIX_DIFF = "-diff"
    FILENAME_SUFFIX_WDIFF = "-wdiff.html"
    FILENAME_SUFFIX_PRETTY_PATCH = "-pretty-diff.html"
    FILENAME_SUFFIX_COMPARE = "-diff.png"

    def __init__(self, port, root_output_dir):
        """Initialize a TestTypeBase object.

        Args:
          port: object implementing port-specific information and methods
          root_output_dir: The unix style path to the output dir.
        """
        self._root_output_dir = root_output_dir
        self._port = port

    def _make_output_directory(self, filename):
        """Creates the output directory (if needed) for a given test
        filename."""
        output_filename = os.path.join(self._root_output_dir,
            self._port.relative_test_filename(filename))
        self._port.maybe_make_directory(os.path.split(output_filename)[0])

    def _save_baseline_data(self, filename, data, modifier, encoding,
                            generate_new_baseline=True):
        """Saves a new baseline file into the port's baseline directory.

        The file will be named simply "<test>-expected<modifier>", suitable for
        use as the expected results in a later run.

        Args:
          filename: path to the test file
          data: result to be saved as the new baseline
          modifier: type of the result file, e.g. ".txt" or ".png"
          encoding: file encoding (none, "utf-8", etc.)
          generate_new_baseline: whether to enerate a new, platform-specific
            baseline, or update the existing one
        """

        if generate_new_baseline:
            relative_dir = os.path.dirname(
                self._port.relative_test_filename(filename))
            baseline_path = self._port.baseline_path()
            output_dir = os.path.join(baseline_path, relative_dir)
            output_file = os.path.basename(os.path.splitext(filename)[0] +
                self.FILENAME_SUFFIX_EXPECTED + modifier)
            self._port.maybe_make_directory(output_dir)
            output_path = os.path.join(output_dir, output_file)
            _log.debug('writing new baseline result "%s"' % (output_path))
        else:
            output_path = self._port.expected_filename(filename, modifier)
            _log.debug('resetting baseline result "%s"' % output_path)

        self._port.update_baseline(output_path, data, encoding)

    def output_filename(self, filename, modifier):
        """Returns a filename inside the output dir that contains modifier.

        For example, if filename is c:/.../fast/dom/foo.html and modifier is
        "-expected.txt", the return value is
        c:/cygwin/tmp/layout-test-results/fast/dom/foo-expected.txt

        Args:
          filename: absolute filename to test file
          modifier: a string to replace the extension of filename with

        Return:
          The absolute windows path to the output filename
        """
        output_filename = os.path.join(self._root_output_dir,
            self._port.relative_test_filename(filename))
        return os.path.splitext(output_filename)[0] + modifier

    def compare_output(self, port, filename, output, test_args, configuration):
        """Method that compares the output from the test with the
        expected value.

        This is an abstract method to be implemented by all sub classes.

        Args:
          filename: absolute filename to test file
          output: a string containing the output of the test
          test_args: a TestArguments object holding optional additional
              arguments
          configuration: Debug or Release

        Return:
          a list of TestFailure objects, empty if the test passes
        """
        raise NotImplementedError

    def _write_into_file_at_path(self, file_path, contents, encoding):
        """This method assumes that byte_array is already encoded
        into the right format."""
        open_mode = 'w'
        if encoding is None:
            open_mode = 'w+b'
        with codecs.open(file_path, open_mode, encoding=encoding) as file:
            file.write(contents)

    def write_output_files(self, filename, file_type,
                           output, expected, encoding,
                           print_text_diffs=False):
        """Writes the test output, the expected output and optionally the diff
        between the two to files in the results directory.

        The full output filename of the actual, for example, will be
          <filename>-actual<file_type>
        For instance,
          my_test-actual.txt

        Args:
          filename: The test filename
          file_type: A string describing the test output file type, e.g. ".txt"
          output: A string containing the test output
          expected: A string containing the expected test output
          print_text_diffs: True for text diffs. (FIXME: We should be able to get this from the file type?)
        """
        self._make_output_directory(filename)
        actual_filename = self.output_filename(filename, self.FILENAME_SUFFIX_ACTUAL + file_type)
        expected_filename = self.output_filename(filename, self.FILENAME_SUFFIX_EXPECTED + file_type)
        # FIXME: This function is poorly designed.  We should be passing in some sort of
        # encoding information from the callers.
        if output:
            self._write_into_file_at_path(actual_filename, output, encoding)
        if expected:
            self._write_into_file_at_path(expected_filename, expected, encoding)

        if not output or not expected:
            return

        if not print_text_diffs:
            return

        # Note: We pass encoding=None for all diff writes, as we treat diff
        # output as binary.  Diff output may contain multiple files in
        # conflicting encodings.
        diff = self._port.diff_text(expected, output, expected_filename, actual_filename)
        diff_filename = self.output_filename(filename, self.FILENAME_SUFFIX_DIFF + file_type)
        self._write_into_file_at_path(diff_filename, diff, encoding=None)

        # Shell out to wdiff to get colored inline diffs.
        wdiff = self._port.wdiff_text(expected_filename, actual_filename)
        wdiff_filename = self.output_filename(filename, self.FILENAME_SUFFIX_WDIFF)
        self._write_into_file_at_path(wdiff_filename, wdiff, encoding=None)

        # Use WebKit's PrettyPatch.rb to get an HTML diff.
        pretty_patch = self._port.pretty_patch_text(diff_filename)
        pretty_patch_filename = self.output_filename(filename, self.FILENAME_SUFFIX_PRETTY_PATCH)
        self._write_into_file_at_path(pretty_patch_filename, pretty_patch, encoding=None)