#!/usr/bin/env python
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"""Classes for failures that occur during tests."""

import os
import test_expectations


def determine_result_type(failure_list):
    """Takes a set of test_failures and returns which result type best fits
    the list of failures. "Best fits" means we use the worst type of failure.

    Returns:
      one of the test_expectations result types - PASS, TEXT, CRASH, etc."""

    if not failure_list or len(failure_list) == 0:
        return test_expectations.PASS

    failure_types = [type(f) for f in failure_list]
    if FailureCrash in failure_types:
        return test_expectations.CRASH
    elif FailureTimeout in failure_types:
        return test_expectations.TIMEOUT
    elif (FailureMissingResult in failure_types or
          FailureMissingImage in failure_types or
          FailureMissingImageHash in failure_types):
        return test_expectations.MISSING
    else:
        is_text_failure = FailureTextMismatch in failure_types
        is_image_failure = (FailureImageHashIncorrect in failure_types or
                            FailureImageHashMismatch in failure_types)
        if is_text_failure and is_image_failure:
            return test_expectations.IMAGE_PLUS_TEXT
        elif is_text_failure:
            return test_expectations.TEXT
        elif is_image_failure:
            return test_expectations.IMAGE
        else:
            raise ValueError("unclassifiable set of failures: "
                             + str(failure_types))


class TestFailure(object):
    """Abstract base class that defines the failure interface."""

    @staticmethod
    def message():
        """Returns a string describing the failure in more detail."""
        raise NotImplemented

    def result_html_output(self, filename):
        """Returns an HTML string to be included on the results.html page."""
        raise NotImplemented

    def should_kill_test_shell(self):
        """Returns True if we should kill the test shell before the next
        test."""
        return False

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

        For example, if filename is fast\dom\foo.html and modifier is
        "-expected.txt", the return value is fast\dom\foo-expected.txt

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

        Return:
          The relative windows path to the output filename
        """
        return os.path.splitext(filename)[0] + modifier


class FailureWithType(TestFailure):
    """Base class that produces standard HTML output based on the test type.

    Subclasses may commonly choose to override the ResultHtmlOutput, but still
    use the standard OutputLinks.
    """

    def __init__(self, test_type):
        TestFailure.__init__(self)
        # TODO(ojan): This class no longer needs to know the test_type.
        self._test_type = test_type

    # Filename suffixes used by ResultHtmlOutput.
    OUT_FILENAMES = []

    def output_links(self, filename, out_names):
        """Returns a string holding all applicable output file links.

        Args:
          filename: the test filename, used to construct the result file names
          out_names: list of filename suffixes for the files. If three or more
              suffixes are in the list, they should be [actual, expected, diff,
              wdiff]. Two suffixes should be [actual, expected], and a
              single item is the [actual] filename suffix.
              If out_names is empty, returns the empty string.
        """
        links = ['']
        uris = [self.relative_output_filename(filename, fn) for
                fn in out_names]
        if len(uris) > 1:
            links.append("<a href='%s'>expected</a>" % uris[1])
        if len(uris) > 0:
            links.append("<a href='%s'>actual</a>" % uris[0])
        if len(uris) > 2:
            links.append("<a href='%s'>diff</a>" % uris[2])
        if len(uris) > 3:
            links.append("<a href='%s'>wdiff</a>" % uris[3])
        return ' '.join(links)

    def result_html_output(self, filename):
        return self.message() + self.output_links(filename, self.OUT_FILENAMES)


class FailureTimeout(TestFailure):
    """Test timed out.  We also want to restart the test shell if this
    happens."""

    @staticmethod
    def message():
        return "Test timed out"

    def result_html_output(self, filename):
        return "<strong>%s</strong>" % self.message()

    def should_kill_test_shell(self):
        return True


class FailureCrash(TestFailure):
    """Test shell crashed."""

    @staticmethod
    def message():
        return "Test shell crashed"

    def result_html_output(self, filename):
        # TODO(tc): create a link to the minidump file
        stack = self.relative_output_filename(filename, "-stack.txt")
        return "<strong>%s</strong> <a href=%s>stack</a>" % (self.message(),
                                                             stack)

    def should_kill_test_shell(self):
        return True


class FailureMissingResult(FailureWithType):
    """Expected result was missing."""
    OUT_FILENAMES = ["-actual.txt"]

    @staticmethod
    def message():
        return "No expected results found"

    def result_html_output(self, filename):
        return ("<strong>%s</strong>" % self.message() +
                self.output_links(filename, self.OUT_FILENAMES))


class FailureTextMismatch(FailureWithType):
    """Text diff output failed."""
    # Filename suffixes used by ResultHtmlOutput.
    OUT_FILENAMES = ["-actual.txt", "-expected.txt", "-diff.txt"]
    OUT_FILENAMES_WDIFF = ["-actual.txt", "-expected.txt", "-diff.txt",
                           "-wdiff.html"]

    def __init__(self, test_type, has_wdiff):
        FailureWithType.__init__(self, test_type)
        if has_wdiff:
            self.OUT_FILENAMES = self.OUT_FILENAMES_WDIFF

    @staticmethod
    def message():
        return "Text diff mismatch"


class FailureMissingImageHash(FailureWithType):
    """Actual result hash was missing."""
    # Chrome doesn't know to display a .checksum file as text, so don't bother
    # putting in a link to the actual result.
    OUT_FILENAMES = []

    @staticmethod
    def message():
        return "No expected image hash found"

    def result_html_output(self, filename):
        return "<strong>%s</strong>" % self.message()


class FailureMissingImage(FailureWithType):
    """Actual result image was missing."""
    OUT_FILENAMES = ["-actual.png"]

    @staticmethod
    def message():
        return "No expected image found"

    def result_html_output(self, filename):
        return ("<strong>%s</strong>" % self.message() +
                self.output_links(filename, self.OUT_FILENAMES))


class FailureImageHashMismatch(FailureWithType):
    """Image hashes didn't match."""
    OUT_FILENAMES = ["-actual.png", "-expected.png", "-diff.png"]

    @staticmethod
    def message():
        # We call this a simple image mismatch to avoid confusion, since
        # we link to the PNGs rather than the checksums.
        return "Image mismatch"


class FailureFuzzyFailure(FailureWithType):
    """Image hashes didn't match."""
    OUT_FILENAMES = ["-actual.png", "-expected.png"]

    @staticmethod
    def message():
        return "Fuzzy image match also failed"


class FailureImageHashIncorrect(FailureWithType):
    """Actual result hash is incorrect."""
    # Chrome doesn't know to display a .checksum file as text, so don't bother
    # putting in a link to the actual result.
    OUT_FILENAMES = []

    @staticmethod
    def message():
        return "Images match, expected image hash incorrect. "

    def result_html_output(self, filename):
        return "<strong>%s</strong>" % self.message()
