# Copyright (C) 2011 Google Inc.  All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

from contextlib import contextmanager
import filecmp
import fnmatch
import os
import shutil
import sys
import tempfile

from webkitpy.common.system.executive import Executive

# engine/ path is needed both to find input IDL files, and to import other
# Python modules.
module_path = os.path.dirname(__file__)
source_path = os.path.normpath(os.path.join(module_path, os.pardir, os.pardir,
                                            os.pardir, os.pardir, 'engine'))
sys.path.append(source_path)  # for engine/bindings imports

import bindings.scripts.compute_interfaces_info_individual
from bindings.scripts.compute_interfaces_info_individual import compute_info_individual, info_individual
import bindings.scripts.compute_interfaces_info_overall
from bindings.scripts.compute_interfaces_info_overall import compute_interfaces_info_overall, interfaces_info
from bindings.scripts.idl_compiler import IdlCompilerV8


PASS_MESSAGE = 'All tests PASS!'
FAIL_MESSAGE = """Some tests FAIL!
To update the reference files, execute:
    run-bindings-tests --reset-results

If the failures are not due to your changes, test results may be out of sync;
please rebaseline them in a separate CL, after checking that tests fail in ToT.
In CL, please set:
NOTRY=true
TBR=(someone in engine/bindings/OWNERS or WATCHLISTS:bindings)
"""

DEPENDENCY_IDL_FILES = frozenset([
    'TestImplements.idl',
    'TestImplements2.idl',
    'TestImplements3.idl',
    'TestPartialInterface.idl',
    'TestPartialInterface2.idl',
])


test_input_directory = os.path.join(source_path, 'bindings', 'tests', 'idls')
reference_directory = os.path.join(source_path, 'bindings', 'tests', 'results')


@contextmanager
def TemporaryDirectory():
    """Wrapper for tempfile.mkdtemp() so it's usable with 'with' statement.

    Simple backport of tempfile.TemporaryDirectory from Python 3.2.
    """
    name = tempfile.mkdtemp()
    try:
        yield name
    finally:
        shutil.rmtree(name)


def generate_interface_dependencies():
    def idl_paths_recursive(directory):
        # This is slow, especially on Windows, due to os.walk making
        # excess stat() calls. Faster versions may appear in Python 3.5 or
        # later:
        # https://github.com/benhoyt/scandir
        # http://bugs.python.org/issue11406
        idl_paths = []
        for dirpath, _, files in os.walk(directory):
            idl_paths.extend(os.path.join(dirpath, filename)
                             for filename in fnmatch.filter(files, '*.idl'))
        return idl_paths

    # We compute interfaces info for *all* IDL files, not just test IDL
    # files, as code generator output depends on inheritance (both ancestor
    # chain and inherited extended attributes), and some real interfaces
    # are special-cased, such as Node.
    #
    # For example, when testing the behavior of interfaces that inherit
    # from Node, we also need to know that these inherit from EventTarget,
    # since this is also special-cased and Node inherits from EventTarget,
    # but this inheritance information requires computing dependencies for
    # the real Node.idl file.

    # 2-stage computation: individual, then overall
    #
    # Properly should compute separately by component (currently test
    # includes are invalid), but that's brittle (would need to update this file
    # for each new component) and doesn't test the code generator any better
    # than using a single component.
    for idl_filename in idl_paths_recursive(source_path):
        compute_info_individual(idl_filename, 'tests')
    info_individuals = [info_individual()]
    compute_interfaces_info_overall(info_individuals)


def bindings_tests(output_directory, verbose):
    executive = Executive()

    def diff(filename1, filename2):
        # Python's difflib module is too slow, especially on long output, so
        # run external diff(1) command
        cmd = ['diff',
               '-u',  # unified format
               '-N',  # treat absent files as empty
               filename1,
               filename2]
        # Return output and don't raise exception, even though diff(1) has
        # non-zero exit if files differ.
        return executive.run_command(cmd, error_handler=lambda x: None)

    def delete_cache_files():
        # FIXME: Instead of deleting cache files, don't generate them.
        cache_files = [os.path.join(output_directory, output_file)
                       for output_file in os.listdir(output_directory)
                       if (output_file in ('lextab.py',  # PLY lex
                                           'lextab.pyc',
                                           'parsetab.pickle') or  # PLY yacc
                           output_file.endswith('.cache'))]  # Jinja
        for cache_file in cache_files:
            os.remove(cache_file)

    def identical_file(reference_filename, output_filename):
        reference_basename = os.path.basename(reference_filename)

        if not os.path.isfile(reference_filename):
            print 'Missing reference file!'
            print '(if adding new test, update reference files)'
            print reference_basename
            print
            return False

        if not filecmp.cmp(reference_filename, output_filename):
            # cmp is much faster than diff, and usual case is "no differance",
            # so only run diff if cmp detects a difference
            print 'FAIL: %s' % reference_basename
            print diff(reference_filename, output_filename)
            return False

        if verbose:
            print 'PASS: %s' % reference_basename
        return True

    def identical_output_files():
        file_pairs = [(os.path.join(reference_directory, output_file),
                       os.path.join(output_directory, output_file))
                      for output_file in os.listdir(output_directory)]
        return all([identical_file(reference_filename, output_filename)
                    for (reference_filename, output_filename) in file_pairs])

    def no_excess_files():
        generated_files = set(os.listdir(output_directory))
        generated_files.add('.svn')  # Subversion working copy directory
        excess_files = [output_file
                        for output_file in os.listdir(reference_directory)
                        if output_file not in generated_files]
        if excess_files:
            print ('Excess reference files! '
                  '(probably cruft from renaming or deleting):\n' +
                  '\n'.join(excess_files))
            return False
        return True

    try:
        generate_interface_dependencies()
        idl_compiler = IdlCompilerV8(output_directory,
                                     interfaces_info=interfaces_info,
                                     only_if_changed=True)

        idl_basenames = [filename
                         for filename in os.listdir(test_input_directory)
                         if (filename.endswith('.idl') and
                             # Dependencies aren't built
                             # (they are used by the dependent)
                             filename not in DEPENDENCY_IDL_FILES)]
        for idl_basename in idl_basenames:
            idl_path = os.path.realpath(
                os.path.join(test_input_directory, idl_basename))
            idl_compiler.compile_file(idl_path)
            definition_name, _ = os.path.splitext(idl_basename)
            if verbose:
                print 'Compiled: %s' % filename
    finally:
        delete_cache_files()

    # Detect all changes
    passed = identical_output_files()
    passed &= no_excess_files()

    if passed:
        if verbose:
            print
            print PASS_MESSAGE
        return 0
    print
    print FAIL_MESSAGE
    return 1


def run_bindings_tests(reset_results, verbose):
    # Generate output into the reference directory if resetting results, or
    # a temp directory if not.
    if reset_results:
        print 'Resetting results'
        return bindings_tests(reference_directory, verbose)
    with TemporaryDirectory() as temp_dir:
        return bindings_tests(temp_dir, verbose)