#!/usr/bin/python
#
# Copyright (C) 2017 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Compares one or more corresponding files from ojluni against one or
more upstream or from upstreams against each other.
The repositories (default: ojluni vs. expected current upstream) and
the diff tool (default: meld) can be specified by command line options.

This tool is for libcore maintenance; if you're not maintaining libcore,
you won't need it (and might not have access to some of the instructions
below).

The naming of the repositories (expected, ojluni, 7u40, 8u121-b13,
9b113+, 9+181) is based on the directory name where corresponding
snapshots are stored when following the instructions at
http://go/libcore-o-verify

This in turn derives from the instructions at the top of:
libcore/tools/upstream/src/main/java/libcore/CompareUpstreams.java

Possible uses:

To verify that ArrayList has been updated to the expected upstream
and that all local patches carry change markers, we compare that
file from ojluni against the expected upstream (the default):
  upstream-diff java/util/ArrayList.java

To verify multiple files:

  upstream-diff java.util.ArrayList java.util.LinkedList

Use a three-way merge to integrate changes from 9+181 into ArrayList:
  upstream-diff -r 8u121-b13,ojluni,9+181 java/util/ArrayList.java
or to investigate which version of upstream introduced a change:
  upstream-diff -r 7u40,8u60,8u121-b13 java/util/ArrayList.java
"""

import argparse
import os
import subprocess
import sys

def run_diff(diff, repositories, rel_paths):
    # Root of checked-out Android sources, set by the "lunch" command.
    android_build_top = os.environ['ANDROID_BUILD_TOP']
    # Root of repository snapshots. See go/libcore-o-verify for how you'd want to set this.
    ojluni_upstreams = os.environ['OJLUNI_UPSTREAMS']
    for rel_path in rel_paths:
        if not rel_path.endswith('.java'):
            # Might be a fully qualified class name
            rel_path = rel_path.replace('.', '/') + '.java'
        paths = []
        for repository in repositories:
            if repository == "ojluni":
                paths.append('%s/libcore/ojluni/src/main/java/%s' % (android_build_top, rel_path))
            else:
                paths.append('%s/%s/%s' % (ojluni_upstreams, repository, rel_path))
        subprocess.call([diff] + paths)

def main():
    parser = argparse.ArgumentParser(
        description='Compare files between libcore/ojluni and ${OJLUNI_UPSTREAMS}.')
    parser.add_argument('-r', '--repositories', default='ojluni,expected',
                    help='Comma-separated list of >= 2 repositories to compare.')
    parser.add_argument('-d', '--diff', default='meld',
                        help='Application to use for diffing.')
    parser.add_argument('rel_path', nargs="+",
                        help='File to compare: either a relative path below '
                             'libcore/ojluni/src/main/java, or a fully qualified class name.')
    args = parser.parse_args()
    repositories = args.repositories.split(',')
    if (len(repositories) < 2):
        print('Expected >= 2 repositories to compare, got: ' + str(repositories))
        parser.print_help()
        sys.exit(1)
    run_diff(args.diff, repositories, args.rel_path)

if __name__ == "__main__":
    main()