#
# Copyright (C) 2010 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.


import re
import sys
from command import Command
from git_command import GitCommand
import portable

CHANGE_ID_RE = re.compile(r'^\s*Change-Id: I([0-9a-f]{40})\s*$')


class CherryPick(Command):
    common = True
    helpSummary = "Cherry-pick a change."
    helpUsage = """
%prog <sha1>
"""
    helpDescription = """
'%prog' cherry-picks a change from one branch to another.
The change id will be updated, and a reference to the old
change id will be added.
"""

    def _Options(self, p):
        pass

    def Execute(self, opt, args):
        if len(args) != 1:
            self.Usage()

        reference = args[0]

        p = GitCommand(None,
                       ['rev-parse', '--verify', reference],
                       capture_stdout=True,
                       capture_stderr=True)
        if p.Wait() != 0:
            print(p.stderr, file=sys.stderr)
            sys.exit(1)
        sha1 = p.stdout.strip()

        p = GitCommand(None, ['cat-file', 'commit', sha1], capture_stdout=True)
        if p.Wait() != 0:
            print("error: Failed to retrieve old commit message", file=sys.stderr)
            sys.exit(1)
        old_msg = self._StripHeader(portable.stream2str(p.stdout))

        p = GitCommand(None,
                       ['cherry-pick', sha1],
                       capture_stdout=True,
                       capture_stderr=True)
        status = p.Wait()

        print(p.stdout, file=sys.stdout)
        print(p.stderr, file=sys.stderr)

        if status == 0:
            # The cherry-pick was applied correctly. We just need to edit the
            # commit message.
            new_msg = self._Reformat(old_msg, sha1)

            p = GitCommand(None, ['commit', '--amend', '-F', '-'],
                           provide_stdin=True,
                           capture_stdout=True,
                           capture_stderr=True)
            p.stdin.write(new_msg)
            if p.Wait() != 0:
                print("error: Failed to update commit message", file=sys.stderr)
                sys.exit(1)

        else:
            print('NOTE: When committing (please see above) and editing the commit'
                  'message, please remove the old Change-Id-line and add:')
            print(self._GetReference(sha1), file=stderr)
            print(file=stderr)

    def _IsChangeId(self, line):
        return CHANGE_ID_RE.match(line)

    def _GetReference(self, sha1):
        return "(cherry picked from commit %s)" % sha1

    def _StripHeader(self, commit_msg):
        lines = commit_msg.splitlines()
        return "\n".join(lines[lines.index("") + 1:])

    def _Reformat(self, old_msg, sha1):
        new_msg = []

        for line in old_msg.splitlines():
            if not self._IsChangeId(line):
                new_msg.append(line)

        # Add a blank line between the message and the change id/reference
        try:
            if new_msg[-1].strip() != "":
                new_msg.append("")
        except IndexError:
            pass

        new_msg.append(self._GetReference(sha1))
        return "\n".join(new_msg)
