# Copyright (c) 2009, 2010, 2011 Google Inc. All rights reserved.
# Copyright (c) 2009 Apple 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:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * 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.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "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 THE COPYRIGHT
# OWNER 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.

import logging
import os
import re

from webkitpy.common.memoized import memoized
from webkitpy.common.system.deprecated_logging import log
from webkitpy.common.system.executive import Executive, ScriptError
from webkitpy.common.system import ospath

from .commitmessage import CommitMessage
from .scm import AuthenticationError, SCM, commit_error_handler
from .svn import SVN, SVNRepository


_log = logging.getLogger(__name__)


def run_command(*args, **kwargs):
    # FIXME: This should not be a global static.
    # New code should use Executive.run_command directly instead
    return Executive().run_command(*args, **kwargs)


class AmbiguousCommitError(Exception):
    def __init__(self, num_local_commits, working_directory_is_clean):
        self.num_local_commits = num_local_commits
        self.working_directory_is_clean = working_directory_is_clean


class Git(SCM, SVNRepository):

    # Git doesn't appear to document error codes, but seems to return
    # 1 or 128, mostly.
    ERROR_FILE_IS_MISSING = 128

    def __init__(self, cwd, executive=None):
        SCM.__init__(self, cwd, executive)
        self._check_git_architecture()

    def _machine_is_64bit(self):
        import platform
        # This only is tested on Mac.
        if not platform.mac_ver()[0]:
            return False

        # platform.architecture()[0] can be '64bit' even if the machine is 32bit:
        # http://mail.python.org/pipermail/pythonmac-sig/2009-September/021648.html
        # Use the sysctl command to find out what the processor actually supports.
        return self.run(['sysctl', '-n', 'hw.cpu64bit_capable']).rstrip() == '1'

    def _executable_is_64bit(self, path):
        # Again, platform.architecture() fails us.  On my machine
        # git_bits = platform.architecture(executable=git_path, bits='default')[0]
        # git_bits is just 'default', meaning the call failed.
        file_output = self.run(['file', path])
        return re.search('x86_64', file_output)

    def _check_git_architecture(self):
        if not self._machine_is_64bit():
            return

        # We could path-search entirely in python or with
        # which.py (http://code.google.com/p/which), but this is easier:
        git_path = self.run(['which', 'git']).rstrip()
        if self._executable_is_64bit(git_path):
            return

        webkit_dev_thread_url = "https://lists.webkit.org/pipermail/webkit-dev/2010-December/015287.html"
        log("Warning: This machine is 64-bit, but the git binary (%s) does not support 64-bit.\nInstall a 64-bit git for better performance, see:\n%s\n" % (git_path, webkit_dev_thread_url))

    @classmethod
    def in_working_directory(cls, path):
        try:
            # FIXME: This should use an Executive.
            return run_command(['git', 'rev-parse', '--is-inside-work-tree'], cwd=path, error_handler=Executive.ignore_error).rstrip() == "true"
        except OSError, e:
            # The Windows bots seem to through a WindowsError when git isn't installed.
            return False

    @classmethod
    def find_checkout_root(cls, path):
        # FIXME: This should use a FileSystem object instead of os.path.
        # "git rev-parse --show-cdup" would be another way to get to the root
        (checkout_root, dot_git) = os.path.split(run_command(['git', 'rev-parse', '--git-dir'], cwd=(path or "./")))
        if not os.path.isabs(checkout_root):  # Sometimes git returns relative paths
            checkout_root = os.path.join(path, checkout_root)
        return checkout_root

    @classmethod
    def to_object_name(cls, filepath):
        # FIXME: This should use a FileSystem object instead of os.path.
        root_end_with_slash = os.path.join(cls.find_checkout_root(os.path.dirname(filepath)), '')
        return filepath.replace(root_end_with_slash, '')

    @classmethod
    def read_git_config(cls, key, cwd=None):
        # FIXME: This should probably use cwd=self.checkout_root.
        # Pass --get-all for cases where the config has multiple values
        # Pass the cwd if provided so that we can handle the case of running webkit-patch outside of the working directory.
        # FIXME: This should use an Executive.
        return run_command(["git", "config", "--get-all", key], error_handler=Executive.ignore_error, cwd=cwd).rstrip('\n')

    @staticmethod
    def commit_success_regexp():
        return "^Committed r(?P<svn_revision>\d+)$"

    def discard_local_commits(self):
        # FIXME: This should probably use cwd=self.checkout_root
        self.run(['git', 'reset', '--hard', self.remote_branch_ref()])

    def local_commits(self):
        return self.run(['git', 'log', '--pretty=oneline', 'HEAD...' + self.remote_branch_ref()], cwd=self.checkout_root).splitlines()

    def rebase_in_progress(self):
        return self._filesystem.exists(self.absolute_path(self._filesystem.join('.git', 'rebase-apply')))

    def working_directory_is_clean(self):
        return self.run(['git', 'diff', 'HEAD', '--no-renames', '--name-only'], cwd=self.checkout_root) == ""

    def clean_working_directory(self):
        # FIXME: These should probably use cwd=self.checkout_root.
        # Could run git clean here too, but that wouldn't match working_directory_is_clean
        self.run(['git', 'reset', '--hard', 'HEAD'])
        # Aborting rebase even though this does not match working_directory_is_clean
        if self.rebase_in_progress():
            self.run(['git', 'rebase', '--abort'])

    def status_command(self):
        # git status returns non-zero when there are changes, so we use git diff name --name-status HEAD instead.
        # No file contents printed, thus utf-8 autodecoding in self.run is fine.
        return ["git", "diff", "--name-status", "--no-renames", "HEAD"]

    def _status_regexp(self, expected_types):
        return '^(?P<status>[%s])\t(?P<filename>.+)$' % expected_types

    def add(self, path, return_exit_code=False):
        return self.run(["git", "add", path], return_exit_code=return_exit_code)

    def delete(self, path):
        return self.run(["git", "rm", "-f", path])

    def exists(self, path):
        return_code = self.run(["git", "show", "HEAD:%s" % path], return_exit_code=True, decode_output=False)
        return return_code != self.ERROR_FILE_IS_MISSING

    def merge_base(self, git_commit):
        if git_commit:
            # Special-case HEAD.. to mean working-copy changes only.
            if git_commit.upper() == 'HEAD..':
                return 'HEAD'

            if '..' not in git_commit:
                git_commit = git_commit + "^.." + git_commit
            return git_commit

        return self.remote_merge_base()

    def changed_files(self, git_commit=None):
        # FIXME: --diff-filter could be used to avoid the "extract_filenames" step.
        status_command = ['git', 'diff', '-r', '--name-status', "--no-renames", "--no-ext-diff", "--full-index", self.merge_base(git_commit)]
        # FIXME: I'm not sure we're returning the same set of files that SVN.changed_files is.
        # Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R)
        return self.run_status_and_extract_filenames(status_command, self._status_regexp("ADM"))

    def _changes_files_for_commit(self, git_commit):
        # --pretty="format:" makes git show not print the commit log header,
        changed_files = self.run(["git", "show", "--pretty=format:", "--name-only", git_commit]).splitlines()
        # instead it just prints a blank line at the top, so we skip the blank line:
        return changed_files[1:]

    def changed_files_for_revision(self, revision):
        commit_id = self.git_commit_from_svn_revision(revision)
        return self._changes_files_for_commit(commit_id)

    def revisions_changing_file(self, path, limit=5):
        # raise a script error if path does not exists to match the behavior of  the svn implementation.
        if not self._filesystem.exists(path):
            raise ScriptError(message="Path %s does not exist." % path)

        # git rev-list head --remove-empty --limit=5 -- path would be equivalent.
        commit_ids = self.run(["git", "log", "--remove-empty", "--pretty=format:%H", "-%s" % limit, "--", path]).splitlines()
        return filter(lambda revision: revision, map(self.svn_revision_from_git_commit, commit_ids))

    def conflicted_files(self):
        # We do not need to pass decode_output for this diff command
        # as we're passing --name-status which does not output any data.
        status_command = ['git', 'diff', '--name-status', '--no-renames', '--diff-filter=U']
        return self.run_status_and_extract_filenames(status_command, self._status_regexp("U"))

    def added_files(self):
        return self.run_status_and_extract_filenames(self.status_command(), self._status_regexp("A"))

    def deleted_files(self):
        return self.run_status_and_extract_filenames(self.status_command(), self._status_regexp("D"))

    @staticmethod
    def supports_local_commits():
        return True

    def display_name(self):
        return "git"

    def head_svn_revision(self):
        _log.debug('Running git.head_svn_revision... (Temporary logging message)')
        git_log = self.run(['git', 'log', '-25'])
        match = re.search("^\s*git-svn-id:.*@(?P<svn_revision>\d+)\ ", git_log, re.MULTILINE)
        if not match:
            return ""
        return str(match.group('svn_revision'))

    def prepend_svn_revision(self, diff):
        revision = self.head_svn_revision()
        if not revision:
            return diff

        return "Subversion Revision: " + revision + '\n' + diff

    def create_patch(self, git_commit=None, changed_files=None):
        """Returns a byte array (str()) representing the patch file.
        Patch files are effectively binary since they may contain
        files of multiple different encodings."""
        command = ['git', 'diff', '--binary', "--no-ext-diff", "--full-index", "--no-renames", self.merge_base(git_commit), "--"]
        if changed_files:
            command += changed_files
        return self.prepend_svn_revision(self.run(command, decode_output=False, cwd=self.checkout_root))

    def _run_git_svn_find_rev(self, arg):
        # git svn find-rev always exits 0, even when the revision or commit is not found.
        return self.run(['git', 'svn', 'find-rev', arg], cwd=self.checkout_root).rstrip()

    def _string_to_int_or_none(self, string):
        try:
            return int(string)
        except ValueError, e:
            return None

    @memoized
    def git_commit_from_svn_revision(self, svn_revision):
        git_commit = self._run_git_svn_find_rev('r%s' % svn_revision)
        if not git_commit:
            # FIXME: Alternatively we could offer to update the checkout? Or return None?
            raise ScriptError(message='Failed to find git commit for revision %s, your checkout likely needs an update.' % svn_revision)
        return git_commit

    @memoized
    def svn_revision_from_git_commit(self, git_commit):
        svn_revision = self._run_git_svn_find_rev(git_commit)
        return self._string_to_int_or_none(svn_revision)

    def contents_at_revision(self, path, revision):
        """Returns a byte array (str()) containing the contents
        of path @ revision in the repository."""
        return self.run(["git", "show", "%s:%s" % (self.git_commit_from_svn_revision(revision), path)], decode_output=False)

    def diff_for_revision(self, revision):
        git_commit = self.git_commit_from_svn_revision(revision)
        return self.create_patch(git_commit)

    def diff_for_file(self, path, log=None):
        return self.run(['git', 'diff', 'HEAD', '--no-renames', '--', path], cwd=self.checkout_root)

    def show_head(self, path):
        return self.run(['git', 'show', 'HEAD:' + self.to_object_name(path)], decode_output=False)

    def committer_email_for_revision(self, revision):
        git_commit = self.git_commit_from_svn_revision(revision)
        committer_email = self.run(["git", "log", "-1", "--pretty=format:%ce", git_commit])
        # Git adds an extra @repository_hash to the end of every committer email, remove it:
        return committer_email.rsplit("@", 1)[0]

    def apply_reverse_diff(self, revision):
        # Assume the revision is an svn revision.
        git_commit = self.git_commit_from_svn_revision(revision)
        # I think this will always fail due to ChangeLogs.
        self.run(['git', 'revert', '--no-commit', git_commit], error_handler=Executive.ignore_error)

    def revert_files(self, file_paths):
        self.run(['git', 'checkout', 'HEAD'] + file_paths)

    def _assert_can_squash(self, working_directory_is_clean):
        squash = Git.read_git_config('webkit-patch.commit-should-always-squash', cwd=self.checkout_root)
        should_squash = squash and squash.lower() == "true"

        if not should_squash:
            # Only warn if there are actually multiple commits to squash.
            num_local_commits = len(self.local_commits())
            if num_local_commits > 1 or (num_local_commits > 0 and not working_directory_is_clean):
                raise AmbiguousCommitError(num_local_commits, working_directory_is_clean)

    def commit_with_message(self, message, username=None, password=None, git_commit=None, force_squash=False, changed_files=None):
        # Username is ignored during Git commits.
        working_directory_is_clean = self.working_directory_is_clean()

        if git_commit:
            # Special-case HEAD.. to mean working-copy changes only.
            if git_commit.upper() == 'HEAD..':
                if working_directory_is_clean:
                    raise ScriptError(message="The working copy is not modified. --git-commit=HEAD.. only commits working copy changes.")
                self.commit_locally_with_message(message)
                return self._commit_on_branch(message, 'HEAD', username=username, password=password)

            # Need working directory changes to be committed so we can checkout the merge branch.
            if not working_directory_is_clean:
                # FIXME: webkit-patch land will modify the ChangeLogs to correct the reviewer.
                # That will modify the working-copy and cause us to hit this error.
                # The ChangeLog modification could be made to modify the existing local commit.
                raise ScriptError(message="Working copy is modified. Cannot commit individual git_commits.")
            return self._commit_on_branch(message, git_commit, username=username, password=password)

        if not force_squash:
            self._assert_can_squash(working_directory_is_clean)
        self.run(['git', 'reset', '--soft', self.remote_merge_base()], cwd=self.checkout_root)
        self.commit_locally_with_message(message)
        return self.push_local_commits_to_server(username=username, password=password)

    def _commit_on_branch(self, message, git_commit, username=None, password=None):
        branch_ref = self.run(['git', 'symbolic-ref', 'HEAD']).strip()
        branch_name = branch_ref.replace('refs/heads/', '')
        commit_ids = self.commit_ids_from_commitish_arguments([git_commit])

        # We want to squash all this branch's commits into one commit with the proper description.
        # We do this by doing a "merge --squash" into a new commit branch, then dcommitting that.
        MERGE_BRANCH_NAME = 'webkit-patch-land'
        self.delete_branch(MERGE_BRANCH_NAME)

        # We might be in a directory that's present in this branch but not in the
        # trunk.  Move up to the top of the tree so that git commands that expect a
        # valid CWD won't fail after we check out the merge branch.
        # FIXME: We should never be using chdir! We can instead pass cwd= to run_command/self.run!
        self._filesystem.chdir(self.checkout_root)

        # Stuff our change into the merge branch.
        # We wrap in a try...finally block so if anything goes wrong, we clean up the branches.
        commit_succeeded = True
        try:
            self.run(['git', 'checkout', '-q', '-b', MERGE_BRANCH_NAME, self.remote_branch_ref()])

            for commit in commit_ids:
                # We're on a different branch now, so convert "head" to the branch name.
                commit = re.sub(r'(?i)head', branch_name, commit)
                # FIXME: Once changed_files and create_patch are modified to separately handle each
                # commit in a commit range, commit each cherry pick so they'll get dcommitted separately.
                self.run(['git', 'cherry-pick', '--no-commit', commit])

            self.run(['git', 'commit', '-m', message])
            output = self.push_local_commits_to_server(username=username, password=password)
        except Exception, e:
            log("COMMIT FAILED: " + str(e))
            output = "Commit failed."
            commit_succeeded = False
        finally:
            # And then swap back to the original branch and clean up.
            self.clean_working_directory()
            self.run(['git', 'checkout', '-q', branch_name])
            self.delete_branch(MERGE_BRANCH_NAME)

        return output

    def svn_commit_log(self, svn_revision):
        svn_revision = self.strip_r_from_svn_revision(svn_revision)
        return self.run(['git', 'svn', 'log', '-r', svn_revision])

    def last_svn_commit_log(self):
        return self.run(['git', 'svn', 'log', '--limit=1'])

    # Git-specific methods:
    def _branch_ref_exists(self, branch_ref):
        return self.run(['git', 'show-ref', '--quiet', '--verify', branch_ref], return_exit_code=True) == 0

    def delete_branch(self, branch_name):
        if self._branch_ref_exists('refs/heads/' + branch_name):
            self.run(['git', 'branch', '-D', branch_name])

    def remote_merge_base(self):
        return self.run(['git', 'merge-base', self.remote_branch_ref(), 'HEAD'], cwd=self.checkout_root).strip()

    def remote_branch_ref(self):
        # Use references so that we can avoid collisions, e.g. we don't want to operate on refs/heads/trunk if it exists.
        remote_branch_refs = Git.read_git_config('svn-remote.svn.fetch', cwd=self.checkout_root)
        if not remote_branch_refs:
            remote_master_ref = 'refs/remotes/origin/master'
            if not self._branch_ref_exists(remote_master_ref):
                raise ScriptError(message="Can't find a branch to diff against. svn-remote.svn.fetch is not in the git config and %s does not exist" % remote_master_ref)
            return remote_master_ref

        # FIXME: What's the right behavior when there are multiple svn-remotes listed?
        # For now, just use the first one.
        first_remote_branch_ref = remote_branch_refs.split('\n')[0]
        return first_remote_branch_ref.split(':')[1]

    def commit_locally_with_message(self, message):
        self.run(['git', 'commit', '--all', '-F', '-'], input=message, cwd=self.checkout_root)

    def push_local_commits_to_server(self, username=None, password=None):
        dcommit_command = ['git', 'svn', 'dcommit']
        if self.dryrun:
            dcommit_command.append('--dry-run')
        if (not username or not password) and not self.has_authorization_for_realm(SVN.svn_server_realm):
            raise AuthenticationError(SVN.svn_server_host, prompt_for_password=True)
        if username:
            dcommit_command.extend(["--username", username])
        output = self.run(dcommit_command, error_handler=commit_error_handler, input=password, cwd=self.checkout_root)
        # Return a string which looks like a commit so that things which parse this output will succeed.
        if self.dryrun:
            output += "\nCommitted r0"
        return output

    # This function supports the following argument formats:
    # no args : rev-list trunk..HEAD
    # A..B    : rev-list A..B
    # A...B   : error!
    # A B     : [A, B]  (different from git diff, which would use "rev-list A..B")
    def commit_ids_from_commitish_arguments(self, args):
        if not len(args):
            args.append('%s..HEAD' % self.remote_branch_ref())

        commit_ids = []
        for commitish in args:
            if '...' in commitish:
                raise ScriptError(message="'...' is not supported (found in '%s'). Did you mean '..'?" % commitish)
            elif '..' in commitish:
                commit_ids += reversed(self.run(['git', 'rev-list', commitish]).splitlines())
            else:
                # Turn single commits or branch or tag names into commit ids.
                commit_ids += self.run(['git', 'rev-parse', '--revs-only', commitish]).splitlines()
        return commit_ids

    def commit_message_for_local_commit(self, commit_id):
        commit_lines = self.run(['git', 'cat-file', 'commit', commit_id]).splitlines()

        # Skip the git headers.
        first_line_after_headers = 0
        for line in commit_lines:
            first_line_after_headers += 1
            if line == "":
                break
        return CommitMessage(commit_lines[first_line_after_headers:])

    def files_changed_summary_for_commit(self, commit_id):
        return self.run(['git', 'diff-tree', '--shortstat', '--no-renames', '--no-commit-id', commit_id])
