# Copyright 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

from webkitpy.w3c.chromium_finder import absolute_chromium_dir, absolute_chromium_wpt_dir

CHROMIUM_WPT_DIR = 'third_party/WebKit/LayoutTests/external/wpt/'


class ChromiumCommit(object):

    def __init__(self, host, sha=None, position=None):
        """
        Args:
            host: A Host object
            sha: A Chromium commit SHA
            position: A string of the form:
                    'Cr-Commit-Position: refs/heads/master@{#431915}'
                or just:
                    'refs/heads/master@{#431915}'
        """
        self.host = host
        self.absolute_chromium_dir = absolute_chromium_dir(host)
        self.absolute_chromium_wpt_dir = absolute_chromium_wpt_dir(host)

        assert sha or position, 'requires sha or position'
        assert not (sha and position), 'cannot accept both sha and position'

        if position and not sha:
            if position.startswith('Cr-Commit-Position: '):
                position = position[len('Cr-Commit-Position: '):]

            sha = self.position_to_sha(position)

        assert len(sha) == 40, 'Expected SHA-1 hash, got {}'.format(sha)
        self.sha = sha
        self.position = position

    def num_behind_master(self):
        """Returns the number of commits this commit is behind origin/master.
        It is inclusive of this commit and of the latest commit.
        """
        return len(self.host.executive.run_command([
            'git', 'rev-list', '{}..origin/master'.format(self.sha)
        ], cwd=self.absolute_chromium_dir).splitlines())

    def position_to_sha(self, commit_position):
        return self.host.executive.run_command([
            'git', 'crrev-parse', commit_position
        ], cwd=self.absolute_chromium_dir).strip()

    def subject(self):
        return self.host.executive.run_command([
            'git', 'show', '--format=%s', '--no-patch', self.sha
        ], cwd=self.absolute_chromium_dir)

    def body(self):
        return self.host.executive.run_command([
            'git', 'show', '--format=%b', '--no-patch', self.sha
        ], cwd=self.absolute_chromium_dir)

    def author(self):
        return self.host.executive.run_command([
            'git', 'show', '--format="%aN <%aE>"', '--no-patch', self.sha
        ], cwd=self.absolute_chromium_dir)

    def message(self):
        """Returns a string with a commit's subject and body."""
        return self.host.executive.run_command([
            'git', 'show', '--format=%B', '--no-patch', self.sha
        ], cwd=self.absolute_chromium_dir)

    def filtered_changed_files(self):
        """Makes a patch with just changes in files in the WPT dir for a given commit."""
        changed_files = self.host.executive.run_command([
            'git', 'diff-tree', '--name-only', '--no-commit-id', '-r', self.sha,
            '--', self.absolute_chromium_wpt_dir
        ], cwd=self.absolute_chromium_dir).splitlines()

        blacklist = [
            'MANIFEST.json',
            self.host.filesystem.join('resources', 'testharnessreport.js'),
        ]
        qualified_blacklist = [CHROMIUM_WPT_DIR + f for f in blacklist]

        return [f for f in changed_files if f not in qualified_blacklist and not self.is_baseline(f)]

    @staticmethod
    def is_baseline(basename):
        # TODO(qyearsley): Find a better, centralized place for this.
        return basename.endswith('-expected.txt')

    def format_patch(self):
        """Makes a patch with only exportable changes."""
        filtered_files = self.filtered_changed_files()

        if not filtered_files:
            return ''

        return self.host.executive.run_command([
            'git', 'format-patch', '-1', '--stdout', self.sha, '--'
        ] + filtered_files, cwd=self.absolute_chromium_dir)