#!/usr/bin/env python
# Copyright 2017 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

### view commits not yet rolled to a layer

import argparse
from argparse import RawTextHelpFormatter
import base64
from datetime import datetime, timedelta, tzinfo
import json
import sys
import urllib2
import xml.etree.ElementTree as xml


LAYERS = [
    'vendor', # For checkouts building on top of Topaz.
    'topaz',
    'peridot',
    'garnet',
    'zircon',
]

# Authors whose commits are not displayed.
IGNORED_AUTHORS = [
    'skia-fuchsia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com',
    'third-party-roller',
    'topaz-roller',
    'peridot-roller',
    'garnet-roller',
    'zircon-roller',
]


def http_get(url):
    """Fetches the content at a given URL."""
    try:
        target = urllib2.urlopen(url)
        return target.read()
    finally:
        if target:
            target.close()


def get_lower_layer(layer):
    """Returns the layer immediately below the given layer."""
    if layer not in LAYERS:
        # Special case for "build" and "scripts".
        return None
    index = LAYERS.index(layer)
    if index == len(LAYERS) - 1:
        return None
    return LAYERS[index + 1]


def get_lower_layer_commit(layer, at, lower_layer):
    """Returns the pinned revision of a layer below the given layer."""
    url = ('https://fuchsia.googlesource.com/%s/+/%s/manifest/%s?format=TEXT'
           % (layer, at, layer))
    content = http_get(url)
    content = base64.b64decode(content)
    manifest = xml.fromstring(content)
    nodes = manifest.findall('./imports/import[@name="%s"]' % lower_layer)
    return (lower_layer, nodes[0].get('revision'))


def get_lower_layer_commits(layer, at):
    """Returns the pinned revision of the 'layers' below the given layer.
       Multiple 'layers' are needed for the Garnet case, where we want to be
       able to inspect the revisions of //build and //scripts.
       """
    if layer != 'garnet':
        lower_layer = get_lower_layer(layer)
        if not lower_layer:
            return []
        return [get_lower_layer_commit(layer, at, lower_layer)]
    return [
        get_lower_layer_commit('garnet', at, 'zircon'),
        get_lower_layer_commit('garnet', at, 'build'),
        get_lower_layer_commit('garnet', at, 'scripts'),
    ]

def get_commits(layer, revision):
    """Returns the commits in the given layer up to a given commit."""
    url = 'https://fuchsia.googlesource.com/%s/+log/master?format=JSON' % layer
    def get_more(result, start=None):
        get_url = url
        if start:
            get_url = '%s&s=%s' % (url, start)
        content = http_get(get_url)
        # Remove the anti-XSSI header.
        content = content[5:]
        data = json.loads(content)
        for commit in data['log']:
            if commit['commit'] == revision:
                return
            result.append(commit)
        get_more(result, start=content['next'])
    result = []
    get_more(result)
    return result


def filter_commit(commit):
    """Returns True if a commit should be listed."""
    return commit['author']['name'] not in IGNORED_AUTHORS


class MyTimezone(tzinfo):
    """Simple timezone implementation, since for some reason Python 2.7 doesn't
       provide one.
       """

    def __init__(self, data=None):
        self.data = data if data else '+0000'

    def utcoffset(self, dt):
        hours = int(self.data[1:3])
        minutes = int(self.data[3:5])
        delta = timedelta(hours=hours, minutes=minutes)
        if self.data[0] == '-':
            delta = -delta
        return delta

    def tzname(self, dt):
        return 'Bogus'

    def dst(self, dt):
        return timedelta(0)


def get_time_since(timestamp):
    """Returns a string describing the amount of time elapsed since the given
       timestamp.
       Timestamp format: Sat Feb 10 03:17:06 2018 +0000
       """
    timestamp_no_tz = timestamp[:-6]
    date_no_tz = datetime.strptime(timestamp_no_tz, '%a %b %d %H:%M:%S %Y')
    date = date_no_tz.replace(tzinfo=MyTimezone(timestamp[-5:]))
    now = datetime.utcnow().replace(tzinfo=MyTimezone())
    delta = now - date
    if delta.days >= 1:
        return '>1d'
    hours = delta.seconds / 3600
    if hours >= 1:
        return '%sh' % hours
    minutes = (delta.seconds % 3600) / 60
    return '%sm' % minutes


def print_commits(layer, commits):
    """Prints the given commits in a user=pleasing format."""
    commits = [c for c in commits if filter_commit(c)]
    if commits:
        timestamp = commits[-1]['committer']['time']
        elapsed_time = get_time_since(timestamp)
    else:
        elapsed_time = ''
    print('--------------')
    print('| %s | %s' % ('{:^10}'.format(layer), elapsed_time))
    print('--------------')
    for commit in commits:
        print('%s | %s | %s' % (commit['commit'][:7],
                                commit['author']['name'][:15].ljust(15),
                                commit['message'].splitlines()[0]))
    if not commits:
        print('None')


def main():
    parser = argparse.ArgumentParser(formatter_class=RawTextHelpFormatter,
        description="""Displays the commits not yet rolled to a given layer.
For vendor layers, specify the Topaz revision with --topaz-revision.""")
    parser.add_argument('--layer',
                        help='Name of the layer to inspect',
                        choices=LAYERS,
                        default='topaz')
    parser.add_argument('--topaz-revision',
                        help='(vendor only) revision of the Topaz layer')
    args = parser.parse_args()

    layer = args.layer
    revision = args.topaz_revision

    if layer != 'vendor' and revision:
        print('Warning: Topaz revision only used with vendor layers.')

    if layer == 'vendor' and not revision:
        print('Error: vendor layers require a Topaz revision.')
        return 1

    print('Pending commits for: %s' % layer.upper())

    if layer == 'vendor':
        commits = get_commits('topaz', revision)
        print_commits('topaz', commits)
        layer = 'topaz'
    else:
        revision = 'master'

    next_layers = [(layer, revision)]
    while next_layers:
        layer, revision = next_layers.pop(0)
        layer_refs = get_lower_layer_commits(layer, revision)
        if not layer_refs:
            continue
        for lower_layer, lower_revision in layer_refs:
            commits = get_commits(lower_layer, lower_revision)
            print_commits(lower_layer, commits)
        next_layers.extend(layer_refs)

    return 0


if __name__ == "__main__":
    sys.exit(main())