#!/usr/bin/python

import os
import sys
import getopt
import subprocess
import urllib2
import json
import re
from xml.etree import ElementTree

cfg = dict()
cfg['nodo'] = False
cfg['post'] = None
cfg['remote'] = None
cfg['revision'] = None
cfg['ssh'] = False
cfg['verbose'] = 0

def verbose(s):
    if cfg['verbose'] > 0:
        sys.stderr.write(s)

def get_topdir():
    dir = os.getcwd()
    while not os.path.exists("%s/.repo" % (dir)):
        dir = os.path.realpath("%s/.." % (dir))
        if dir == '/':
            raise OSError(2, 'No such file or directory', dir)
    return dir

def usage():
    print "Usage: gerrit-fetch [args] <change-num>"
    print "  --nodo     Do not apply the change"
    print "  --post     Apply change after fetching (cherry-pick|merge)"
    print "  --remote   Use specified remote"
    print "  --revision Use specified change revision"
    print "  --ssh      Use ssh, do not attempt http"
    print "  --verbose  Increase verbose level"
    sys.exit(1)

optargs, argv = getopt.getopt(sys.argv[1:], 'np:sv',
        ['nodo', 'post=', 'remote=', 'revision=', 'ssh', 'verbose'])
for k, v in optargs:
    if k in ('-n', '--nodo'):
        cfg['nodo'] = True
    if k in ('-p', '--post'):
        cfg['post'] = v
    if k in ('--remote'):
        cfg['remote'] = v
    if k in ('--revision'):
        cfg['revision'] = v
    if k in ('-s', '--ssh'):
        cfg['ssh'] = True
    if k in ('-v', '--verbose'):
        cfg['verbose'] += 1

if not cfg['post'] is None:
    if cfg['post'] != 'cherry-pick' and cfg['post'] != 'merge':
        usage()

if len(argv) != 1:
    usage()

change_number = int(argv[0])

cur_dir = os.getcwd()
verbose("cur_dir=%s\n" % (cur_dir))
prj_dir = None
try:
    top_dir = get_topdir()
except OSError:
    sys.stderr.write("Cannot find top of android tree\n")
    sys.exit(1)
verbose("top_dir=%s\n" % (top_dir))
if len(top_dir) < len(cur_dir):
    prj_dir = cur_dir[len(top_dir)+1:]
    verbose("prj_dir=%s\n" % (prj_dir))

# Read our manifest
args = []
args.append('repo')
args.append('manifest')
child = subprocess.Popen(args, stdin=None, stdout=subprocess.PIPE, stderr=None)
out, err = child.communicate()
if child.returncode != 0:
    sys.stderr.write('Failed to read manifest\n')
    sys.exit(1)
manifest = ElementTree.fromstring(out)

# Figure out which remote to use
remote_name = cfg['remote']
if remote_name is None:
    if not prj_dir is None:
        for elem in manifest.findall('project'):
            if elem.get('path') == prj_dir:
                remote_name = elem.get('remote')
    if remote_name is None:
        for elem in manifest.findall('default'):
            remote_name = elem.get('remote')
if remote_name is None:
    sys.stderr.write("Cannot find appropriate remote entry in manifest\n");
    sys.exit(1);
verbose("remote_name=%s\n" % (remote_name))

review_url = None
review_host = None
for elem in manifest.findall('remote'):
    if elem.get('name') == remote_name:
        review_url = elem.get('review')
        if review_url.find(':') == -1:
            review_host = review_url
            review_url = "http://%s" % (review_url)
        else:
            review_host = review_url.strip_url_schema()
if review_url is None or review_host is None:
    sys.stderr.write("Cannot find appropriate remote url in manifest\n");
    sys.exit(1);
verbose("review_url=%s, review_host=%s\n" % (review_url, review_host))

# Fetch the change props
props = None
project_name = None
change_revision = cfg['revision']
if not cfg['ssh']:
    try:
        # NB: o=DOWNLOAD_COMMANDS is not reliable so don't use it
        url = '%s/changes/?q=%d&o=CURRENT_REVISION' % (review_url, change_number)
        verbose("Attempting to fetch change from url=%s\n" % (url))
        response = urllib2.urlopen(url)
        doc = response.read()
        if not doc.startswith(")]}'\n"):
            sys.stderr.write('Error: malformed change props (url=%s)\n' % (url))
            raise Exception('Malformed change props')
        proplist = json.loads(doc[5:])
        if len(proplist) == 1:
            verbose("proplist loads and has one element\n");
            props = proplist[0]
            project_name = props['project']
            if change_revision is None:
                change_rev_id = props['current_revision']
                change_rev = None
                for rev in props['revisions']:
                    if rev == change_rev_id:
                        change_revision = props['revisions'][rev]['_number']
    except:
        sys.stderr.write('Failed to fetch change props\n')

if project_name is None:
    args = []
    args.append('ssh')
    args.append(review_host)
    args.append('gerrit')
    args.append('query')
    args.append('--format=JSON')
    args.append('--current-patch-set')
    args.append("%d" %(change_number))
    verbose("Attempting to fetch change from cmd=\"%s\"\n" % (" ".join(args)))
    child = subprocess.Popen(args, stdin=None, stdout=subprocess.PIPE, stderr=None)
    out, err = child.communicate()
    if child.returncode != 0:
        sys.stderr.write('Failed to read manifest\n')
        sys.exit(1)
    lines = out.split('\n')
    props = json.loads(lines[0])
    project_name = props['project']
    if change_revision is None:
        change_revision = props['currentPatchSet']['number']

    # If we used ssh to access the change, also use ssh to fetch it
    review_url = "ssh://%s" % (review_host)

if project_name is None:
    sys.stderr.write('Error: cannot fetch change properties\n')
    sys.exit(1)
verbose("project=%s\n" % (project_name))

if change_revision is None:
    sys.stderr.write('Error: cannot fetch change revision\n')
    sys.exit(1)
verbose("change_revision=%s\n" % (change_revision))

project = None
for elem in manifest.findall('project'):
    if elem.get('name') == project_name:
        project = elem
if project is None:
    sys.stderr.write('Error: project not found\n')
    sys.exit(1)
project_path = project.get('path')

if prj_dir is None:
    # Switch to the project directory
    verbose("Switching to project directory %s\n" % (project_path))
    try:
        os.chdir(project_path)
    except:
        sys.stderr.write('Error: path not found\n')
        sys.exit(1)
else:
    # Verify correct directory
    verbose("Verifying project directory %s vs %s\n" % (project_path, prj_dir))
    if prj_dir != project_path:
        sys.stderr.write("Error: change applies to %s, we are in %s\n" % (project_path, prj_dir))
        sys.exit(1)

change_hash = "%02d" % (change_number % 100)

# Fetch the change
args = []
args.append('git')
args.append('fetch')
args.append('%s/%s' % (review_url, project_name))
args.append('refs/changes/%s/%s/%s' % (change_hash, change_number, change_revision))
if cfg['nodo']:
    print ' '.join(args)
else:
    child = subprocess.Popen(args, stdin=None, stdout=None, stderr=None)
    out, err = child.communicate()
    if child.returncode != 0:
        sys.stderr.write('Failed to fetch change\n')
        sys.exit(1)

if not cfg['post'] is None:
    # Pick the change
    args = []
    args.append('git')
    args.append(cfg['post'])
    args.append('FETCH_HEAD')
    if cfg['nodo']:
        print ' '.join(args)
    else:
        child = subprocess.Popen(args, stdin=None, stdout=None, stderr=None)
        out, err = child.communicate()
        if child.returncode != 0:
            sys.stderr.write("Failed to %s change\n" % (cfg['post']))
            sys.exit(1)

verbose('Success\n')
sys.exit(0)