#!/usr/bin/python

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

cfg = dict()
cfg['verbose'] = 0
cfg['nosync'] = False

cwd = os.getcwd()
if not os.path.exists('.repo'):
    sys.stderr.write("Not a repo\n")
    sys.exit(1)

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

# Valid formats:
#   YYYY-MM-DD-HH-MM-SS
#   YYYY-MM-DD-HH
#   YYYY-MM-DD
def string_to_datetime(s):
    fields = s.split('-')
    if len(fields) == 6:
        return datetime.datetime(int(fields[0]), int(fields[1]), int(fields[2]),
                                 int(fields[3]), int(fields[4]), int(fields[5]))
    if len(fields) == 4:
        return datetime.datetime(int(fields[0]), int(fields[1]), int(fields[2]),
                                 int(fields[3]))
    if len(fields) == 3:
        return datetime.datetime(int(fields[0]), int(fields[1]), int(fields[2]))
    return None

def datetime_to_string(dt):
    if dt.hour == 0 and dt.minute == 0 and dt.second == 0:
        return dt.strftime("%Y-%m-%d")
    return dt.strftime("%Y-%m-%d-%H-%M-%S")

# Find mid point between two datetime objects.
#
# Granularity is 1 hour.
#
# If the objects differ by less than 2 hours, exit.
#
# If the objects differ by at least 2 days and both hour components are
# zero, the resulting hour component will be zero.
def datetime_mid(d1, d2):
    delta = (d2 - d1) / 2
    if delta.total_seconds() < 3600:
        print "No more dates left to test"
        sys.exit(0)
    mid = d1 + delta
    if mid.minute != 0 or mid.second != 0:
        mid = mid.replace(minute=0, second=0)
    if delta.total_seconds() > 86400 and d1.hour == 0 and d2.hour == 0:
        if mid.hour != 0:
            mid = mid.replace(hour=0)
    return mid

def git_config(key):
    args = ['git', 'config', key]
    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 git config\n')
        sys.exit(1)
    return out.strip()

def git_reset_hard(rev):
    args = ['git', 'reset', '--hard', rev]
    child = subprocess.Popen(args, stdin=None, stdout=subprocess.PIPE, stderr=None)
    out, err = child.communicate()
    if child.returncode != 0:
        sys.stderr.write('Failed to reset git tree\n')
        sys.exit(1)

def git_checkout(rev):
    args = ['git', 'checkout', rev]
    child = subprocess.Popen(args, stdin=None, stdout=subprocess.PIPE, stderr=None)
    out, err = child.communicate()
    if child.returncode != 0:
        sys.stderr.write('Failed to checkout git tree\n')
        sys.exit(1)

def git_rev_by_date(date, branch):
    args = ['git', 'rev-list', '--max-count=1']
    args.append('--until=%s' % (date))
    args.append(branch)
    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 git log\n')
        sys.exit(1)
    if not out:
        sys.stderr.write('Failed to find rev')
        sys.exit(1)
    return out.strip()

def repo_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)
    return ElementTree.fromstring(out)

def repo_sync_to_date(date):
    print "bisect: sync to %s" % (date)

    # Set manifest revision
    os.chdir('.repo/manifests')
    remote = git_config('branch.default.remote')
    branch = git_config('branch.default.merge')
    manifest_rev = git_rev_by_date(date, '%s/%s' % (remote, branch))
    verbose("manifest revision %s\n" % (manifest_rev))
    git_reset_hard(manifest_rev)
    os.chdir(cwd)

    # Fetch the manifest
    manifest = repo_manifest()

    # Find default remote and revision
    for elem in manifest.findall('default'):
        def_remote = elem.get('remote')
        def_revision = elem.get('revision')
        if def_revision.startswith('refs/heads/'):
            # refs/heads/branch => branch
            def_revision = def_revision.split('/')[2]

    # Update manifest revisions
    for elem in manifest.findall('project'):
        project_name = elem.get('name')
        project_path = elem.get('path', project_name)
        project_remote = elem.get('remote', def_remote)
        project_revision = elem.get('revision', def_revision)
        if project_revision.startswith('refs/tags'):
            manifest_revision = project_revision.split('/')[2]
        else:
            manifest_revision = "%s/%s" % (project_remote, project_revision)
        os.chdir(".repo/projects/%s.git" % (project_path))
        rev = git_rev_by_date(date, manifest_revision)
        os.chdir(cwd)
        elem.set('revision', rev)

    # Write new manifest
    pathname = "%s/.repo/manifests/bisect-%s.xml" % (cwd, date)

    ElementTree.ElementTree(manifest).write(pathname)

    # Sync the working tree.  Note:
    #
    #  - Both "repo manifest" and "repo sync -m" include local manifests,
    #    so we must move the local manifests out of the way temporarily
    #    to avoid duplicate project errors.
    #
    #  - "repo sync" always syncs up the main manifest (even with -m), so
    #    we must reset the main manifest after we sync.

    have_local = os.path.exists('.repo/local_manifests')
    if have_local:
        os.rename('.repo/local_manifests', '.repo/local_manifests.hide')

    args = ['repo', 'sync', '-l', '-m', pathname]
    child = subprocess.Popen(args, stdin=None, stdout=subprocess.PIPE, stderr=None)
    out, err = child.communicate()
    if child.returncode != 0:
        sys.stderr.write('Failed to sync\n')

    if have_local:
        os.rename('.repo/local_manifests.hide', '.repo/local_manifests')

    os.chdir('.repo/manifests')
    git_reset_hard(manifest_rev)
    os.chdir(cwd)

def state_read():
    s = dict()
    f = open('.repo/bisect', 'r')
    for line in f:
        k,v = line.strip().split('=')
        s[k] = v
    f.close()
    return s

def state_write(s):
    f = open('.repo/bisect', 'w')
    f.write("start=%s\n" % (s['start']))
    f.write("end=%s\n" % (s['end']))
    f.close()

def state_delete():
    os.unlink('.repo/bisect')

def usage():
    print "Usage:"
    print "  repo-bisect [args] start yyyy-mm-dd yyyy-mm-dd"
    print "  repo-bisect [args] <good|bad|reset>"
    print "    --verbose  Increase verbose level"
    sys.exit(1)

### Main code ###

optargs, argv = getopt.getopt(sys.argv[1:], 'v',
        ['verbose', 'nosync'])
for k, v in optargs:
    if k in ('-n', '--nosync'):
        cfg['nosync'] = True
    if k in ('-v', '--verbose'):
        cfg['verbose'] += 1

if len(argv) < 1:
    usage()

action = argv[0]
if action == 'start':
    if len(argv) < 3:
        usage()
    state = dict()
    state['start'] = argv[1]
    state['end'] = argv[2]
    state_write(state)
    if not cfg['nosync']:
        repo_sync_to_date(state['start'])
if action == 'good':
    state = state_read()
    d1 = string_to_datetime(state['start'])
    d2 = string_to_datetime(state['end'])
    mid = datetime_mid(d1, d2)
    state['start'] = datetime_to_string(mid)
    state_write(state)
    print "bisect: start=%s, end=%s" % (state['start'], state['end'])
    if not cfg['nosync']:
        repo_sync_to_date(state['start'])
if action == 'bad':
    state = state_read()
    d1 = string_to_datetime(state['start'])
    d2 = string_to_datetime(state['end'])
    mid = datetime_mid(d1, d2)
    state['end'] = datetime_to_string(mid)
    state_write(state)
    print "bisect: start=%s, end=%s" % (state['start'], state['end'])
    if not cfg['nosync']:
        repo_sync_to_date(state['start'])
if action == 'reset':
    state_delete()

sys.exit(0)