# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Repository module to handle different types of repositories."""

import constants
import logging
import os
import re
import shutil

from chromite.lib import cros_build_lib
from chromite.lib import git
from chromite.lib import osutils
from chromite.lib import rewrite_git_alternates

# File that marks a buildroot as being used by a trybot
_TRYBOT_MARKER = '.trybot'


class SrcCheckOutException(Exception):
  """Exception gets thrown for failure to sync sources"""
  pass


def IsARepoRoot(directory):
  """Returns True if directory is the root of a repo checkout."""
  return os.path.exists(os.path.join(directory, '.repo'))


def IsInternalRepoCheckout(root):
  """Returns whether root houses an internal 'repo' checkout."""
  manifest_dir = os.path.join(root, '.repo', 'manifests')
  manifest_url = git.RunGit(
      manifest_dir, ['config', 'remote.origin.url']).output.strip()
  return (os.path.splitext(os.path.basename(manifest_url))[0]
          == os.path.splitext(os.path.basename(constants.MANIFEST_INT_URL))[0])


def CloneGitRepo(working_dir, repo_url, reference=None, bare=False,
                 mirror=False, depth=None):
  """Clone given git repo

  Args:
    working_dir: location where it should be cloned to
    repo_url: git repo to clone
    reference: If given, pathway to a git repository to access git objects
      from.  Note that the reference must exist as long as the newly created
      repo is to be usable.
    bare: Clone a bare checkout.
    mirror: Clone a mirror checkout.
    depth: If given, do a shallow clone limiting the objects pulled to just
      that # of revs of history.  This option is mutually exclusive to
      reference.
  """
  osutils.SafeMakedirs(working_dir)
  cmd = ['clone', repo_url, working_dir]
  if reference:
    if depth:
      raise ValueError("reference and depth are mutually exclusive "
                       "options; please pick one or the other.")
    cmd += ['--reference', reference]
  if bare:
    cmd += ['--bare']
  if mirror:
    cmd += ['--mirror']
  if depth:
    cmd += ['--depth', str(int(depth))]
  git.RunGit(working_dir, cmd)


def UpdateGitRepo(working_dir, repo_url, **kwargs):
  """Update the given git repo, blowing away any local changes.

  If the repo does not exist, clone it from scratch.

  Args:
    working_dir: location where it should be cloned to
    repo_url: git repo to clone
    **kwargs: See CloneGitRepo.
  """
  assert not kwargs.get('bare'), 'Bare checkouts are not supported'
  if git.IsGitRepo(working_dir):
    try:
      git.CleanAndCheckoutUpstream(working_dir)
    except cros_build_lib.RunCommandError:
      cros_build_lib.Warning('Could not update %s', working_dir, exc_info=True)
      shutil.rmtree(working_dir)
      CloneGitRepo(working_dir, repo_url, **kwargs)
  else:
    CloneGitRepo(working_dir, repo_url, **kwargs)


def GetTrybotMarkerPath(buildroot):
  """Get path to trybot marker file given the buildroot."""
  return os.path.join(buildroot, _TRYBOT_MARKER)


def CreateTrybotMarker(buildroot):
  """Create the file that identifies a buildroot as being used by a trybot."""
  osutils.WriteFile(GetTrybotMarkerPath(buildroot), '')

def ClearBuildRoot(buildroot, preserve_paths=()):
  """Remove and recreate the buildroot while preserving the trybot marker."""
  trybot_root = os.path.exists(GetTrybotMarkerPath(buildroot))
  if os.path.exists(buildroot):
    cmd = ['find', buildroot, '-mindepth', '1', '-maxdepth', '1']

    ignores = []
    for path in preserve_paths:
      if ignores:
        ignores.append('-a')
      ignores += ['!', '-name', path]
    cmd.extend(ignores)

    cmd += ['-exec', 'rm', '-rf', '{}', '+']
    cros_build_lib.SudoRunCommand(cmd)
  else:
    os.makedirs(buildroot)
  if trybot_root:
    CreateTrybotMarker(buildroot)


class RepoRepository(object):
  """ A Class that encapsulates a repo repository.

  Args:
    repo_url: gitserver URL to fetch repo manifest from.
    directory: local path where to checkout the repository.
    branch: Branch to check out the manifest at.
    referenced_repo: Repository to reference for git objects, if possible.
    manifest: Which manifest.xml within the branch to use.  Effectively
      default.xml if not given.
    depth: Mutually exclusive option to referenced_repo; this limits the
      checkout to a max commit history of the given integer.
  """
  # Use our own repo, in case android.kernel.org (the default location) is down.
  _INIT_CMD = ['repo', 'init', '--repo-url', constants.REPO_URL]

  # If a repo hasn't been used in the last 5 runs, wipe it.
  LRU_THRESHOLD = 5

  def __init__(self, repo_url, directory, branch=None, referenced_repo=None,
               manifest=constants.DEFAULT_MANIFEST, depth=None):
    self.repo_url = repo_url
    self.directory = directory
    self.branch = branch

    # It's perfectly acceptable to pass in a reference pathway that isn't
    # usable.  Detect it, and suppress the setting so that any depth
    # settings aren't disabled due to it.
    if referenced_repo is not None:
      if depth is not None:
        raise ValueError("referenced_repo and depth are mutually exclusive "
                         "options; please pick one or the other.")
      if not IsARepoRoot(referenced_repo):
        referenced_repo = None
    self._referenced_repo = referenced_repo
    self._manifest = manifest

    # If the repo exists already, force a selfupdate as the first step.
    self._repo_update_needed = IsARepoRoot(self.directory)
    if not self._repo_update_needed and git.FindRepoDir(self.directory):
      raise ValueError('Given directory %s is not the root of a repository.'
                       % self.directory)

    self._depth = int(depth) if depth is not None else None

  def _SwitchToLocalManifest(self, local_manifest):
    """Reinitializes the repository if the manifest has changed."""
    logging.debug('Moving to manifest defined by %s', local_manifest)
    # TODO: use upstream repo's manifest logic when we bump repo version.
    manifest_path = self.GetRelativePath('.repo/manifest.xml')
    os.unlink(manifest_path)
    shutil.copyfile(local_manifest, manifest_path)

  def Initialize(self, local_manifest=None, extra_args=()):
    """Initializes a repository.  Optionally forces a local manifest.

    Args:
      local_manifest: The absolute path to a custom manifest to use.  This will
                      replace .repo/manifest.xml.
      extra_args: Extra args to pass to 'repo init'
    """

    # Do a sanity check on the repo; if it exists and we can't pull a
    # manifest from it, we know it's fairly screwed up and needs a fresh
    # rebuild.
    if os.path.exists(os.path.join(self.directory, '.repo', 'manifest.xml')):
      try:
        cros_build_lib.RunCommandCaptureOutput(
            ['repo', 'manifest'], cwd=self.directory)
      except cros_build_lib.RunCommandError:
        cros_build_lib.Warning("Wiping %r due to `repo manifest` failure",
                               self.directory)
        paths = [os.path.join(self.directory, '.repo', x) for x in
                 ('manifest.xml', 'manifests.git', 'manifests', 'repo')]
        cros_build_lib.SudoRunCommand(['rm', '-rf'] + paths)
        self._repo_update_needed = False

    # Wipe local_manifest.xml if it exists- it can interfere w/ things in
    # bad ways (duplicate projects, etc); we control this repository, thus
    # we can destroy it.
    osutils.SafeUnlink(os.path.join(self.directory, 'local_manifest.xml'))

    # Force a repo self update first; during reinit, repo doesn't do the
    # update itself, but we could be doing the init on a repo version less
    # then v1.9.4, which didn't have proper support for doing reinit that
    # involved changing the manifest branch in use; thus selfupdate.
    # Additionally, if the self update fails for *any* reason, wipe the repo
    # innards and force repo init to redownload it; same end result, just
    # less efficient.
    # Additionally, note that this method may be called multiple times;
    # thus code appropriately.
    if self._repo_update_needed:
      try:
        cros_build_lib.RunCommand(['repo', 'selfupdate'], cwd=self.directory)
      except cros_build_lib.RunCommandError:
        osutils.RmDir(os.path.join(self.directory, '.repo', 'repo'),
                      ignore_missing=True)
      self._repo_update_needed = False

    init_cmd = self._INIT_CMD + ['--manifest-url', self.repo_url]
    if self._referenced_repo:
      init_cmd.extend(['--reference', self._referenced_repo])
    if self._manifest:
      init_cmd.extend(['--manifest-name', self._manifest])
    if self._depth is not None:
      init_cmd.extend(['--depth', str(self._depth)])
    init_cmd.extend(extra_args)
    # Handle branch / manifest options.
    if self.branch:
      init_cmd.extend(['--manifest-branch', self.branch])

    cros_build_lib.RunCommand(init_cmd, cwd=self.directory, input='\n\ny\n')
    if local_manifest and local_manifest != self._manifest:
      self._SwitchToLocalManifest(local_manifest)

  @property
  def _ManifestConfig(self):
    return os.path.join(self.directory, '.repo', 'manifests.git', 'config')

  def _EnsureMirroring(self, post_sync=False):
    """Ensure git is usable from w/in the chroot if --references is enabled

    repo init --references hardcodes the abspath to parent; this pathway
    however isn't usable from the chroot (it doesn't exist).  As such the
    pathway is rewritten to use relative pathways pointing at the root of
    the repo, which via I84988630 enter_chroot sets up a helper bind mount
    allowing git/repo to access the actual referenced repo.

    This has to be invoked prior to a repo sync of the target trybot to
    fix any pathways that may have been broken by the parent repo moving
    on disk, and needs to be invoked after the sync has completed to rewrite
    any new project's abspath to relative.
    """

    if not self._referenced_repo:
      return

    proj_root = os.path.join(self.directory, '.repo', 'project-objects')
    if not os.path.exists(proj_root):
      # Not yet synced, nothing to be done.
      return

    rewrite_git_alternates.RebuildRepoCheckout(self.directory,
                                               self._referenced_repo)

    if post_sync:
      chroot_path = os.path.join(self._referenced_repo, '.repo', 'chroot',
                                 'external')
      chroot_path = git.ReinterpretPathForChroot(chroot_path)
      rewrite_git_alternates.RebuildRepoCheckout(
          self.directory, self._referenced_repo, chroot_path)

    # Finally, force the git config marker that enter_chroot looks for
    # to know when to do bind mounting trickery; this normally will exist,
    # but if we're converting a pre-existing repo checkout, it's possible
    # that it was invoked w/out the reference arg.  Note this must be
    # an absolute path to the source repo- enter_chroot uses that to know
    # what to bind mount into the chroot.
    cmd = ['config', '--file', self._ManifestConfig, 'repo.reference',
           self._referenced_repo]
    git.RunGit('.', cmd)

  def Detach(self):
    """Detach projects back to manifest versions.  Effectively a 'reset'."""
    cros_build_lib.RunCommand(['repo', '--time', 'sync', '-d'],
                              cwd=self.directory)

  def _ForceSyncSupported(self):
    """Detect whether --force-sync is supported

    When repo changes its internal object layout, it'll refuse to sync unless
    this option is specified.
    """
    result = cros_build_lib.RunCommand(['repo', 'sync', '--help'],
                                       redirect_stdout=True, redirect_stderr=True,
                                       cwd=self.directory)
    return '--force-sync' in result.output

  def Sync(self, local_manifest=None, jobs=None, all_branches=False,
           network_only=False):
    """Sync/update the source.  Changes manifest if specified.

    Args:
      local_manifest: If true, checks out source to manifest.  DEFAULT_MANIFEST
        may be used to set it back to the default manifest.
      jobs: May be set to override the default sync parallelism defined by
        the manifest.
      all_branches: If False (the default), a repo sync -c is performed; this
        saves on sync'ing via grabbing only what is needed for the manifest
        specified branch.
      network_only: If true, perform only the network half of the sync; skip
        the checkout.  Primarily of use to validate a manifest (although
        if the manifest has bad copyfile statements, via skipping checkout
        the broken copyfile tag won't be spotted), or of use when the
        invoking code is fine w/ operating on bare repos, ie .repo/projects/*.
    """
    try:
      # Always re-initialize to the current branch.
      self.Initialize(local_manifest)
      # Fix existing broken mirroring configurations.
      self._EnsureMirroring()

      cmd = ['repo', '--time', 'sync']
      if self._ForceSyncSupported():
        cmd += ['--force-sync']
      if jobs:
        cmd += ['--jobs', str(jobs)]
      if not all_branches:
        cmd.append('-c')
      # Do the network half of the sync; retry as necessary to get the content.
      cros_build_lib.RunCommandWithRetries(constants.SYNC_RETRIES, cmd + ['-n'],
                                           cwd=self.directory)

      if network_only:
        return

      # Do the local sync; note that there is a couple of corner cases where
      # the new manifest cannot transition from the old checkout cleanly-
      # primarily involving git submodules.  Thus we intercept, and do
      # a forced wipe, then a retry.
      try:
        cros_build_lib.RunCommand(cmd + ['-l'], cwd=self.directory)
      except cros_build_lib.RunCommandError:
        manifest = git.ManifestCheckout.Cached(self.directory)
        targets = set(project['path'].split('/', 1)[0]
                      for project in manifest.ListCheckouts())
        if not targets:
          # No directories to wipe, thus nothing we can fix.
          raise

        cros_build_lib.SudoRunCommand(['rm', '-rf'] + sorted(targets),
                                      cwd=self.directory)

        # Retry the sync now; if it fails, let the exception propagate.
        cros_build_lib.RunCommand(cmd + ['-l'], cwd=self.directory)

      # We do a second run to fix any new repositories created by repo to
      # use relative object pathways.  Note that cros_sdk also triggers the
      # same cleanup- we however kick it erring on the side of caution.
      self._EnsureMirroring(True)
      self._DoCleanup()

    except cros_build_lib.RunCommandError as e:
      err_msg = e.Stringify(error=False, output=False)
      logging.error(err_msg)
      raise SrcCheckOutException(err_msg)

  def _DoCleanup(self):
    """Wipe unused repositories."""

    # Find all projects, even if they're not in the manifest.  Note the find
    # trickery this is done to keep it as fast as possible.
    repo_path = os.path.join(self.directory, '.repo', 'projects')
    current = set(cros_build_lib.RunCommandCaptureOutput(
        ['find', repo_path, '-type', 'd', '-name', '*.git', '-printf', '%P\n',
         '-a', '!', '-wholename',  '*.git/*', '-prune'],
        print_cmd=False).output.splitlines())
    data = {}.fromkeys(current, 0)

    path = os.path.join(self.directory, '.repo', 'project.lru')
    if os.path.exists(path):
      existing = [x.strip().split(None, 1)
                  for x in osutils.ReadFile(path).splitlines()]
      data.update((k, int(v)) for k, v in existing if k in current)

    # Increment it all...
    data.update((k, v + 1) for k, v in data.iteritems())
    # Zero out what is now used.
    checkouts = git.ManifestCheckout.Cached(self.directory).ListCheckouts()
    data.update(('%s.git' % x['path'], 0) for x in checkouts)

    # Finally... wipe anything that's greater than our threshold.
    wipes = [k for k, v in data.iteritems() if v > self.LRU_THRESHOLD]
    if wipes:
      cros_build_lib.SudoRunCommand(
          ['rm', '-rf'] + [os.path.join(repo_path, proj) for proj in wipes])
      map(data.pop, wipes)

    osutils.WriteFile(path, "\n".join('%s %i' % x for x in data.iteritems()))

  def GetRelativePath(self, path):
    """Returns full path including source directory of path in repo."""
    return os.path.join(self.directory, path)

  def ExportManifest(self, mark_revision=False, revisions=True):
    """Export the revision locked manifest

    Args:
      mark_revision: If True, then the sha1 of manifest.git is recorded
        into the resultant manifest tag as a version attribute.
        Specifically, if manifests.git is at 1234, <manifest> becomes
        <manifest revision="1234">.
      revisions: If True, then rewrite all branches/tags into a specific
        sha1 revision.  If False, don't.

    Returns:
      The manifest as a string.
    """
    cmd = ['repo', 'manifest', '-o', '-']
    if revisions:
      cmd += ['-r']
    output = cros_build_lib.RunCommandCaptureOutput(
        cmd, cwd=self.directory, print_cmd=False,
        extra_env={'PAGER':'cat'}).output

    if not mark_revision:
      return output
    modified = git.RunGit(os.path.join(self.directory, '.repo/manifests'),
                          ['rev-list', '-n1', 'HEAD'])
    assert modified.output
    return output.replace("<manifest>", '<manifest revision="%s">' %
                          modified.output.strip())

  def IsManifestDifferent(self, other_manifest):
    """Checks whether this manifest is different than another.

    May blacklists certain repos as part of the diff.

    Args:
      other_manifest: Second manifest file to compare against.

    Returns:
      True: If the manifests are different
      False: If the manifests are same
    """
    logging.debug('Calling IsManifestDifferent against %s', other_manifest)

    black_list = ['="chromium/']
    blacklist_pattern = re.compile(r'|'.join(black_list))
    manifest_revision_pattern = re.compile(r'<manifest revision="[a-f0-9]+">',
                                           re.I)

    current = self.ExportManifest()
    with open(other_manifest, 'r') as manifest2_fh:
      for (line1, line2) in zip(current.splitlines(), manifest2_fh):
        line1 = line1.strip()
        line2 = line2.strip()
        if blacklist_pattern.search(line1):
          logging.debug('%s ignored %s', line1, line2)
          continue

        if line1 != line2:
          logging.debug('Current and other manifest differ.')
          logging.debug('current: "%s"', line1)
          logging.debug('other  : "%s"', line2)

          # Ignore revision differences on the manifest line. The revision of
          # the manifest.git repo is uninteresting when determining if the
          # current manifest describes the same sources as the other manifest.
          if manifest_revision_pattern.search(line2):
            logging.debug('Ignoring difference in manifest revision.')
            continue

          return True

      return False