#!/bin/bash
# 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.

# Note:
# We do *not* source any other files as this is meant to be used as a
# standalone helper script with no other dependencies.  So please do
# not try to refactor this to rely on anything else.

ARGV0="cros_mirror"

MANIFEST_URL_EXT='https://git.chromium.org/git/chromiumos/manifest.git'
MANIFEST_URL_INT='ssh://gerrit-int.chromium.org:29419/chromeos/manifest-internal.git'
REPO_URL='https://git.chromium.org/git/external/repo.git'
# When we make commits to manifest git repos, we want the owner info to be the
# same, and we want it to map to info that end users are unlikely to use.  That
# way when the local repo rebase runs, it handles the update gracefully.
export GIT_AUTHOR_NAME='Elmur Fudsicle' GIT_AUTHOR_EMAIL='<baba@booya.bizzle>'

set -e

#
# Helper functions.
#
info() {
  if [[ -z ${QUIET} ]]; then
    echo "info: $*"
  fi
}

error() {
  echo "error: $*" >&2
}

die() {
  error "$*"
  exit 1
}

_pushd() { pushd "$@" >/dev/null; }
_popd()  { popd "$@" >/dev/null; }

#
# Process user flags.
#
usage() {
  cat <<EOF
Create or maintain a mirror of the ChromiumOS repository.

Usage: ${ARGV0} [options] --root <dir>

Options:
  --external          Pull the external ChromiumOS manifest
  --internal          Pull the internal ChromeOS manifest (note: Googler-only)
  -j, --jobs          Number of fetch jobs to run in parallel (default ${JOBS})
  -q, --quiet         Be quiet!
  -r, --root          The directory to hold all mirroring information
  -u, --url           The URL that people will use to pull from this mirror
  -h, --help          This!

You must specify the --url option at least once so that all of the paths can
be rewritten for external users.  After that, it should be automatically saved
and restored at runtime by this script.

Example:
# Create a full mirror in \${PWD} and have users fetch from the local machine.
\$ ${ARGV0} -r . -u git://$(hostname -f)
# Update the mirror (put this into a cronjob).
\$ ${ARGV0} -q -r ${ROOT:-${PWD}}

See this page for more information:
http://dev.chromium.org/chromium-os/how-tos-and-troubleshooting/creating-local-mirrors
EOF
  exit ${1:-0}
}

JOBS=$(getconf _NPROCESSORS_ONLN 2>/dev/null || echo 4)
MANIFEST_URL=
QUIET=
ROOT=
URL=
while [[ $# -gt 0 ]]; do
  case $1 in
  --external) MANIFEST_URL=${MANIFEST_URL_EXT};;
  --internal) MANIFEST_URL=${MANIFEST_URL_INT};;
  -j|--jobs)  JOBS=$2;;
  -q|--quiet) QUIET="-q";;
  -r|--root)  ROOT=$2; shift;;
  -u|--url)   URL=$2; shift;;
  -h|--help)  usage;;
  -x)         set -x;;
  *)          usage 1;;
  esac
  shift
done

if [[ -z ${ROOT} ]]; then
  die "need to specify root dir with --root"
fi
if [[ ! -d ${ROOT} ]]; then
  die "specified root dir does not exist; please run: mkdir '${ROOT}'"
fi

cd "${ROOT}"

#
# Make sure our tools are up-to-date.
#
if ! which repo >/dev/null; then
  die "you must have repo installed and in your \$PATH; please see:" \
      "http://dev.chromium.org/developers/how-tos/install-depot-tools"
fi
# This has been tested against 1.7.7.x, so require at least that.
if ! gver=$(git --version); then
  die "you must have git installed!"
fi
bver="1.7.7"
ver_to_int() {
  local v i=0
  local ver=( $(echo $(IFS=.; echo $*)) )
  for v in 0 1 2; do
    : $(( i = (i << 8) | ${ver[v]} ))
  done
  echo ${i}
}
if [[ $(ver_to_int "${bver}") -gt $(ver_to_int "${gver##* }") ]]; then
  die "your git version is too old (${gver}); we require at least git ${bver}"
fi


#
# Initialize the whole tree mirror style.
#
repo_init() {
  repo init -u "${MANIFEST_URL}" --repo-url="${REPO_URL}" ${QUIET} "$@"
}
if [[ ! -d .repo ]]; then
  # Default to external manifest.
  : ${MANIFEST_URL:=${MANIFEST_URL_EXT}}
  repo_init --mirror
else
  # Allow people to change manifests on the fly (internal<->external).
  CURRENT_URL=$(git --git-dir=.repo/manifests.git config remote.origin.url)
  # If no manifest was selected, default to the current one.
  : ${MANIFEST_URL:=${CURRENT_URL}}
  if [[ "${CURRENT_URL}" != "${MANIFEST_URL}" ]]; then
    info "re-initing due to URL change: ${CURRENT_URL} -> ${MANIFEST_URL}"
    repo_init
  fi
fi
if [[ ! -e git ]]; then
  ln -s . git
fi

#
# Pull down any updates.
#
info "syncing the whole tree"
repo sync -j${JOBS} ${QUIET}

#
# Setup our local manifests repo which we'll hack on to point
# to our local mirror.  We can't modify the repo in place as
# we want to make sure updates are atomic -- don't want other
# people to be able to accidentally pull in an unmodified repo.
#
update_manifests() {
  local git_repo=$1
  local checkout=${git_repo##*/}
  checkout=${checkout%.git}

  if [[ ${MANIFEST_URL} == "${MANIFEST_URL_INT}" ]]; then
    # Try to head off leakage of Google data.
    case ${URL} in
    ssh://* | file://*) ;;
    *)
      die "You *must* use a secure channel like ssh:// or file://" \
          "when mirroring internal Google repositories."
      ;;
    esac
  fi

  if [[ ! -d ${checkout} ]]; then
    info "cloning ${checkout}"
    git clone ${QUIET} ./${git_repo} ${checkout}
    # Make the path relative so the whole tree can be moved w/out breaking.
    git --git-dir=${checkout}/.git config remote.origin.url ../${git_repo}
  fi

  info "updating ${checkout}"
  _pushd ${checkout}
  git fetch ${QUIET}
  if [[ -z ${URL} ]]; then
    # Extract the local URI if they didn't specify one.
    URL=$(eval $(grep -h fetch= *.xml); echo ${fetch})
    if [[ ${URL} == "https://git.chromium.org/git" ]]; then
      # Guess they want the current system.
      URL="git://$(hostname -f)"
    fi
  fi

  # Setup the fetch= field of the manifest to point to our local mirror.
  local b branches=(
    $(git ls-remote | sed 's:.*/::' | egrep -v '\<(HEAD|^master)$')
    "master"
  )
  info "rewriting ${checkout} branches to ${URL}"
  for b in "${branches[@]}"; do
    git checkout -q -f -B ${b} origin/${b} >/dev/null
    find -name '*.xml' -type f \
      -exec sed -i "/fetch=/s|=\"[^\"]*\"|=\"${URL}\"|" {} +
    git commit -q -a -m 'set fetch references to local mirror'
  done

  # Push out our updates.
  local pub="../${git_repo%.git}-mirror.git"
  if [[ ! -e ${pub} ]]; then
    git --git-dir="${pub}" init ${QUIET}
  fi
  git push ${QUIET} -f "${pub}" 'refs/heads/*:refs/heads/*'
  _popd
}
update_manifests chromiumos/manifest.git
if [[ ${MANIFEST_URL} == "${MANIFEST_URL_INT}" ]]; then
  update_manifests chromeos/manifest-internal.git
fi

#
# All done!
#
if [[ -z ${QUIET} ]]; then
  if [[ ${MANIFEST_URL} == "${MANIFEST_URL_EXT}" ]]; then
    cat <<EOF

You can now serve this tree with:
git daemon --base-path=${ROOT} --export-all

Your users can pull from this mirror with:
repo init -u ${URL}/chromiumos/manifest-mirror.git --repo-url=${URL}/external/repo.git
EOF
  else
    cat <<EOF

You must only serve these resources over encrypted channels like ssh://.

Your users can pull from this mirror with:
repo init -u ${URL}/chromeos/manifest-internal-mirror.git --repo-url=${URL}/external/repo.git
EOF
  fi
fi