#!/bin/bash 
# A simple script to make live backups of an organization's GitHub repositories.

# Where to store the backup files
GHBU_BACKUP_DIR=${GHBU_BACKUP_DIR-"==/FULL/PATH/TO/BACKUPDIR=="} 

# The GitHub organization whose repos will be backed up
GHBU_ORG=${GHBU_ORG-"==ORGANIZATION=="}

# GitHub API token.
GBHU_TOKEN=${GBHU_TOKEN-"==AUTHTOKEN=="}

# the GitHub hostname.
GHBU_GITHOST=${GHBU_GITHOST-"github.com"}

# base URI for the GitHub API.
GHBU_API=${GHBU_API-"https://api.github.com"}

# Options for the API call.
GHBU_API_OPTS="access_token=${GBHU_TOKEN}&"

# base command to use to clone GitHub repos
GHBU_GIT_CLONE_CMD="git clone --quiet --mirror git@${GHBU_GITHOST}:"

# base command to use to clone GitHub repos
GHBU_GIT_FETCH_CMD="git --bare fetch"

# when `true`, old backups will be deleted
GHBU_PRUNE_OLD=${GHBU_PRUNE_OLD-true}

# the min age (in days) of backup files to delete
GHBU_PRUNE_AFTER_N_DAYS=${GHBU_PRUNE_AFTER_N_DAYS-3}

# when `true`, only show error messages 
GHBU_SILENT=${GHBU_SILENT-false}

TSTAMP=`date "+%Y%m%d-%H%M"`

# The function `check` will exit the script if the given command fails.
function check {
  "$@"
  status=$?
  if [ $status -ne 0 ]; then
    echo "ERROR: Encountered error (${status}) while running the following:" >&2
    echo "           $@"  >&2
    echo "       (at line ${BASH_LINENO[0]} of file $0.)"  >&2
    echo "       Aborting." >&2
    exit $status
  fi
}

# The function `tgz` will create a gzipped tar archive of the specified file ($1) and then remove the original
function tgz {
   check tar zcf $1.tar.gz $1 && check rm -rf $1
}

$GHBU_SILENT || (echo "" && echo "=== INITIALIZING ===" && echo "")

$GHBU_SILENT || echo "Using backup directory $GHBU_BACKUP_DIR"
check mkdir -p $GHBU_BACKUP_DIR

$GHBU_SILENT || echo -n "Fetching list of repositories for ${GHBU_ORG}..."

REPOURL="${GHBU_API}/orgs/${GHBU_ORG}/repos?${GHBU_API_OPTS}per_page=2"

REPOLIST=""
while [ $REPOURL ]; do
  REPOREQCONTENT=`curl --silent -i $GHBU_CURLOPTS $REPOURL -q`
  REPOURL=`check echo "${REPOREQCONTENT}" | grep "\"next\"" | check awk -F'<' '{print $2}' | check sed -e 's/>;.*//g'`
  REPOLIST=$REPOLIST`check echo "${REPOREQCONTENT}" | grep "\"name\"" | check awk -F': "' '{print $2}' | check sed -e 's/",//g'`$'\n'
done

$GHBU_SILENT || echo " found `echo $REPOLIST | wc -w | awk '$1=$1'` repositories."

$GHBU_SILENT || (echo "" && echo "=== BACKING UP ===" && echo "")

for REPO in $REPOLIST; do

  # if the repository exists, update it from GitHub.
  if [ -d ${GHBU_BACKUP_DIR}/${REPO}.git ] ; then
    $GHBU_SILENT || echo "Syncing existing repo ${GHBU_ORG}/${REPO}"
    check cd ${GHBU_BACKUP_DIR}/${REPO}.git && check ${GHBU_GIT_FETCH_CMD}
  # if the repository is new, clone it.
  else 
    $GHBU_SILENT || echo "Backing up ${GHBU_ORG}/${REPO}"
    check ${GHBU_GIT_CLONE_CMD}${GHBU_ORG}/${REPO}.git ${GHBU_BACKUP_DIR}/${REPO}.git 
  fi

  # if the wiki exists, update it from GitHub.
  if [ -d ${GHBU_BACKUP_DIR}/${REPO}.wiki.git ] ; then
    $GHBU_SILENT || echo "Syncing existing wiki for ${GHBU_ORG}/${REPO}"
    check cd ${GHBU_BACKUP_DIR}/${REPO}.wiki.git && check ${GHBU_GIT_FETCH_CMD}
	# if the wiki is new, attempt to clone it (and ignore it if it doesn't exist).
  else
    $GHBU_SILENT || echo "Backing up ${GHBU_ORG}/${REPO}.wiki (if any)"
    ${GHBU_GIT_CLONE_CMD}${GHBU_ORG}/${REPO}.wiki.git ${GHBU_BACKUP_DIR}/${REPO}.wiki.git 2>/dev/null 
  fi

  # Have to read the API docs to see how to do this via the API using a token.
#  $GHBU_SILENT || echo "Backing up ${GHBU_ORG}/${REPO} issues"
#  check curl --silent -u $GHBU_UNAME:$GHBU_PASSWD ${GHBU_API}/repos/${GHBU_ORG}/${REPO}/issues -q > ${GHBU_BACKUP_DIR}/${GHBU_ORG}-${REPO}.issues-${TSTAMP} && tgz ${GHBU_BACKUP_DIR}/${GHBU_ORG}-${REPO}.issues-${TSTAMP}

done

if $GHBU_PRUNE_OLD; then
  $GHBU_SILENT || (echo "" && echo "=== PRUNING ===" && echo "")
  $GHBU_SILENT || echo "Pruning issues backup files ${GHBU_PRUNE_AFTER_N_DAYS} days old or older."
  $GHBU_SILENT || echo "Found `find $GHBU_BACKUP_DIR -name '*.tar.gz' -mtime +$GHBU_PRUNE_AFTER_N_DAYS | wc -l` files to prune."
  find $GHBU_BACKUP_DIR -name '*.tar.gz' -mtime +$GHBU_PRUNE_AFTER_N_DAYS -exec rm -fv {} > /dev/null \; 
fi

$GHBU_SILENT || (echo "" && echo "=== DONE ===" && echo "")
$GHBU_SILENT || (echo "GitHub backup completed." && echo "")