#!/usr/bin/env bash
# git-directory-deploy.sh
# https://github.com/X1011/git-directory-deploy

# BSD 3-Clause License:

# Copyright Daniel Smith
# All rights reserved.

# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:

#   Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.

#   Redistributions in binary form must reproduce the above copyright notice, this
#   list of conditions and the following disclaimer in the documentation and/or
#   other materials provided with the distribution.

#   The names of the contributors may not be used to endorse or promote products
#   derived from this software without specific prior written permission.

# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


set -o errexit #abort if any command fails


# Start modifications
# --------------------
while getopts "d:b:u:e:v:r:a:m:i:" opt; do
  declare "opt_$opt=${OPTARG:-0}"
done

#set directory and branch
deploy_directory=$opt_d
deploy_branch=$opt_b

#if no user identity is already set in the current git environment, use this:
default_username=$opt_u
default_email=$opt_e

#Parse arg flags
verbose=$opt_v
allow_empty=$opt_a
ignore_removal=$opt_i

# possibly append commit message
append_message=${opt_m:-""}
if [ -n "$append_message" ]; then
    append_message=" $append_message"
fi

#repository to deploy to. must be readable and writable.
repo=$opt_r
# --------------------
# End modifications


#echo expanded commands as they are executed (for debugging)
function enable_expanded_output {
    if [ $verbose ]; then
        set -o xtrace
        set +o verbose
    fi
}

#this is used to avoid outputting the repo URL, which may contain a secret token
function disable_expanded_output {
    if [ $verbose ]; then
        set +o xtrace
        set -o verbose
    fi
}

enable_expanded_output

function set_user_id {
    if [[ -z `git config user.name` ]]; then
        git config user.name "$default_username"
    fi
    if [[ -z `git config user.email` ]]; then
        git config user.email "$default_email"
    fi
}

function restore_head {
    if [[ $previous_branch = "HEAD" ]]; then
        #we weren't on any branch before, so just set HEAD back to the commit it was on
        git update-ref --no-deref HEAD $commit_hash $deploy_branch
    else
        git symbolic-ref HEAD refs/heads/$previous_branch
    fi

    git reset --mixed
}

if ! git diff --exit-code --quiet --cached; then
    echo Aborting due to uncommitted changes in the index >&2
    exit 1
fi

commit_title=`git log -n 1 --format="%s" HEAD`
commit_hash=`git log -n 1 --format="%H" HEAD`
previous_branch=`git rev-parse --abbrev-ref HEAD`

initial_deploy() {
	git --work-tree "$deploy_directory" checkout --orphan $deploy_branch
	git --work-tree "$deploy_directory" add --all
	commit+push
}

incremental_deploy() {
  #make deploy_branch the current branch
  git symbolic-ref HEAD refs/heads/$deploy_branch

  #put the previously committed contents of deploy_branch branch into the index
  git --work-tree "$deploy_directory" reset --mixed --quiet

  if [ $ignore_removal ]; then
    git --work-tree "$deploy_directory" add . --ignore-removal
    git --work-tree "$deploy_directory" checkout -- .
  else
    git --work-tree "$deploy_directory" add --all
  fi

  set +o errexit
  diff=$(git --work-tree "$deploy_directory" diff --exit-code --quiet HEAD)$?
  set -o errexit
  case $diff in
      0) echo No changes to files in $deploy_directory. Skipping commit.;;
      1) commit+push;;
      *)
          echo git diff exited with code $diff. Aborting. Staying on branch $deploy_branch so you can debug. To switch back to master, use: git symbolic-ref HEAD refs/heads/master && git reset --mixed >&2
          exit $diff
          ;;
  esac
}

commit+push() {
  set_user_id
  git --work-tree "$deploy_directory" commit -nm \
      "publish: $commit_title$append_message"$'\n\n'"generated from commit $commit_hash"

  disable_expanded_output
  #--quiet is important here to avoid outputting the repo URL, which may contain a secret token
  git push --quiet $repo $deploy_branch
  enable_expanded_output
}


if [ ! -d "$deploy_directory" ]; then
    echo "Deploy directory '$deploy_directory' does not exist. Aborting." >&2
    exit 1
fi

if [[ -z `ls -A "$deploy_directory" 2> /dev/null` && -z $allow_empty ]]; then
    echo "Deploy directory '$deploy_directory' is empty. Aborting. If you're sure you want to deploy an empty tree, use the -e flag." >&2
    exit 1
fi

if git ls-remote --exit-code $repo "refs/heads/$deploy_branch" ; then
  # deploy_branch exists in $repo; make sure we have the latest version
  disable_expanded_output
  git fetch --force $repo $deploy_branch:$deploy_branch
  enable_expanded_output
fi

if git show-ref --verify --quiet "refs/heads/$deploy_branch"
  then incremental_deploy
  else initial_deploy
fi

restore_head