monify

#!  /usr/local/bin/bash

# Example: monify create my_repo "api-module web-module mobile-module" https://amitassaraf@bitbucket.org/project
# Example: monify clean

set -e
set -x

BASH_VERSION=$(/usr/bin/env bash --version)

if [[ $string = *"version 3"* ]]; then
  echo "bash version 4 and higher is required."
  exit
else
	if [[ $string = *"version 4"* ]]; then
  		echo "bash version is good."
  	fi
fi

COMMAND=$1

if [[ $COMMAND == clean ]]; then
	sudo unmount $TMPFS_DIR || :
	rmdir $TMPFS_DIR || :
	rm -rf $BUILD_DIR
	exit
fi

REPO_NAME=$2

BUILD_DIR="$PWD/mega$REPO_NAME"
MERGED_DIR="$BUILD_DIR/uni$REPO_NAME"

GIT_URL=$4
REPOS=$3

INITIAL_COMMIT="init"
TMPFS_DIR="$BUILD_DIR/tmp"
GRAFTS_FILE="$MERGED_DIR/.git/info/grafts"

function clone_repos {
	for repo in $REPOS; do
		cd $BUILD_DIR
		mkdir $repo
		git clone --mirror "$GIT_URL/$repo.git" "$repo/.git"
		cd $repo

		git config --bool core.bare false
		git reset --hard HEAD

		# We dont want tto later filter the remote branches
		# This is also a safeguard against pushing any changes we make to the server
		git remote remove origin
	done
}

# sed "s,\t\"*,&'"$1"'/,"
function move_to_dir {
	repo_upper=$(echo $repo | tr /a-z/ /A-Z/)
	git ls-files -s | sed "s,	,&"$1"/,"

	case "$(uname -s)" in
	   Darwin)
	     echo 'Mac OS X'
	     git filter-branch -d "$TMPFS_DIR/$1" --tag-name-filter cat --index-filter '
	git ls-files -s | gsed "s,\t\"*,&'"$1"'/," |
	GIT_INDEX_FILE=$GIT_INDEX_FILE.new git update-index --index-info &&
	mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' --msg-filter '
	echo "['$repo_upper']: " && cat
	' -- --all;
	     ;;
	   Linux)
	     echo 'Linux'
		 sudo mount -t tmpfs -o size=512m tmpfs $TMPFS_DIR
		 git filter-branch -d "$TMPFS_DIR/$1" --tag-name-filter cat --index-filter '
	git ls-files -s | sed "s,\t\"*,&'"$1"'/," |
	GIT_INDEX_FILE=$GIT_INDEX_FILE.new git update-index --index-info &&
	mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' --msg-filter '
	echo -n "['$repo_upper']: " && cat
	' -- --all;
	     ;;
	   CYGWIN*|MINGW32*|MSYS*)
	     echo 'MS Windows is not supported.'
	     exit
	     ;;
	   *)
	     echo 'OS is not supported.'
	     exit
	     ;;
	esac
}

function filter_all_branches {
	# Setup tmpfs if on linux to speed up filtering
	mkdir $TMPFS_DIR
	case "$(uname -s)" in
	   Darwin)
	     echo 'Mac OS X'
	     ;;
	   Linux)
	     echo 'Linux'
		 sudo mount -t tmpfs -o size=512m tmpfs $TMPFS_DIR
	     ;;
	   CYGWIN*|MINGW32*|MSYS*)
	     echo 'MS Windows is not supported.'
	     exit
	     ;;
	   *)
	     echo 'OS is not supported.'
	     exit
	     ;;
	esac

	for repo in $REPOS; do
		cd $BUILD_DIR/$repo
		move_to_dir $repo
		# Remove original refs
		git for-each-ref --format="$(refname)" refs/original | xargs -n 1 git update-ref -d
		git reflog expire --expire=now --all
		git gc --prune=now
	done
}

function setup_merged_repo {
	# Creates and initializes the final merged repo, adds a remove for each repo to pull in
	mkdir -p $MERGED_DIR
	cd $MERGED_DIR
	git init
	touch .gitignore
	git add .
	git commit -m "Root commit to be shared (grafted) in merge"
	git branch $INITIAL_COMMIT
	INITIAL_COMMIT_HASH=$(git rev-list $INITIAL_COMMIT)
	echo $INITIAL_COMMIT_HASH >> $GRAFTS_FILE

	for repo in $REPOS; do
		git remote add $repo $BUILD_DIR/$repo
		# The following solution was taken from stackoverflow "git octopus merge with unrelated repositories"
		# The octupus merge will fail since they have unrelated history
		# Add each root of repo to the grafts file
		cd $BUILD_DIR/$repo
		for root in $(git rev-list --all --max-parents=0); do
			echo $root $INITIAL_COMMIT_HASH >> $GRAFTS_FILE
		done
		cd $MERGED_DIR
	done
}

function clean_merged_repo {
	git branch -d $INITIAL_COMMIT
	> $GRAFTS_FILE
	for repo in $REPOS; do git remote remove $repo; done
}

function merge_branches {
	# Expects <local_branch> <remote:branch>
	# where the second argument is an associative array of repo name to branch to be merged
	git checkout $INITIAL_COMMIT
	git checkout -B "$1"
	local -n branch_map=$2
	BRANCHES_TO_MERGE=""
	for remote in "${!branch_map[@]}"; do
		git fetch ${remote} ${branch_map[${remote}]}
		BRANCHES_TO_MERGE+="${remote}/${branch_map[${remote}]} "
	done
	# BRANCHES_TO_MERGE is purposely unquoted so the branches expand to seperate arguments
	# this will be one large octupus merge, there can be no conflicts since every repo is
	# in a different subdirectory
	git merge --no-edit $BRANCHES_TO_MERGE
}

if [[ $COMMAND == create ]]; then
	mkdir -p $BUILD_DIR
	cd $BUILD_DIR
	clone_repos

	filter_all_branches

	setup_merged_repo

	cd $MERGED_DIR
	declare -A branches

	IFS=' ' read -r -a repo_names <<< "$REPOS"

	for index in "${!repo_names[@]}"
	do
		branches["${repo_names[index]}"]=master
	done

	merge_branches master branches

	for index in "${!repo_names[@]}"
	do
		branches["${repo_names[index]}"]=develop
	done

	merge_branches develop branches

	clean_merged_repo
	exit
fi