updateGitSubtree.sh

#!/bin/sh

# Written by Nicolas Strike, Aug 2018

##############################################################################################################################
# The purpose of this script is to update a git repo's external dependencies
#     that are included as a subtree in the repo.
#
#               Example use case:
#
#		Folder in 3rd party/external repo: (paths are relative to the root of the repo)
#		  /src/folder/what-I-need
#		  /random-dir/another-folder/something-else-I-need
#		Copy in my repo:
#		  /src/what-I-need
#		  /src/something-else-I-need
#         
#               These paths are just examples, you could map any level of dir's to any other
#                 set of dirs.
#
# How it works:
# 	It does this by cloning the external git repo, and locally creating a branch of the 
# 	your repo. Using the subtree command, it then creates local branches
# 	that contain only the desired folder. Once these new branches
#	are made, the script merges the branches with your repo's folders and pushes
#	the updates.
# Notes:
# 	This script is best used when ran automatically and reglarly
# 	This script was modeled after the process detailed here: https://stackoverflow.com/a/22335955
###############################################################################################################################


srcbranch=master
destbranch=master
forceupdate=0
    while [ "$1" != "" ]; do
        case $1 in
            -m | --my-repo )        shift
                                    myrepo=$1
                                    ;;
            -t | --their-repo )     shift
                                    theirrepo=$1
                                    ;;
            --source-branch )       shift
                                    srcbranch=$1
                                    ;;
            --dest-branch )         shift
                                    destbranch=$1
                                    ;;
            -f | --map-file )       shift
                                    mapfile=$1
                                    ;;
           # -f | --force-update )   forceupdate=1
            #                        ;;
            -h | --help )           usage
                                    exit
                                    ;;
            # * )                     usage
              #                      exit 1
        esac
        shift
done

declare -a srcArray
declare -a destArray

echo "myrepo: $myrepo theirrepo: $theirrepo branch:$branch mapfile:$mapfile"



#####################################################################################################
#This sends out an email notification to system admins if any errors were detected during runtime.
# The content of the email can be found in $emailMessage
#####################################################################################################
#sendEmailNotification(){
#
#	if [ $errorsDetected != 0 ]
#	then
#	  echo "Errors during run detected. Sending email notification."
#	  #Set the email
#	  EMAIL=messneradmin@uwm.edu
 #         echo -e "\n\n Thank you,\n\n -camClubbUpdate Nightly Script: " $(readlink --canonicalize --no-newline $BASH_SOURCE) >> $emailMessage
#          mail -s " `date +%Y-%m-%d` camClubb autoupdate script `hostname` " $EMAIL < $emailMessage
#	  exit 1
#	else
#	  echo "No errors detected. Run successful."
#	fi
#}

#####################################################################################################
#Sets up common variables (excluding the emailMessage location),
# such as repo URLs and temporary directory locations.
#####################################################################################################
setup(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Setting up working environment"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	theirdir=theirDir
    mydir=myDir
    errorsDetected=0
	rm -rf $theirdir
	rm -rf $mydir
	#echo -e "Hello,\nThis email is automatically generated by a nightly script in charge of updated CAM's Clubb subtrees." >> $emailMessage
	echo "Done"
}

#####################################################################################################
# Read the map file provided by the user to dictate which folders on the
# dependancy repo to associate with which folders on their destination repo.
#####################################################################################################
readMapFile(){
    counter=0

    while IFS=, read src dest;do
        srcArray[$counter]=$src
        destArray[$counter]s=$dest
        counter=$((counter+1))
    done < $mapfile
}

#####################################################################################################
#Clones the github repos to a temporary folder. This is necessary for doing things using git.
#####################################################################################################
clone(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Cloning git repo"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -

	git clone $myrepo $mydir
    cd $mydir
	git fetch
	git checkout $destbranch
	#testing	
	git lfs install
	git config lfs.cachecredentials 1
	#git lfs track *.exe
	#git add .gitattributes
	#git commit .gitattributes -m "Added gitattributes"
	#end testing
	myErrorCode=$?

	git config --global credential.helper store
	git remote add theirrepo $theirrepo
	theirErrorCode=$?
	git fetch theirrepo
	git branch their_branch theirrepo/$srcbranch

	# Error handling, run 'exit 1' if clone() failed to complete
	if [ $theirErrorCode != 0 ]
	then
	  echo -e "\nI was unable to clone their ('$theirrepo') repo. Please make sure the URL has not changed, there is access to the internet, and that the git servers are operational." 
	fi
	if [ $myErrorCode != 0 ]
	then
	  echo -e "\nI was unable to fetch your repo ('$myrepo'). Please make sure the URL has not changed, there is access to the internet, and that the git servers are operational."
	fi

	if [ $theirErrorCode != 0 ] || [ $myErrorCode != 0 ] || [ $srcBranch ]
	then
	  echo "Errors detected, exiting"
	  errorsDetected=1
	  exit 1
	fi

	echo "Done"
}

#####################################################################################################
#Creates a number of subtrees (of clubb) that consist of just 1 specific folder each. 
#These are to be merged with the CAM to update it's dependancies.
#####################################################################################################
generateSubtrees(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Generating temporary subtrees"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	errorCodeSum=0
	git checkout -f their_branch
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0

        for i in "${srcArray[@]}"
           do
           :
                echo "Creating subtree from ${srcArray[@]}"
             	git subtree split --squash --prefix="${srcArray[@]}" -b branch$i -m "Autoupdated subtree"
                # Add resulting error code to the error sum. If there is no error, this adds 0
                errorCodeSum=$(($errorCodeSum + $?))
           done
  

	if [ $errorCodeSum != 0 ]
	then
	  echo -e "\nThere was an issue generating the subtree's. I reccomend running the script manually to see what went wrong." >> $emailMessage
	  errorsDetected=$((errorsDetected + errorCodeSum))
          exit 1
	fi
	echo "Done"
}

#####################################################################################################
#If new files have been added to clubb, add these files to CAM
#####################################################################################################
addUntrackedFiles(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Adding any untracked files"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	errorCodeSum=0
	git checkout -f $destbranch
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0

    for i in "${destArray[@]}"
       do
       :
            #There is no errorCode check here because if it tries to add a subtree that already exists it will return an error code. We dont' want this.
           git subtree add --prefix="${destArray[@]}" branch$i -m "Added "${srcArray[@]}" as subtree in ${destArray[@]}"

    done

	if [ $errorCodeSum != 0 ]
	then
	  echo -e "\nThere may have been an issue when attempting to add unrevisioned files to CAM"
	  errorsDetected=$((errorsDetected + errorCodeSum))
	fi
	echo "Done"
}

#####################################################################################################
#Merge any differences from the subtrees to CAM-CLUBBS copy of clubb files. 
#If there are no differences, nothing will be updated (git does this automagically)
#####################################################################################################
merge(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Merging Changes"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	errorCodeSum=0
	git checkout -f $destbranch
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0



    for i in "${destArray[@]}"
       do
       :
        git subtree merge --prefix="${destArray[@]}" branch$i -m "Autoupdated ${destArray[@]}"
        errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
        mergeFail=$?
		if [ $errorCodeSum != 0 ]
		then
			echo "While attempting to auto merge, there were conflicts. Attempting to force an update now"
			#if [ $mergeFail != 0 ]
			#then
		#		git rm -r "${srcArray[@]}"
		#	fi
		#	git commit -a -m "resetting folder"
		#	addUntrackedFiles
		#	git commit -a -m "Auto updated, forced CAM update to Larson-Group/CLUBB version. If something is broke, check out the previous working version and compare the differences with this version."
		#	errorCodeSum=$?  # Add resulting error code to the error sum. If there is no error, this adds 0
		fi
   	 	git commit -a -m "Auto updated, forced update to Larson-Group/CLUBB version"
    		if [ $errorCodeSum != 0 ]
    		then
	    	echo -e "\There were some issues when attempting to merge updates. This is unusual, and shouldn't happen."
	      errorsDetected=$((errorsDetected + errorCodeSum))
	    fi
        done
	echo "Done"
}

#####################################################################################################
#Pushes changes made to CAM-CLUBB up to GitHub. If no changes were made, nothing will get pushed.
#####################################################################################################
push(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Pushing Changes"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	errorCodeSum=0
	git push -u $myrepo $destbranch

	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
	if [ $errorCodeSum != 0 ]
	then
	  echo -e "\nGit ran into issues when attempting to push. You may run this script manually to help determine the cause."
	  errorsDetected=$(($errorsDetected + $errorCodeSum))
	fi
	echo "Done"
}

#####################################################################################################
#Deletes the temporary folders
#####################################################################################################
cleanup(){
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	echo "Cleaning up local directory"
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
	errorCodeSum=0
	cd ..
	rm -rf $their
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
	rm -rf $mydir
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
	rm -rf $srcbranch
    errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
	rm -rf $destbranch
	errorCodeSum=$(($errorCodeSum + $?))  # Add resulting error code to the error sum. If there is no error, this adds 0
	if [ $errorCodeSum != 0 ]
	then
	  echo -e "\nFailed to cleanup directory/remove temporary folders. Please ensure the script has the correct permissions, or delete these folders manually: \n\t$theirdir\n\t$mydir"
	  errorsDetected=$(($errorsDetected + $errorCodeSum))
	fi
	echo "Done"
}


#####################################################################################################
#Runs the script.
#####################################################################################################
setup
#clone
generateSubtrees
addUntrackedFiles
merge
push
#cleanup
#sendEmailNotification