Simplifies the workflow of having to ... * Check if a branch can be fast-forward merged * If it is not, checking that branch out * Rebasing that branch into the branch you were originally on. * Ensuring that if you were kicked into a headless state after the rebase, that your actual branch ref points to the new rebased commits. * Checking out th…

git-merge-rebase-first.sh

#!/bin/bash

function get_merge_revs {
  MERGE=$(git rev-parse --abbrev-ref $REV);
	MERGE_REV=$(git rev-parse $REV);
	SHORT_MERGE_REV=$(echo $MERGE_REV | cut -c 1-7);
}

function get_orig_merge_revs {
	ORIG_MERGE=$(git rev-parse --abbrev-ref $REV);
	ORIG_MERGE_REV=$(git rev-parse $REV);
	ORIG_SHORT_MERGE_REV=$(echo $MERGE_REV | cut -c 1-7);
}

function get_current_revs {
	CURRENT=$(git rev-parse --abbrev-ref $REV);
	CURRENT_REV=$(git rev-parse $REV);
	SHORT_CURRENT_REV=$(echo $CURRENT_REV | cut -c 1-7);
}

function is_ffable {
	echo ".....";
	git merge-base --is-ancestor $CURRENT_REV $MERGE_REV;
	ffable=$?;

	if [ $VERBOSE == true ]; then
		echo -e "(A): ($CURRENT) \t[$CURRENT_REV]";
		echo -e "(B): ($MERGE) \t[$MERGE_REV]\n";


		if [  $ffable == 0 ]; then
			echo -e "[*] Yes! Revision (B) CAN be Fast-Forward merged into (A)."
		else
			echo -e "[!] Well, fuck! Revision (B) can NOT be Fast-Forward merged into (A)!"
		fi 
	fi
}

function ferge {
	echo "Performing a Fast-Forward merge of $MERGE";
	echo ".....";

	git merge --ff-only $MERGE_REV;
}

# Performs a reverse rebase where the current revision becomes the base for the revision that is passed.
function mebase {

	echo "Checking out $MERGE.....";
 	git checkout --quiet $MERGE;

 	TMP_REV=$(git rev-parse HEAD);

 	# Verify that we have checked out the correct revision
 	if [ "$MERGE_REV" == "$TMP_REV" ]; then

 		echo "Performing REBASE of  ($MERGE) [$SHORT_MERGE_REV] onto ($CURRENT) [$SHORT_CURRENT_REV].....";
 		echo ".....";
		git rebase -i $CURRENT_REV;

		

		#Reset the merge vars
		REV="HEAD";

		#update_merge_branch;
		get_merge_revs;
		get_orig_merge_revs;


		echo "Checkout out your original branch: ($CURRENT) [$SHORT_CURRENT_REV].....";
		git checkout --quiet $CURRENT;
	else
		echo "Checkout of $MERGE seems to have failed."
		exit() { return $1;}
    fi

}

function update_merge_branch {

	if [ "$MERGE" -ne "$BRANCH" ]; then
		git update-ref refs/heads/$BRANCH $REV;
	fi

	echo "[*] Revision ($MERGE) [$SHORT_MERGE_REV] has been properly rebased onto ($CURRENT) [$SHORT_CURRENT_REV] and updated.";

}

function ask_rebase {
	printf "[?] Perform rebase? [Yes/no] : "
	read do_rebase;
	echo ".....";
}

function ask_ferge {
	printf "[?] Perform merge? [Yes/no] : "
	read do_ferge;
	echo ".....";
}


echo "Current position is [$SHORT_CURRENT_REV] ($CURRENT)"


REV=$1;
get_merge_revs;

REV="HEAD";
get_current_revs;

#Backup var for safe keeping after rebases.
BRANCH=$MERGE;

VERBOSE=true;
is_ffable;

if [ "$ffable" -gt 0 ]; then
	ask_rebase;

	if [ $do_rebase == "Yes" ]; then
		mebase;

		echo -e "\nNew revisions (after rebase)"
		is_ffable;
	else
		echo "Nothing left to do...";
		exit() { return $1;}
	fi
fi 


if [ "$ffable" -eq 0 ]; then
	ask_ferge;

	if [ $do_ferge == "Yes" ]; then
		ferge;
	else
		echo "Nothing left to do...";
		exit() { return $1;}
	fi
fi