Bash script to update frontend theme

update-frontend-templete.sh

#!/bin/bash

UPSTREAM_TAG=$1
RESET_BRANCHES=${2:-"1"}

CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)

# Delete branches created.
if [[ "$RESET_BRANCHES" == "1" ]]; then
  git branch -D "$CURRENT_BRANCH-preview" upstream
fi


echo "Upstream branch/tag selected: \"$UPSTREAM_TAG\""
echo "Current branch: \"$CURRENT_BRANCH\""

git checkout -b "$CURRENT_BRANCH-preview"

# It will take the base commit, it is the squash commit from upstream.
BASE_COMMIT=$(git rev-list --reverse HEAD | sed -n 1p)
# SECOND_COMMIT=$(git rev-list --reverse HEAD | sed -n 2p)

echo "Base commit \"$BASE_COMMIT\""
git log $BASE_COMMIT

git fetch upstream $UPSTREAM_TAG:upstream
git checkout upstream

#Squash all commits from upstream
git reset --soft $(git rev-list --max-parents=0 HEAD) && git commit --amend -m "Initial commit from upstream ($UPSTREAM_TAG)" --no-edit
BASE_PREVIEW_COMMIT=$(git rev-list --reverse HEAD | sed -n 1p)


git checkout "$CURRENT_BRANCH-preview"
#Take all commits after base commit in main branch and put o top of preview.
#In other words take all your changes.
git rebase --onto $BASE_PREVIEW_COMMIT $BASE_COMMIT $CURRENT_BRANCH-preview

cat << EOF
Check the "$CURRENT_BRANCH-preview" branch and in case there are conflicts solve them.

TIP: In case you have changes in files that you deleted like upstream blog's post, you can just remove ignore them. e.g:

git rm -r src/data/blog

After solve all conflicts finish the rebase.

git rebase --continue


If everything looks fine, then update your main branch and push your changes running commands bellow.

git checkout $CURRENT_BRANCH
git reset --hard $CURRENT_BRANCH-preview
git push -f
EOF