git-branch-stat

#!/bin/sh

#    Git branch stat - Code change statistics between Git branches.
#    Copyright (C) 2017-2022  Richard Huang <rickypc@users.noreply.github.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as
#    published by the Free Software Foundation, either version 3 of the
#    License, or (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

usage () {
  echo "Usage: $@"
  exit 127
}

die () {
  echo $@
  exit 128
}

if test $# -lt 1 || test $# -gt 2; then
  usage "$0 <base-branch> [current-branch]"
fi

BASE=$1
CURRENT=$2

if [ -z "$CURRENT" ]; then
  CURRENT=$(git rev-parse --abbrev-ref HEAD)
fi

DELTA=$(git diff --shortstat $(git merge-base $BASE $CURRENT))

if [ -z "$DELTA" ]; then
  # After changes merged.
  FIRST=$(git log --first-parent --merges --pretty='format:%h %s' | grep $CURRENT | tail -1 | cut -d' ' -f1)
  if [ -n "$FIRST" ]; then
    PARENT=$(git rev-parse $FIRST^)
    COMMIT=$(git rev-list --count $PARENT..$BASE)
    DELTA=$(git diff --shortstat $PARENT)
  fi
else
  COMMIT=$(git rev-list --count $BASE..$CURRENT)
fi

if [ -n "$DELTA" ]; then
  echo "$COMMIT commits,$DELTA"
fi