#!/bin/bash

if [ $# -lt 1 ]; then
	echo "usage: git-branch-stat [branch1] branch2"
	exit
fi

if [ $# -lt 2 ]; then
	b1="HEAD"
	b2=$1
else
	b1=$1
	b2=$2
fi


c1=`git rev-list $b1..$b2 | wc -l`
if [ $? -gt 0 ]; then
	echo error in git
	exit
fi

c2=`git rev-list $b2..$b1 | wc -l`
if [ $? -gt 0 ]; then
	echo error in git
	exit
fi

if [ $c1 -eq 0 -a $c2 -eq 0 ]; then
	echo "Branch $b1 and $b2 are equal"
	exit
fi

if [ $c1 -eq 0 ]; then
	echo "Branch $b2 can be fast forward to $b1 in $c2 commits"
	exit
fi

if [ $c2 -eq 0 ]; then
	echo "Branch $b1 can be fast forward to $b2 in $c1 commits"
	exit
fi

if [ $c1 -lt $c2 ]; then
	echo "Common root: "`git rev-list --max-count=1 $b2~$c1`
else
	echo "Common root: "`git rev-list --max-count=1 $b1~$c2`
fi
echo "Branch $b1 and $b2"
echo "differ by $c2 and $c1 commit(s) respectively"