merge stats

#!/bin/bash -e
set -o pipefail

# Any arguments are incorrect.  Note that git intercepts --help and tries to
# open the man page.
#if [ $# -gt 0 ]; then
#   echo 'Usage: git merge-stats'
#   exit 1
#fi

echo "% of Total Merges               Author  # of Merges  % of Commits"
# Use --first-parent to only count merges into the current branch; this gets
# rid of commits where you merge upstream into your feature branch.
mergeCounts=`git log --first-parent --merges --pretty='format:%an' $* | sort | uniq -c | sort -nr`
totalMerges=`git log --first-parent --merges --oneline $* | wc -l`

if [ $totalMerges -eq 0 ]; then
   echo 'No merges found.'
   exit 0
fi

while read -r line; do
   authorMerges=`awk '{print $1}' <<< "$line"`
   author=`sed "s/$authorMerges //" <<< "$line"`
   authorCommits=`git log --oneline --author="$author" | wc -l`
   totalPercentage=`echo "scale=2; (100*$authorMerges) / $totalMerges" | bc`
   authorPercentage=`echo "scale=2; (100*$authorMerges) / $authorCommits" | bc`
   printf "%17.2f %20s %12i %13.2f\n" "$totalPercentage" "$author" "$authorMerges" "$authorPercentage"
done <<< "$mergeCounts"