#!/bin/sh

# situation: work tree is unknown rev
# arguments: git rev-list arguments
# we now identify the one revision with least differences

case "$1" in
	--cached)
		use_worktree=false
		shift
		;;
	*)
		use_worktree=true
		;;
esac

diffopts="-M -C"

if $use_worktree; then
	echo >&2 "Saving index..."
	oldindex=`git write-tree`
	# set up resetting
	trap 'echo >&2 "Restoring index..."; git reset "$oldindex" .' EXIT
	trap 'exit 1' INT TERM

	echo >&2 "Creating index..."
	git add -A
fi

echo >&2 "Listing candidates..."
allrevs=`git rev-list "$@"`

echo >&2 "Evaluating candidates..."
bestrev=
bestrevscore=
for rev in $allrevs; do
	score=`git diff $diffopts --cached "$rev" | wc -l`
	if [ -z "$bestrevscore" ] || [ "$score" -lt "$bestrevscore" ]; then
		echo >&2 "Improved to $rev (score: $score)"
		bestrev=$rev
		bestrevscore=$score
	fi
done
echo >&2 "Done."

echo "$bestrev"
git diff $diffopts --cached "$bestrev" >&2