#!/bin/sh
# Copyright (c) 2008, Nanako Shiraishi
# Prime rerere database from existing merge commits

me=rerere-train
USAGE="$me rev-list-args"

SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. "$(git --exec-path)/git-sh-setup"
require_work_tree
cd_to_toplevel

# Remember original branch
branch=$(git symbolic-ref -q HEAD) ||
original_HEAD=$(git rev-parse --verify HEAD) || {
        echo >&2 "Not on any branch and no commit yet?"
        exit 1
}

mkdir -p "$GIT_DIR/rr-cache" || exit

git rev-list --parents "$@" |
while read commit parent1 other_parents
do
        if test -z "$other_parents"
        then
                # Skip non-merges
                continue
        fi
        git checkout -q "$parent1^0"
        if git merge $other_parents >/dev/null 2>&1
        then
                # Cleanly merges
                continue
        fi
        if test -s "$GIT_DIR/MERGE_RR"
        then
                git show -s --pretty=format:"Learning from %h %s" "$commit"
                git rerere
                git checkout -q $commit -- .
                git rerere
        fi
        git reset -q --hard
done

if test -z "$branch"
then
        git checkout "$original_HEAD"
else
        git checkout "${branch#refs/heads/}"
fi