#!/bin/bash

# Usage: ./reflogk [N]
# optional argument N (defaults to 10) to limit how many reflog entries to go
# back

# shows the following, using gitk:
# - unreachable entries among the first N reflog entries, cropped at their
#   common merge-base (which ought to be far enough away!)
# - the topmost references that are not reachable from some other
#   reference

# sound confusing?  try it...!

# grab top N entries from the reflog
refs=`git reflog -${1:-10} | cut -f1 -d' '  | sort -u`

# find their common merge-base
export common
for r in $refs
do
    common=$(git merge-base ${common:-$r} $r)
done
echo $common

# for each ref, we use the special construct that says "just this commit and
# *not* any of its parents" (see git help rev-parse)
parents=$(git for-each-ref --format='%(objectname)^! %(objecttype) %(*objecttype)' |
    grep commit | cut -d' ' -f1)
gitk HEAD $refs $parents --not $common