#!/bin/bash
#
#  git-last.sh - helper app for listing the early history of a git head
#  Copyright (C) 2008  Clifford Wolf <clifford@clifford.at>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.

export LC_ALL=C

SUBDIRECTORY_OK=Yes
OPTIONS_SPEC="\
git-last [options] [<rev>...]

git-last lists the early history of a git head.
--
h,help      show the help
l,limit=    larger number results in longer output (default=20)
b,branch    use git-show-branch instead of normal output
s,straight  only show first parents (not the merged stuff)
x,noextra   suppress lookup of extra ref names
a,sha1      also print (abbreviated) SHA1 commit name
"
. "$(git --exec-path)/git-sh-setup"

limit=20
withmerges=true
withextras=true
withsha1=false
useshowbranch=false
revlist=( )
subjlist=( )
revlist_idx=0
revlist_n=0

while (( $# > 0 )); do
	if [ "$1" = "--" ]; then
		shift; break
	fi
	if [ "$1" = "-l" ]; then
		limit=$2
		shift; shift; continue
	fi
	if [ "$1" = "-b" ]; then
		useshowbranch=true
		shift; continue
	fi
	if [ "$1" = "-s" ]; then
		withmerges=false
		shift; continue
	fi
	if [ "$1" = "-x" ]; then
		withextras=false
		shift; continue
	fi
	if [ "$1" = "-a" ]; then
		withsha1=true
		shift; continue
	fi
	usage
done

for r; do
	revlist=( "${revlist[@]}" "$r" )
	(( revlist_n++ ))
done

if [ $revlist_n -eq 0 ]; then
	revlist=( "${revlist[@]}" "HEAD" )
	(( revlist_n++ ))
fi

show_branch_args=( "${revlist[@]}" )

get_parents_num() {
	q="'" qq="'\\\\''"
	git cat-file commit "$1" | gawk '
		BEGIN { c=0; subjectline=0; }
		/^parent/ { c++; }
		subjectline {
			gsub(/'$q'/, "'$qq'");
			print "s='$q'" $0 "'$q'";
			nextfile;
		}
		/^$/ { subjectline=1; }
		END { print "n=" c; }
	'
}

nicerevname() {
	if $withsha1; then
		echo -n "`git rev-parse "$1" | cut -c1-7` "
	fi
	echo "$1" | perl -pe 's:((\^1)+)(?![0-9]):"~".length($1)/2:eg;' # s:~1(?![0-9]):^:g;'
}

sortrevname() {
	echo "$1" | perl -pe 's:((\^1)+)(?![0-9]):"~".length($1)/2:eg; s:([0-9]+):sprintf"%010d",$1:eg'
}

while (( $revlist_idx < $revlist_n )) && ( (( limit > 0 )) || ! $useshowbranch ); do
	r="${revlist[$revlist_idx]}" n="" s=""
	eval "$( get_parents_num "$r" )"
	if $withextras; then
		xtra="$( git show-ref -d | grep "^$(git rev-parse $r) " | sed -r 's,^.* (refs/)?,,'; )"
	else
		xtra=""
	fi
	if [ -n "$xtra" ]; then
		subjlist[$revlist_idx]="$s (`echo $xtra`)"
	else
		subjlist[$revlist_idx]="$s"
	fi
	if (( n == 0 )); then
		if $useshowbranch; then
			revlist=( "${revlist[@]}" "$r" )
			(( revlist_n++ ))
			(( limit--))
		fi
	else
		if (( limit > 0 )); then
			for ((i=1; i <= n; i++)); do
				if (( $i == 1 )) || $withmerges; then
					revlist=( "${revlist[@]}" "$r^$i" )
					(( revlist_n++ ))
					(( limit--))
				fi
			done
		fi
	fi
	(( revlist_idx++ ))
done

if $useshowbranch; then
	git show-branch "${show_branch_args[@]}" $(
		for ((i=revlist_idx; i < revlist_n; i++)); do
			s=$( sortrevname "${revlist[$i]}" )
			r=$( nicerevname "${revlist[$i]}" )
			printf "%s\t%s\n" "$s" "$r"
		done | sort | cut -f2-
	)
else
	maxrlen=0;
	sortlist=( )
	for ((i=0; i < revlist_n; i++)); do
		sortlist[$i]="$( sortrevname "${revlist[$i]}" )"
		revlist[$i]="$( nicerevname "${revlist[$i]}" )"
		if (( maxrlen <= ${#revlist[$i]} )); then
			maxrlen=${#revlist[$i]}
		fi
	done
	for ((i=0; i < revlist_n; i++)); do
		s="${sortlist[$i]}" r="${revlist[$i]}"
		printf "%s\t%-*s %s\n" "$s" $maxrlen "$r" "${subjlist[$i]}"
	done | sort | cut -f2-
fi