#!/bin/sh

proc usage
{
	echo "Usage: $0 [--spec] <target>"
	exit 2
}

test -z $1 && usage

if test $1 = "--spec"  {
	setglobal spec_format = '1'
	shift
	test -z $1 && usage
}

setglobal TARGET = $1

setglobal GIT_DIR = $[git rev-parse --git-dir]

test -z $GIT_DIR && usage


export GIT_DIR
export GIT_PAGER=""
export PAGER=""


proc mkchlog
{
	setglobal target = $1
	setglobal format = $2

	setglobal prev_tag = ''""

	for tag in [$[git tag -l $(target)-'*]]  {
		setglobal obj = $[git cat-file tag $tag | awk '/^object /{print $2}]
		setglobal base = $[git merge-base $obj HEAD]
		if test -z $base -o $base != $obj  {
			continue
		}
		setglobal all_vers = ""$prev_tag$tag $all_vers""
		setglobal prev_tag = "$tag.."
	}

	if test -z $prev_tag  {
		setglobal all_vers = 'HEAD'
	} else {
		setglobal all_vers = ""$(prev_tag)HEAD $all_vers""
	}

	for ver in [$all_vers]  {
		setglobal log_out = $[git log $ver -- $target]
		if test -z $log_out  {
			continue
		}
		setglobal ver_name = $[echo $ver | sed -e 's/^.*\.\.//]
		echo ""
		echo "** Version: $ver_name"
		echo ""
		git log --no-merges $(format) $ver -- $target
		setglobal prev_t = "$tag.."
	}
}


if test -z $spec_format  {
	mkchlog $TARGET --pretty=format:"%ad %an%n%H%n%n* %s%n" \
		| sed -e 's/^\* /\t* /'
} else {
	echo "%changelog"
	mkchlog $TARGET --pretty=format:"- %ad %an: %s"
	echo ""
}