#!/bin/bash
set -euo pipefail
IFS=$'\n\t'

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin

cleanup() {
	if [ -f "${tmpfile}" ]; then
		rm -f "${tmpfile}"
	fi
}

trap "{ cleanup; }" EXIT SIGTERM

getCommits() {
	prevtag="${1}"
	tag="${2}"
	local -a authors
	local ver="${tag}-1"
	local h

	echo "»»» Processing ${prevtag}..${tag}"
	numCommits=$(git --no-pager rev-list --count "${prevtag}".."${tag}")
	if ((numCommits>0)); then
		echo "	${numCommits} commits found"

		if [ "${tag}" == "HEAD" ]; then
			h=$(git rev-list --max-count=1 --abbrev-commit HEAD)
			ver="${prevtag}~1.${h}"
		fi

		echo "${pkgname} (${ver}) UNRELEASED; urgency=low" >> "${tmpfile}"

		authors=($(git log --format='%aN' "${prevtag}".."${tag}" | sort | uniq))
		for author in "${authors[@]}"; do
			echo "	Gathering commits from ${author}"
			{
				echo "	[ ${author} ]"
				git --no-pager log --author="${author}" --pretty=format:'  * %s' "${prevtag}".."${tag}"
				echo ""
			} >> "${tmpfile}"
		done

		git --no-pager log -n 1 --pretty='format:%n -- %aN <%aE>  %aD%n%n' "${tag}" >> "${tmpfile}"
	else
		echo "	0 commits found, skipping"
	fi
}

if [ ! -d "debian" ]; then
	echo "Directory ./debian not found"
	exit 1
fi

tmpfile=$(mktemp)
firstHash=$(git rev-list --max-parents=0 HEAD) # This should yield the very first commit hash
pkgname=$(grep '^Package: ' debian/control | sed 's/^Package: //')
tags=($(git tag | sort -r -V))

echo "»»» Gathering untagged commits"
tag=${tags[0]}
untagged=$(git rev-list --count "${tag}"..HEAD)
if ((untagged>0)); then
	getCommits "${tag}" HEAD
fi


for ((i=1; i<${#tags[@]}; i++)); do
	tag="${tags[${i}]}"
	nexttag="${tags[$((i-1))]}"
	getCommits "${tag}" "${nexttag}"
done

getCommits "${firstHash}" "${tags[-1]}"

mv "${tmpfile}" debian/changelog