#!/bin/bash

err() { echo "error: $*" >&2; exit 1; }

_cvs_url() {
	[[ $# -gt 1 ]] && err "accepted args: <file>[:rev1[:rev2]]"

	# spec has the form file:rev1[:rev2]
	# rev2 defaults to rev1-1
	export IFS=:
	set -- $1
	unset IFS

	local file=$1
	if [[ ! -e ${file} ]] ; then
		echo "file '${file}' does not exist"
		return 1
	fi
	local dir="."
	[[ ${file} == */* ]] && dir=${file%/*}
	file=${file##*/}

	local rev2=$2
	if [[ -z ${rev2} ]] ; then
		rev2=$(
			cd ${dir}
			export IFS=/
			set -- $(grep /${file}/ CVS/Entries)
			unset IFS
			echo $3
		)
		if [[ ${rev2} == "0" ]] ; then
			# new file
			rev2="1.1"
		else
			# existing file, bump rev automatically
			rev2="1.$((${rev2#1.}+1))"
		fi
	fi
	local rev2r=${rev2#1.}
	local rev1=${3:-1.$((rev2r - 1))}

	local cvsroot=$(<${dir}/CVS/Repository)
	if [[ ${cvsroot} == gentoo-x86* ]] ; then
		cvsroot=${cvsroot#gentoo-x86}
		cvsroot=${cvsroot#/}
	fi

	local urirev
	[[ ${rev2} == "1.1" || ${rev1} == "${rev2}" ]] \
		&& urirev="?rev=${rev2}" \
		|| urirev="?r1=${rev1}&r2=${rev2}"
	echo "https://sources.gentoo.org/${cvsroot}/${file}${urirev}"
}
cvs_url() {
	local f
	for f in "$@" ; do
		_cvs_url "${f}"
	done
}

git_url() {
	[[ $# -gt 1 ]] && err "accepted args: <rev>"

	local repo url
	local remote=$(git config remote.origin.url)

	if [[ -z ${remote} ]] ; then
		# Maybe the repo doesn't use "origin".  Try harder.
		local branch=$(git rev-parse --abbrev-ref HEAD)
		remote=$(git config "branch.${branch}.remote")
		if [[ -n ${remote} ]] ; then
			remote=$(git config "remote.${remote}.url")
		else
			# Still try harder.
			local remotes=$(git config --get-regexp 'remote\..*\.url')
			if [[ -n ${remotes} ]]; then
				remote=$(echo "${remotes}" | awk '{print $2; exit}')
			fi
		fi
	fi

	case ${remote} in
	*://uclibc.org/*|*://git.uclibc.org/*|\
	*://busybox.net/*|*://git.busybox.net/*|\
	*://buildroot.org/*|*://git.buildroot.org/*|\
	*://buildroot.net/*|*://git.buildroot.net/*)
		repo=$(echo "${remote}" | sed -e 's,^[^:]*://[^/]*/,,' -e 's:[.]git$::')
		url="https://git."
		case ${repo} in
		uclibc)    url+="uclibc.org" ;;
		buildroot) url+="buildroot.org" ;;
		*)         url+="busybox.net" ;;
		esac
		url+="/${repo}/commit/?id="
		;;
	*://git@git.gentoo.org/*|\
	*://anongit.gentoo.org/*)
		repo=$(echo "${remote}" | sed 's:.*git[.a-z]*.gentoo.org/::')
		url="https://gitweb.gentoo.org/${repo}/commit/?id="
		;;
	git@github.com[:/]*|\
	*://github.com/*)
		repo=$(echo "${remote}" | sed -e 's,^git@github.com[:/],,' -e 's,^https://github.com/,,' -e 's,^git://github.com/,,' -e 's:[.]git$::')
		url="https://github.com/${repo}/commit/"
		;;
	git@gitlab.com[:/]*|\
	*://gitlab.com/*)
		repo=$(echo "${remote}" | sed -e 's,^git@gitlab.com[:/],,' -e 's,^https://gitlab.com/,,' -e 's,^git://gitlab.com/,,' -e 's:[.]git$::')
		url="https://gitlab.com/${repo}/commit/"
		;;
	git://git.sv.gnu.org/*|git://git.savannah.gnu.org/*|https://git.savannah.gnu.org/*)
		repo=$(echo "${remote}" | sed -E -e 's,^(git|https)://git.(sv|savannah).gnu.org/(git/)?,,' -e 's:[.]git$::')
		url="https://git.savannah.gnu.org/cgit/${repo}.git/commit/?h="
		;;
	git://git.sv.nongnu.org/*|git://git.savannah.nongnu.org/*)
		repo=$(echo "${remote}" | sed -r -e 's,^git://git.(sv|savannah).nongnu.org/,,' -e 's:[.]git$::')
		url="https://git.savannah.nongnu.org/cgit/${repo}.git/commit/?h="
		;;
	git://git.code.sf.net/p/*|ssh://*@git.code.sf.net/p/*)
		repo=$(echo "${remote}" | sed -r -e 's,(git://|ssh://([^@]*@)?)git.code.sf.net/p/([^/]*)/.*,\3,')
		url="https://sourceforge.net/p/${repo}/code/ci/"
		;;
	*://sourceware.org/*)
		repo=$(echo "${remote}" | sed -e 's,.*/,,' -e 's,[.]git$,,')
		url="https://sourceware.org/git/?p=${repo}.git;a=commit;h="
		;;
	*://gcc.gnu.org/*)
		repo=$(echo "${remote}" | sed -e 's,.*/,,' -e 's,[.]git$,,')
		url="https://gcc.gnu.org/git/?p=${repo}.git;a=commit;h="
		;;
	rpc://*)
		url="${remote#rpc://}"
		url="https://${url/\//.googlesource.com/}/+/"
		;;
	*.googlesource.com/*)
		url="${remote%.git}/+/"
		;;
	*://git.enlightenment.org/*)
		repo=$(echo "${remote}" | sed -e 's,^[^/]*//[^/]*/,,' -e 's,[.]git$,,')
		url="https://git.enlightenment.org/${repo}.git/commit/?id="
		;;
	*://git.qemu.org/*)
		repo=$(echo "${remote}" | sed -e 's,^[^/]*//[^/]*/,,' -e 's,[.]git$,,')
		url="https://git.qemu.org/?p=${repo}.git;a=commit;h="
		;;
	*://git.kernel.org/*)
		repo=$(echo "${remote}" | sed -e 's,^[^/]*//[^/]*/,,' -e 's,[.]git$,,')
		url="https://git.kernel.org/${repo}.git/commit/?id="
		;;
	*)
		echo "Unknown remote: '${remote}'"
		exit 1
		;;
	esac

	git log -n${num} ${1:-HEAD} | sed "s,^commit ,${url},"
}

svn_url() {
	if [[ $# -eq 0 ]] ; then
		svn info | \
		awk '{
			if ($1 == "URL:") {
				URL = "http://sources.gentoo.org/" gensub(/.*svnroot\/([^/]*).*/, "\\1", 1);
			} else if ($1 == "Revision:") {
				rev = $2
				URL = URL "?rev=" (rev + 1) "&view=rev"
			}
		}
		END { print URL }'
		return 0
	fi

	local f
	for f in "$@" ; do
		svn info "${f}" | \
		awk '{
			if ($1 == "URL:") {
				sub(/.*svnroot/,"")
				URL = "http://sources.gentoo.org" $1 "?"
			} else if ($1 == "Revision:") {
				rev = $2
				URL = URL "r1=" rev "&r2=" (rev + 1)
			}
		}
		END { print URL }'
	done
}

usage() {
	exec cat <<-EOF
	Usage: $0 [options] [args]

	Options:
	  -#       Number of commits to show (default: 3)
	  -n#      Number of commits to show
	  -c       CVS URL
	  -g       GIT URL (default)
	  -s       SVN URL
	  -x       Trace the script
	  -h       Help
	EOF
}

main() {
	local vcs="auto" num="3" args=()
	while [[ $# -gt 0 ]] ; do
		case $1 in
		-n[0-9]*) num="${1:2}";;
		-[0-9]*) num="${1:1}";;
		-c) vcs="cvs";;
		-s) vcs="svn";;
		-g) vcs="git";;
		-x) set -x;;
		-h) usage;;
		--) shift; break;;
		-*) usage;;
		*)  args+=( "$1" );;
		esac
		shift
	done
	set -- "${args}"

	if [[ ${vcs} == "auto" ]] ; then
		if [[ -d CVS ]] ; then
			vcs="cvs"
		elif svn info >&/dev/null ; then
			vcs="svn"
		else
			vcs="git"
		fi
	fi

	case ${vcs} in
	cvs) cvs_url "$@";;
	git) git_url "$@";;
	svn) svn_url "$@";;
	esac
}
main "$@"