#!/bin/bash

VCS_SUPPORTED="Mercurial"

# Optional prefix before patch name
PATCH_NAME_PREFIX=""

# Default revision if not specified
REVS=tip

print_usage()
{
    echo "$(basename $0) -- git format-patch equivalent for Mercurial"
    echo "Usage: $(basename $0) [OPTIONS...]"
    echo
    echo "Options:"
    echo "  -h   display this help and exit"
    echo "  -r   [a..b] or [a-b] or [a:b]: sequence of revisions"
    echo "       [a,b,c]: specific revisions list"
    echo "       [a]: single revision"
    echo "       if not specified, default is tip"
}

while getopts "hr:" flag ;do
    case ${flag} in
	h)
	    print_usage
            exit 0
	    ;;
	r)
	    REVS=${OPTARG}
	    ;;
	?)
	    echo "${PROG_NAME}: Invalid option: ${OPTARG}."
	    echo "Try \`${PROG_NAME} --help' for more information."
	    exit 1
	    ;;
    esac
done
shift `expr "${OPTIND}" - 1`

# `$#' now represents the number of arguments after the options.
# `$1' is the first argument, etc.
if [ $# -ne 0 ]; then
    echo "${PROG_NAME}: Too many arguments."
    echo "Try \`${PROG_NAME} --help' for more information."
    exit 1
fi

if echo ${REVS} | grep -F -q ':'; then
    SEP_CHAR=":"
elif echo ${REVS} | grep -F -q '-'; then
    SEP_CHAR="-"
elif echo ${REVS} | grep -F -q '..'; then
    SEP_CHAR="\.\."
elif echo ${REVS} | grep -F -q ','; then
    SEQ="${REVS//,/ }"
fi

if [ -z "${SEQ}" ]; then
    if [ -n "${SEP_CHAR}" ]; then
        START=$(echo ${REVS} | sed "s/\(.*\)${SEP_CHAR}.*/\1/")
        END=$(echo ${REVS}   | sed "s/.*${SEP_CHAR}\(.*\)/\1/")
    fi

    if [ -z "${START}" ]; then
        SEQ=${REVS}
    else
        SEQ=$(seq ${START} ${END})
    fi
fi

if hg status 1> /dev/null 2>&1; then
    for r in ${SEQ}; do
        NAME=${PATCH_NAME_PREFIX}${r}.patch
        echo [PATCH] ${NAME}
        hg export -r ${r} > ${NAME}
    done
else
    echo "Not a ${VCS_SUPPORTED} repository"
    exit 1
fi