# Functions for parsing changelogs
#
# Copyright (C) 2012, 2018, 2019 Patrick McDermott
#
# This file is part of opkbuild.
#
# opkbuild 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 3 of the License, or
# (at your option) any later version.
#
# opkbuild is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with opkbuild.  If not, see <http://www.gnu.org/licenses/>.

_ob_parse_changelog_error()
{
	local file="${1}"
	local line_nr="${2}"
	local msg_id="${3}"
	shift 3 || _ob_abort
	local file_info=

	file_info="$(printf '%20s(l%d)' "${file}" "${line_nr}")"

	_ob_warn_msg "${msg_id}" "${file_info}" "${@}"

	return 0
}

_ob_get_changelog_expect_str()
{
	_ob_get_msg "changelog_expect_${1}"

	return 0
}

## @brief Parse a changelog file
## @details \fBob_parse_changelog\fP parses a \fIchangelog\fP file, formatted as
##          specified at
##          <http://specs.proteanos.com/spf-2.0/metadata.html#changelog>.  For
##          each version entry, \fBob_parse_changelog\fP calls \fIentry_cb\fP
##          with the source package name, the source package version, the list
##          of distributions into which the package should be installed, the
##          formatted heading (source package name, source package version, and
##          distributions list) and change details, the name and e-mail address
##          of the package maintainer, and the date of packaging as arguments. 
##          \fBob_parse_changelog\fP stops parsing either at the end of the
##          \fIchangelog\fP file or when \fIentry_cb\fP returns non-zero.
## @operand file     req The file to parse, or "-" for standard input.
## @operand entry_cb req Callback to run for each entry.
## @return Returns 0 after parsing.
## @stderr Prints error messages on parse errors.
## @pure maybe This function has no side effects.  Whether this function is
##             subshell-safe in practice depends on whether \fIentry_cb\fP is
##             subshell-safe.
ob_parse_changelog()
{
	local file="${1}"
	local entry_cb="${2}"
	shift 2 || _ob_abort
	local line_nr=
	local line=
	local line_=
	local expect=
	local changes=
	local blank_lines=
	local source=
	local distribution=
	local version=
	local maintainer=
	local date=

	# Parsing logic based on that of dpkg.

	line_nr=0
	expect='first_heading'

	while IFS='' read line; do
		line_nr=$(($line_nr + 1))
		case "${line}" in
			'')
				if [ "${expect}" = 'start_changes' ]; then
					changes="${changes}${_OB_LF}${line}"
				elif [ "${expect}" = 'next_or_eof' ]; then
					:
				elif [ "${expect}" != 'changes_or_trailer' ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_found_blank_line' \
						"$(_ob_get_changelog_expect_str "${expect}")"
				else
					blank_lines="${blank_lines}${_OB_LF}${line}"
				fi
				;;
			[!\ ]*)
				if [ "${expect}" != 'first_heading' -a \
						"${expect}" != 'next_or_eof' ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_found_heading' \
						"$(_ob_get_changelog_expect_str "${expect}")"
				fi
				source="${line%% (*}"
				line_="${line#* (}"
				distribution="${line_##*) }"
				line_="${line_%) *}"
				version="${line_}"
				if [ -z "${source}" -o -z "${distribution}" -o \
						-z "${version}" -o \
						"${version% *}" != "${version}" ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_bad_heading'
					source=''
					version=''
					distribution=''
					changes=''
				else
					if ! ob_validate_source_name "${source}"; then
						_ob_parse_changelog_error \
							"${file}" "${line_nr}" \
							'changelog_bad_source' "${source}"
					fi
					if ! ob_parse_version "${version}"; then
						_ob_parse_changelog_error \
							"${file}" "${line_nr}" \
							'changelog_bad_source_version' "${version}"
					fi
					changes="${line}"
				fi
				expect='start_changes'
				blank_lines=''
				;;
			' -- '*)
				if [ "${expect}" != 'changes_or_trailer' ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_found_trailer' \
						"$(_ob_get_changelog_expect_str "${expect}")"
				fi
				line="${line# -- }"
				maintainer="${line%%  *}"
				date="${line#*  }"
				if [ -z "${maintainer}" -o -z "${date}" -o \
						"${maintainer}" = "${date}" ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_bad_trailer'
					maintainer=''
					date=''
				elif [ -n "${source}" ]; then
					"${entry_cb}" "${source}" "${version}" \
						"${distribution}" "${changes}" \
						"${maintainer}" "${date}" || \
						return 0
				fi
				expect='next_or_eof'
				blank_lines=''
				;;
			' --'*)
				_ob_parse_changelog_error "${file}" "${line_nr}" \
					'changelog_bad_trailer'
				;;
			'  '*)
				if [ "${expect}" != 'start_changes' -a \
						"${expect}" != 'changes_or_trailer' ]; then
					_ob_parse_changelog_error "${file}" "${line_nr}" \
						'changelog_found_change' \
						"$(_ob_get_changelog_expect_str "${expect}")"
				fi
				changes="${changes}${_OB_LF}${blank_lines}${line}"
				expect='changes_or_trailer'
				blank_lines=''
				;;
			*)
				_ob_parse_changelog_error "${file}" "${line_nr}" \
					'changelog_bad_line'
				blank_lines=''
				;;
		esac
	done <<-EOF
		$(cat "${file}")
		EOF

	if [ "${expect}" != 'next_or_eof' ]; then
		_ob_parse_changelog_error "${file}" "${line_nr}" \
			'changelog_found_eof' \
			"$(_ob_get_changelog_expect_str "${expect}")"
	fi

	return 0
}