#!/bin/sh
set -euo pipefail


usage() {
	echo <<-'EOF'
		Usage:
		  conf GLOBALCONF FILENAME.adoc
		  conf -G BASECONF > GLOBALCONF
	EOF
}


GENERATE=false
while getopts 'G' flag; do
	case "$flag" in
		(G)
			GENERATE=true
			;;
		(*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))


needs() {
	if [ -z "${1:-}" ]; then
		printf '%s\n' "$2" >&2
		exit 1
	fi
}

DATE_I='+%Y-%m-%d'
DATE_Is="${DATE_I}T%H:%M:%S%:z"
datex() {
	# date(1), plus non-POSIX -d option
	DATESTR="$1"
	shift
	date -d "$DATESTR" "$@"
}

dateiso() {
	datex "$1" -u "$DATE_Is"
}

dateepoch() {
	datex "$1" '+%s'
}


unset header_links categories custombody

unset url_pre site_name feed_title feed_url feed_alternate_url
unset list_addr discussions_url_prefix
unset email author sourcecode_url sourcecode_url_prefix
unset logo_alt

unset root_dir img_dir
unset updatedat

unset css_url feed_url favicon_url
unset feedicon_url logo_url_prefix envelopeicon_url_prefix \
	lockicon_url_prefix

unset publickey_url
unset sort



CONF="${1:-}"
FILENAME="${2:-}"
eval "$(assert-arg -- "$CONF" 'CONF')"
. ./"$CONF"


needs "${url_pre:-}"            'Missing required $url_pre (e.g. https://example.com)'
needs "${site_name:-}"          'Missing required $site_name'
needs "${feed_title:-}"         'Missing required $feed_title'
needs "${feed_url:-}"           'Missing required $feed_url'
needs "${feed_alternate_url:-}" 'Missing required $feed_alternate_url'

needs "${list_addr:-}"              'Missing required $list_addr'
needs "${discussions_url_prefix:-}" 'Missing required $discussions_url_prefix'

needs "${email:-}"                 'Missing required $email'
needs "${author:-}"                'Missing required $author'
needs "${sourcecode_url:-}"        'Missing required $sourcecode_url'
needs "${sourcecode_url_prefix:-}" 'Missing required $sourcecode_url_prefix'


if [ "$GENERATE" = true ]; then
	now_iso="$(dateiso "@${SOURCE_DATE_EPOCH:-$(date '+%s')}" | shesc)"
	now_epoch="$(dateepoch "$now_iso" | shesc)"
	feed_title_html="$(printf '%s\n' "$feed_title" | htmlesc | shesc)"
	site_name_html="$( printf '%s\n' "$site_name"  | htmlesc | shesc)"
	if [ -z "${logo_alt:-}" ]; then
		logo_alt='The website logo'
	fi
	logo_alt="$(printf '%s\n' "$logo_alt" | htmlesc | shesc)"

	cat -- "$CONF"
	cat <<-EOF
		export now_iso="$now_iso"
		export now_epoch="$now_epoch"
		export feed_title_html="$feed_title_html"
		export site_name_html="$site_name_html"
		export feed_url_absolute="$url_pre/$feed_url"
		export feed_alternate_url_absolute="$url_pre/$feed_alternate_url"
		export logo_alt="$logo_alt"
	EOF
	exit
fi

eval "$(assert-arg -- "$FILENAME" 'FILENAME')"

trap 'rm -f -- "$FILENAME".embedded-config' EXIT

awk '
$0 == "" {exit}
/^= /    {next}
{ printf "export %s=\"%s\"\n",
	substr($1, 2, length($1) - 2),
	substr($0, length($1) + 2) }
' "$FILENAME" > "$FILENAME".embedded-config
. ./"$FILENAME".embedded-config

is_article() {
	printf '%s\n' "$FILENAME" | grep -qE \
		'^[-a-zA-Z0-9/]*/[0-9]{4}/[0-9]{2}/[0-9]{2}/[-A-Za-z0-9]+\.adoc$'
		#^src/a/b/c/     /1970    /01      /01/     /some-file-N4me.adoc
}

base_url() {
	# src/sub/dirs/file.txt -> ../..
	# src/file.txt -> .
	printf '%s/\n' "$(dirname -- "$UNPREFIXED")" |
		sed 's|^\./$|.|' |
		sed \
			-e 's|[^/]*/|../|g' \
			-e 's|/$||'
}

last3dirnames() {
	dirname -- "$UNPREFIXED" | tr '/' '\n' | tail -n3 | paste -sd-
}

datefmt() {
	LANG=en_GB.UTF-8 datex "$1" -u '+%B %-d, %Y'
}


if [ -z "${root_dir:-}" ]; then
	root_dir="$(dirname -- "$CONF")"
fi
root_dir="${root_dir%/}"

if [ -z "${img_dir:-}" ]; then
	img_dir=img
fi
img_dir="${img_dir%/}"

UNPREFIXED="${FILENAME#$root_dir/}"

cat -- "$CONF"

url="$(printf '%s\n' "${UNPREFIXED%.adoc}.html" | shesc)"


lastmod_epoch="$(stat --printf='%Y' "$FILENAME" | shesc)"

collurl=
date_iso=
date_epoch=
date_formatted=
updatedat_iso=
updatedat_epoch=
updatedat_formatted=
if is_article; then
	lastdirnames="$(last3dirnames)"
	date_iso="$(dateiso "$lastdirnames"      | shesc)"
	date_epoch="$(dateepoch "$date_iso"      | shesc)"
	date_formatted="$(datefmt "$date_iso"    | shesc)"
	lastmod_epoch="$date_epoch"
	if [ -n "${updatedat:-}" ]; then
		updatedat_iso="$(dateiso "$updatedat" | shesc)"
		updatedat_epoch="$(dateepoch "$updatedat_iso"   | shesc)"
		updatedat_formatted="$(datefmt "$updatedat_iso" | shesc)"
		lastmod_epoch="$updatedat_epoch"
	fi
	file="$(basename "$url")"
	collurl="$(printf '%s\n' "$lastdirnames" | sed 's|-|/|g' | shesc)/$file"
fi

lastmod_iso="$(dateiso "@$lastmod_epoch"    | shesc)"
lastmod_formatted="$(datefmt "$lastmod_iso" | shesc)"


LEN="$( printf '%s..' "$root_dir" | sed -e 's|//|/|g' -e 's|/$||' | wc -c)"
lang="$(printf '%s' "$FILENAME" | cut -c "$LEN"- | cut -d/ -f1 | shesc)"


BASE_URL="$(base_url)"
TITLE_RAW="$(cat -- "$FILENAME" | grep '^= .*' | head -n1 | cut -d' ' -f2- ||
	echo 'MISSING')"
TITLEFULL_RAW="$TITLE_RAW | $site_name"

if [ -z "${css_url:-}" ]; then
	css_url="$BASE_URL/style.css"
fi
if [ -z "${feed_url:-}" ]; then
	feed_url="$BASE_URL/feed.xml"
fi
if [ -z "${feedicon_url:-}" ]; then
	needs "${img_dir:-}" 'Define either $feedicon_url or $img_dir'
	feedicon_url="$BASE_URL/$img_dir/atom.svg"
fi
if [ -z "${favicon_url:-}" ]; then
	needs "${img_dir:-}" 'Define either $favicon_url or $img_dir'
	favicon_url="$BASE_URL/$img_dir/favicon.svg"
fi
if [ -z "${logo_url_prefix:-}" ]; then
	needs "${img_dir:-}" 'Define either $logo_url_prefix or $img_dir'
	logo_url_prefix="$BASE_URL/$img_dir/logo"
fi
if [ -z "${envelopeicon_url_prefix:-}" ]; then
	needs "${img_dir:-}" 'Define either $envelopeicon_url_prefix or $img_dir'
	envelopeicon_url_prefix="$BASE_URL/$img_dir/envelope"
fi
if [ -z "${lockicon_url_prefix:-}" ]; then
	needs "${img_dir:-}" 'Define either $lockicon_url_prefix or $img_dir'
	lockicon_url_prefix="$BASE_URL/$img_dir/lock"
fi

title_uri="$(printf '%s' "$TITLE_RAW" | uri)"
comment_url="$(printf 'mailto:%s?Subject=Re%%3A%%20%s\n' "$list_addr" "$title_uri" | shesc)"
discussions_url="$(printf '%s%s\n' "$discussions_url_prefix" "$title_uri" | shesc)"

css_url="$(                printf '%s\n' "$css_url"                 | shesc)"
feed_url="$(               printf '%s\n' "$feed_url"                | shesc)"
feedicon_url="$(           printf '%s\n' "$feedicon_url"            | shesc)"
favicon_url="$(            printf '%s\n' "$favicon_url"             | shesc)"
logo_url_prefix="$(        printf '%s\n' "$logo_url_prefix"         | shesc)"
envelopeicon_url_prefix="$(printf '%s\n' "$envelopeicon_url_prefix" | shesc)"
lockicon_url_prefix="$(    printf '%s\n' "$lockicon_url_prefix"     | shesc)"

source_path="$(printf '%s\n' "$FILENAME" | shesc)"
base_url_prefix="$(printf '%s\n' "$BASE_URL" | shesc)"
title="$(         printf '%s\n' "$TITLE_RAW"     |           shesc)"
title_html="$(    printf '%s\n' "$TITLE_RAW"     | htmlesc | shesc)"
titlefull="$(     printf '%s\n' "$TITLEFULL_RAW" |           shesc)"
titlefull_html="$(printf '%s\n' "$TITLEFULL_RAW" | htmlesc | shesc)"
cat <<-EOF
	export css_url="$css_url"
	export feed_url="$feed_url"
	export feedicon_url="$feedicon_url"
	export favicon_url="$favicon_url"
	export logo_url_prefix="$logo_url_prefix"
	export envelopeicon_url_prefix="$envelopeicon_url_prefix"
	export lockicon_url_prefix="$lockicon_url_prefix"
	export source_path="$source_path"
	export publickey_url="$base_url_prefix/${publickey_url:-}"
	export url="$url"
	export collurl="$collurl"
	export url_absolute="$url_pre/$url"
	export base_url_prefix="$base_url_prefix"
	export title="$title"
	export title_html="$title_html"
	export titlefull="$titlefull"
	export titlefull_html="$titlefull_html"
	export lastmod_iso="$lastmod_iso"
	export lastmod_epoch="$lastmod_epoch"
	export lastmod_formatted="$lastmod_formatted"
	export date_iso="$date_iso"
	export date_epoch="$date_epoch"
	export date_formatted="$date_formatted"
	export updatedat_iso="$updatedat_iso"
	export updatedat_epoch="$updatedat_epoch"
	export updatedat_formatted="$updatedat_formatted"
	export comment_url="$comment_url"
	export discussions_url="$discussions_url"
	export lang="$lang"
EOF

cat "$FILENAME".embedded-config

if [ -z "${sort:-}" ]; then
	echo 'export sort=0'
fi