#!/bin/sh

SSG_MEDIA_DIR="${SSG_MEDIA_DIR:-media}"
SSG_SRC_DIR="${SSG_SRC_DIR:-src}"
SSG_TMP_DIR="${SSG_TMP_DIR:-tmp}"
SSG_OUT_DIR="${SSG_OUT_DIR:-out}"

SSG_TMP_FILE="${SSG_TMP_DIR}/tmp"
SSG_RSS_DIR="${SSG_SRC_DIR}/b"
SSG_RSS_OUT_FILE="${SSG_OUT_DIR}/rss.xml"

SSG_WEBSITE_DOMAIN="${SSG_WEBSITE_DOMAIN:-example.org}"
SSG_WEBSITE_TITLE="${SSG_WEBSITE_TITLE:-Example}"
SSG_WEBSITE_LINK="${SSG_WEBSITE_LINK:-https://${SSG_WEBSITE_DOMAIN}}"
SSG_WEBSITE_EMAIL="${SSG_WEBSITE_EMAIL:-contact@${SSG_WEBSITE_DOMAIN}}"
SSG_WEBSITE_GENERATOR="${SSG_WEBSITE_GENERATOR:-${SSG_WEBSITE_DOMAIN} ssg}}"
SSG_WEBSITE_DESCRIPTION="${SSG_WEBSITE_DESCRIPTION:-example}"
SSG_WEBSITE_LANGUAGE="${SSG_WEBSITE_LANGUAGE:-en}"

SSG_DATE_DEFAULT_HOUR="${SSG_DATE_DEFAULT_HOUR:-17:00:00}"
SSG_DATE_DEFAULT_TIMEZONE="${SSG_DATE_DEFAULT_TIMEZONE:-+0200}"

uname=$(uname)

__sha256="sha256"

if [ "${uname}" = "Linux" ]; then
	__sha256="sha256sum"
fi

__to_html_id() {
	cat /dev/stdin | sed 's/ /%20/g'
}

__get_value() {
	# 1: filename
	# 2: Attribute name
	# Retrieve and return the key/value of a lowdown source file.
	lowdown -T ms -X "${2}" "${1}" 2>/dev/null
}

__get_value_title() {
	# 1: filename
	# Get the title of a file and return a safe string.
	local _title

	_title="$(__get_value ${1} title || true)"
	if [ "${_title}" = "" ]; then
		_title="$(basename ${1} |
			rev |
			cut -d "." -f 2 |
			rev |
			sed 's/-/ /g')"
	fi

	echo "${_title}"
}

__get_value_date() {
	# 1: filename
	# Get the date of a file and return a safe string.
	local _date

	_date="$(__get_value ${1} date || true)"
	if [ "${_date}" = "" ]; then
		_date="1970-01-01"
	fi

	echo "${_date}"
}

__get_value_date_human() {
	# 1: filename
	# Get a human readable date from a file and return a safe string.
	if [ "${uname}" = "Linux" ]; then
		__get_value_date "${1}" | xargs date +"%d %b %Y" -d
	else
		__get_value_date "${1}" | xargs date -j -f "%Y-%m-%d" +"%d %b %Y"
	fi
}

__get_value_date_publication() {
	# 1: filename
	# Get publication date according to rfc 2822 and return a safe string.
	local _date

	_date="$(__get_value_date ${1})"
	_date="${_date} ${SSG_DATE_DEFAULT_HOUR} ${SSG_DATE_DEFAULT_TIMEZONE}"

	if [ "${uname}" = "Linux" ]; then
		date -d "${_date}" +"%a, %d %b %Y %H:%M:%S %z"
	else
		date -j -f "%Y-%m-%d %H:%M:%S %z" +"%a, %d %b %Y %H:%M:%S %z" "${_date}"
	fi
}

__get_out_filename() {
	# 1: filename
	# Convert the source filename to its output destination.
	local _filename

	_filename="${1}"

	if $(__get_value "${1}" draft || false); then
		_filename="$(dirname ${1})/$(basename ${1} | "${__sha256}").html"
	fi
	
	echo "${_filename}" |
		sed 's/.md$/.html/g' |
		sed "s/${SSG_SRC_DIR}/${SSG_OUT_DIR}/g"
}

__get_final_filename() {
	# 1: filename
	# Convert the source filename to its final filename for a webserver.
	__get_out_filename "${1}" | cut -d "/" -f 2-
}

__list_files() {
	# 1: directory
	# List all regular files in a directory and its subdirectories.
	find "${1}" -type f
}

__list_files_date() {
	# 1: directory
	local _files
	local _file
	local _tmp_file
	
	_files=$(__list_files "${1}")
	_tmp_file="${SSG_TMP_FILE}.list_files_date"

	cp /dev/null "${_tmp_file}"

	for _file in ${_files}; do
		echo "$(__get_value_date ${_file})" "${_file}" >> "${_tmp_file}"
	done

	sort -r "${_tmp_file}" | cut -d " " -f 2-
}

__install() {
	# 1: filename
	# Copy a file to the output directory.
	install -D -m 0644 "${1}" "${2}"
}

__lowdown() {
	# Output a file to html
	lowdown --html-no-skiphtml --html-no-escapehtml "${1}"
}

__generate_rss_body() {
	lowdown -tgemini "${1}" | sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g'
}

__apply_template() {
	# 1: template name or default
	m4 "templates/${1:-default}"
}

__generate_index_line() {
	# 1: filename where index will be displayed
	# 2: filename contained in line
	local _show_date

	_show_date="$(__get_value ${1} index_date || echo false)"

	if "${_show_date}"; then
		cat <<-EOF
		<span>
		$(__get_value_date_human ${2})
		</span>
		EOF
	fi

	cat <<-EOF
	<a href="/$(__get_final_filename ${2})">
	$(__get_value_title ${2})
	</a>
	EOF
}

__generate_index() {
	# 1: filename
	# Generate and output to stdout the index of a file.
	local _file
	local _index_dir

	_index_dir="${SSG_SRC_DIR}/$(__get_value "${1}" index)"
	[ -f "${_index_dir}" ] && _index_dir=$(dirname "${_index_dir}")
	[ ! -d "${_index_dir}" ] && return

	echo "<ul class=\"index\">"

	for _file in $(__list_files_date "${_index_dir}"); do
		[ "${1}" = "${_file}" ] && continue
		__get_value "${_file}" "draft" >/dev/null && continue

		echo "<li>"
		__generate_index_line "${1}" "${_file}"
		echo "</li>"
	done

	echo "</ul>"
}

__generate_metadata() {
	# 1: filename
	# Generate metadata with title
	local _title
	local _show_title

	_show_title=$(__get_value "${1}" show_title || true)

	if [ "${_show_title}" = "" ]; then
		_title=$(__get_value_title "${1}")
		_title_id=$(echo ${_title} | __to_html_id)

		cat <<-EOF
		<h1 id="${_title_id}">
		${_title}
		</h1>
		EOF
	fi
}

__handle_md() {
	# 1: filename
	# Handle markdown files.
	__lowdown "${1}" > "${SSG_TMP_FILE}.body"

	__generate_metadata "${1}" > "${SSG_TMP_FILE}.metadata"

	if [ ! "$(__get_value "${1}" index)" = "" ]; then
		__generate_index "${1}" > "${SSG_TMP_FILE}.index"
	else
		[ -f "${SSG_TMP_FILE}.index" ] && rm "${SSG_TMP_FILE}.index"
	fi

	__apply_template "$(__get_value "${1}" template)" > "${SSG_TMP_FILE}"
	__install "${SSG_TMP_FILE}" "$(__get_out_filename "${1}")"
}

__handle() {
	# 1: filename
	# Handle file depending on its filename and filetype.
	case "${1}" in
		*.md)
			__handle_md "${1}"
			;;
		*)
			__install "${1}" "$(__get_out_filename ${1})"
			;;
	esac
}