#!/usr/bin/env ruby
#
# Nick's web site: Autogenerate timestamps for nanoc items.
#
# Copyright © 2020 Nick Bowler
#
# This program 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.
#
# This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.

require 'yaml'

updatetime = Time.now

content = STDIN.read
if content =~ /\A---(--)?\s*$/
    parts = content.split(/^---(--)?[ \t]*\r?\n?/, 3)
    metadata = parts[1]
    content = parts[2]
end

if metadata
    meta = YAML.load(metadata, permitted_classes: [Time])
    timefmt = "%FT%T%z"
    updatestr = updatetime.round.strftime(timefmt)
    autoset = nil

    if meta["published"] and meta["updated"].is_a?(Time)
        s = meta["updated"].strftime(timefmt)
        if metadata.sub!(/^updated:\s*#{s}\s*$/, "updated: " + updatestr)
            autoset = "updated"
        end
    elsif meta["published"] and !meta["updated"]
        metadata += "updated: " + updatestr
        autoset = "updated"
    elsif !meta["published"]
        metadata += "published: " + updatestr
        autoset = "published"
    end

    if autoset
        # Revalidate YAML
        meta = YAML.load(metadata, permitted_classes: [Time])
        unless meta[autoset] == updatetime.round
            raise "failed to auto-insert " + autoset
        end
    end

    puts("---")
    puts(metadata)
    puts("---")
end
puts(content)