# Nick's web site: Generate a project page from a submodule README.md
#
# Copyright © 2021 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/>.

def project_readme(item = @item)
    tag = item.fetch(:release, "HEAD")
    shortname = item.fetch(:shortname, item[:module])

    data, status = Open3.capture2("git", "submodule", "foreach", "--quiet",
      "case $sm_path in */" + item[:module] + ")" +
      "git fetch --quiet --tags;" +
      "git log --max-count=1 --format=%cI #{tag}; printf '\\35';" +
      "git show #{tag}:NEWS 2>/dev/null; printf '\\35';" +
      "git remote get-url origin; printf '\\35';" +
      "git show #{tag}:README.md ;;" +
      "esac")
    raise "git submodule foreach failed" if status != 0

    date, news, gituri, contents = data.split("\35", 4)
    intro, contents = contents.split("#", 2)
    contents = if contents.nil? then "" else "\n#" + contents end

    gituri.strip!
    gitweb = gituri.sub(%r{^[^/]*(.*)(/.*)}, '\1/gitweb\2')
    date = Date.iso8601(date).to_time

    obtaining = <<~EOF
        # Obtaining #{item[:title]}
    EOF

    if item[:release].nil?
        obtaining += "\n" + <<~EOF
            There are presently no released versions of #{shortname}.
        EOF
    else
        newsver, news = news.split("\n", 2)
        newsver.sub!(/^.*?([[:digit:]][^:]*).*$/, '\1')

        targz = "#{shortname}-#{newsver}.tar.gz"
        distbase = "/archive/#{shortname}"
        obtaining += <<~EOF
            [archive]: #{distbase}

            All released files are available from the [#{shortname} archive
            directory][archive].
        EOF
    end

    obtaining += <<~EOF
        The latest development sources [may be browsed online](#{gitweb}) or
        cloned directly using git, e.g.,

        <kbd>git clone #{gituri}</kbd>
    EOF

    unless item[:release].nil?
        obtaining += "\n" + <<~EOF
            [targz]: #{distbase}/#{targz}
            [targzsig]: #{distbase}/#{targz}.sig

            The most recent release is version #{newsver}, released on
            #{date.getutc.strftime("%Y-%m-%d")}.  Source code for this version
            is available in [#{targz}][targz] ([signature][targzsig]).
            Noteworthy changes in this release:
        EOF
        obtaining += "\n"
        news.each_line do |line|
            break if line =~ /^[^[:space:]]/
            obtaining += line.lstrip
        end

        obtaining += "\n\n" + <<~EOF
            [gpg]: https://gnupg.org/

            Use the signature file to verify that the corresponding source
            bundle is intact.  After downloading both files, if [GnuPG][gpg]
            is installed, the signature can be verified with a command like:

            <kbd>gpg --verify #{targz}.sig</kbd>

            If the verification fails because you don't have the required
            public key, that key can be imported with a command such as:

            <kbd>gpg --keyserver keys.gnupg.net --recv-keys 5B45D3D185B8E1F6</kbd>

            Then run the verify command again.
        EOF
    end

    return "#{intro}\n\n#{obtaining}\n\n#{contents}"
end