# XHTML generation
# Copyright (C) 2023  Nguyễn Gia Phong
#
# This file if part of hybring.
#
# Hybring is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Hybring 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with hybring.  If not, see <https://www.gnu.org/licenses/>.

require "uri"
require "xml"

CSS = "
      html {
          margin: auto;
          max-width: 72ch;
      }
      body { margin-bottom: 2rem }
      h1, h2, h3, h4, h5, h6 { margin: 1ex 0 }
      form {
          display: grid;
          grid-template-columns: max-content 1fr 0;
      }
      form label { margin-right: 1ch }
      form input { margin-bottom: 1ex }
      .error { color: red }
    "

class Page
  def initialize(static_dir : String, static_url : String, api_url : String)
    Dir.mkdir_p static_dir
    @static_file = Path[static_dir] / "index.xhtml"
    @static_url = static_url
    @static_host = URI.parse(static_url).host
    @api_url = api_url
  end

  def criteria(xml)
    xml.element "h2" do xml.text "criteria" end
    xml.element "p" do
      xml.text "We accept pretty much any site"
      xml.text " served under an OpenNIC domain"
      xml.text " meeting the following requirements."
    end
    xml.element "ul" do
      xml.element "li" do xml.text "Family-friendly content" end
      xml.element "li" do xml.text "No violence incitation or doxing" end
      xml.element "li" do xml.text "No user tracking" end
      xml.element "li" do
        xml.text "ICANN counterpart accessible via HTTPS"
      end
      xml.element "li" do
        xml.text "Both linking to neighboring members"
      end
    end
    xml.element "p" do
      xml.text "Note that the two sites needn't be the same, as long as"
      xml.text " they represent the same entity, e.g. person or organization."
      xml.text "  The clear net site is for serving visitors"
      xml.text " without OpenNIC access or preferring secure connections."
    end
  end

  def input(xml, name, label, hint, error, value)
    if error
      xml.element "span"
      xml.element "span", class: "error" do xml.text error end
    end
    xml.element "label", for: name do xml.text label end
    xml.element "input", name: name, placeholder: hint, value: value,
                required: "required"
    xml.element "br"
  end

  def form(xml, errors = {} of String => String,
           params = {} of String => String)
    xml.element "p" do xml.text "Then, please fill out the form below." end
    xml.element "form", action: @api_url, method: "POST" do
      input xml, "nick", "Nickname", "digits and lowercase letters",
        errors.fetch("nick", nil), params.fetch("nick", nil)
      input xml, "opennic", "OpenNIC URL", "e.g. http://example.null",
        errors.fetch("opennic", nil), params.fetch("opennic", nil)
      input xml, "icann", "ICANN URL", "e.g. https://example.net",
        errors.fetch("icann", nil), params.fetch("icann", nil)
      xml.element "span" do
        xml.element "input", type: "hidden", name: "host", value: @static_host
      end
      xml.element "input", type: "submit", value: "Let me in!"
      xml.element "br"
    end
  end

  def member(xml, nick, opennic, icann, feed? = false)
    xml.element "p" do
      xml.text "The following membership is pending for approval."
      xml.text "  Please subscribe to this "
      xml.element "a", href: "#{@static_url}/#{nick}.atom" do
          xml.text "web feed"
      end
      xml.text " for further instructions."
    end if feed?
    xml.element "h3" do xml.text nick end
    xml.text "OpenNIC: "
    xml.element "a", href: opennic do xml.text opennic end
    xml.element "br"
    xml.text "ICANN: "
    xml.element "a", href: icann do xml.text icann end
    xml.element "br"
  end

  def build(members, errors = {} of String => String,
            params = {} of String => String) : String
    XML.build encoding: "UTF-8", indent: "  " do |xml|
      xml.element "html", xmlns: "http://www.w3.org/1999/xhtml", lang: "en" do
        xml.element "head" do
          xml.element "meta", name: "viewport",
                      content: "width=device-width,initial-scale=1.0"
          xml.element "link", rel: "icon", href: "data:,"
          xml.element "style" do xml.text CSS end
          xml.element "title" do xml.text "le cercle libre" end
        end
        xml.element "body" do
          xml.element "h1" do xml.text "le cercle libre" end
          xml.element "p" do
            xml.text "The Free Circle is a web ring for sites"
            xml.text " with an OpenNIC domain."
          end
          criteria xml

          xml.element "h2" do xml.text "joining" end
          xml.element "p" do
            xml.text "First, add "
            xml.element "a",
                        href: "https://html.spec.whatwg.org/#the-a-element" do
                xml.text "anchors"
            end
            xml.text " refering to the following neighbors to your sites"
            xml.text " on both OpenNIC and ICANN domains."
            xml.text "  Your neighbors will change as people come and go,"
            xml.text " so you will be given an Atom feed with instructions"
            xml.text " to keep the hyperlinks up to date."
          end
          xml.element "ul" do
            xml.element "li" do
              xml.text "Left: "
              _, left, _ = members[-1]
              xml.element "a", href: left do xml.text left end
            end
            xml.element "li" do
              xml.text "Right: "
              _, right, _ = members[0]
              xml.element "a", href: right do xml.text right end
            end
          end

          if params.empty? # static page
            form xml
          elsif errors.empty?
            member xml, params["nick"], params["opennic"], params["icann"], true
          else
            form xml, errors, params
          end

          xml.element "h2" do xml.text "members" end
          members.each do |nick, opennic, icann|
            member xml, nick, opennic, icann
          end
        end
      end
    end
  end

  def write(members)
    File.write @static_file, self.build members
  end
end