#!/usr/bin/ruby
# 
#Copyright 2022 Yessiest (yessiest@memeware.net)
#
#Licensed under the Apache License, Version 2.0 (the "License");
#you may not use this file except in compliance with the License.
#You may obtain a copy of the License at
#
#http://www.apache.org/licenses/LICENSE-2.0
#
#Unless required by applicable law or agreed to in writing, software
#distributed under the License is distributed on an "AS IS" BASIS,
#WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#See the License for the specific language governing permissions and
#limitations under the License.

# Ruby CGI module to produce human-readable HTML from markdown pages
# Variables
ROOT_PATH="/www/"
TAB_MULTIPLIER=10
TAB_UNIT="px"
QUOTE_TAB=4
TEMPLATE_PRE="template.pre.html"
TEMPLATE_POST="template.post.html"
TEMPLATE_CSS="template.css"
# Script
require 'cgi'

cgi = CGI.new("html5")

def ident(ident)
  return "<span style=\"margin-left: #{(ident*TAB_MULTIPLIER).to_s+TAB_UNIT}\">"
end

def _parse_list(text,mode=["ul",/ *-/])
  new_text = ""
  list_started = false
  text.each_line do |line|
    starts = line.start_with?(mode[1])
    l_ident = line.match(/ */)[0].length
    if (not list_started) and (starts) then
      list_started = true
      new_text=new_text+"<#{mode[0]}>\n<li>#{ident l_ident}\n"+line.gsub(mode[1],"")+"</span></li>\n"
    elsif (list_started) and (not starts) then
      list_started = false
      new_text=new_text+"</#{mode[0]}>\n"+line
    elsif (list_started) and (starts) then
      new_text = new_text+"<li>#{ident l_ident}\n"+line.gsub(mode[1],"")+"</span></li>\n"
    else
      new_text = new_text+line
    end
  end
  return new_text
end

def _env(text,env)
  return text
      .gsub(/(?<!\\)\$PATH/,env["PATH"])
      .gsub(/(?<!\\)\$FILE/,env["FILE"])
      .gsub(/(?<!\\)\$CRUMB/,env["CRUMB"])
end

template_css = ""
template_pre = ""
template_post = ""
if File::exists?( ROOT_PATH+TEMPLATE_CSS ) then
   template_css = "<link rel=\"stylesheet\" href=\"#{TEMPLATE_CSS}\">\n"
end
if File::exists?( ROOT_PATH+TEMPLATE_PRE) then
   template_pre_f = File.new( ROOT_PATH+TEMPLATE_PRE, "r")
   template_pre = template_pre_f.read
   template_pre_f.close
end
if File::exists?( ROOT_PATH+TEMPLATE_POST) then
   template_post_f = File.new( ROOT_PATH+TEMPLATE_POST, "r")
   template_post = template_post_f.read
   template_post_f.close
end

doc = "---
# Error 404: Document not available

Document you requested is not available
---"
# Absolutely containing the script to the ROOT_PATH and making it only read .md
if cgi["docfile"].end_with?(".md") and
   (File.absolute_path(ROOT_PATH+cgi["docfile"]).start_with?(ROOT_PATH)) and
   File::exists?( ROOT_PATH+cgi["docfile"] ) then
  docfile = File.new(ROOT_PATH+cgi["docfile"],"r")
  doc = docfile.read
  docfile.close
end

content = cgi.body {
  doc = "\n"+CGI.escapeHTML(doc)

  # Extra
  # - Horizontal rule
  doc = doc.gsub(/-{3,}/,"<hr />")
  # - Linebreak
  doc = doc.gsub("\n\n","<br />\n")

  # Parse lists
  # - Unordered lists
  doc = _parse_list(doc)
  # - Ordered lists
  doc = _parse_list(doc,mode = ["ol",/ *\d*\./])
  
  # Bounded markup
  # - Bold/Italics
  doc = doc.gsub(/(?<!\\)\*{3}(.*?)(?<!\\)\*{3}/m,"<i><b>\\1</b></i>")
  doc = doc.gsub(/(?<!\\)\*{2}(.*?)(?<!\\)\*{2}/m,"<b>\\1</b>")
  doc = doc.gsub(/(?<!\\)\*{1}(.*?)(?<!\\)\*{1}/m,"<i>\\1</i>")
  # - Underline
  doc = doc.gsub(/(?<!\\)_(.*?)_(?<!\\)/m,"<span style=\"text-decoration:underline;\">\\1</span>")
  # - Strikethrough
  doc = doc.gsub(/(?<!\\)~(.*?)~(?<!\\)/m,"<strike>\\1</strike>")
  
  # Unbounded (line) markup
  # - Headers
  doc = doc.gsub(/(?<=\n)\#{4} ?(.*)/,"<h4>\\1</h4>")
  doc = doc.gsub(/(?<=\n)\#{3} ?(.*)/,"<h3>\\1</h3>")
  doc = doc.gsub(/(?<=\n)\#{2} ?(.*)/,"<h2>\\1</h2>")
  doc = doc.gsub(/(?<=\n)\# ?(.*)/,"<h1>\\1</h1>")

  # - Quote
  doc = doc.gsub(/(?<=\n)&gt;(.*)/,"#{ident QUOTE_TAB}<span class=\"quote\">\\1</span></span>")

  # Links
  # - Images
  doc = doc.gsub(/!\[(.*?)\]\((.*?)\)/,"<img src=\"\\2\" alt=\"\\1\" />")
  # - Hyperlinks
  doc = doc.gsub(/\[(.*?)\]\((.*?)\)/,"<a href=\"\\2\">\\1</a>")
 
  # Code blocks
  # - Full block
  doc = doc.gsub(/(?<!\\)`{3}(.*?)(?<!\\)`{3}/m,"<pre><code class=\"codeblock\">\n\\1</pre></code>")
  # - Inline block
  doc = doc.gsub(/(?<!\\)`{2}(.*?)(?<!\\)`{2}/m,"<code class=\"codeinline\">\\1</code>")

  env = {
    "PATH" => cgi["docfile"].match("^(.*?)/?[^/]*$")[1].gsub(ROOT_PATH,""),
    "FILE" => cgi["docfile"].match("[^/]*$")[0],
    "CRUMB" => cgi["docfile"].gsub("/"," / ")
  }
  _env(template_pre,env)+"\n"+
  doc+"\n"+
  _env(template_post,env)+"\n"
}

cgi.out {
  cgi.html {
    cgi.head { "\n"+
      cgi.title { cgi["docfile"].gsub(/.md$/,"") }+"\n"+
      template_css
    } +
    content
  }
}