#!/usr/bin/env ruby
require 'fileutils'
require 'nokogiri'
require 'optparse'
require 'erb'

def class_exists?(class_name)
  klass = Module.const_get(class_name)
  return klass.is_a?(Class)
rescue NameError
  return false
end

if class_exists? 'Encoding'
  Encoding.default_external = Encoding::UTF_8 if Encoding.respond_to?('default_external')
  Encoding.default_internal = Encoding::UTF_8 if Encoding.respond_to?('default_internal')
end

class String
  def unpack
    [self].pack('H*')
  end

  def indent
    out = ''
    self.split("\n").each {|line|
      out += "    #{line}\n"
    }
    out
  end

  def to_js
    self.gsub(/(?mi)(?<!\\)\//,'\/')
  end
end

class RegexRX
  attr_reader :title, :search, :flags, :replace, :source

  def initialize(file)
    doc = File.open(file) { |f| Nokogiri::XML(f) }
    @content = doc.xpath('RegExRX_Document')

    @title = doc.xpath("//Window").first["Title"].strip

    @search = grabString('fldSearch')

    @flags = ''

    @flags += 's' if grabOpt('Dot Matches Newline')
    @flags += 'i' unless grabOpt('Case Sensitive')
    @flags += 'm' if grabOpt('Treat Target As One Line')

    if @flags.length == 0
      @flags = false
    end

    # @regex = '/' + @search + '/' + @flags

    if grabPref('Do Replace')
      @replace = grabString('fldReplace')
    else
      @replace = false
    end

    @source = false
    source = grabString('fldSource')
    if source.length > 0
      @source = source
    end
  end

  def to_markdown(template)
    out = ERB.new(template).result(binding)

    out.force_encoding('utf-8')
  end


  def grabString(name)
    out = @content.xpath("//Control[@name=\"#{name}\"]").first
    .content
    .strip
    .force_encoding('utf-8')
    out.unpack
  end

  def grabPref(name)
    @content.xpath("//Preference[@name=\"#{name}\"]").first["value"] == "true"
  end

  def grabOpt(name)
    @content.xpath("//OptionMenu[@text=\"#{name}\"]").first["checked"] == "true"
  end
end

options = {}
optparse = OptionParser.new do|opts|
  opts.banner = "Usage: #{__FILE__} [OPTIONS]"
  options[:prefix] = ''
  options[:output] = 'markdown output'
  opts.on( '-o', '--output-dir=DIRECTORY', 'Output folder, defaults to "markdown output"') do |output|
    options[:output] = output
  end
  opts.on( '-p','--prefix=PREFIX', 'Prefix added before output filenames' ) do |prefix|
    options[:prefix] = prefix.strip + ' '
  end
  options[:template] = nil
  opts.on( '-t','--template=TEMPLATE', 'Use alternate ERB template' ) do |template|
    options[:template] = template
  end
  opts.on( '-h', '--help', 'Display this screen' ) do
    puts opts
    exit
  end
end
optparse.parse!

default_template = <<-ENDOFTEMPLATE
# <%= @title %>
<% if @flags %>

**Flags:** _<%= @flags %>_
<% end %>

**Search:**

<%= @search.indent %>
<% if @replace %>

**Replace:**

<%= @replace.indent %>
<% end %>
<% if @source %>
---

## Test string:

```text
<%= @source %>
```
<% end %>

ENDOFTEMPLATE

# If ERB template is specified, use that instead of the default
if options[:template]
  if File.exists?(File.expand_path(options[:template])) && File.basename(options[:template]) =~ /\.erb$/
    template = IO.read(File.expand_path(options[:template]))
  else
    $stderr.puts %Q{Specified template "#{options[:template]}" is not a valid template}
    Process.exit 1
  end
else
  template = default_template
end

FileUtils.mkdir_p(options[:output]) unless File.exists?(options[:output])

Dir.glob('*.regexrx').each {|file|
  # $stderr.puts "Reading #{file}"
  rx = RegexRX.new(file)
  filename = File.join(options[:output], options[:prefix] + rx.title + '.md')
  File.open(filename, 'w') {|f|
    f.print(rx.to_markdown(template))
  }
  $stderr.puts "Regex written to #{filename}"
}