#!/bin/env ruby
###########################################################################
# mkdwc: Behaves like wc(1) but operates on the raw text of one or more
#        Markdown or Textile files.
# Tammy Cravit, tammy@tammycravit.us
###########################################################################
# This code can also be included into another script if you want to extend
# the MarkdownWC class.
###########################################################################
# This is the third take on this script, and abstracts out the markup-
# specific stuff as much as I know how to do. That way, the script can
# fairly easily be expanded to support just about any markup that can be
# easily converted to HTML, just by plugging in whatever code is needed
# to render the markup, and writing a new formatter.
###########################################################################

# Include the gems and packages we need
%w[rubygems peg_markdown RedCloth stringray optparse on_execute].each {
  |dep|
  require dep
}

OPTIONS = {
  :chars              => false,
  :words              => false,
  :lines              => false,
  :ingore_underscores => true,
}

###########################################################################
# Load the StringRay stuff
###########################################################################

String.send :include, StringRay

###########################################################################
# These classes abstract out the markup-specific formatting stuff
# so we can use one utility script for multiple markup languages.
#
# To create a new markup formatter engine, do the following:
#
# 1. Define a class that inherits from MarkupEngineFormatter
# 2. Add a markup_engine method that returns the class name of the
#    markup processor. The markup processor must take the marked-up
#    text as an argument to initialize, and must define a to_html
#    method which returns valid HTML.
# 3. Add a file_masks method that returns an array of the file extensions
#    which are valid for the new markup language.
# 4. Add a file_type method that returns the name of the markup language.
#    This is used by optparse in displaying the usage message.
# 5. Add a test to the on_execute block at the end of the script, which
#    dispatches to your new class based on the script name.
# 6. Create a symlink from markupwc to the new script name you defined in
#    step 5.
###########################################################################

class MarkupEngineFormatter
  def initialize
    @file_content = ""
  end

  def set_content(content)
    @file_content = content
  end

  def strip(s)
    s.gsub(/<\/?[^>]*>/, "").gsub(/\&\#[0123456789]+\;/, "?")
  end

  def strip_markup
    engine = markup_engine.new(@file_content)
    strip engine.to_html
  end

  def select_files(alist)
    filemask = file_masks.join("|")
    alist.find_all{|item| item =~ /\.(#{filemask})$/}
  end
end

# Formatter for Markdown files
class MarkdownFormatter < MarkupEngineFormatter
  def markup_engine
    PEGMarkdown
  end

  def file_masks
    %w[markdown mkd mdown markdn md]
  end

  def file_type
    "Markdown"
  end
end

# Formatter for Textile files
class TextileFormatter < MarkupEngineFormatter
  def markup_engine
    RedCloth
  end

  def file_masks
    %w[textile]
  end

  def file_type
    "Textile"
  end
end

###########################################################################
# MarkupWC is the main class for the application.
###########################################################################

class MarkupWC

  def initialize(formatter,filetype)
    @formatter = formatter
    @filetype  = @formatter.file_type
  end

  # Count the characters, words and lines in a single Markdown file.
  def count_file(filepath)
    if File.exists?(filepath)
      file_lines = IO.readlines(filepath)
      lines      = file_lines.count
      @formatter.set_content(file_lines.join("\n"))
      stripped = @formatter.strip_markup
      characters = stripped.length
      words      = stripped.to_stray.select {
                        |w| w.is_a? StringRay::Word }.size
      [characters,words,lines]
    else
      [0,0,0]
    end
  end

  # Invoke count_file on a group of files, and display individual and
  # aggregate results
  def count_many_files(filelist)
    tchars = twords = tlines = 0

    unless filelist.empty?
      filelist.each { |f|
        chars, words, lines = count_file(f)
        print_result f, chars, words, lines
        tchars += chars ; twords += words ; tlines += lines
      }
      if filelist.count > 1
        print_result "total", tchars, twords, tlines
      end
    end
  end

  # Parse the command line options
  def parse_command_line
    o = OptionParser.new do |o|
      script_name = $0.split('/').last

      o.set_summary_indent('   ')

      o.banner =    "Usage: #{script_name} [ -c | -w | -l ] <file> [file] ..."
      o.define_head "Count words, lines, and characters in one or more #{@filetype} files."
      o.separator   ""

      o.on("-c", "--chars", "Count only characters") { |OPTIONS[:chars]| }
      o.on("-w", "--words", "Count only words")      { |OPTIONS[:words]| }
      o.on("-l", "--lines", "Count only lines")      { |OPTIONS[:lines]| }
      o.on("-a", "--all-files",
        "Include files beginning with _")     { |OPTIONS[:ignore_underscores]|}
      o.separator ""

      o.on_tail("-h", "--help", "Show this help message") { puts o; exit }
      o.parse!(ARGV)

      if ARGV.count == 0
        puts o
        exit
      end

      numopts = 0
      %w[chars words lines].each { |opt| numopts += 1 if OPTIONS[opt.intern] }
      if numopts > 1
        puts "The -c, -w and -l options are mututally exclusive"
        puts ""
        puts o
        exit
      end
    end
  end

  # Process a group of files specified on the command line. This is the
  # entrypoint for the script when it's invoked interactively.
  def process_files
    parse_command_line

    filelist = @formatter.select_files(ARGV)
    unless OPTIONS[:ignore_underscores]
      filelist = filelist.find_all{|item| item !~ /^_/}
    end
    if filelist.empty?
      puts "#{$0.split('/').last}: filelist is empty"
      exit
    end
    count_many_files filelist
  end

private
  # Display the results for a single file.
  def print_result(file, chars, words, lines)
    if OPTIONS[:chars]
      printf "%6d %s\n", chars, file
    elsif OPTIONS[:words]
      printf "%6d %s\n", words, file
    elsif OPTIONS[:lines]
      printf "%6d %s\n", lines, file
    else
      printf "%6d %6d %6d %s\n", lines, words, chars, file
    end
  end
end

###########################################################################
# Actually run the script from the command line
###########################################################################

on_execute do
  script_name = $0.split('/').last
  formatter, filetype = nil, ""

  if script_name == "mkdwc" or script_name == "mmwc"
    formatter, filetype = MarkdownFormatter.new, "Markdown"
  elsif script_name == "ttwc"
    formatter, filetype = TextileFormatter.new, "Textile"
  else
    puts "Don't know what to do for script: #{$0}"
    exit
  end

  unless formatter.nil?
    MarkupWC.new(formatter, filetype).process_files
  end
end