#!/usr/bin/env ruby
 
# Based on rstakeout, originally by Mike Clark, from
# http://www.pragmaticautomation.com/cgi-bin/pragauto.cgi/Monitor/StakingOutFileChanges.rdoc
 
require 'find'
 
class Watch < Thor
  desc "path <command> <path> <path> ...", "Watch the given paths and execute the command every time they change. Put FILE in the filename to substitute it for the changed file."
  def path(command, *paths)
    exit if paths.empty?
    
    files = {}
    paths = paths.select { |path| File.exist?(path) }
    
    paths.each do |path|      
      Find.find(File.expand_path(path)) do |file|
        if FileTest.directory?(file)
          if File.basename(file) =~ /^\.\w+/            
            Find.prune
          else
            next
          end          
        else
          files[file] = File.mtime(file)
        end
      end
    end
            
    puts "Watching #{paths.join(', ')}\n\nFiles: #{files.keys.length}"
 
    trap('INT') do
      puts "\nQuitting..."
      exit
    end
    
    loop do
      sleep 1
 
      changed_file, last_changed = files.find { |file, last_changed|
        File.mtime(file) > last_changed
      }
 
      if changed_file
        files[changed_file] = File.mtime(changed_file)
        puts "=> #{changed_file} changed, running #{command}"
        puts `#{command.gsub(/FILE/, changed_file)}`
        puts "=> done"
      end
    end
  end
end