module Getopt

   REQUIRED  = 0
   BOOLEAN   = 1
   OPTIONAL  = 2
   INCREMENT = 3
   NEGATABLE = 4

   class LongError < StandardError; end

   class Long
      VERSION = "1.3.4"

      # Takes an array of switches.  Each array consists of three elements.
      def self.getopts(*switches)
         if switches.empty?
            raise ArgumentError, "no switches provided"
         end

         hash  = {} # Hash returned to user
         valid = [] # Tracks valid switches
         types = {} # Tracks argument types
         syns  = {} # Tracks long and short arguments, or multiple shorts

         # If a string is passed, split it and convert it to an array of arrays
         if switches.first.kind_of?(String)
            switches = switches.join.split
            switches.map!{ |switch| switch = [switch] }
         end

         # Set our list of valid switches, and proper types for each switch
         switches.each{ |switch|
            valid.push(switch[0])       # Set valid long switches

            # Set type for long switch, default to BOOLEAN.
            # Create synonym hash.  Default to first char of long switch for 
            # short switch, e.g. "--verbose" creates a "-v" synonym.
            if switch[1].kind_of?(Fixnum)
               switch[2] = switch[1]
               types[switch[0]] = switch[2]
               switch[1] = switch[0][1..2]
            else
               switch[2] ||= BOOLEAN
               types[switch[0]] = switch[2]
               switch[1] ||= switch[0][1..2]
            end

            syns[switch[0]] = switch[1]
            syns[switch[1]] = switch[0]

            switch[1].each{ |char|      
               types[char] = switch[2]  # Set type for short switch
               valid.push(char)         # Set valid short switches
            }
         }

         re_long     = /^(--\w+[-\w+]*)?$/
         re_short    = /^(-\w)$/
         re_long_eq  = /^(--\w+[-\w+]*)?=(.*?)$|(-\w?)=(.*?)$/
         re_short_sq = /^(-\w)(\S+?)$/

         ARGV.each_with_index{ |opt, index|

            # Allow either -x -v or -xv style for single char args
            if re_short_sq.match(opt)
               chars = opt.split("")[1..-1].map{ |s| s = "-#{s}" }

               chars.each_with_index{ |char, i|
                  unless valid.include?(char)  
                     raise LongError, "invalid switch '#{char}'"
                  end

                  # Grab the next arg if the switch takes a required arg
                  if types[char] == REQUIRED
                     # Deal with a argument squished up against switch
                     if chars[i+1]
                        arg = chars[i+1..-1].join.tr("-","")
                        ARGV.push(char, arg)
                        break
                     else
                        arg = ARGV.delete_at(index+1)
                        if arg.nil? || valid.include?(arg) # Minor cheat here
                           err = "no value provided for required argument '#{char}'"
                           raise LongError, err
                        end
                        ARGV.push(char, arg)
                     end
                  elsif types[char] == OPTIONAL
                     if chars[i+1] && !valid.include?(chars[i+1])
                        arg = chars[i+1..-1].join.tr("-","")
                        ARGV.push(char, arg)
                        break
                     elsif
                        if ARGV[index+1] && !valid.include?(ARGV[index+1])
                           arg = ARGV.delete_at(index+1)
                           ARGV.push(char, arg)
                        end
                     else
                        ARGV.push(char)
                     end
                  else
                     ARGV.push(char)
                  end
               }
               next
            end

            if match = re_long.match(opt) || match = re_short.match(opt)
               switch = match.captures.first
            end

            if match = re_long_eq.match(opt)
               switch, value = match.captures.compact
               ARGV.push(switch, value)
               next
            end

            # Make sure that all the switches are valid.  If 'switch' isn't
            # defined at this point, it means an option was passed without
            # a preceding switch, e.g. --option foo bar.
            unless valid.include?(switch)
               switch ||= opt
               raise LongError, "invalid switch '#{switch}'"
            end

            # Required arguments
            if types[switch] == REQUIRED
               nextval = ARGV[index+1]

               # Make sure there's a value for mandatory arguments
               if nextval.nil?
                  err = "no value provided for required argument '#{switch}'"
                  raise LongError, err
               end

               # If there is a value, make sure it's not another switch
               if valid.include?(nextval)
                  err = "cannot pass switch '#{nextval}' as an argument"
                  raise LongError, err
               end

               # If the same option appears more than once, put the values
               # in array.
               if hash[switch]
                  hash[switch] = [hash[switch], nextval].flatten
               else
                  hash[switch] = nextval
               end
               ARGV.delete_at(index+1)
            end

            # For boolean arguments set the switch's value to true.
            if types[switch] == BOOLEAN
               if hash.has_key?(switch)
                  raise LongError, "boolean switch already set"
               end
               hash[switch] = true
            end

            # For increment arguments, set the switch's value to 0, or
            # increment it by one if it already exists.
            if types[switch] == INCREMENT
               if hash.has_key?(switch)
                  hash[switch] += 1
               else
                  hash[switch] = 1
               end
            end

            # For optional argument, there may be an argument.  If so, it
            # cannot be another switch.  If not, it is set to true.
            if types[switch] == OPTIONAL
               nextval = ARGV[index+1]
               if valid.include?(nextval)
                  hash[switch] = true
               else
                  hash[switch] = nextval
                  ARGV.delete_at(index+1)
               end
            end
         }

         # Set synonymous switches to the same value, e.g. if -t is a synonym
         # for --test, and the user passes "--test", then set "-t" to the same
         # value that "--test" was set to.
         #
         # This allows users to refer to the long or short switch and get
         # the same value
         hash.each{ |switch, val|
            if syns.keys.include?(switch)
               syns[switch].each{ |key|
                  hash[key] = val   
               }
            end
         }

         # Get rid of leading "--" and "-" to make it easier to reference
         hash.each{ |key, value|
            if key[0,2] == '--'
               nkey = key.sub('--', '')
            else
               nkey = key.sub('-', '')
            end
            hash.delete(key)
            hash[nkey] = value
         }

         hash
      end

   end
end