module Pry::InputCompleter

def self.build_completion_proc(target, commands=[""])
  proc do |input|
    bind = target
    case input
    when /^(\/[^\/]*\/)\.([^.]*)$/
      # Regexp
      receiver = $1
      message = Regexp.quote($2)
      candidates = Regexp.instance_methods.collect{|m| m.to_s}
      select_message(receiver, message, candidates)
    when /^([^\]]*\])\.([^.]*)$/
      # Array
      receiver = $1
      message = Regexp.quote($2)
      candidates = Array.instance_methods.collect{|m| m.to_s}
      select_message(receiver, message, candidates)
    when /^([^\}]*\})\.([^.]*)$/
      # Proc or Hash
      receiver = $1
      message = Regexp.quote($2)
      candidates = Proc.instance_methods.collect{|m| m.to_s}
      candidates |= Hash.instance_methods.collect{|m| m.to_s}
      select_message(receiver, message, candidates)
    when /^(:[^:.]*)$/
      # Symbol
      if Symbol.respond_to?(:all_symbols)
        sym = $1
        candidates = Symbol.all_symbols.collect{|s| ":" + s.id2name}
        candidates.grep(/^#{sym}/)
      else
        []
      end
    when /^::([A-Z][^:\.\(]*)$/
      # Absolute Constant or class methods
      receiver = $1
      candidates = Object.constants.collect{|m| m.to_s}
      candidates.grep(/^#{receiver}/).collect{|e| "::" + e}
    when /^([A-Z].*)::([^:.]*)$/
      # Constant or class methods
      receiver = $1
      message = Regexp.quote($2)
      begin
        candidates = eval("#{receiver}.constants.collect{|m| m.to_s}", bind)
        candidates |= eval("#{receiver}.methods.collect{|m| m.to_s}", bind)
      rescue RescuableException
        candidates = []
      end
      candidates.grep(/^#{message}/).collect{|e| receiver + "::" + e}
    when /^(:[^:.]+)\.([^.]*)$/
      # Symbol
      receiver = $1
      message = Regexp.quote($2)
      candidates = Symbol.instance_methods.collect{|m| m.to_s}
      select_message(receiver, message, candidates)
    when /^(-?(0[dbo])?[0-9_]+(\.[0-9_]+)?([eE]-?[0-9]+)?)\.([^.]*)$/
      # Numeric
      receiver = $1
      message = Regexp.quote($5)
      begin
        candidates = eval(receiver, bind).methods.collect{|m| m.to_s}
      rescue RescuableException
        candidates = []
      end
      select_message(receiver, message, candidates)
    when /^(-?0x[0-9a-fA-F_]+)\.([^.]*)$/
      # Numeric(0xFFFF)
      receiver = $1
      message = Regexp.quote($2)
      begin
        candidates = eval(receiver, bind).methods.collect{|m| m.to_s}
      rescue RescuableException
        candidates = []
      end
      select_message(receiver, message, candidates)
    when /^(\$[^.]*)$/
      regmessage = Regexp.new(Regexp.quote($1))
      candidates = global_variables.collect{|m| m.to_s}.grep(regmessage)
    when /^([^."].*)\.([^.]*)$/
      # variable
      receiver = $1
      message = Regexp.quote($2)
      gv = eval("global_variables", bind).collect{|m| m.to_s}
      lv = eval("local_variables", bind).collect{|m| m.to_s}
      cv = eval("self.class.constants", bind).collect{|m| m.to_s}
      if (gv | lv | cv).include?(receiver) or /^[A-Z]/ =~ receiver && /\./ !~ receiver
        # foo.func and foo is local var. OR
        # Foo::Bar.func
        begin
          candidates = eval("#{receiver}.methods", bind).collect{|m| m.to_s}
        rescue RescuableException
          candidates = []
        end
      else
        # func1.func2
        candidates = []
        ObjectSpace.each_object(Module){|m|
          begin
            name = m.name.to_s
          rescue RescuableException
            name = ""
          end
          next if name != "IRB::Context" and
          /^(IRB|SLex|RubyLex|RubyToken)/ =~ name
          candidates.concat m.instance_methods(false).collect{|x| x.to_s}
        }
        candidates.sort!
        candidates.uniq!
      end
      select_message(receiver, message, candidates)
    when /^\.([^.]*)$/
      # unknown(maybe String)
      receiver = ""
      message = Regexp.quote($1)
      candidates = String.instance_methods(true).collect{|m| m.to_s}
      select_message(receiver, message, candidates)
    else
      candidates = eval("methods | private_methods | local_variables | self.class.constants", bind).collect{|m| m.to_s}
      (candidates|ReservedWords|commands).grep(/^#{Regexp.quote(input)}/)
    end
  end
end

def self.select_message(receiver, message, candidates)
  candidates.grep(/^#{message}/).collect do |e|
  	case e
  	when /^[a-zA-Z_]/
  	  receiver + "." + e
  	when /^[0-9]/
  	when *Operators
  	  #receiver + " " + e
  	end
  end
end