module Trepan
  # Mix-in module to assist in command parsing.
  module FrameFunctions # :nodoc:
    def adjust_frame(frame_pos, absolute, context=@state.context)
      @state.frame_pos = 0 if context != @state.context
      if absolute
        if frame_pos < 0
          abs_frame_pos = context.stack_size + frame_pos
        else
          abs_frame_pos = frame_pos
        end
      else
        abs_frame_pos = @state.frame_pos + frame_pos
      end

      if abs_frame_pos >= context.stack_size then
        errmsg "Adjusting would put us beyond the oldest (initial) frame.\n"
        return
      elsif abs_frame_pos < 0 then
        errmsg "Adjusting would put us beyond the newest (innermost) frame.\n"
        return
      end
      if @state.frame_pos != abs_frame_pos then
        @state.previous_line = nil
        @state.frame_pos = abs_frame_pos
      end
      
      @state.file = context.frame_file(@state.frame_pos)
      @state.line = context.frame_line(@state.frame_pos)
      
      print_frame(@state.frame_pos, true)
    end
    
    def get_frame_call(prefix, pos, context)
      id = context.frame_method(pos)
      klass = context.frame_class(pos)
      call_str = ""
      if id
        args = context.frame_args(pos)
        locals = context.frame_locals(pos)
        if OldCommand.settings[:callstyle] != :short && klass
          if OldCommand.settings[:callstyle] == :tracked
            arg_info = context.frame_args_info(pos)
          end
          call_str << "#{klass}." 
        end
        call_str << id.id2name
        if args.any?
          call_str << "("
          args.each_with_index do |name, i|
            case OldCommand.settings[:callstyle] 
            when :short
              call_str += "%s, " % [name]
            when :last
              klass = locals[name].class
              if klass.inspect.size > 20+3
                klass = klass.inspect[0..20]+"..." 
              end
              call_str += "%s#%s, " % [name, klass]
            when :tracked
              if arg_info && arg_info.size > i
                call_str += "#{name}: #{arg_info[i].inspect}, "
              else
                call_str += "%s, " % name
              end
            end
            if call_str.size > self.class.settings[:width] - prefix.size
              # Strip off trailing ', ' if any but add stuff for later trunc
              call_str[-2..-1] = ",...XX"
              break
            end
          end
          call_str[-2..-1] = ")" # Strip off trailing ', ' if any 
        end
      end
      return call_str
    end

    def print_frame(pos, adjust = false, context=@state.context)
      file = context.frame_file(pos)
      line = context.frame_line(pos)
      klass = context.frame_class(pos)

      unless OldCommand.settings[:full_path]
        path_components = file.split(/[\\\/]/)
        if path_components.size > 3
          path_components[0...-3] = '...'
          file = path_components.join(File::ALT_SEPARATOR || File::SEPARATOR)
        end
      end

      frame_num = "#%d " % pos
      call_str = get_frame_call(frame_num, pos, context)
      file_line = "at line %s:%d\n" % [CommandProcessor.canonic_file(file), line]
      print frame_num
      unless call_str.empty?
        print call_str
        print ' '
        if call_str.size + frame_num.size + file_line.size > self.class.settings[:width]
          print "\n       "
        end
      end
      print file_line
      if Trepan.inside_emacs? && adjust
        fmt = (Trepan.annotate.to_i > 1 ?
               "\032\032source %s:%d\n" : "\032\032%s:%d\n")
        print fmt % [CommandProcessor.canonic_file(file), line]
      end
    end

    # Check if call stack is truncated.  This can happen if
    # Trepan.start is not called low enough in the call stack. An
    # array of additional callstack lines from caller is returned if
    # definitely truncated, false if not, and nil if we don't know.
    #
    # We determine truncation based on a passed in sentinal set via
    # caller which can be nil.  
    #
    # First we see if we can find our position in caller. If so, then
    # we compare context position to that in caller using sentinal
    # as a place to start ignoring additional caller entries. sentinal
    # is set by rdebug, but if it's not set, i.e. nil then additional
    # entries are presumably ones that we haven't recorded in context
    def truncated_callstack?(context, sentinal=nil, cs=caller)
      recorded_size = context.stack_size
      to_find_fl = "#{context.frame_file(0)}:#{context.frame_line(0)}"
      top_discard = false
      cs.each_with_index do |fl, i|
        fl.gsub!(/in `.*'$/, '')
        fl.gsub!(/:$/, '')
        if fl == to_find_fl
          top_discard = i
          break 
        end
      end
      if top_discard
        cs = cs[top_discard..-1]
        return false unless cs
        return cs unless sentinal
        if cs.size > recorded_size+2 && cs[recorded_size+2] != sentinal 
          # caller seems to truncate recursive calls and we don't.
          # See if we can find sentinal in the first 0..recorded_size+1 entries
          return false if cs[0..recorded_size+1].any?{ |f| f==sentinal }
          return cs
        end
        return false
      end
      return nil
    end


  end

  # Implements debugger "where" or "backtrace" command.
  class OldWhereCommand < OldCommand
    def regexp
      /^\s*(?:old\-where)$/
    end

    def execute
      (0...@state.context.stack_size).each do |idx|
        if idx == @state.frame_pos
          print "--> "
        else
          print "    "
        end
        print_frame(idx)

      end
      if truncated_callstack?(@state.context, Trepan.start_sentinal)
        print "Warning: saved frames may be incomplete;\n"
        print "compare debugger backtrace (bt) with Ruby caller(0).\n" 
      end
    end

    class << self
      def help_command
        %w|oldwhere|
      end

      def help(cmd)
        s = if cmd == 'oldwhere'
          %{
            w[here]\tdisplay stack frames
            }
            else
          %{
            bt|backtrace\t\talias for where - display stack frames
         }
            end
        s += %{
Print the entire stack frame. Each frame is numbered, the most recent
frame is 0. frame number can be referred to in the "frame" command;
"up" and "down" add or subtract respectively to frame numbers shown.
The position of the current frame is marked with -->.  } 
      end 
    end
  end
end