module Antlr4::Runtime

  class LexerActionExecutor
    attr_reader :lexer_actions
    attr_reader :hash_code

    def initialize(lexer_actions)
      @lexer_actions = lexer_actions
      @hash_code = MurmurHash.hash_objs(lexer_actions)
    end

    def self.append(lexer_action_executor, lexer_action)
      return LexerActionExecutor.new([lexer_action]) if lexer_action_executor.nil?

      lexer_actions = lexer_action_executor.lexer_actions.dup
      lexer_actions << lexer_action
      LexerActionExecutor.new(lexer_actions)
    end

    def fix_offset_before_match(offset)
      updated_lexer_actions = nil
      i = 0
      while i < @lexer_actions.length
        if @lexer_actions[i].position_dependent? && !(@lexer_actions[i].is_a? LexerIndexedCustomAction)
          updated_lexer_actions = @lexer_actions.dup if updated_lexer_actions.nil?

          updated_lexer_actions[i] = LexerIndexedCustomAction.new(offset, @lexer_actions[i])
        end
        i += 1
      end

      return self if updated_lexer_actions.nil?

      LexerActionExecutor.new(updated_lexer_actions)
    end

    def execute(lexer, input, start_index)
      requires_seek = false
      stop_index = input.index
      begin
        i = 0
        while i < @lexer_actions.length
          lexerAction = @lexer_actions[i]
          if lexerAction.is_a? LexerIndexedCustomAction
            offset = lexerAction.getOffset
            input.seek(start_index + offset)
            requires_seek = ((start_index + offset) != stop_index)
          else
            if lexerAction.position_dependent?
              input.seek(stop_index)
              requires_seek = false
            end

            lexerAction.execute(lexer)
          end
          i += 1
        end
      ensure
        input.seek(stop_index) if requires_seek
      end
    end

    def eql?(obj)
      if obj == self
        return true
      else
        return false unless obj.is_a? LexerActionExecutor
      end

      @hash_code == obj.hash_code && (@lexer_actions == obj._a)
    end
  end
end