##
## $Release:$
## $Copyright$
##


require 'erubis/generator'
require 'erubis/converter'
require 'erubis/evaluator'
require 'erubis/context'


module Erubis


  ##
  ## (abstract) abstract engine class.
  ## subclass must include evaluator and converter module.
  ##
  class Engine
    #include Evaluator
    #include Converter
    #include Generator

    def initialize(input=nil, properties={})
      #@input = input
      init_generator(properties)
      init_converter(properties)
      init_evaluator(properties)
      @src    = convert(input) if input
    end


    ##
    ## convert input string and set it to @src
    ##
    def convert!(input)
      @src = convert(input)
    end


    ##
    ## load file, write cache file, and return engine object.
    ## this method create code cache file automatically.
    ## cachefile name can be specified with properties[:cachename],
    ## or filname + 'cache' is used as default.
    ##
    def self.load_file(filename, properties={})
      cachename = properties[:cachename] || (filename + '.cache')
      properties[:filename] = filename
      if test(?f, cachename) && File.mtime(filename) <= File.mtime(cachename)
        engine = self.new(nil, properties)
        engine.src = File.read(cachename)
      else
        input = File.open(filename, 'rb') {|f| f.read }
        engine = self.new(input, properties)
        File.open(cachename, 'wb') do |f|
          f.flock(File::LOCK_EX)
          f.write(engine.src)
          f.flush()
        end
      end
      engine.src.untaint   # ok?
      return engine
    end


    ##
    ## helper method to convert and evaluate input text with context object.
    ## context may be Binding, Hash, or Object.
    ##
    def process(input, context=nil, filename=nil)
      code = convert(input)
      filename ||= '(erubis)'
      if context.is_a?(Binding)
        return eval(code, context, filename)
      else
        context = Context.new(context) if context.is_a?(Hash)
        return context.instance_eval(code, filename)
      end
    end


    ##
    ## helper method evaluate Proc object with contect object.
    ## context may be Binding, Hash, or Object.
    ##
    def process_proc(proc_obj, context=nil, filename=nil)
      if context.is_a?(Binding)
        filename ||= '(erubis)'
        return eval(proc_obj, context, filename)
      else
        context = Context.new(context) if context.is_a?(Hash)
        return context.instance_eval(&proc_obj)
      end
    end


  end  # end of class Engine


  ##
  ## (abstract) base engine class for Eruby, Eperl, Ejava, and so on.
  ## subclass must include generator.
  ##
  class Basic::Engine < Engine
    include Evaluator
    include Basic::Converter
    include Generator
  end


  class PI::Engine < Engine
    include Evaluator
    include PI::Converter
    include Generator
  end


end