require "hache"

class Mote
  PATTERN = /^(\n)|^\s*(%)\s*(.*?)(?:\n|\Z)|(<\?)\s+(.*?)\s+\?>|(\{\{>?)(.*?)\}\}/m

  def self.parse(template, context = self, vars = [])
    terms = template.split(PATTERN)

    parts = "Proc.new do |params, __o|\n params ||= {}; __o ||= ''\n"

    vars.each do |var|
      parts << "%s = params[%s]\n" % [var, var.inspect]
    end

    while term = terms.shift
      case term
      when "<?"  then parts << "#{terms.shift}\n"
      when "%"   then parts << "#{terms.shift}\n"
      when "{{"  then parts << "__o << Hache.h((#{terms.shift}).to_s)\n"
      when "{{>" then parts << "__o << (#{terms.shift}).to_s\n"
      else            parts << "__o << #{term.dump}\n"
      end
    end

    parts << "__o; end"

    compile(context, parts)
  end

  def self.compile(context, parts)
    context.instance_eval(parts)
  end

  module Helpers
    def mote(file, params = {}, context = self)
      mote_cache[file] ||= Mote.parse(File.read(file), context, params.keys)
      mote_cache[file][params]
    end

    def mote_cache
      Thread.current[:_mote_cache] ||= {}
    end
  end
end