module Rid
  module Makros
    # inject makros, that is:
    # replace makro with content from libs
    #
    def inject_makros!
      inject_makro! "code" do |filename|
        value = libs.at(filename)
        raise "code makro injection failed!\nNo lib available for %s" % filename unless value

        value
      end
      
      inject_makro! "json" do |filename|
        value = libs.at(filename)
        raise "json makro injection failed!\nNo lib available for %s" % filename unless value

        expand_json_makro filename, value
      end
    end

    # reject makros, that is:
    # replace makro generated content with makro
    #
    def reject_makros!
      return if injections.empty?

      injections.reverse.each do |inj|
        makro, target, lib, start, size = inj["makro"], inj["target"], inj["lib"], inj["start"], inj["size"] 

        value = hash.at(target)
        value[start, size] = "// !#{makro} #{lib}"
      end
    end


    private

    # provide access to lib hash
    #
    def libs
      hash["lib"] || {}
    end

    # provide access to injections array
    #
    def injections
      hash["injections"] || []
    end


    # builds a javascript variable assignment line for filename with value
    # 'var %s = %s;' % [filename.split(/[\.\/]/).join('_'), value.to_json]
    def expand_json_makro(filename, value)
      name = filename.sub(/\..*$/, '')
      parts = name.split('/')

      if parts.size > 1
        var = "var #{parts.first};"
        0.upto(parts.size - 2) do |i|
          v = parts[0..i].join('.')
          var << " if (!#{v}) #{v} = {};"
        end
        var << "\n"
        var << "#{parts.join('.')} = %s;"
      else
        var = "var #{name} = %s;"
      end
      
      var % value.to_json
    end

    # injects a makro and yields block with the filenames for found makros
    #
    def inject_makro!(makro, &block)
      hash.flatten.each do |key, value|
        next unless value.is_a?(String)

        # do not try to inject makros in attachments, libs and injections array
        next if key =~ /^_attachments|libs|injections/

        new_value = value.gsub(/\/\/\s*!#{makro}\s+[\S]+$/) do |match|
          start = Regexp.last_match.begin(0)
          filename = match.sub(/^.*!#{makro}\s*(\S+).*$/, '\1')

          value = block.call(filename)

          store_injection makro, key, filename, start, value.size

          value
        end

        self.hash.update_at key, new_value
      end
    end

    # Store injection values in injections array
    #
    def store_injection(makro, target, lib, start, size)
      hash["injections"] ||= []
      hash["injections"] << {
        "makro"  => makro,
        "target" => target,
        "lib"    => lib,
        "start" => start,
        "size" => size
      }
    end
  end
end