require 'nokogiri'
require 'ostruct'

module Anemone
  class Page

    # The URL of the page
    attr_reader :url
    # The raw HTTP response body of the page
    attr_reader :body
    # Headers of the HTTP response
    attr_reader :headers
    # URL of the page this one redirected to, if any
    attr_reader :redirect_to
    # Exception object, if one was raised during HTTP#fetch_page
    attr_reader :error
    # HTML body
    attr_reader :body

    # OpenStruct for user-stored data
    attr_accessor :data
    # Integer response code of the page
    attr_accessor :code
    # Boolean indicating whether or not this page has been visited in PageStore#shortest_paths!
    attr_accessor :visited
    # Depth of this page from the root of the crawl. This is not necessarily the
    # shortest path; use PageStore#shortest_paths! to find that value.
    attr_accessor :depth
    # URL of the page that brought us to this page
    attr_accessor :referer
    # Response time of the request for this page in milliseconds
    attr_accessor :response_time

    #
    # Create a new page
    #
    def initialize(url, params = {})
      @url = url
      @data = OpenStruct.new

      @code = params[:code]
      @headers = params[:headers] || {}
      @headers['content-type'] ||= ['']
      @aliases = Array(params[:aka]).compact
      @referer = params[:referer]
      @depth = params[:depth] || 0
      @redirect_to = to_absolute(params[:redirect_to])
      @response_time = params[:response_time]
      @body = params[:body]
      @error = params[:error]

      @fetched = !params[:code].nil?
    end

    #
    # Array of distinct A tag HREFs from the page
    #
    def links
      return @links unless @links.nil?
      @links = []
      return @links if !doc

      doc.css('a').each do |a|
        u = a.attributes['href'].content rescue nil
        next if u.nil? or u.empty?
        abs = to_absolute(URI(u)) rescue next
        @links << abs if in_domain?(abs)
      end
      @links.uniq!
      @links
    end

    #
    # Nokogiri document for the HTML body
    #
    def doc
      return @doc if @doc
      @doc = Nokogiri::HTML(@body) if @body && html? rescue nil
    end

    #
    # Delete the Nokogiri document and response body to conserve memory
    #
    def discard_doc!
      links # force parsing of page links before we trash the document
      @doc = @body = nil
    end

    #
    # Was the page successfully fetched?
    # +true+ if the page was fetched with no error, +false+ otherwise.
    #
    def fetched?
      @fetched
    end

    #
    # The content-type returned by the HTTP request for this page
    #
    def content_type
      headers['content-type'].first
    end

    #
    # Returns +true+ if the page is a HTML document, returns +false+
    # otherwise.
    #
    def html?
      !!(content_type =~ %r{^(text/html|application/xhtml+xml)\b})
    end

    #
    # Returns +true+ if the page is a HTTP redirect, returns +false+
    # otherwise.
    #
    def redirect?
      (300..399).include?(@code)
    end

    #
    # Returns +true+ if the page was not found (returned 404 code),
    # returns +false+ otherwise.
    #
    def not_found?
      404 == @code
    end

    #
    # Converts relative URL *link* into an absolute URL based on the
    # location of the page
    #
    def to_absolute(link)
      return nil if link.nil?

      # remove anchor
      link = URI.encode(link.to_s.gsub(/#[a-zA-Z0-9_-]*$/,''))

      relative = URI(link)
      absolute = @url.merge(relative)

      absolute.path = '/' if absolute.path.empty?

      return absolute
    end

    #
    # Returns +true+ if *uri* is in the same domain as the page, returns
    # +false+ otherwise
    #
    def in_domain?(uri)
      uri.host == @url.host
    end

    def marshal_dump
      [@url, @headers, @data, @body, @links, @code, @visited, @depth, @referer, @redirect_to, @response_time, @fetched]
    end

    def marshal_load(ary)
      @url, @headers, @data, @body, @links, @code, @visited, @depth, @referer, @redirect_to, @response_time, @fetched = ary
    end

  end
end