#
# nysagallery class/function library
# Part of nysagallery
#
# Copyright (c) 2006, 2007 Stephen Williams, all rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. The name of the copyright holder may not be used to endorse or
#    promote products derived from this software without specific prior
#    written permission.
#
# THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
# WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY DIRECT,
# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#

require 'date'
require 'rexml/document'

module GalleryLib

  RCS_ID = "$Id: gallery_lib.rb,v 1.6 2007/01/02 14:23:38 stephen Exp $"

  URL_BASE = "/gallery/"


  # Exception with HTTP status code
  class NysaGalleryException < Exception

    attr_reader :status

    def initialize(msg, status)
      super(msg)
      @status = status
    end
  end


  # Produces HTML formatting of a picture:
  #
  # *Title* (dimensions)
  # /Added: date/
  #
  # Description
  #
  # "added" and "description" are omitted if absent
  def GalleryLib.format_picture(gallery, section, picture)
    url = format_url(gallery, section, picture)

    heading = "<p><strong><a href='#{url}'>#{picture.title}</a></strong>"
    heading << " (#{picture.width}&nbsp;x&nbsp;#{picture.height})"
    heading << "<br><em>Added: #{picture.added}</em>" if picture.added
    heading << "</p>"

    picture.description ? "#{heading}<p>#{picture.description}</p>" : heading
  end


  # Produces HTML formatting of a thumbnail, linking to its
  # picture or to the supplied URL
  def GalleryLib.format_thumbnail(gallery, section, picture,
                                  alt_text = picture.title,
                                  url = nil)
    gdir = gallery.directory ? gallery.directory + "/" : ""
    sdir = section.directory ? section.directory + "/" : ""
    url = format_url(gallery, section, picture) unless url
    alt_text = CGI::escapeHTML(alt_text)

    <<END
<a href='#{url}'><img
     src='#{Picture::THUMBNAIL_URL_BASE}#{gdir}#{sdir}#{picture.thumbnail_filename}'
     width='#{picture.thumbnail_width}'
     height='#{picture.thumbnail_height}'
     title="#{alt_text}" alt="#{alt_text}"></a>
END
  end


  # Constructs a picture URL, including gallery and section
  # directories if defined, suitable for use in an <img>
  # element
  def GalleryLib.format_imgsrc_url(gallery, section, picture)
    gdir = gallery.directory ? gallery.directory + "/" : ""
    sdir = section.directory ? section.directory + "/" : ""

    "#{Picture::RAW_URL_BASE}#{gdir}#{sdir}#{picture.filename}." +
      "#{picture.format}"
  end


  # Constructs a picture URL, including gallery and section
  # directories if defined.
  #
  # Picture URLs are of the form:
  # URL_BASE/gallery_name,section_name,picture_filename
  # so the web server needs to rewrite incoming requests thusly:
  # URL_BASE/gallery_picture.rbx?gallery=gallery_name&section=section_name& \
  #   picture=picture_filename
  def GalleryLib.format_url(gallery, section, picture)
    "#{URL_BASE}#{gallery.name},#{section.name},#{picture.filename}"
  end


  # Mangle RCS ID string to include linked filename
  def GalleryLib.rcs_mangle(rcsid)

    rcsmatch = /^(.Id: )([^,]*)(,v.*)$/.match(rcsid)
    if rcsmatch
      filename = rcsmatch[2]
      filename2 = filename.tr('.', '_') + '.txt'
      "#{rcsmatch[1]}<a href='#{URL_BASE}#{filename2}'>#{filename}</a>#{rcsmatch[3]}"
    else
      rcsid
    end
  end


  # Hash subclass that preserves insertion order
  class OHash < Hash

    attr_reader :keys

    def initialize
      super
      @keys = []
    end

    def []=(k, v)
      super(k, v)
      @keys.delete(k) if @keys.include?(k)
      @keys << k
    end

    def delete(k)
      @keys.delete(k) if @keys.include?(k)
      super(k)
    end

    def each_key
      @keys.each do |key|
        yield key
      end
    end

    def each
      @keys.each do |key|
        yield [key, self[key]]
      end
    end

    def each_value
      @keys.each do |key|
        yield self[key]
      end
    end

    def store(k, v)
      self[k] = v
    end
  end


  # Encapsulation of a gallery picture
  class Picture

    public

    # Constants
    RAW_URL_BASE = "http://nysa.cx/img/"
    THUMBNAIL_URL_BASE = RAW_URL_BASE
    URL_BASE = "http://nysa.cx/localimg,"


    attr_reader :added, :description, :filename, :format, :height,
                :thumbnail_filename, :thumbnail_height, :thumbnail_width,
                :title, :width
    

    # Constructor
    def initialize(node)
      parse(node)
    end


    private

    # Constants
    DEFAULT_FORMAT = "jpg"
    DEFAULT_WIDTH = 640
    DEFAULT_HEIGHT = 427
    THUMBNAIL_WIDTH = 80
    THUMBNAIL_HEIGHT = 53


    def die(status, message)
      raise NysaGalleryException.new(message, status)
    end


    # Parses picture information from an XML node
    def parse(node)

      @title = node.attributes["title"]
      die("SERVER_ERROR", "Picture has no title") unless @title

      @filename = node.attributes["filename"]
      die("SERVER_ERROR", "Picture has no filename") unless @filename
      @thumbnail_filename = @filename + ".jpg"
      i = @thumbnail_filename.rindex('/')
      if i
        @thumbnail_filename.insert(i + 1, "thumb_")
      else
        @thumbnail_filename.insert(0, "thumb_")
      end

      element = node.elements["added"]
      if element
        @added = element.text
        begin
          @added = Date.parse(@added)
        rescue
          die("SERVER_ERROR", "Bad picture date: #{@added}")
        end
      end
      
      attr = node.attributes["height"]
      @height = attr ? attr.to_i : DEFAULT_HEIGHT
      attr = node.attributes["width"]
      @width = attr ? attr.to_i : DEFAULT_WIDTH
      if @width >= @height
        @thumbnail_height = THUMBNAIL_HEIGHT
        @thumbnail_width = THUMBNAIL_WIDTH
      else
        @thumbnail_height = THUMBNAIL_WIDTH
        @thumbnail_width = THUMBNAIL_HEIGHT
      end

      attr = node.attributes["format"]
      @format = attr ? attr : DEFAULT_FORMAT

      element = node.elements["desc"]
      @description = element.text if element
    end
  end


  # Encapsulation of a gallery section
  class Section

    attr_reader :description, :directory, :name, :pictures, :title

    public

    # Constructor
    def initialize(node)
      @node = node
      parse(node)
    end


    # Picks a random picture from the section
    def random_picture
      elements = @node.get_elements("picture")
      Picture.new(elements[rand(elements.size)])
    end


    private

    def die(status, message)
      raise NysaGalleryException.new(message, status)
    end


    # Parses section information from an XML node
    def parse(node)
      @name = node.attributes["name"]
      die("SERVER_ERROR", "No section name") unless @name

      @title = node.attributes["title"]
      die("SERVER_ERROR", "No section title") unless @title

      element = node.elements["desc"]
      @description = element.text if element

      element = node.elements["directory"]
      @directory = element.text if element

      @pictures = []
      node.elements.each("picture") do |pic_element|
        picture = Picture.new(pic_element)
        @pictures << picture
      end
    end
    
  end


  # Encapsulation of a complete gallery
  class Gallery

    public

    attr_reader :title, :created, :description, :directory, :name, :sections

    # Constructor
    def initialize(filename)
      die("NOT_FOUND", "No such gallery") unless File.exists?(filename)
      @name = /^(.*)\.xml$/.match(filename)[1]
      File.open(filename) do |file|
        @doc = REXML::Document.new(file)
      end
      @updated = nil
      parse_basic
    end


    # Parses complete information about the gallery
    def parse_sections
      @sections = OHash.new
      @doc.elements.each("gallery/section") do |sec_element|
        section = Section.new(sec_element)
        @sections[section.name] = section
      end
    end


    # The number of pictures in the gallery
    def picture_count
      @doc.get_elements("gallery/section/picture").size
    end


    # Returns a random section from the gallery
    def random_section
      sections = @doc.get_elements("gallery/section")
      Section.new(sections[rand(sections.size)])
    end


    # The date when the gallery was updated
    def updated
      unless @updated
        @updated = @created
        @doc.get_elements("gallery/section/picture/added").each do |element|
          added = element.text
          begin
            added = Date.parse(added)
          rescue
            die("SERVER_ERROR", "Bad picture date: #{added}")
          end
          @updated = added if added > @updated
        end
      end
      @updated
    end


    private

    def die(status, message)
      raise NysaGalleryException.new(message, status)
    end

    # Parses basic information about the gallery
    def parse_basic
      gal_element = @doc.elements["gallery"]
      die("SERVER_ERROR", "Invalid gallery") unless gal_element

      @title = gal_element.attributes["title"]
      die("SERVER_ERROR", "Gallery has no title") unless @title

      die("SERVER_ERROR", "Gallery has no sections") unless
        gal_element.elements["section"]

      element = gal_element.elements["created"]
      @created = element.text if element
      die("SERVER_ERROR", "Gallery has no creation date") unless @created
      begin
        @created = Date.parse(@created)
      rescue
        die("SERVER_ERROR", "Bad gallery date: #{@created}")
      end

      element = gal_element.elements["desc"]
      @description = element.text if element

      element = gal_element.elements["directory"]
      @directory = element.text if element
    end

  end
end