require 'cgi'

module Plate
  # Various view helpers related to blogging. Tags, categories, archives and the like.
  module BloggingHelper
    # Returns a customized hash of post archives for the given category
    def category_archives(category)
      result = {}

      posts.archives.keys.each do |year|
        posts.archives[year].keys.each do |month|
          posts.archives[year][month].keys.each do |day|
            posts.archives[year][month][day].each do |post|
              if post.category == category
                result[year] ||= {}
                result[year][month] ||= {}
                result[year][month][day] ||= []
                result[year][month][day] << post
              end
            end
          end
        end
      end

      result
    end

    # Escape markup for use in XML or HTML
    def html_escape(text)
      ::CGI.escapeHTML(text)
    end
    alias_method :xml_escape, :html_escape

    def month_name(year, month)
      Date.new(year.to_i, month.to_i, 1).strftime('%B %Y')
    end

    # Grab the next blog post.
    #
    # Returns nil if this is the last post.
    def next_post
      return nil if post_index < 0 or post_index >= post_count
      @next_post ||= self.posts[post_index + 1]
    end

    # Grab the post previous to this one.
    #
    # Returns nil if this is the first post.
    def previous_post
      return nil if post_index < 1
      @previous_post ||= self.posts[post_index - 1]
    end

    # The total number blog posts
    def post_count
      @post_count ||= self.posts.length
    end

    # Returns a number of where this post is in all posts
    def post_index
      @post_index ||= self.posts.index(self.post)
    end

    # Find all posts for the given category
    def posts_for_category(category)
      self.posts.select { |p| p.category == category }
    end

    # Find all posts for the given year, month and optional category.
    def posts_for_month(year, month, category = nil)
      result = []

      if months = self.posts.archives[year.to_s]
        if month = months[month.to_s]
          month.each_value do |day|
            result << day.select { |post| category == nil or post.category == category }
          end
        end
      end

      result.flatten
    end

    # Find all posts for the given year and optional category.
    def posts_for_year(year, category = nil)
      result = []

      if months = self.posts.archives[year.to_s]
        months.each_value do |month|
          month.each_value do |day|
            result << day.select { |post| category == nil or post.category == category }
          end
        end
      end

      result.flatten
    end

    def years_for_category(category)
      result = []

      self.posts.archives.keys.each do |year|
        if posts_for_year(year, category).size > 0
          result << year
        end
      end

      result.sort
    end
  end
end