FEATURE: Embeddable Discourse comments, now with simple-rss instead of feedzirra

app/models/topic_embed.rb

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+require_dependency 'nokogiri'
+
+class TopicEmbed < ActiveRecord::Base
+  belongs_to :topic
+  belongs_to :post
+  validates_presence_of :embed_url
+  validates_presence_of :content_sha1
+
+  # Import an article from a source (RSS/Atom/Other)
+  def self.import(user, url, title, contents)
+    return unless url =~ /^https?\:\/\//
+
+    contents << "\n<hr>\n<small>#{I18n.t('embed.imported_from', link: "<a href='#{url}'>#{url}</a>")}</small>\n"
+
+    embed = TopicEmbed.where(embed_url: url).first
+    content_sha1 = Digest::SHA1.hexdigest(contents)
+    post = nil
+
+    # If there is no embed, create a topic, post and the embed.
+    if embed.blank?
+      Topic.transaction do
+        creator = PostCreator.new(user, title: title, raw: absolutize_urls(url, contents), skip_validations: true, cook_method: Post.cook_methods[:raw_html])
+        post = creator.create
+        if post.present?
+          TopicEmbed.create!(topic_id: post.topic_id,
+                             embed_url: url,
+                             content_sha1: content_sha1,
+                             post_id: post.id)
+        end
+      end
+    else
+      post = embed.post
+      # Update the topic if it changed
+      if content_sha1 != embed.content_sha1
+        revisor = PostRevisor.new(post)
+        revisor.revise!(user, absolutize_urls(url, contents), skip_validations: true, bypass_rate_limiter: true)
+        embed.update_column(:content_sha1, content_sha1)
+      end
+    end
+
+    post
+  end
+
+  def self.import_remote(user, url, opts=nil)
+    require 'ruby-readability'
+
+    opts = opts || {}
+    doc = Readability::Document.new(open(url).read,
+                                        tags: %w[div p code pre h1 h2 h3 b em i strong a img],
+                                        attributes: %w[href src])
+
+    TopicEmbed.import(user, url, opts[:title] || doc.title, doc.content)
+  end
+
+  # Convert any relative URLs to absolute. RSS is annoying for this.
+  def self.absolutize_urls(url, contents)
+    uri = URI(url)
+    prefix = "#{uri.scheme}://#{uri.host}"
+    prefix << ":#{uri.port}" if uri.port != 80 && uri.port != 443
+
+    fragment = Nokogiri::HTML.fragment(contents)
+    fragment.css('a').each do |a|
+      href = a['href']
+      if href.present? && href.start_with?('/')
+        a['href'] = "#{prefix}/#{href.sub(/^\/+/, '')}"
+      end
+    end
+    fragment.css('img').each do |a|
+      src = a['src']
+      if src.present? && src.start_with?('/')
+        a['src'] = "#{prefix}/#{src.sub(/^\/+/, '')}"
+      end
+    end
+
+    fragment.to_html
+  end
+
+  def self.topic_id_for_embed(embed_url)
+    TopicEmbed.where(embed_url: embed_url).pluck(:topic_id).first
+  end
+
+end