DEV: move discourse_dev gem to the core. (#13360)

And get avatar images from `discourse_dev_assets` gem.

lib/faker/discourse_markdown.rb

@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+require 'faker'
+require 'net/http'
+require 'json'
+
+module Faker
+  class DiscourseMarkdown < Markdown
+    class << self
+      attr_writer(:user_id)
+
+      def user_id
+        @user_id || ::Discourse::SYSTEM_USER_ID
+      end
+
+      def with_user(user_id)
+        current_user_id = self.user_id
+        self.user_id = user_id
+        begin
+          yield
+        ensure
+          self.user_id = current_user_id
+        end
+      end
+
+      def image
+        image = next_image
+        image_file = load_image(image)
+
+        upload = ::UploadCreator.new(
+          image_file,
+          image[:filename],
+          origin: image[:url]
+        ).create_for(user_id)
+
+        ::UploadMarkdown.new(upload).to_markdown if upload.present? && upload.persisted?
+      rescue => e
+        STDERR.puts e
+        STDERR.puts e.backtrace.join("\n")
+      end
+
+      private
+
+      def next_image
+        if @images.blank?
+          if @stop_loading_images
+            @images = @all_images.dup
+          else
+            @next_page = (@next_page || 0) + 1
+            url = URI("https://picsum.photos/v2/list?page=#{@next_page}&limit=50")
+            response = Net::HTTP.get(url)
+            json = JSON.parse(response)
+
+            if json.blank?
+              @stop_loading_images = true
+              @images = @all_images.dup
+            else
+              @images = json.sort_by { |image| image["id"] }
+              @all_images = (@all_images || []).concat(@images)
+            end
+          end
+        end
+
+        image = @images.pop
+        { filename: "#{image['id']}.jpg", url: "#{image['download_url']}.jpg" }
+      end
+
+      def image_cache_dir
+        @image_cache_dir ||= ::File.join(Rails.root, "tmp", "discourse_dev", "images")
+      end
+
+      def load_image(image)
+        cache_path = ::File.join(image_cache_dir, image[:filename])
+
+        if !::File.exists?(cache_path)
+          FileUtils.mkdir_p(image_cache_dir)
+          temp_file = ::FileHelper.download(
+            image[:url],
+            max_file_size: [SiteSetting.max_image_size_kb.kilobytes, 10.megabytes].max,
+            tmp_file_name: "image",
+            follow_redirect: true
+          )
+          FileUtils.cp(temp_file, cache_path)
+        end
+
+        ::File.open(cache_path)
+      end
+
+      def available_methods
+        methods = super
+        methods << :image if ::DiscourseDev.config.post[:include_images]
+        methods
+      end
+    end
+  end
+end