add ArtifactDownloader for artifact images

downloads square (s) and wide (m) sizes from game CDN

lib/granblue/downloaders/artifact_downloader.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+module Granblue
+  module Downloaders
+    # Downloads artifact image assets from the game server in different sizes.
+    # Artifacts have two sizes: square (s) and wide/medium (m).
+    #
+    # @example Download images for a specific artifact
+    #   downloader = ArtifactDownloader.new("301010101", storage: :both)
+    #   downloader.download
+    #
+    # @note Artifacts don't have variants like characters/weapons - just two sizes
+    class ArtifactDownloader < BaseDownloader
+      # Artifact images come in two sizes: square and wide
+      SIZES = %w[square wide].freeze
+
+      # Downloads images for an artifact
+      #
+      # @param selected_size [String] The size to download. If nil, downloads all sizes.
+      # @return [void]
+      # @note Skips download if artifact is not found in database
+      def download(selected_size = nil)
+        artifact = Artifact.find_by(granblue_id: @id)
+        return unless artifact
+
+        log_info("-> #{@id}") if @verbose
+        return if @test_mode
+
+        sizes = selected_size ? [selected_size] : SIZES
+
+        sizes.each_with_index do |size, index|
+          path = download_path(size)
+          url = build_url(size)
+          process_download(url, size, path, last: index == sizes.size - 1)
+        end
+      end
+
+      private
+
+      # Gets object type for file paths and storage keys
+      # @return [String] Returns "artifact"
+      def object_type
+        'artifact'
+      end
+
+      # Gets base URL for artifact assets
+      # @return [String] Base URL for artifact images
+      def base_url
+        'https://prd-game-a1-granbluefantasy.akamaized.net/assets_en/img/sp/assets/artifact'
+      end
+
+      # Gets directory name for a size variant
+      #
+      # @param size [String] Image size variant
+      # @return [String] Directory name in game asset URL structure
+      # @note Maps "square" -> "s", "wide" -> "m"
+      def directory_for_size(size)
+        case size.to_s
+        when 'square' then 's'
+        when 'wide' then 'm'
+        end
+      end
+
+      # Build complete URL for a size variant
+      # @param size [String] Image size variant
+      # @return [String] Complete download URL
+      def build_url(size)
+        directory = directory_for_size(size)
+        "#{base_url}/#{directory}/#{@id}.jpg"
+      end
+    end
+  end
+end