add artifact import from game data

- Add ArtifactImportService to parse game JSON and create collection artifacts
- Maps game skill_id to our (group, modifier) format using verified mapping
- Handles skill quality -> strength lookup via ArtifactSkill.base_values
- Supports duplicate detection via game_id, with optional update_existing flag
- Quirk artifacts get proficiency from game data; skills stored as empty
- Add POST /collection/artifacts/import endpoint
- Add game_id column to collection_artifacts, collection_weapons,
  collection_summons for tracking game inventory instance IDs

app/controllers/api/v1/collection_artifacts_controller.rb

@@ -9,7 +9,7 @@ module Api
       before_action :set_collection_artifact_for_read, only: %i[show]
 
       # Write actions: require auth, use current_user
-      before_action :restrict_access, only: %i[create update destroy batch]
+      before_action :restrict_access, only: %i[create update destroy batch import]
       before_action :set_collection_artifact_for_write, only: %i[update destroy]
 
       def index
@@ -95,6 +95,37 @@ module Api
         ), status: status
       end
 
+      # POST /collection/artifacts/import
+      # Imports artifacts from game JSON data
+      #
+      # @param data [Hash] Game data containing artifact list
+      # @param update_existing [Boolean] Whether to update existing artifacts (default: false)
+      def import
+        game_data = import_params[:data]
+
+        unless game_data.present?
+          return render json: { error: 'No data provided' }, status: :bad_request
+        end
+
+        service = ArtifactImportService.new(
+          current_user,
+          game_data,
+          update_existing: import_params[:update_existing] == true
+        )
+
+        result = service.import
+
+        status = result.success? ? :created : :multi_status
+
+        render json: {
+          success: result.success?,
+          created: result.created.size,
+          updated: result.updated.size,
+          skipped: result.skipped.size,
+          errors: result.errors
+        }, status: status
+      end
+
       private
 
       def set_target_user
@@ -142,6 +173,10 @@ module Api
           { skill4: %i[modifier strength level] }
         ])
       end
+
+      def import_params
+        params.permit(:update_existing, data: {})
+      end
     end
   end
 end

app/services/artifact_import_service.rb

@@ -0,0 +1,275 @@
+# frozen_string_literal: true
+
+##
+# Service for importing artifacts from game JSON data.
+# Parses the game's skill_id format and converts to our (group, modifier) format.
+#
+# @example Import artifacts for a user
+#   service = ArtifactImportService.new(user, game_data)
+#   result = service.import
+#   if result.success?
+#     puts "Imported #{result.created_count} artifacts"
+#   end
+#
+class ArtifactImportService
+  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, keyword_init: true)
+
+  # Mapping from game skill base ID (skill_id / 10) to [group, modifier]
+  # Built from analyzing game data samples and verified against artifact_skills.json
+  GAME_SKILL_MAPPING = {
+    # === GROUP I (Lines 1-2) ===
+    1001 => [1, 1],   # ATK
+    2001 => [1, 2],   # HP
+    3001 => [1, 6],   # Critical Hit Rate
+    3002 => [1, 3],   # C.A. DMG
+    3003 => [1, 4],   # Skill DMG
+    3004 => [1, 13],  # Debuff Success Rate
+    3005 => [1, 7],   # Double Attack Rate
+    3006 => [1, 8],   # Triple Attack Rate
+    3007 => [1, 9],   # DEF
+    3008 => [1, 14],  # Debuff Resistance
+    3009 => [1, 11],  # Dodge Rate
+    3010 => [1, 12],  # Healing
+    3011 => [1, 5],   # Elemental ATK
+    3012 => [1, 10],  # Superior Element Reduction
+
+    # === GROUP II (Line 3) ===
+    3013 => [2, 1],   # N.A. DMG Cap
+    3014 => [2, 2],   # Skill DMG Cap
+    3015 => [2, 3],   # C.A. DMG Cap
+    3016 => [2, 9],   # Supplemental N.A. DMG
+    3017 => [2, 10],  # Supplemental Skill DMG
+    3018 => [2, 11],  # Supplemental C.A. DMG
+    3019 => [2, 4],   # Special C.A. DMG Cap
+    3020 => [2, 6],   # N.A. DMG cap boost tradeoff
+    3021 => [2, 18],  # Turn-Based DMG Reduction
+    3022 => [2, 17],  # Regeneration
+    3023 => [2, 14],  # Amplify DMG at 100% HP
+    3024 => [2, 13],  # Boost TA at 50%+ HP
+    3025 => [2, 16],  # DMG reduction when at or below 50% HP
+    3026 => [2, 5],   # Boost DMG cap for critical hits
+    3027 => [2, 15],  # Max HP boost for a 70% hit to DEF
+    3028 => [2, 12],  # Chain DMG Amplify
+    3029 => [2, 7],   # Skill DMG cap boost tradeoff
+    3030 => [2, 8],   # C.A. DMG cap boost tradeoff
+    4000 => [2, 19],  # Chance to remove 1 debuff before attacking
+    4001 => [2, 20],  # Chance to cancel incoming dispels
+
+    # === GROUP III (Line 4) ===
+    3031 => [3, 28],  # Boost item drop rate
+    3032 => [3, 27],  # Boost EXP earned
+    5001 => [3, 2],   # At battle start: Gain x random buff(s)
+    5002 => [3, 8],   # Upon using a debuff skill: Amplify foe's DMG taken
+    5003 => [3, 9],   # Upon using a healing skill: Ally bonus
+    5004 => [3, 12],  # Cut linked skill cooldowns
+    5005 => [3, 10],  # Gain 1% DMG Cap Up (Stackable)
+    5006 => [3, 11],  # After using a skill with a cooldown of 10+ turns
+    5007 => [3, 22],  # Gain Supplemental Skill DMG (Stackable)
+    5008 => [3, 13],  # Gain Supplemental DMG based on charge bar spent
+    5009 => [3, 20],  # Gain Flurry (3-hit)
+    5010 => [3, 21],  # Plain DMG based on HP lost
+    5011 => [3, 23],  # Upon single attacks: Gain random buff
+    5012 => [3, 25],  # When foe has 3 or fewer debuffs: Armored
+    5013 => [3, 6],   # When foe HP at 50% or lower: Restore HP
+    5014 => [3, 26],  # When a sub ally: random debuff to foes
+    5015 => [3, 19],  # Gain 20% Bonus DMG after being targeted
+    5016 => [3, 14],  # At end of turn if didn't attack: Gain buff
+    5017 => [3, 24],  # Upon using potion: Boost FC bar
+    5018 => [3, 3],   # Start with 20% HP consumed / Cap Up
+    5019 => [3, 4],   # When knocked out: All allies gain buffs
+    5020 => [3, 5],   # When switching to main ally: Amplify DMG
+    5021 => [3, 1],   # At battle start: Gain DMG Mitigation
+    5022 => [3, 18],  # Chance to gain Flurry (6-hit)
+    5023 => [3, 17],  # At battle start and every 5 turns: Shield
+    5024 => [3, 16],  # Chance of turn progressing by 5
+    5025 => [3, 7],   # Upon first-slot skill: Cut CD
+    5026 => [3, 15],  # Chance to remove all buffs from foe
+    5029 => [3, 29]   # May find earrings
+  }.freeze
+
+  # Game element values to our element enum values
+  # Game: 1=Fire, 2=Water, 3=Earth, 4=Wind, 5=Light, 6=Dark
+  # Ours: wind=1, fire=2, water=3, earth=4, dark=5, light=6
+  ELEMENT_MAPPING = {
+    '1' => 2,  # Fire
+    '2' => 3,  # Water
+    '3' => 4,  # Earth
+    '4' => 1,  # Wind
+    '5' => 6,  # Light
+    '6' => 5   # Dark
+  }.freeze
+
+  def initialize(user, game_data, options = {})
+    @user = user
+    @game_data = game_data
+    @update_existing = options[:update_existing] || false
+    @created = []
+    @updated = []
+    @skipped = []
+    @errors = []
+  end
+
+  ##
+  # Imports artifacts from game data.
+  #
+  # @return [Result] Import result with counts and errors
+  def import
+    items = extract_items
+    return Result.new(success?: false, errors: ['No artifact items found in data']) if items.empty?
+
+    ActiveRecord::Base.transaction do
+      items.each_with_index do |item, index|
+        import_item(item, index)
+      rescue StandardError => e
+        @errors << { index: index, game_id: item['id'], error: e.message }
+      end
+    end
+
+    Result.new(
+      success?: @errors.empty?,
+      created: @created,
+      updated: @updated,
+      skipped: @skipped,
+      errors: @errors
+    )
+  end
+
+  private
+
+  def extract_items
+    return @game_data['list'] if @game_data['list'].is_a?(Array)
+    return @game_data if @game_data.is_a?(Array)
+
+    []
+  end
+
+  def import_item(item, _index)
+    artifact = find_artifact(item['artifact_id'])
+    unless artifact
+      @errors << { game_id: item['id'], artifact_id: item['artifact_id'], error: 'Artifact not found' }
+      return
+    end
+
+    # Check for existing collection artifact with same game ID
+    existing = @user.collection_artifacts.find_by(game_id: item['id'].to_s)
+
+    if existing
+      if @update_existing
+        update_existing_artifact(existing, item, artifact)
+      else
+        @skipped << { game_id: item['id'], reason: 'Already exists' }
+      end
+      return
+    end
+
+    create_collection_artifact(item, artifact)
+  end
+
+  def find_artifact(artifact_id)
+    Artifact.find_by(granblue_id: artifact_id.to_s)
+  end
+
+  def create_collection_artifact(item, artifact)
+    attrs = build_collection_artifact_attrs(item, artifact)
+
+    collection_artifact = @user.collection_artifacts.build(attrs)
+
+    if collection_artifact.save
+      @created << collection_artifact
+    else
+      @errors << {
+        game_id: item['id'],
+        artifact_id: item['artifact_id'],
+        error: collection_artifact.errors.full_messages.join(', ')
+      }
+    end
+  end
+
+  def update_existing_artifact(existing, item, artifact)
+    attrs = build_collection_artifact_attrs(item, artifact)
+
+    if existing.update(attrs)
+      @updated << existing
+    else
+      @errors << {
+        game_id: item['id'],
+        artifact_id: item['artifact_id'],
+        error: existing.errors.full_messages.join(', ')
+      }
+    end
+  end
+
+  def build_collection_artifact_attrs(item, artifact)
+    {
+      artifact: artifact,
+      game_id: item['id'].to_s,
+      element: map_element(item['attribute']),
+      proficiency: artifact.quirk? ? map_proficiency(item['kind']) : nil,
+      level: item['level'].to_i,
+      skill1: parse_skill(item['skill1_info']),
+      skill2: parse_skill(item['skill2_info']),
+      skill3: parse_skill(item['skill3_info']),
+      skill4: parse_skill(item['skill4_info'])
+    }
+  end
+
+  def map_element(game_element)
+    ELEMENT_MAPPING[game_element.to_s]
+  end
+
+  def map_proficiency(kind)
+    # Game 'kind' field maps directly to proficiency enum (1-10)
+    kind.to_i
+  end
+
+  def parse_skill(skill_info)
+    return {} if skill_info.blank?
+
+    skill_id = skill_info['skill_id']
+    quality = skill_info['skill_quality'] || skill_info['level']
+    level = skill_info['level'] || 1
+
+    group, modifier = decode_skill_id(skill_id)
+    return {} unless group && modifier
+
+    # Get the strength value from ArtifactSkill
+    strength = calculate_strength(group, modifier, quality.to_i)
+
+    {
+      'modifier' => modifier,
+      'strength' => strength,
+      'level' => level.to_i
+    }
+  end
+
+  ##
+  # Decodes a game skill_id to [group, modifier].
+  # skill_id format: {base_id}{quality} where last digit is quality (1-5)
+  #
+  # @param skill_id [Integer] The game's skill ID
+  # @return [Array<Integer, Integer>, nil] [group, modifier] or nil if unknown
+  def decode_skill_id(skill_id)
+    base_id = skill_id.to_i / 10
+    GAME_SKILL_MAPPING[base_id]
+  end
+
+  ##
+  # Calculates the strength value based on quality tier.
+  # Quality 1-5 maps to base_values[0-4] in ArtifactSkill.
+  #
+  # @param group [Integer] Skill group (1, 2, or 3)
+  # @param modifier [Integer] Skill modifier within group
+  # @param quality [Integer] Quality tier (1-5)
+  # @return [Float, Integer, nil] The strength value
+  def calculate_strength(group, modifier, quality)
+    skill = ArtifactSkill.find_skill(group, modifier)
+    return nil unless skill
+
+    base_values = skill.base_values
+    return nil if base_values.blank?
+
+    # Quality 1-5 maps to index 0-4
+    index = (quality - 1).clamp(0, base_values.size - 1)
+    base_values[index]
+  end
+end

config/routes.rb

@@ -180,6 +180,7 @@ Rails.application.routes.draw do
       resources :artifacts, only: [:create, :update, :destroy], controller: '/api/v1/collection_artifacts' do
         collection do
           post :batch
+          post :import
         end
       end
     end

db/migrate/20251203221115_add_game_id_to_collection_items.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class AddGameIdToCollectionItems < ActiveRecord::Migration[8.0]
+  def change
+    # Add game_id to collection_artifacts
+    # This stores the unique instance ID from the game's inventory (the "id" field in game data)
+    add_column :collection_artifacts, :game_id, :string
+    add_index :collection_artifacts, %i[user_id game_id], unique: true, where: 'game_id IS NOT NULL'
+
+    # Add game_id to collection_weapons
+    add_column :collection_weapons, :game_id, :string
+    add_index :collection_weapons, %i[user_id game_id], unique: true, where: 'game_id IS NOT NULL'
+
+    # Add game_id to collection_summons
+    add_column :collection_summons, :game_id, :string
+    add_index :collection_summons, %i[user_id game_id], unique: true, where: 'game_id IS NOT NULL'
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_12_03_211939) do
+ActiveRecord::Schema[8.0].define(version: 2025_12_03_221115) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "btree_gin"
   enable_extension "pg_catalog.plpgsql"
@@ -151,9 +151,11 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_211939) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "reroll_slot"
+    t.string "game_id"
     t.index ["artifact_id"], name: "index_collection_artifacts_on_artifact_id"
     t.index ["element"], name: "index_collection_artifacts_on_element"
     t.index ["user_id", "artifact_id"], name: "index_collection_artifacts_on_user_id_and_artifact_id"
+    t.index ["user_id", "game_id"], name: "index_collection_artifacts_on_user_id_and_game_id", unique: true, where: "(game_id IS NOT NULL)"
     t.index ["user_id"], name: "index_collection_artifacts_on_user_id"
   end
 
@@ -195,7 +197,9 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_211939) do
     t.integer "transcendence_step", default: 0, null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.string "game_id"
     t.index ["summon_id"], name: "index_collection_summons_on_summon_id"
+    t.index ["user_id", "game_id"], name: "index_collection_summons_on_user_id_and_game_id", unique: true, where: "(game_id IS NOT NULL)"
     t.index ["user_id", "summon_id"], name: "index_collection_summons_on_user_id_and_summon_id"
     t.index ["user_id"], name: "index_collection_summons_on_user_id"
   end
@@ -218,7 +222,9 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_211939) do
     t.integer "element"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.string "game_id"
     t.index ["awakening_id"], name: "index_collection_weapons_on_awakening_id"
+    t.index ["user_id", "game_id"], name: "index_collection_weapons_on_user_id_and_game_id", unique: true, where: "(game_id IS NOT NULL)"
     t.index ["user_id", "weapon_id"], name: "index_collection_weapons_on_user_id_and_weapon_id"
     t.index ["user_id"], name: "index_collection_weapons_on_user_id"
     t.index ["weapon_id"], name: "index_collection_weapons_on_weapon_id"