# Tasks: Add Custom Fields

## Backend Tasks

### 1. Create CustomField and TaskCustomValue models
- [x] Create `backend/app/models/custom_field.py` with CustomField model
- [x] Create `backend/app/models/task_custom_value.py` with TaskCustomValue model
- [x] Update `backend/app/models/__init__.py` to export new models
- [x] Create Alembic migration for new tables
- **驗證**: Migration 成功執行，tables 建立正確

### 2. Create Custom Fields API endpoints
- [x] Create `backend/app/api/custom_fields/router.py`
- [x] Implement `POST /api/projects/{project_id}/custom-fields` - 新增欄位
- [x] Implement `GET /api/projects/{project_id}/custom-fields` - 列出欄位
- [x] Implement `PUT /api/custom-fields/{field_id}` - 更新欄位
- [x] Implement `DELETE /api/custom-fields/{field_id}` - 刪除欄位
- [x] Add permission checks (only project owner/manager can manage fields)
- [x] Register router in main.py
- **驗證**: API endpoints 可正常呼叫，權限檢查正確

### 3. Implement formula calculation engine
- [x] Create `backend/app/services/formula_service.py`
- [x] Implement formula parsing (extract field references)
- [x] Implement formula validation (detect circular references)
- [x] Implement formula calculation
- [x] Add unit tests for formula service
- **驗證**: 公式計算正確，循環引用被拒絕

### 4. Integrate custom values with Tasks API
- [x] Modify `TaskCreate` schema to accept `custom_values`
- [x] Modify `TaskUpdate` schema to accept `custom_values`
- [x] Modify `TaskResponse` schema to include `custom_values`
- [x] Update `create_task` endpoint to save custom values
- [x] Update `update_task` endpoint to save custom values
- [x] Update `get_task` endpoint to return custom values
- [x] Trigger formula recalculation on value change
- **驗證**: 任務 CRUD 包含自定義欄位值

### 5. Add backend tests
- [x] Test custom field CRUD operations
- [x] Test permission checks
- [x] Test formula calculation
- [x] Test task integration with custom values
- **驗證**: 所有測試通過 (20/20 tests passed)

## Frontend Tasks

### 6. Create Custom Fields management UI
- [x] Create `frontend/src/pages/ProjectSettings.tsx` or extend existing
- [x] Create `frontend/src/components/CustomFieldEditor.tsx` - 欄位編輯表單
- [x] Create `frontend/src/components/CustomFieldList.tsx` - 欄位列表
- [x] Add custom fields API service in `frontend/src/services/customFields.ts`
- **驗證**: 可在專案設定中管理自定義欄位

### 7. Dynamic field rendering in Task forms
- [x] Create `frontend/src/components/CustomFieldInput.tsx` - 動態欄位輸入
- [x] Integrate into TaskDetailModal.tsx
- [x] Integrate into task creation form
- [x] Handle different field types (text, number, dropdown, date, person)
- [x] Display formula fields as read-only
- **驗證**: 任務表單正確顯示和儲存自定義欄位

### 8. Display custom fields in task views
- [x] Add custom field columns to List view
- [x] Display custom field values in Kanban cards (optional, configurable)
- [x] Add column visibility toggle for custom fields
- **驗證**: 自定義欄位值在各視角中正確顯示

## Task Dependencies

```
[1] Models -> [2] API -> [4] Task Integration -> [5] Tests
                    \
                      [3] Formula Engine /

[6] Management UI -> [7] Task Forms -> [8] View Display
```

- Tasks 1-5 (Backend) 可平行於 Tasks 6-8 (Frontend) 開發
- Task 2 完成後 Task 6 可開始（需要 API）
- Task 4 完成後 Task 7 可開始（需要 Task API 支援 custom values）