import { v4 as uuidv4 } from 'uuid';
import { type ChartInstance, type LayoutItem, type Template } from '@/domain';
import { type ITemplateUseCase } from '../ports/input/ITemplateUseCase';
import { type IStorageGateway } from '../ports/output/IStorageGateway';

const TEMPLATE_KEY_PREFIX = 'template:';

export class TemplateUseCase implements ITemplateUseCase {
  constructor(private readonly storage: IStorageGateway) {}

  save(
    name: string,
    description: string,
    charts: ChartInstance[],
    layout: LayoutItem[],
    theme: string,
  ): Template {
    const template: Template = {
      id: uuidv4(),
      name,
      description,
      charts: charts.map(({ dataSetId: _, ...rest }) => rest),
      layout,
      theme,
      createdAt: new Date().toISOString(),
    };

    this.storage.save(`${TEMPLATE_KEY_PREFIX}${template.id}`, template);
    return template;
  }

  load(templateId: string): Template | null {
    return this.storage.load<Template>(`${TEMPLATE_KEY_PREFIX}${templateId}`);
  }

  list(): Template[] {
    const keys = this.storage.listKeys(TEMPLATE_KEY_PREFIX);
    const templates: Template[] = [];
    for (const key of keys) {
      const template = this.storage.load<Template>(key);
      if (template) {
        templates.push(template);
      }
    }
    return templates;
  }

  remove(templateId: string): void {
    this.storage.remove(`${TEMPLATE_KEY_PREFIX}${templateId}`);
  }

  exportTemplate(templateId: string): string {
    const template = this.load(templateId);
    if (!template) {
      throw new Error(`Template not found: ${templateId}`);
    }
    return JSON.stringify(template);
  }

  importTemplate(json: string): Template {
    const parsed = JSON.parse(json) as Template;

    // Assign a new ID to avoid collisions
    const template: Template = {
      ...parsed,
      id: uuidv4(),
      createdAt: new Date().toISOString(),
    };

    this.storage.save(`${TEMPLATE_KEY_PREFIX}${template.id}`, template);
    return template;
  }
}