import type { InvoiceTemplate } from "../types";

const templates = new Map<string, InvoiceTemplate>();

// Register built-in templates (lazy import to avoid loading all at once)
let registered = false;
async function ensureRegistered(): Promise<void> {
  if (registered) return;
  const { mandalaTemplate } = await import("./mandala");
  const { minimalTemplate } = await import("./minimal");
  templates.set("mandala", mandalaTemplate);
  templates.set("minimal", minimalTemplate);
  registered = true;
}

export function getTemplate(name: string): InvoiceTemplate {
  // Synchronous lookup — templates must be registered first
  // For built-in templates, they self-register on import
  const template = templates.get(name);
  if (!template) {
    const available = Array.from(templates.keys()).join(", ");
    throw new Error(
      `Unknown template "${name}". Available: ${available || "none (call ensureTemplatesLoaded() first)"}`,
    );
  }
  return template;
}

export async function ensureTemplatesLoaded(): Promise<void> {
  await ensureRegistered();
}

export function listTemplates(): InvoiceTemplate[] {
  return Array.from(templates.values());
}

export function registerTemplate(template: InvoiceTemplate): void {
  templates.set(template.name, template);
}