// server/templates/render.ts
import Mustache from "mustache";
import { readFileSync, existsSync } from "node:fs";
import { resolve } from "node:path";

const TEMPLATES_ROOT = resolve(process.cwd(), "templates");

export interface TemplateVars {
  aptProxy?: string | null;
}

export function renderTemplate(relPath: string, vars: TemplateVars): string {
  const tpl = readFileSync(resolve(TEMPLATES_ROOT, relPath), "utf8");
  // Mustache échappe le HTML par défaut; on désactive (ce sont des scripts shell).
  return Mustache.render(tpl, vars, {}, { escape: (s) => s });
}

/** Existence par défaut d'un template relatif à templates/. */
function defaultExists(rel: string): boolean {
  return existsSync(resolve(TEMPLATES_ROOT, rel));
}

/**
 * Résout le chemin de template le plus spécifique pour (action, OS) :
 * `<osFamily>/<action>.sh.tpl` s'il existe, sinon fallback base `apt/<action>.sh.tpl`.
 * `exists` est injectable pour les tests.
 */
export function resolveTemplate(
  action: string,
  osFamily: string,
  exists: (rel: string) => boolean = defaultExists,
): string {
  const specific = `${osFamily}/${action}.sh.tpl`;
  if (osFamily !== "unknown" && osFamily !== "apt" && exists(specific)) return specific;
  return `apt/${action}.sh.tpl`;
}