// 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;
  aptProxyUrl?: string | null;   // proxy persistant (apt_proxy_persistent)
  // Docker template vars
  composeRoots?: string | number | null;
  composeScanDepth?: string | number | null;
  stackDir?: string | null;
}

export function renderTemplate(
  relPath: string,
  vars: TemplateVars,
  opts?: { tags?: [string, string] },
): string {
  const tpl = readFileSync(resolve(TEMPLATES_ROOT, relPath), "utf8");
  // Les templates Docker contiennent des Go-templates {{...}} : on bascule les
  // délimiteurs Mustache sur <% %> pour ne pas les interpréter.
  const tags = opts?.tags ?? (relPath.startsWith("docker/") ? (["<%", "%>"] as [string, string]) : undefined);
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  return Mustache.render(tpl, vars, {}, { escape: (s: any) => s, ...(tags ? { tags } : {}) } as any);
}

/** 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`;
}