import fs from "node:fs/promises";
import path from "node:path";
import type { ScaffoldRecipe } from "./scaffold-recipes.js";
import type { StructuralRequest } from "./structural-plan.js";
export async function scaffoldController(
  root: string,
  prefix: string,
  spec: ScaffoldRecipe,
): Promise<StructuralRequest> {
  const entry = { id: spec.id, ...spec.controller };
  const fields = ["id", "subject", "snapshot", "remote", "input"];
  if (
    Object.keys(entry).some((key) => ![...fields, "registry"].includes(key)) ||
    (entry.registry !== undefined && typeof entry.registry !== "string") ||
    fields.some((key) => typeof (entry as Record<string, unknown>)[key] !== "string") ||
    !["unit", "value"].includes(entry.input ?? "")
  )
    throw Error("Controller requires id, subject, snapshot, remote and input (unit/value)");
  const file = prefix + "quixos.controllers.json";
  let before: string | undefined;
  try {
    before = await fs.readFile(path.join(root, file), "utf8");
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
  }
  const catalog = before ? JSON.parse(before) : { schemaVersion: 1, controllers: [] };
  if (
    catalog.schemaVersion !== 1 ||
    !Array.isArray(catalog.controllers) ||
    catalog.controllers.length >= 1000 ||
    catalog.controllers.some((c: { id: string }) => c.id === entry.id)
  )
    throw Error("Invalid catalog or duplicate controller ID");
  catalog.controllers.push(entry);
  const content = JSON.stringify(catalog, null, 2) + "\n";
  return {
    kind: "package",
    source: spec.source,
    resourceRoot: spec.directory,
    validation: "syntax",
    files: [before === undefined ? { file, create: content } : { file, expected: before, replace: content }],
  };
}