import { readFileSync, writeFileSync } from "node:fs";

export type RuleStore = Record<string, string>; // "router:key" → prompt file path

const _G = globalThis as Record<string, unknown>;
const RULES_KEY = "_prismFacetRules";
const RULES_PATH_KEY = "_prismFacetRulesPath";

function getRules(): RuleStore {
  if (!_G[RULES_KEY] || typeof _G[RULES_KEY] !== "object") {
    _G[RULES_KEY] = {};
  }
  return _G[RULES_KEY] as RuleStore;
}

function getRulesPath(): string {
  return (_G[RULES_PATH_KEY] as string) || "";
}

function save(): void {
  const p = getRulesPath();
  if (!p) return;
  writeFileSync(p, JSON.stringify(getRules(), null, 2) + "\n", "utf8");
}

export function initRuleStore(filePath: string): void {
  _G[RULES_PATH_KEY] = filePath;
  try {
    const raw = readFileSync(filePath, "utf8");
    _G[RULES_KEY] = JSON.parse(raw) as RuleStore;
  } catch {
    _G[RULES_KEY] = {};
  }
}

export function addRule(router: string, key: string, promptFile: string): void {
  getRules()[`${router}:${key}`] = promptFile;
  save();
}

export function removeRule(router: string, key: string): boolean {
  const rules = getRules();
  const ruleKey = `${router}:${key}`;
  if (!(ruleKey in rules)) return false;
  delete rules[ruleKey];
  save();
  return true;
}

export function getRule(router: string, key: string): string | undefined {
  return getRules()[`${router}:${key}`];
}

export function listRules(): Record<string, string> {
  return { ...getRules() };
}