/**
 * Typed environment for the API. Values come from process.env; in development the repo-root `.env`
 * is loaded through node's `process.loadEnvFile` (never overriding already-set variables).
 */
import { existsSync } from "node:fs";
import { dirname, join, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import process from "node:process";

export interface ApiEnv {
  port: number;
  host: string;
  databaseUrl: string;
  redisUrl: string;
  clickhouseUrl: string;
  clickhouseDb: string;
  s3Endpoint: string;
  s3Bucket: string;
  s3AccessKey: string;
  s3SecretKey: string;
  s3Region: string;
  /** null when DCI_ADMIN_TOKEN is missing, empty or the "change-me" placeholder → admin API answers 503 */
  adminToken: string | null;
  /** internal HTTP server of the worker (GET /trace/<documentId>, GET /data-gaps) */
  workerUrl: string;
  /** directory holding connector YAML files */
  configDir: string;
  /** optional path to the worker connectors registry (parsers) for the dev tool; null = generic only */
  workerConnectorsDir: string | null;
  logLevel: string;
  cacheEnabled: boolean;
  publicRateLimit: number;
  adminRateLimit: number;
  trustedProxies: string[];
  siteUrl: string;
}

export function findRepoRoot(start: string = process.cwd()): string {
  let dir = resolve(start);
  for (let i = 0; i < 8; i++) {
    if (existsSync(join(dir, "pnpm-workspace.yaml"))) return dir;
    const parent = dirname(dir);
    if (parent === dir) break;
    dir = parent;
  }
  const here = dirname(fileURLToPath(import.meta.url));
  return resolve(here, "..", "..", "..");
}

let envFileLoaded = false;
export function loadEnvFile(file = ".env"): boolean {
  if (envFileLoaded) return true;
  const path = file.startsWith("/") ? file : join(findRepoRoot(), file);
  if (!existsSync(path)) return false;
  const loader = (process as unknown as { loadEnvFile?: (p: string) => void }).loadEnvFile;
  if (typeof loader !== "function") return false;
  loader.call(process, path);
  envFileLoaded = true;
  return true;
}

function num(v: string | undefined, fallback: number): number {
  const n = Number(v);
  return v !== undefined && v !== "" && Number.isFinite(n) ? n : fallback;
}

let cached: ApiEnv | null = null;
export function getEnv(): ApiEnv {
  if (cached) return cached;
  const e = process.env;
  const root = findRepoRoot();
  const workerDir = e.DCI_WORKER_CONNECTORS_DIR ?? join(root, "apps", "worker", "src", "connectors");
  cached = {
    port: num(e.API_PORT, 8311),
    host: e.API_HOST ?? "0.0.0.0",
    databaseUrl: e.DATABASE_URL ?? "postgres://dci:dci@127.0.0.1:5432/dci",
    redisUrl: e.REDIS_URL ?? "redis://127.0.0.1:6379/0",
    clickhouseUrl: e.CLICKHOUSE_URL ?? "http://127.0.0.1:8123",
    clickhouseDb: e.CLICKHOUSE_DB ?? "dci",
    s3Endpoint: e.S3_ENDPOINT ?? "http://127.0.0.1:9000",
    s3Bucket: e.S3_BUCKET ?? "dci-raw",
    s3AccessKey: e.S3_ACCESS_KEY ?? "dci",
    s3SecretKey: e.S3_SECRET_KEY ?? "",
    s3Region: e.S3_REGION ?? "us-east-1",
    adminToken: e.DCI_ADMIN_TOKEN && e.DCI_ADMIN_TOKEN.trim() !== "" && e.DCI_ADMIN_TOKEN !== "change-me" ? e.DCI_ADMIN_TOKEN : null,
    workerUrl: (e.DCI_WORKER_URL && e.DCI_WORKER_URL.trim()) || "http://127.0.0.1:8320",
    configDir: e.DCI_CONFIG_DIR ? resolve(e.DCI_CONFIG_DIR) : join(root, "config", "connectors"),
    workerConnectorsDir: existsSync(workerDir) ? workerDir : null,
    logLevel: (e.DCI_LOG_LEVEL ?? "info").toLowerCase(),
    cacheEnabled: e.DCI_API_CACHE !== "0",
    publicRateLimit: num(e.DCI_API_RATE_LIMIT, 240),
    adminRateLimit: num(e.DCI_ADMIN_RATE_LIMIT, 60),
    trustedProxies: (e.DCI_TRUSTED_PROXIES ?? "127.0.0.0/8,10.0.0.0/8,172.16.0.0/12,::1/128").split(",").map((s) => s.trim()).filter(Boolean),
    siteUrl: e.NEXT_PUBLIC_SITE_URL ?? "https://www.datacenterindex.io",
  };
  return cached;
}

/** Test hook: forget the cached env (after mutating process.env). */
export function resetEnv(): void {
  cached = null;
}