import { parseDocument, stringify } from "yaml";

export class CustomProxyValidationError extends Error {}

function isRecord(value: unknown): value is Record<string, unknown> {
  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
}

/** Accept a single proxy, a one-item list, or the legacy `proxies:` wrapper. */
export function parseCustomProxyYaml(
  source: string,
): Record<string, unknown> & { name: string; type: string } {
  if (!source.trim()) throw new CustomProxyValidationError("请填写节点 YAML。");
  if (source.length > 128 * 1024)
    throw new CustomProxyValidationError("单个节点 YAML 不能超过 128 KiB。");
  const doc = parseDocument(source, { prettyErrors: false, uniqueKeys: true });
  if (doc.errors.length || doc.warnings.length) {
    // Parser messages can contain credentials from the YAML; do not echo them.
    throw new CustomProxyValidationError(
      "YAML 格式错误，请检查缩进、引号和重复字段。",
    );
  }
  let value: unknown;
  try {
    value = doc.toJS({ maxAliasCount: 100 });
  } catch {
    throw new CustomProxyValidationError(
      "YAML 引用无效或过多，请使用独立的节点配置。",
    );
  }
  if (isRecord(value) && "proxies" in value) value = value.proxies;
  if (Array.isArray(value)) {
    if (value.length !== 1)
      throw new CustomProxyValidationError(
        "每条节点记录只能包含一个 proxy，请将多个节点分别添加。",
      );
    value = value[0];
  }
  if (!isRecord(value))
    throw new CustomProxyValidationError(
      "请填写一个 Clash proxy 对象或单节点列表。",
    );
  if (typeof value.name !== "string" || !value.name.trim()) {
    throw new CustomProxyValidationError(
      "节点 YAML 必须包含非空的 name 字段（字符串）。",
    );
  }
  if (typeof value.type !== "string" || !value.type.trim()) {
    throw new CustomProxyValidationError(
      "节点 YAML 必须包含非空的 type 字段，例如 anytls。",
    );
  }
  return value as Record<string, unknown> & { name: string; type: string };
}

/** Re-serialize only for output; stored source and comments remain untouched. */
export function renderCustomProxyYaml(source: string) {
  return stringify([parseCustomProxyYaml(source)], { lineWidth: 0 }).trimEnd();
}

export function extractProxyNameFromYaml(source: string) {
  try {
    return parseCustomProxyYaml(source).name;
  } catch {
    return null;
  }
}