// Copyright (C) 2026 Whiterun LLC,
// This software is licensed under the GNU Lesser General Public License (LGPL), version 3.0 or later.
// A copy of the license can be found in the LICENSE file or at https://www.gnu.org/licenses/lgpl-3.0.html

/**
 * Serialization helpers for converting between native libauth types and the
 * relay-safe JSON format used by the WizardConnect protocol.
 *
 * The relay transmits messages as JSON, which cannot represent BigInt or
 * Uint8Array natively. This module provides the canonical encoding:
 *
 * - Uint8Array → hex string  (or `<Uint8Array: 0x...>` extended format)
 * - BigInt     → `<bigint: Xn>` string
 *
 * Both dapps and wallets should use these helpers to ensure interoperability.
 */

import { hexToBin } from "@bitauth/libauth";

// ---------------------------------------------------------------------------
// Deserialization (relay JSON → native types)
// ---------------------------------------------------------------------------

const BIGINT_RE = /^<bigint: (?<bigint>[0-9]*)n>$/;
const UINT8_RE = /^<Uint8Array: 0x(?<hex>[0-9a-f]*)>$/u;

/**
 * Parse a full JSON string that may contain extended-format values.
 * Handles both `<Uint8Array: 0x...>` and `<bigint: ...n>` formats.
 */
export function parseExtendedJson(jsonString: string): any {
  return JSON.parse(jsonString, (_key, value) => {
    if (typeof value === "string") {
      const bigintMatch = value.match(BIGINT_RE);
      if (bigintMatch) return BigInt(bigintMatch[1]);
      const uint8Match = value.match(UINT8_RE);
      if (uint8Match) return hexToBin(uint8Match[1]);
    }
    return value;
  });
}

/**
 * Check if a string contains extended JSON markers.
 */
export function isExtendedJsonFormat(str: string): boolean {
  return UINT8_RE.test(str) || BIGINT_RE.test(str);
}

/**
 * Parse a single extended JSON value string to its native type.
 * Returns the original string if it doesn't match any known format.
 */
export function parseExtendedJsonValue(
  value: string,
): Uint8Array | bigint | string {
  const bigintMatch = value.match(BIGINT_RE);
  if (bigintMatch) return BigInt(bigintMatch[1]);
  const uint8Match = value.match(UINT8_RE);
  if (uint8Match) return hexToBin(uint8Match[1]);
  return value;
}

/**
 * Convert a value to Uint8Array. Accepts:
 * - Uint8Array (returned as-is)
 * - hex string
 * - extended JSON format string (`<Uint8Array: 0x...>`)
 */
export function toUint8Array(value: string | Uint8Array): Uint8Array {
  if (value instanceof Uint8Array) return value;
  if (isExtendedJsonFormat(value))
    return parseExtendedJsonValue(value) as Uint8Array;
  return hexToBin(value);
}

/**
 * Convert a value to bigint. Accepts:
 * - bigint (returned as-is)
 * - number
 * - numeric string
 * - extended JSON format string (`<bigint: Xn>`)
 */
export function toBigInt(value: string | number | bigint): bigint {
  if (typeof value === "bigint") return value;
  if (typeof value === "string") {
    if (isExtendedJsonFormat(value))
      return parseExtendedJsonValue(value) as bigint;
    return BigInt(value);
  }
  return BigInt(value);
}