/**
 * Load token mapping from config/token-mapping.json and config/token-mapping-multichain.json.
 * Used by relay service, bridge/LP tooling, and docs. Safe to publish (no secrets).
 *
 * Usage:
 *   const { getRelayTokenMapping, getTokenMappingForPair } = require('../config/token-mapping-loader.cjs');
 *   const map = getRelayTokenMapping();  // 138 -> Mainnet (chain138Address -> mainnetAddress)
 *   const pair = getTokenMappingForPair(138, 651940);  // { tokens, addressMapFromTo, addressMapToFrom }
 *
 * @version 2026-02-16
 */

const path = require('path');
const fs = require('fs');

const DEFAULT_JSON_PATH = path.resolve(__dirname, 'token-mapping.json');
const DEFAULT_MULTICHAIN_JSON_PATH = path.resolve(__dirname, 'token-mapping-multichain.json');

let _cache = null;
let _multichainCache = null;

function loadTokenMappingJson(jsonPath = DEFAULT_JSON_PATH) {
  if (_cache && _cache.path === jsonPath) return _cache.data;
  try {
    const raw = fs.readFileSync(jsonPath, 'utf8');
    const data = JSON.parse(raw);
    _cache = { path: jsonPath, data };
    return data;
  } catch (e) {
    return null;
  }
}

function loadTokenMappingMultichainJson(jsonPath = DEFAULT_MULTICHAIN_JSON_PATH) {
  if (_multichainCache && _multichainCache.path === jsonPath) return _multichainCache.data;
  try {
    const raw = fs.readFileSync(jsonPath, 'utf8');
    const data = JSON.parse(raw);
    _multichainCache = { path: jsonPath, data };
    return data;
  } catch (e) {
    return null;
  }
}

/**
 * Build object suitable for relay config.tokenMapping: Chain 138 address -> Mainnet address.
 * Only includes tokens that have a mainnetAddress (canonical or wrapped).
 *
 * @param {string} [jsonPath]
 * @returns {{ [chain138Address: string]: string }}
 */
function getRelayTokenMapping(jsonPath) {
  const data = loadTokenMappingJson(jsonPath);
  if (!data || !Array.isArray(data.tokens)) return {};
  const out = {};
  for (const t of data.tokens) {
    if (t.chain138Address && t.mainnetAddress) {
      out[t.chain138Address] = t.mainnetAddress;
    }
  }
  return out;
}

/**
 * Get full token list with relaySupported and mainnet info.
 *
 * @param {string} [jsonPath]
 * @returns {Array<{ key: string, name: string, chain138Address: string, mainnetAddress: string|null, relaySupported: boolean, notes: string }>}
 */
function getTokenList(jsonPath) {
  const data = loadTokenMappingJson(jsonPath);
  if (!data || !Array.isArray(data.tokens)) return [];
  return data.tokens;
}

/**
 * Get token mapping for a chain pair from token-mapping-multichain.json.
 * Tries (fromChainId, toChainId) then (toChainId, fromChainId) and returns tokens in from→to order.
 *
 * @param {number|string} fromChainId
 * @param {number|string} toChainId
 * @param {string} [jsonPath]
 * @returns {{ tokens: Array<{ key: string, name: string, addressFrom: string, addressTo: string, notes?: string }>, addressMapFromTo: Record<string, string>, addressMapToFrom: Record<string, string> } | null}
 */
function getTokenMappingForPair(fromChainId, toChainId, jsonPath) {
  const data = loadTokenMappingMultichainJson(jsonPath);
  if (!data || !Array.isArray(data.pairs)) return null;
  const from = Number(fromChainId);
  const to = Number(toChainId);
  let pair = data.pairs.find((p) => p.fromChainId === from && p.toChainId === to);
  let reverse = false;
  if (!pair) {
    pair = data.pairs.find((p) => p.fromChainId === to && p.toChainId === from);
    reverse = true;
  }
  if (!pair || !Array.isArray(pair.tokens)) return null;
  const tokens = reverse
    ? pair.tokens.map((t) => ({ key: t.key, name: t.name, addressFrom: t.addressTo, addressTo: t.addressFrom, notes: t.notes }))
    : pair.tokens;
  const addressMapFromTo = {};
  const addressMapToFrom = {};
  for (const t of tokens) {
    if (t.addressFrom && t.addressTo) {
      addressMapFromTo[t.addressFrom.toLowerCase()] = t.addressTo;
      addressMapToFrom[t.addressTo.toLowerCase()] = t.addressFrom;
    }
  }
  return { tokens, addressMapFromTo, addressMapToFrom };
}

/**
 * Get all chain pairs defined in token-mapping-multichain.json.
 *
 * @param {string} [jsonPath]
 * @returns {Array<{ fromChainId: number, toChainId: number, notes?: string }>}
 */
function getAllMultichainPairs(jsonPath) {
  const data = loadTokenMappingMultichainJson(jsonPath);
  if (!data || !Array.isArray(data.pairs)) return [];
  return data.pairs.map((p) => ({ fromChainId: p.fromChainId, toChainId: p.toChainId, notes: p.notes }));
}

/**
 * Resolve token address on target chain from source chain address using multichain mapping.
 *
 * @param {number|string} fromChainId
 * @param {number|string} toChainId
 * @param {string} tokenAddressOnSource - address on fromChainId
 * @param {string} [jsonPath]
 * @returns {string|undefined} address on toChainId, or undefined if not mapped
 */
function getMappedAddress(fromChainId, toChainId, tokenAddressOnSource, jsonPath) {
  const result = getTokenMappingForPair(fromChainId, toChainId, jsonPath);
  if (!result) return undefined;
  return result.addressMapFromTo[String(tokenAddressOnSource).toLowerCase()];
}

module.exports = {
  loadTokenMappingJson,
  loadTokenMappingMultichainJson,
  getRelayTokenMapping,
  getTokenList,
  getTokenMappingForPair,
  getAllMultichainPairs,
  getMappedAddress,
  DEFAULT_JSON_PATH,
  DEFAULT_MULTICHAIN_JSON_PATH
};