import {
  fetchMalwareDatabase,
  fetchMalwareDatabaseVersion,
} from "../api/aikido.js";
import {
  readDatabaseFromLocalCache,
  writeDatabaseToLocalCache,
} from "../config/configFile.js";
import { ui } from "../environment/userInteraction.js";
import { getEcoSystem, ECOSYSTEM_PY } from "../config/settings.js";

/**
 * @typedef {Object} MalwareDatabase
 * @property {function(string, string): string} getPackageStatus
 * @property {function(string, string): boolean} isMalware
 */

// Caching the Promise (rather than the resolved database) prevents duplicate fetches. If we cached the resolved
// value, multiple callers could pass the null-check before the first fetch completes (because each `await` yields
// control back to the event loop, allowing other callers to run). Since the Promise assignment is synchronous, all
// concurrent callers see it immediately and share a single fetch.
/** @type {Promise<MalwareDatabase> | null} */
let cachedMalwareDatabasePromise = null;

/**
 * Normalize package name for comparison.
 * For Python packages (PEP-503): lowercase and replace _, -, . with -
 * For js packages: keep as-is (case-sensitive)
 * @param {string} name
 * @returns {string}
 */
function normalizePackageName(name) {
  const ecosystem = getEcoSystem();
  if (ecosystem === ECOSYSTEM_PY) {
    return name.toLowerCase().replace(/[-_.]+/g, "-");
  }

  return name;
}

export function openMalwareDatabase() {
  if (!cachedMalwareDatabasePromise) {
    cachedMalwareDatabasePromise = getMalwareDatabase().then((malwareDatabase) => {
      /**
       * @param {string} name
       * @param {string} version
       * @returns {string}
       */
      function getPackageStatus(name, version) {
        const normalizedName = normalizePackageName(name);
        const packageData = malwareDatabase.find(
          (pkg) => {
            const normalizedPkgName = normalizePackageName(pkg.package_name);
            return normalizedPkgName === normalizedName &&
              (pkg.version === version || pkg.version === "*");
          }
        );

        if (!packageData) {
          return MALWARE_STATUS_OK;
        }

        return packageData.reason;
      }

      return {
        getPackageStatus,
        isMalware: (/** @type {string} */ name, /** @type {string} */ version) => {
          const status = getPackageStatus(name, version);
          return isMalwareStatus(status);
        },
      };
    }).catch((error) => {
      cachedMalwareDatabasePromise = null;
      throw error;
    });
  }
  return cachedMalwareDatabasePromise;
}

/**
 * @returns {Promise<import("../api/aikido.js").MalwarePackage[]>}
 */
async function getMalwareDatabase() {
  const { malwareDatabase: cachedDatabase, version: cachedVersion } =
    readDatabaseFromLocalCache();

  try {
    if (cachedDatabase) {
      const currentVersion = await fetchMalwareDatabaseVersion();
      if (cachedVersion === currentVersion) {
        return cachedDatabase;
      }
    }

    const { malwareDatabase, version } = await fetchMalwareDatabase();

    if (version) {
      // Only cache the malware database when we have a version.
      writeDatabaseToLocalCache(malwareDatabase, version);
      return malwareDatabase;
    } else {
      // We received a valid malware database, but the response
      // did not contain an etag header with the version
      ui.writeWarning(
        "The malware database was downloaded, but could not be cached due to a missing version."
      );
      return malwareDatabase;
    }
  } catch (/** @type any */ error) {
    if (cachedDatabase) {
      ui.writeWarning(
        "Failed to fetch the latest malware database. Using cached version."
      );
      return cachedDatabase;
    }
    throw error;
  }
}

/**
 * @param {string} status
 *
 * @returns {boolean}
 */
function isMalwareStatus(status) {
  let malwareStatus = status.toUpperCase();
  return malwareStatus === MALWARE_STATUS_MALWARE;
}

export const MALWARE_STATUS_OK = "OK";
export const MALWARE_STATUS_MALWARE = "MALWARE";
export const MALWARE_STATUS_TELEMETRY = "TELEMETRY";
export const MALWARE_STATUS_PROTESTWARE = "PROTESTWARE";