/**

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 *

 * @flow

 */

// A pure JS implementation of a string hashing function. We do not use it for

// security or obfuscation purposes, only to create compact hashes. So we

// prioritize speed over collision avoidance. For example, we use this to hash

// the component key path used by useFormState for MPA-style submissions.

//

// In environments where built-in hashing functions are available, we prefer

// those instead. Like Node's crypto module, or Bun.hash. Unfortunately this

// does not include the web standard crypto API because those methods are all

// async. For our purposes, we need it to be sync because the cost of context

// switching is too high to be worth it.

//

// The most popular hashing algorithm that meets these requirements in the JS

// ecosystem is MurmurHash3, and almost all implementations I could find used

// some version of the implementation by Gary Court inlined below.

export function createFastHashJS(key: string): number {

  return murmurhash3_32_gc(key, 0);

}

/* eslint-disable prefer-const, no-fallthrough */

/**

 * @license

 *

 * JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)

 *

 * Copyright (c) 2011 Gary Court

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

function murmurhash3_32_gc(key: string, seed: number): number {

  let remainder, bytes, h1, h1b, c1, c2, k1, i;

  remainder = key.length & 3; // key.length % 4

  bytes = key.length - remainder;

  h1 = seed;

  c1 = 0xcc9e2d51;

  c2 = 0x1b873593;

  i = 0;

  while (i < bytes) {

    k1 =

      (key.charCodeAt(i) & 0xff) |

      ((key.charCodeAt(++i) & 0xff) << 8) |

      ((key.charCodeAt(++i) & 0xff) << 16) |

      ((key.charCodeAt(++i) & 0xff) << 24);

    ++i;

    k1 =

      ((k1 & 0xffff) * c1 + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;

    k1 = (k1 << 15) | (k1 >>> 17);

    k1 =

      ((k1 & 0xffff) * c2 + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;

    h1 ^= k1;

    h1 = (h1 << 13) | (h1 >>> 19);

    h1b =

      ((h1 & 0xffff) * 5 + ((((h1 >>> 16) * 5) & 0xffff) << 16)) & 0xffffffff;

    h1 = (h1b & 0xffff) + 0x6b64 + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16);

  }

  k1 = 0;

  switch (remainder) {

    case 3:

      k1 ^= (key.charCodeAt(i + 2) & 0xff) << 16;

    case 2:

      k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;

    case 1:

      k1 ^= key.charCodeAt(i) & 0xff;

      k1 =

        ((k1 & 0xffff) * c1 + ((((k1 >>> 16) * c1) & 0xffff) << 16)) &

        0xffffffff;

      k1 = (k1 << 15) | (k1 >>> 17);

      k1 =

        ((k1 & 0xffff) * c2 + ((((k1 >>> 16) * c2) & 0xffff) << 16)) &

        0xffffffff;

      h1 ^= k1;

  }

  h1 ^= key.length;

  h1 ^= h1 >>> 16;

  h1 =

    ((h1 & 0xffff) * 0x85ebca6b +

      ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) &

    0xffffffff;

  h1 ^= h1 >>> 13;

  h1 =

    ((h1 & 0xffff) * 0xc2b2ae35 +

      ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16)) &

    0xffffffff;

  h1 ^= h1 >>> 16;

  return h1 >>> 0;

}