const compareArrayBufferViews = (
  a: ArrayBufferView,
  b: ArrayBufferView
): boolean => {
  if (a.byteLength !== b.byteLength) {
    return false;
  }

  const viewA = new Uint8Array(a.buffer, a.byteOffset, a.byteLength);
  const viewB = new Uint8Array(b.buffer, b.byteOffset, b.byteLength);

  for (let index = 0; index < viewA.length; index++) {
    if (viewA[index] !== viewB[index]) {
      return false;
    }
  }

  return true;
};

export const deepEqual = (a: unknown, b: unknown): boolean => {
  if (a === b) {
    return true;
  }

  if (a && b && typeof a === "object" && typeof b === "object") {
    if (a.constructor !== b.constructor) {
      return false;
    }

    let i: number | [unknown, unknown];
    let length: number;
    if (Array.isArray(a)) {
      const bArray = b as unknown[];
      length = a.length;
      if (length !== bArray.length) {
        return false;
      }
      for (i = length; i-- !== 0; ) {
        if (!deepEqual(a[i], bArray[i])) {
          return false;
        }
      }
      return true;
    }

    if (a instanceof Map && b instanceof Map) {
      if (a.size !== b.size) {
        return false;
      }
      for (i of a.entries()) {
        if (!b.has(i[0])) {
          return false;
        }
      }
      for (i of a.entries()) {
        if (!deepEqual(i[1], b.get(i[0]))) {
          return false;
        }
      }
      return true;
    }

    if (a instanceof Set && b instanceof Set) {
      if (a.size !== b.size) {
        return false;
      }
      for (i of a.entries()) {
        if (!b.has(i[0])) {
          return false;
        }
      }
      return true;
    }

    if (ArrayBuffer.isView(a) && ArrayBuffer.isView(b)) {
      return compareArrayBufferViews(a, b);
    }

    if (a instanceof RegExp && b instanceof RegExp) {
      return a.source === b.source && a.flags === b.flags;
    }
    if (a.valueOf !== Object.prototype.valueOf) {
      return a.valueOf() === b.valueOf();
    }
    if (a.toString !== Object.prototype.toString) {
      return a.toString() === b.toString();
    }

    const aRecord = a as Record<string, unknown>;
    const bRecord = b as Record<string, unknown>;
    const keys = Object.keys(aRecord);
    length = keys.length;
    if (length !== Object.keys(bRecord).length) {
      return false;
    }
    for (i = length; i-- !== 0; ) {
      if (!Object.prototype.hasOwnProperty.call(b, keys[i])) {
        return false;
      }
    }

    for (i = length; i-- !== 0; ) {
      const key = keys[i];

      if (!deepEqual(aRecord[key], bRecord[key])) {
        return false;
      }
    }

    return true;
  }

  return a !== a && b !== b;
};