const globalScope = globalThis as Record<string, unknown>;
const stringPrototype = String.prototype as typeof String.prototype & {
  isWellFormed?: () => boolean;
  toWellFormed?: () => string;
};

const arrayBufferByteLength = Object.getOwnPropertyDescriptor(ArrayBuffer.prototype, 'byteLength')?.get;

function toWellFormedString(value: string): string {
  let result = '';

  for (let index = 0; index < value.length; index += 1) {
    const code = value.charCodeAt(index);

    if (code >= 0xd800 && code <= 0xdbff) {
      const next = value.charCodeAt(index + 1);
      if (next >= 0xdc00 && next <= 0xdfff) {
        result += value[index] + value[index + 1];
        index += 1;
      } else {
        result += '\uFFFD';
      }
    } else if (code >= 0xdc00 && code <= 0xdfff) {
      result += '\uFFFD';
    } else {
      result += value[index];
    }
  }

  return result;
}

if (typeof stringPrototype.toWellFormed !== 'function') {
  Object.defineProperty(String.prototype, 'toWellFormed', {
    configurable: true,
    value() {
      return toWellFormedString(String(this));
    },
  });
}

if (typeof stringPrototype.isWellFormed !== 'function') {
  Object.defineProperty(String.prototype, 'isWellFormed', {
    configurable: true,
    value() {
      const value = String(this);
      return toWellFormedString(value) === value;
    },
  });
}

if (!Object.getOwnPropertyDescriptor(ArrayBuffer.prototype, 'resizable')) {
  Object.defineProperty(ArrayBuffer.prototype, 'resizable', {
    configurable: true,
    get() {
      return false;
    },
  });
}

if (typeof globalScope.SharedArrayBuffer === 'undefined') {
  class SharedArrayBufferPolyfill extends ArrayBuffer {
    get byteLength() {
      return arrayBufferByteLength?.call(this) ?? 0;
    }

    get growable() {
      return false;
    }
  }

  Object.defineProperty(SharedArrayBufferPolyfill.prototype, Symbol.toStringTag, {
    configurable: true,
    value: 'SharedArrayBuffer',
  });

  globalScope.SharedArrayBuffer = SharedArrayBufferPolyfill;
}