/**
 * Utilities for hex, bytes, CSPRNG.
 * @module
 */
/*! noble-ciphers - MIT License (c) 2023 Paul Miller (paulmillr.com) */

/**
 * Bytes API type helpers for old + new TypeScript.
 *
 * TS 5.6 has `Uint8Array`, while TS 5.9+ made it generic `Uint8Array<ArrayBuffer>`.
 * We can't use specific return type, because TS 5.6 will error.
 * We can't use generic return type, because most TS 5.9 software will expect specific type.
 *
 * Maps typed-array input leaves to broad forms.
 * These are compatibility adapters, not ownership guarantees.
 *
 * - `TArg` keeps byte inputs broad.
 * - `TRet` marks byte outputs for TS 5.6 and TS 5.9+ compatibility.
 */
export type TypedArg<T> = T extends BigInt64Array
  ? BigInt64Array
  : T extends BigUint64Array
    ? BigUint64Array
    : T extends Float32Array
      ? Float32Array
      : T extends Float64Array
        ? Float64Array
        : T extends Int16Array
          ? Int16Array
          : T extends Int32Array
            ? Int32Array
            : T extends Int8Array
              ? Int8Array
              : T extends Uint16Array
                ? Uint16Array
                : T extends Uint32Array
                  ? Uint32Array
                  : T extends Uint8ClampedArray
                    ? Uint8ClampedArray
                    : T extends Uint8Array
                      ? Uint8Array
                      : never;
/** Maps typed-array output leaves to narrow TS-compatible forms. */
export type TypedRet<T> = T extends BigInt64Array
  ? ReturnType<typeof BigInt64Array.of>
  : T extends BigUint64Array
    ? ReturnType<typeof BigUint64Array.of>
    : T extends Float32Array
      ? ReturnType<typeof Float32Array.of>
      : T extends Float64Array
        ? ReturnType<typeof Float64Array.of>
        : T extends Int16Array
          ? ReturnType<typeof Int16Array.of>
          : T extends Int32Array
            ? ReturnType<typeof Int32Array.of>
            : T extends Int8Array
              ? ReturnType<typeof Int8Array.of>
              : T extends Uint16Array
                ? ReturnType<typeof Uint16Array.of>
                : T extends Uint32Array
                  ? ReturnType<typeof Uint32Array.of>
                  : T extends Uint8ClampedArray
                    ? ReturnType<typeof Uint8ClampedArray.of>
                    : T extends Uint8Array
                      ? ReturnType<typeof Uint8Array.of>
                      : never;
/** Recursively adapts byte-carrying API input types. See {@link TypedArg}. */
export type TArg<T> =
  | T
  | ([TypedArg<T>] extends [never]
      ? T extends (...args: infer A) => infer R
        ? ((...args: { [K in keyof A]: TRet<A[K]> }) => TArg<R>) & {
            [K in keyof T]: T[K] extends (...args: any) => any ? T[K] : TArg<T[K]>;
          }
        : T extends [infer A, ...infer R]
          ? [TArg<A>, ...{ [K in keyof R]: TArg<R[K]> }]
          : T extends readonly [infer A, ...infer R]
            ? readonly [TArg<A>, ...{ [K in keyof R]: TArg<R[K]> }]
            : T extends (infer A)[]
              ? TArg<A>[]
              : T extends readonly (infer A)[]
                ? readonly TArg<A>[]
                : T extends Promise<infer A>
                  ? Promise<TArg<A>>
                  : T extends object
                    ? { [K in keyof T]: TArg<T[K]> }
                    : T
      : TypedArg<T>);
/** Recursively adapts byte-carrying API output types. See {@link TypedArg}. */
export type TRet<T> = T extends unknown
  ? T &
      ([TypedRet<T>] extends [never]
        ? T extends (...args: infer A) => infer R
          ? ((...args: { [K in keyof A]: TArg<A[K]> }) => TRet<R>) & {
              [K in keyof T]: T[K] extends (...args: any) => any ? T[K] : TRet<T[K]>;
            }
          : T extends [infer A, ...infer R]
            ? [TRet<A>, ...{ [K in keyof R]: TRet<R[K]> }]
            : T extends readonly [infer A, ...infer R]
              ? readonly [TRet<A>, ...{ [K in keyof R]: TRet<R[K]> }]
              : T extends (infer A)[]
                ? TRet<A>[]
                : T extends readonly (infer A)[]
                  ? readonly TRet<A>[]
                  : T extends Promise<infer A>
                    ? Promise<TRet<A>>
                    : T extends object
                      ? { [K in keyof T]: TRet<T[K]> }
                      : T
        : TypedRet<T>)
  : never;

/**
 * Checks if something is Uint8Array. Be careful: nodejs Buffer will return true.
 * @param a - Value to inspect.
 * @returns `true` when the value is a Uint8Array view, including Node's `Buffer`.
 * @example
 * Guards a value before treating it as raw key material.
 *
 * ```ts
 * isBytes(new Uint8Array());
 * ```
 */
export function isBytes(a: unknown): a is Uint8Array {
  // Plain `instanceof Uint8Array` is too strict for some Buffer / proxy /
  // cross-realm cases. The fallback still requires a real ArrayBuffer view
  // so plain JSON-deserialized `{ constructor: ... }`
  // spoofing is rejected, and `BYTES_PER_ELEMENT === 1` keeps the fallback on byte-oriented views.
  return (
    a instanceof Uint8Array ||
    (ArrayBuffer.isView(a) &&
      a.constructor.name === 'Uint8Array' &&
      'BYTES_PER_ELEMENT' in a &&
      a.BYTES_PER_ELEMENT === 1)
  );
}

/**
 * Asserts something is boolean.
 * @param b - Value to validate.
 * @throws On wrong argument types. {@link TypeError}
 * @example
 * Validates a boolean option before branching on it.
 *
 * ```ts
 * abool(true);
 * ```
 */
export function abool(b: boolean): void {
  if (typeof b !== 'boolean') throw new TypeError(`boolean expected, not ${b}`);
}

/**
 * Asserts something is a non-negative safe integer.
 * @param n - Value to validate.
 * @throws On wrong argument types. {@link TypeError}
 * @throws On wrong argument ranges or values. {@link RangeError}
 * @example
 * Validates a non-negative length or counter.
 *
 * ```ts
 * anumber(1);
 * ```
 */
export function anumber(n: number): void {
  if (typeof n !== 'number') throw new TypeError('number expected, got ' + typeof n);
  if (!Number.isSafeInteger(n) || n < 0)
    throw new RangeError('positive integer expected, got ' + n);
}

/**
 * Asserts something is Uint8Array.
 * @param value - Value to validate.
 * @param length - Expected byte length.
 * @param title - Optional label used in error messages.
 * @returns The validated byte array.
 * On Node, `Buffer` is accepted too because it is a Uint8Array view.
 * @throws On wrong argument types. {@link TypeError}
 * @throws On wrong argument lengths. {@link RangeError}
 * @example
 * Validates a fixed-length nonce or key buffer.
 *
 * ```ts
 * abytes(new Uint8Array([1, 2]), 2);
 * ```
 */
export function abytes(
  value: TArg<Uint8Array>,
  length?: number,
  title: string = ''
): TRet<Uint8Array> {
  const bytes = isBytes(value);
  const len = value?.length;
  const needsLen = length !== undefined;
  if (!bytes || (needsLen && len !== length)) {
    const prefix = title && `"${title}" `;
    const ofLen = needsLen ? ` of length ${length}` : '';
    const got = bytes ? `length=${len}` : `type=${typeof value}`;
    const message = prefix + 'expected Uint8Array' + ofLen + ', got ' + got;
    if (!bytes) throw new TypeError(message);
    throw new RangeError(message);
  }
  return value as TRet<Uint8Array>;
}

/**
 * Asserts a hash- or MAC-like instance has not been destroyed or finished.
 * @param instance - Stateful instance to validate.
 * @param checkFinished - Whether to reject finished instances.
 * When `false`, only `destroyed` is checked.
 * @throws If the hash instance has already been destroyed or finalized. {@link Error}
 * @example
 * Guards against calling `update()` or `digest()` on a finished hash.
 *
 * ```ts
 * aexists({ destroyed: false, finished: false });
 * ```
 */
export function aexists(instance: any, checkFinished = true): void {
  if (instance.destroyed) throw new Error('Hash instance has been destroyed');
  if (checkFinished && instance.finished) throw new Error('Hash#digest() has already been called');
}

/**
 * Asserts output is a properly-sized byte array.
 * @param out - Output buffer to validate.
 * @param instance - Hash-like instance providing `outputLen`.
 * This is the relaxed `digestInto()`-style contract: output must be at least `outputLen`,
 * unlike one-shot cipher helpers elsewhere in the repo that often require exact lengths.
 * @throws On wrong argument types. {@link TypeError}
 * @param onlyAligned - Whether `out` must be 4-byte aligned for zero-allocation word views.
 * @throws On wrong output buffer lengths. {@link RangeError}
 * @throws On wrong output buffer alignment. {@link Error}
 * @example
 * Verifies that a caller-provided output buffer is large enough.
 *
 * ```ts
 * aoutput(new Uint8Array(16), { outputLen: 16 });
 * ```
 */
export function aoutput(out: any, instance: any, onlyAligned = false): void {
  abytes(out, undefined, 'output');
  const min = instance.outputLen;
  if (out.length < min) {
    throw new RangeError('digestInto() expects output buffer of length at least ' + min);
  }
  if (onlyAligned && !isAligned32(out)) throw new Error('invalid output, must be aligned');
}

/** One-shot hash helper with `.create()`. */
export type IHash = {
  (data: string | TArg<Uint8Array>): TRet<Uint8Array>;
  /** Input block size in bytes. */
  blockLen: number;
  /** Digest size in bytes. */
  outputLen: number;
  /** Creates a fresh incremental hash instance of the same algorithm. */
  create: any;
};

/** One-shot MAC helper with `.create()`. */
export type CMac<H extends IHash2 = IHash2, A extends any[] = []> = {
  (msg: TArg<Uint8Array>, key: TArg<Uint8Array>): TRet<Uint8Array>;
  /** Input block size in bytes. */
  blockLen: number;
  /** Digest size in bytes. */
  outputLen: number;
  /**
   * Creates a fresh incremental MAC instance of the same algorithm.
   * @param key - MAC key bytes.
   * @param args - Additional constructor arguments, when the MAC wrapper needs them.
   * @returns Fresh incremental MAC instance.
   */
  create(key: TArg<Uint8Array>, ...args: A): H;
};

/** Generic type encompassing 8/16/32-bit typed arrays, but not 64-bit. */
// prettier-ignore
export type TypedArray = Int8Array | Uint8ClampedArray | Uint8Array |
  Uint16Array | Int16Array | Uint32Array | Int32Array;

/**
 * Casts a typed-array view to Uint8Array.
 * @param arr - Typed-array view to reinterpret.
 * @returns Uint8Array view over the same bytes.
 * @example
 * Views 32-bit words as raw bytes without copying.
 *
 * ```ts
 * u8(new Uint32Array([1]));
 * ```
 */
export function u8(arr: TArg<TypedArray>): TRet<Uint8Array> {
  return new Uint8Array(arr.buffer, arr.byteOffset, arr.byteLength) as TRet<Uint8Array>;
}

/**
 * Casts a typed-array view to Uint32Array.
 * @param arr - Typed-array view to reinterpret.
 * @returns Uint32Array view over the same bytes. Callers are expected to provide a
 * 4-byte-aligned offset; trailing `1..3` bytes are silently dropped.
 * @example
 * Views a byte buffer as 32-bit words for block processing.
 *
 * ```ts
 * u32(new Uint8Array(4));
 * ```
 */
export function u32(arr: TArg<TypedArray>): TRet<Uint32Array> {
  return new Uint32Array(
    arr.buffer,
    arr.byteOffset,
    Math.floor(arr.byteLength / 4)
  ) as TRet<Uint32Array>;
}

/**
 * Zeroizes typed arrays in place.
 * Warning: JS provides no guarantees.
 * @param arrays - Arrays to wipe.
 * @example
 * Wipes a temporary key buffer after use.
 *
 * ```ts
 * const bytes = new Uint8Array([1]);
 * clean(bytes);
 * ```
 */
export function clean(...arrays: TArg<TypedArray[]>): void {
  for (let i = 0; i < arrays.length; i++) {
    arrays[i].fill(0);
  }
}

/**
 * Creates a DataView for byte-level manipulation.
 * @param arr - Typed-array view to wrap.
 * @returns DataView over the same bytes.
 * @example
 * Creates an endian-aware view for length encoding.
 *
 * ```ts
 * createView(new Uint8Array(4));
 * ```
 */
export function createView(arr: TArg<TypedArray>): DataView {
  return new DataView(arr.buffer, arr.byteOffset, arr.byteLength);
}

/**
 * Whether the current platform is little-endian.
 * Most are; some IBM systems are not.
 */
export const isLE: boolean = /* @__PURE__ */ (() =>
  new Uint8Array(new Uint32Array([0x11223344]).buffer)[0] === 0x44)();

/**
 * Reverses byte order of one 32-bit word.
 * @param word - Unsigned 32-bit word to swap.
 * @returns The same word with bytes reversed.
 * @example
 * Swaps a big-endian word into little-endian byte order.
 *
 * ```ts
 * byteSwap(0x11223344);
 * ```
 */
export const byteSwap = (word: number): number =>
  ((word << 24) & 0xff000000) |
  ((word << 8) & 0xff0000) |
  ((word >>> 8) & 0xff00) |
  ((word >>> 24) & 0xff);

/**
 * Normalizes one 32-bit word to the little-endian representation expected by cipher cores.
 * @param n - Unsigned 32-bit word to normalize.
 * @returns Little-endian normalized word on big-endian hosts, else the input word unchanged.
 * @example
 * Normalizes a host-endian word before passing it into an ARX/AES core.
 *
 * ```ts
 * swap8IfBE(0x11223344);
 * ```
 */
export const swap8IfBE: (n: number) => number = isLE
  ? (n: number) => n
  : (n: number) => byteSwap(n) >>> 0;

/**
 * Byte-swaps every word of a Uint32Array in place.
 * @param arr - Uint32Array whose words should be swapped.
 * @returns The same array after in-place byte swapping.
 * @example
 * Swaps every 32-bit word in a word-view buffer.
 *
 * ```ts
 * byteSwap32(new Uint32Array([0x11223344]));
 * ```
 */
export const byteSwap32 = (arr: TArg<Uint32Array>): TRet<Uint32Array> => {
  for (let i = 0; i < arr.length; i++) arr[i] = byteSwap(arr[i]);
  return arr as TRet<Uint32Array>;
};

/**
 * Normalizes a Uint32Array view to the little-endian representation expected by cipher cores.
 * @param u - Word view to normalize in place.
 * @returns Little-endian normalized word view.
 * @example
 * Normalizes a word-view buffer before block processing.
 *
 * ```ts
 * swap32IfBE(new Uint32Array([0x11223344]));
 * ```
 */
export const swap32IfBE: (u: TArg<Uint32Array>) => TRet<Uint32Array> = isLE
  ? (u: TArg<Uint32Array>) => u as TRet<Uint32Array>
  : byteSwap32;

// Built-in hex conversion:
// {@link https://caniuse.com/mdn-javascript_builtins_uint8array_fromhex | caniuse entry}
const hasHexBuiltin: boolean = /* @__PURE__ */ (() =>
  // @ts-ignore
  typeof Uint8Array.from([]).toHex === 'function' && typeof Uint8Array.fromHex === 'function')();

// Array where index 0xf0 (240) is mapped to string 'f0'
const hexes = /* @__PURE__ */ Array.from({ length: 256 }, (_, i) =>
  i.toString(16).padStart(2, '0')
);

/**
 * Convert byte array to hex string. Uses built-in function, when available.
 * @param bytes - Bytes to encode.
 * @returns Lowercase hexadecimal string.
 * @throws On wrong argument types. {@link TypeError}
 * @example
 * Formats ciphertext bytes for logs or test vectors.
 *
 * ```ts
 * bytesToHex(Uint8Array.from([0xca, 0xfe, 0x01, 0x23])); // 'cafe0123'
 * ```
 */
export function bytesToHex(bytes: TArg<Uint8Array>): string {
  abytes(bytes);
  // @ts-ignore
  if (hasHexBuiltin) return bytes.toHex();
  // pre-caching improves the speed 6x
  let hex = '';
  for (let i = 0; i < bytes.length; i++) {
    hex += hexes[bytes[i]];
  }
  return hex;
}

// We use optimized technique to convert hex string to byte array
const asciis = { _0: 48, _9: 57, A: 65, F: 70, a: 97, f: 102 } as const;
function asciiToBase16(ch: number): number | undefined {
  if (ch >= asciis._0 && ch <= asciis._9) return ch - asciis._0; // '2' => 50-48
  if (ch >= asciis.A && ch <= asciis.F) return ch - (asciis.A - 10); // 'B' => 66-(65-10)
  if (ch >= asciis.a && ch <= asciis.f) return ch - (asciis.a - 10); // 'b' => 98-(97-10)
  return;
}

/**
 * Convert hex string to byte array. Uses built-in function, when available.
 * @param hex - Hexadecimal string to decode.
 * @returns Decoded bytes.
 * @throws On wrong argument types. {@link TypeError}
 * @throws On malformed hexadecimal input. {@link RangeError}
 * @example
 * Parses a hex test vector into bytes.
 *
 * ```ts
 * hexToBytes('cafe0123'); // Uint8Array.from([0xca, 0xfe, 0x01, 0x23])
 * ```
 */
export function hexToBytes(hex: string): TRet<Uint8Array> {
  if (typeof hex !== 'string') throw new TypeError('hex string expected, got ' + typeof hex);
  if (hasHexBuiltin) {
    try {
      return (Uint8Array as any).fromHex(hex);
    } catch (error) {
      if (error instanceof SyntaxError) throw new RangeError(error.message);
      throw error;
    }
  }
  const hl = hex.length;
  const al = hl / 2;
  if (hl % 2) throw new RangeError('hex string expected, got unpadded hex of length ' + hl);
  const array = new Uint8Array(al);
  for (let ai = 0, hi = 0; ai < al; ai++, hi += 2) {
    const n1 = asciiToBase16(hex.charCodeAt(hi));
    const n2 = asciiToBase16(hex.charCodeAt(hi + 1));
    if (n1 === undefined || n2 === undefined) {
      const char = hex[hi] + hex[hi + 1];
      throw new RangeError(
        'hex string expected, got non-hex character "' + char + '" at index ' + hi
      );
    }
    array[ai] = n1 * 16 + n2; // multiply first octet, e.g. 'a3' => 10*16+3 => 160 + 3 => 163
  }
  return array as TRet<Uint8Array>;
}

// Used in micro
/**
 * Converts a big-endian hex string into bigint.
 * @param hex - Hexadecimal string without `0x`.
 * @returns Parsed bigint value. The empty string is treated as `0n`.
 * @throws On wrong argument types. {@link TypeError}
 * @example
 * Parses a big-endian field element or counter from hex.
 *
 * ```ts
 * hexToNumber('ff');
 * ```
 */
export function hexToNumber(hex: string): bigint {
  if (typeof hex !== 'string') throw new TypeError('hex string expected, got ' + typeof hex);
  return BigInt(hex === '' ? '0' : '0x' + hex); // Big Endian
}

// Used in ff1
// BE: Big Endian, LE: Little Endian
/**
 * Converts big-endian bytes into bigint.
 * @param bytes - Big-endian bytes.
 * @returns Parsed bigint value. Empty input is treated as `0n`.
 * @throws On invalid byte input passed to the internal hex conversion. {@link TypeError}
 * @example
 * Reads a big-endian integer from serialized bytes.
 *
 * ```ts
 * bytesToNumberBE(new Uint8Array([1, 0]));
 * ```
 */
export function bytesToNumberBE(bytes: TArg<Uint8Array>): bigint {
  return hexToNumber(bytesToHex(bytes));
}

// Used in micro, ff1
/**
 * Converts a number into big-endian bytes of fixed length.
 * @param n - Number to encode.
 * @param len - Output length in bytes.
 * @returns Big-endian bytes padded to `len`.
 * Validation is indirect through `hexToBytes(...)`, so negative values, `len = 0`,
 * and values that do not fit surface through the downstream hex parser instead of a
 * dedicated range guard here.
 * @throws On wrong argument types. {@link TypeError}
 * @throws If the requested output length cannot represent the encoded value. {@link RangeError}
 * @example
 * Encodes a counter as fixed-width big-endian bytes.
 *
 * ```ts
 * numberToBytesBE(1, 2);
 * ```
 */
export function numberToBytesBE(n: number | bigint, len: number): TRet<Uint8Array> {
  // Reject coercible non-numeric inputs before string/hex conversion changes behavior.
  if (typeof n === 'number') anumber(n);
  else if (typeof n !== 'bigint') throw new TypeError(`number or bigint expected, got ${typeof n}`);
  anumber(len);
  return hexToBytes(n.toString(16).padStart(len * 2, '0'));
}

// Global symbols, but ts doesn't see them:
// {@link https://github.com/microsoft/TypeScript/issues/31535 | TypeScript issue 31535}
declare const TextEncoder: any;
declare const TextDecoder: any;

/**
 * Converts string to bytes using UTF8 encoding.
 * @param str - String to encode.
 * @returns UTF-8 bytes in a detached fresh Uint8Array copy.
 * @throws On wrong argument types. {@link TypeError}
 * @example
 * Encodes application text before encryption or MACing.
 *
 * ```ts
 * utf8ToBytes('abc'); // new Uint8Array([97, 98, 99])
 * ```
 */
export function utf8ToBytes(str: string): TRet<Uint8Array> {
  if (typeof str !== 'string') throw new TypeError('string expected');
  return new Uint8Array(new TextEncoder().encode(str)) as TRet<Uint8Array>; // {@link https://bugzil.la/1681809 | Firefox bug 1681809}
}

/**
 * Converts bytes to string using UTF8 encoding.
 * @param bytes - UTF-8 bytes.
 * @returns Decoded string. Input validation is delegated to `TextDecoder`, and malformed
 * UTF-8 is replacement-decoded instead of rejected.
 * @example
 * Decodes UTF-8 plaintext back into a string.
 *
 * ```ts
 * bytesToUtf8(new Uint8Array([97, 98, 99])); // 'abc'
 * ```
 */
export function bytesToUtf8(bytes: TArg<Uint8Array>): string {
  return new TextDecoder().decode(bytes);
}

/**
 * Checks if two U8A use same underlying buffer and overlaps.
 * This is invalid and can corrupt data.
 * @param a - First byte view.
 * @param b - Second byte view.
 * @returns `true` when the views overlap in memory.
 * @example
 * Detects whether two slices alias the same backing buffer.
 *
 * ```ts
 * overlapBytes(new Uint8Array(4), new Uint8Array(4));
 * ```
 */
export function overlapBytes(a: TArg<Uint8Array>, b: TArg<Uint8Array>): boolean {
  // Zero-length views cannot overwrite anything, even if their offset sits inside another range.
  if (!a.byteLength || !b.byteLength) return false;
  return (
    a.buffer === b.buffer && // best we can do, may fail with an obscure Proxy
    a.byteOffset < b.byteOffset + b.byteLength && // a starts before b end
    b.byteOffset < a.byteOffset + a.byteLength // b starts before a end
  );
}

/**
 * If input and output overlap and input starts before output, we will overwrite end of input before
 * we start processing it, so this is not supported for most ciphers
 * (except chacha/salsa, which were designed for this)
 * @param input - Input bytes.
 * @param output - Output bytes.
 * @throws If the output view would overwrite unread input bytes. {@link Error}
 * @example
 * Rejects an in-place layout that would overwrite unread input bytes.
 *
 * ```ts
 * complexOverlapBytes(new Uint8Array(4), new Uint8Array(4));
 * ```
 */
export function complexOverlapBytes(input: TArg<Uint8Array>, output: TArg<Uint8Array>): void {
  // This is very cursed. It works somehow, but I'm completely unsure,
  // reasoning about overlapping aligned windows is very hard.
  if (overlapBytes(input, output) && input.byteOffset < output.byteOffset)
    throw new Error('complex overlap of input and output is not supported');
}

/**
 * Copies several Uint8Arrays into one.
 * @param arrays - Byte arrays to concatenate.
 * @returns Combined byte array.
 * @throws On wrong argument types inside the byte-array list. {@link TypeError}
 * @example
 * Builds a `nonce || ciphertext` style buffer.
 *
 * ```ts
 * concatBytes(new Uint8Array([1]), new Uint8Array([2]));
 * ```
 */
export function concatBytes(...arrays: TArg<Uint8Array[]>): TRet<Uint8Array> {
  let sum = 0;
  for (let i = 0; i < arrays.length; i++) {
    const a = arrays[i];
    abytes(a);
    sum += a.length;
  }
  const res = new Uint8Array(sum);
  for (let i = 0, pad = 0; i < arrays.length; i++) {
    const a = arrays[i];
    res.set(a, pad);
    pad += a.length;
  }
  return res as TRet<Uint8Array>;
}

// Used in ARX only
type EmptyObj = {};
/**
 * Merges user options into defaults.
 * @param defaults - Default option values.
 * @param opts - User-provided overrides.
 * @returns Combined options object.
 * The merge mutates `defaults` in place and returns the same object.
 * @throws If options are missing or not an object. {@link Error}
 * @example
 * Applies user overrides to the default cipher options.
 *
 * ```ts
 * checkOpts({ rounds: 20 }, { rounds: 8 });
 * ```
 */
export function checkOpts<T1 extends EmptyObj, T2 extends EmptyObj>(
  defaults: T1,
  opts: T2
): T1 & T2 {
  if (opts == null || typeof opts !== 'object') throw new Error('options must be defined');
  const merged = Object.assign(defaults, opts);
  return merged as T1 & T2;
}

/**
 * Compares two byte arrays in kinda constant time once lengths already match.
 * @param a - First byte array.
 * @param b - Second byte array.
 * @returns `true` when the arrays contain the same bytes. Different lengths still return early.
 * @example
 * Compares an expected authentication tag with the received one.
 *
 * ```ts
 * equalBytes(new Uint8Array([1]), new Uint8Array([1]));
 * ```
 */
export function equalBytes(a: TArg<Uint8Array>, b: TArg<Uint8Array>): boolean {
  if (a.length !== b.length) return false;
  let diff = 0;
  for (let i = 0; i < a.length; i++) diff |= a[i] ^ b[i];
  return diff === 0;
}

// TODO: remove
/** Incremental hash interface used internally. */
export interface IHash2 {
  /** Bytes processed per compression block. */
  blockLen: number;
  /** Bytes produced by the final digest. */
  outputLen: number;
  /**
   * Absorbs one more chunk into the hash state.
   * @param buf - Data chunk to hash.
   * @returns The same hash instance for chaining.
   */
  update(buf: string | TArg<Uint8Array>): this;
  /**
   * Writes the final digest into a caller-provided buffer.
   * @param buf - Destination buffer for the digest bytes.
   * @returns Nothing. Implementations write into `buf` in place.
   */
  digestInto(buf: TArg<Uint8Array>): void;
  /**
   * Finalizes the hash and returns a fresh digest buffer.
   * @returns Digest bytes.
   */
  digest(): TRet<Uint8Array>;
  /**
   * Resets internal state. Makes Hash instance unusable.
   * Reset is impossible for keyed hashes if key is consumed into state. If digest is not consumed
   * by user, they will need to manually call `destroy()` when zeroing is necessary.
   */
  destroy(): void;
}

/**
 * Wraps a keyed MAC constructor into a one-shot helper with `.create()`.
 * @param keyLen - Valid probe-key length used to read static metadata once.
 * The probe key is only used for `outputLen` / `blockLen`, so callers with several valid key sizes
 * can pass any representative size as long as those values stay fixed.
 * @param macCons - Keyed MAC constructor or factory.
 * @param fromMsg - Optional adapter that derives extra constructor args from the one-shot message.
 * @returns Callable MAC helper with `.create()`.
 */
export function wrapMacConstructor<H extends IHash2, A extends any[] = []>(
  keyLen: number,
  macCons: TArg<(key: Uint8Array, ...args: A) => H>,
  fromMsg?: TArg<(msg: Uint8Array) => A>
): TRet<CMac<H, A>> {
  const mac = macCons as (key: TArg<Uint8Array>, ...args: A) => H;
  const getArgs = (fromMsg || (() => [] as unknown as A)) as (msg: TArg<Uint8Array>) => A;
  const macC: any = (msg: TArg<Uint8Array>, key: TArg<Uint8Array>): TRet<Uint8Array> =>
    mac(key, ...getArgs(msg))
      .update(msg)
      .digest();
  const tmp = mac(new Uint8Array(keyLen), ...getArgs(new Uint8Array(0)));
  macC.outputLen = tmp.outputLen;
  macC.blockLen = tmp.blockLen;
  macC.create = (key: TArg<Uint8Array>, ...args: A) => mac(key, ...args);
  return macC as TRet<CMac<H, A>>;
}

// This will allow to re-use with composable things like packed & base encoders
// Also, we probably can make tags composable

/** Sync cipher: takes byte array and returns byte array. */
export type Cipher = {
  /**
   * Encrypts plaintext bytes.
   * @param plaintext - Data to encrypt.
   * @returns Ciphertext bytes.
   */
  encrypt(plaintext: TArg<Uint8Array>): TRet<Uint8Array>;
  /**
   * Decrypts ciphertext bytes.
   * @param ciphertext - Data to decrypt.
   * @returns Plaintext bytes.
   */
  decrypt(ciphertext: TArg<Uint8Array>): TRet<Uint8Array>;
};

/** Async cipher e.g. from built-in WebCrypto. */
export type AsyncCipher = {
  /**
   * Encrypts plaintext bytes.
   * @param plaintext - Data to encrypt.
   * @returns Promise resolving to ciphertext bytes.
   */
  encrypt(plaintext: TArg<Uint8Array>): Promise<TRet<Uint8Array>>;
  /**
   * Decrypts ciphertext bytes.
   * @param ciphertext - Data to decrypt.
   * @returns Promise resolving to plaintext bytes.
   */
  decrypt(ciphertext: TArg<Uint8Array>): Promise<TRet<Uint8Array>>;
};

/** Cipher with `output` argument which can optimize by doing 1 less allocation. */
export type CipherWithOutput = Cipher & {
  /**
   * Encrypts plaintext bytes into an optional caller-provided buffer.
   * @param plaintext - Data to encrypt.
   * @param output - Optional destination buffer.
   * @returns Ciphertext bytes.
   */
  encrypt(plaintext: TArg<Uint8Array>, output?: TArg<Uint8Array>): TRet<Uint8Array>;
  /**
   * Decrypts ciphertext bytes into an optional caller-provided buffer.
   * @param ciphertext - Data to decrypt.
   * @param output - Optional destination buffer.
   * @returns Plaintext bytes.
   */
  decrypt(ciphertext: TArg<Uint8Array>, output?: TArg<Uint8Array>): TRet<Uint8Array>;
};

/**
 * Params are outside of return type, so it is accessible before calling constructor.
 * If function support multiple nonceLength's, we return the best one.
 */
export type CipherParams = {
  /** Cipher block size in bytes. */
  blockSize: number;
  /** Nonce length in bytes when the cipher uses a fixed nonce size. */
  nonceLength?: number;
  /** Authentication-tag length in bytes for AEAD modes. */
  tagLength?: number;
  /** Whether nonce length is variable at runtime. */
  varSizeNonce?: boolean;
};
/**
 * ARX AEAD cipher, like salsa or chacha.
 * @param key - Secret key bytes.
 * @param nonce - Nonce bytes.
 * @param AAD - Optional associated data.
 * @returns Cipher instance with caller-managed output buffers.
 */
export type ARXCipher = ((
  key: TArg<Uint8Array>,
  nonce: TArg<Uint8Array>,
  AAD?: TArg<Uint8Array>
) => CipherWithOutput) & {
  blockSize: number;
  nonceLength: number;
  tagLength: number;
};
/**
 * Cipher constructor signature.
 * @param key - Secret key bytes.
 * @param args - Additional constructor arguments, such as nonce or IV.
 * @returns Cipher instance.
 */
export type CipherCons<T extends any[]> = (key: TArg<Uint8Array>, ...args: T) => Cipher;
/**
 * Wraps a cipher: validates args, ensures encrypt() can only be called once.
 * Used internally by the exported cipher constructors.
 * Output-buffer support is inferred from the wrapped `encrypt` / `decrypt`
 * arity (`fn.length === 2`), and tag-bearing constructors are expected to use
 * `args[1]` for optional AAD.
 * @__NO_SIDE_EFFECTS__
 * @param params - Static cipher metadata. See {@link CipherParams}.
 * @param constructor - Cipher constructor.
 * @returns Wrapped constructor with validation.
 */
export const wrapCipher = <C extends CipherCons<any>, P extends CipherParams>(
  params: P,
  constructor: C
): C & P => {
  function wrappedCipher(key: TArg<Uint8Array>, ...args: any[]): TRet<CipherWithOutput> {
    // Validate key
    abytes(key, undefined, 'key');

    // Validate nonce if nonceLength is present
    if (params.nonceLength !== undefined) {
      const nonce = args[0];
      abytes(nonce, params.varSizeNonce ? undefined : params.nonceLength, 'nonce');
    }

    // Validate AAD if tagLength present
    const tagl = params.tagLength;
    if (tagl && args[1] !== undefined) abytes(args[1], undefined, 'AAD');

    const cipher = constructor(key, ...args);
    const checkOutput = (fnLength: number, output?: TArg<Uint8Array>) => {
      if (output !== undefined) {
        if (fnLength !== 2) throw new Error('cipher output not supported');
        abytes(output, undefined, 'output');
      }
    };
    // Create wrapped cipher with validation and single-use encryption
    let called = false;
    const wrCipher = {
      encrypt(data: TArg<Uint8Array>, output?: TArg<Uint8Array>) {
        if (called) throw new Error('cannot encrypt() twice with same key + nonce');
        called = true;
        abytes(data);
        checkOutput(cipher.encrypt.length, output);
        return (cipher as CipherWithOutput).encrypt(data, output);
      },
      decrypt(data: TArg<Uint8Array>, output?: TArg<Uint8Array>) {
        abytes(data);
        if (tagl && data.length < tagl)
          throw new Error('"ciphertext" expected length bigger than tagLength=' + tagl);
        checkOutput(cipher.decrypt.length, output);
        return (cipher as CipherWithOutput).decrypt(data, output);
      },
    };

    return wrCipher as TRet<CipherWithOutput>;
  }

  Object.assign(wrappedCipher, params);
  return wrappedCipher as C & P;
};

/**
 * Represents a Salsa or ChaCha xor stream.
 * @param key - Secret key bytes.
 * @param nonce - Nonce bytes.
 * @param data - Input bytes to xor with the keystream.
 * @param output - Optional destination buffer.
 * @param counter - Optional starting block counter.
 * @returns Output bytes.
 */
export type XorStream = (
  key: TArg<Uint8Array>,
  nonce: TArg<Uint8Array>,
  data: TArg<Uint8Array>,
  output?: TArg<Uint8Array>,
  counter?: number
) => TRet<Uint8Array>;

/**
 * By default, returns u8a of length.
 * When out is available, it checks it for validity and uses it.
 * @param expectedLength - Required output length.
 * @param out - Optional destination buffer.
 * @param onlyAligned - Whether `out` must be 4-byte aligned.
 * @returns Output buffer ready for writing.
 * @throws On wrong argument types. {@link TypeError}
 * @throws If the provided output buffer has the wrong size or alignment. {@link Error}
 * @example
 * Reuses a caller-provided output buffer when lengths match.
 *
 * ```ts
 * getOutput(16, new Uint8Array(16));
 * ```
 */
export function getOutput(
  expectedLength: number,
  out?: TArg<Uint8Array>,
  onlyAligned = true
): TRet<Uint8Array> {
  if (out === undefined) return new Uint8Array(expectedLength) as TRet<Uint8Array>;
  // Keep Buffer/cross-realm Uint8Array support here instead of trusting a shape-compatible object.
  abytes(out, undefined, 'output');
  if (out.length !== expectedLength)
    throw new Error(
      '"output" expected Uint8Array of length ' + expectedLength + ', got: ' + out.length
    );
  if (onlyAligned && !isAligned32(out)) throw new Error('invalid output, must be aligned');
  return out as TRet<Uint8Array>;
}

/**
 * Encodes data and AAD bit lengths into a 16-byte buffer.
 * @param dataLength - Data length in bits.
 * @param aadLength - AAD length in bits.
 * The serialized block is still `aadLength || dataLength`, matching GCM/Poly1305
 * conventions even though the helper parameter order is `(dataLength, aadLength)`.
 * @param isLE - Whether to encode lengths as little-endian.
 * @returns 16-byte length block.
 * @throws On wrong argument types passed to the endian validator. {@link TypeError}
 * @throws On wrong argument ranges or values. {@link RangeError}
 * @example
 * Builds the length block appended by GCM and Poly1305.
 *
 * ```ts
 * u64Lengths(16, 8, true);
 * ```
 */
export function u64Lengths(dataLength: number, aadLength: number, isLE: boolean): TRet<Uint8Array> {
  // Reject coercible non-number lengths like '10' and true before BigInt(...) accepts them.
  anumber(dataLength);
  anumber(aadLength);
  abool(isLE);
  const num = new Uint8Array(16);
  const view = createView(num);
  view.setBigUint64(0, BigInt(aadLength), isLE);
  view.setBigUint64(8, BigInt(dataLength), isLE);
  return num as TRet<Uint8Array>;
}

/**
 * Checks whether a byte array is aligned to a 4-byte offset.
 * @param bytes - Byte array to inspect.
 * @returns `true` when the view is 4-byte aligned.
 * @example
 * Checks whether a buffer can be safely viewed as Uint32Array.
 *
 * ```ts
 * isAligned32(new Uint8Array(4));
 * ```
 */
export function isAligned32(bytes: TArg<Uint8Array>): boolean {
  return bytes.byteOffset % 4 === 0;
}

/**
 * Copies bytes into a new Uint8Array.
 * @param bytes - Bytes to copy.
 * @returns Copied byte array.
 * @throws On wrong argument types. {@link TypeError}
 * @example
 * Copies input into an aligned Uint8Array before block processing.
 *
 * ```ts
 * copyBytes(new Uint8Array([1, 2]));
 * ```
 */
export function copyBytes(bytes: TArg<Uint8Array>): TRet<Uint8Array> {
  // `Uint8Array.from(...)` would also accept arrays / other typed arrays. Keep this helper strict
  // because callers use it at byte-validation boundaries before mutating the detached copy.
  return Uint8Array.from(abytes(bytes)) as TRet<Uint8Array>;
}

/**
 * Cryptographically secure PRNG.
 * Uses internal OS-level `crypto.getRandomValues`.
 * @param bytesLength - Number of bytes to produce.
 * Validation is delegated to `Uint8Array(bytesLength)` and `getRandomValues`, so
 * non-integers, negative lengths, and oversize requests surface backend/runtime errors.
 * @returns Random byte array.
 * @throws On wrong argument types. {@link TypeError}
 * @throws On wrong argument ranges or values. {@link RangeError}
 * @throws If the runtime does not expose `crypto.getRandomValues`. {@link Error}
 * @example
 * Generates a fresh nonce or key.
 *
 * ```ts
 * randomBytes(16);
 * ```
 */
export function randomBytes(bytesLength = 32): TRet<Uint8Array> {
  // Validate upfront so fractional / coercible lengths do not silently
  // truncate through Uint8Array().
  anumber(bytesLength);
  const cr = typeof globalThis === 'object' ? (globalThis as any).crypto : null;
  if (typeof cr?.getRandomValues !== 'function')
    throw new Error('crypto.getRandomValues must be defined');
  return cr.getRandomValues(new Uint8Array(bytesLength)) as TRet<Uint8Array>;
}

/**
 * The pseudorandom number generator doesn't wipe current state:
 * instead, it generates new one based on previous state + entropy.
 * Not reseed/rekey, since AES CTR DRBG does rekey on each randomBytes,
 * which is in fact `reseed`, since it changes counter too.
 */
export interface PRG {
  /**
   * Mixes fresh entropy into the current generator state.
   * @param seed - Entropy bytes to absorb.
   */
  addEntropy(seed: TArg<Uint8Array>): void;
  /**
   * Produces a requested number of pseudorandom bytes.
   * @param bytesLength - Number of bytes to generate.
   * @returns Random byte array.
   */
  randomBytes(bytesLength: number): TRet<Uint8Array>;
  /** Destroys the generator state. */
  clean(): void;
}

/** Removes the nonce argument from a cipher constructor type. */
export type RemoveNonce<T extends (...args: any) => any> = T extends (
  arg0: any,
  arg1: any,
  ...rest: infer R
) => infer Ret
  ? (key: TArg<Uint8Array>, ...args: R) => Ret
  : never;
/**
 * Cipher constructor that requires a nonce argument.
 * @param key - Secret key bytes.
 * @param nonce - Nonce bytes.
 * @param args - Additional cipher-specific arguments.
 * @returns Cipher instance.
 */
export type CipherWithNonce = ((
  key: TArg<Uint8Array>,
  nonce: TArg<Uint8Array>,
  ...args: any[]
) => Cipher | AsyncCipher) & {
  nonceLength: number;
};

/**
 * Uses CSPRNG for nonce, nonce injected in ciphertext.
 * For `encrypt`, a `nonceBytes`-length buffer is fetched from CSPRNG and
 * prepended to encrypted ciphertext. For `decrypt`, first `nonceBytes` of ciphertext
 * are treated as nonce. The wrapper always allocates a fresh `nonce || ciphertext`
 * buffer on encrypt and intentionally does not support caller-provided destination buffers.
 * Too-short decrypt inputs are split into short/empty nonce views and then delegated
 * to the wrapped cipher instead of being rejected here first.
 *
 * NOTE: Under the same key, using random nonces (e.g. `managedNonce`) with AES-GCM and ChaCha
 * should be limited to `2**23` (8M) messages to get a collision chance of
 * `2**-50`. Stretching to `2**32` (4B) messages would raise that chance to
 * `2**-33`, still negligible but creeping up.
 * @param fn - Cipher constructor that expects a nonce.
 * @param randomBytes_ - Random-byte source used for nonce generation.
 * @returns Cipher constructor that prepends the nonce to ciphertext.
 * @throws On wrong argument types. {@link TypeError}
 * @throws On invalid nonce lengths observed at wrapper construction or use. {@link RangeError}
 * @example
 * Prepends a fresh random nonce to every ciphertext.
 *
 * ```ts
 * import { gcm } from '@noble/ciphers/aes.js';
 * import { managedNonce, randomBytes } from '@noble/ciphers/utils.js';
 * const wrapped = managedNonce(gcm);
 * const key = randomBytes(16);
 * const ciphertext = wrapped(key).encrypt(new Uint8Array([1, 2, 3]));
 * wrapped(key).decrypt(ciphertext);
 * ```
 */
export function managedNonce<T extends CipherWithNonce>(
  fn: T,
  randomBytes_: typeof randomBytes = randomBytes
): TRet<RemoveNonce<T>> {
  const { nonceLength } = fn;
  anumber(nonceLength);
  const addNonce = (
    nonce: TArg<Uint8Array>,
    ciphertext: TArg<Uint8Array>,
    plaintext: TArg<Uint8Array>
  ) => {
    const out = concatBytes(nonce, ciphertext);
    // Wrapped ciphers may alias caller plaintext on encrypt(); never zero
    // caller-owned buffers here.
    if (!overlapBytes(plaintext, ciphertext)) ciphertext.fill(0);
    return out;
  };
  // NOTE: we cannot support DST here, it would be mistake:
  // - we don't know how much dst length cipher requires
  // - nonce may unalign dst and break everything
  // - we create new u8a anyway (concatBytes)
  // - previously we passed all args to cipher, but that was mistake!
  const res = ((key: TArg<Uint8Array>, ...args: any[]): any => ({
    encrypt(plaintext: TArg<Uint8Array>) {
      abytes(plaintext);
      const nonce = randomBytes_(nonceLength);
      const encrypted = fn(key, nonce, ...args).encrypt(plaintext);
      // @ts-ignore
      if (encrypted instanceof Promise)
        return encrypted.then((ct) => addNonce(nonce, ct, plaintext));
      return addNonce(nonce, encrypted, plaintext);
    },
    decrypt(ciphertext: TArg<Uint8Array>) {
      abytes(ciphertext);
      const nonce = ciphertext.subarray(0, nonceLength);
      const decrypted = ciphertext.subarray(nonceLength);
      return fn(key, nonce, ...args).decrypt(decrypted);
    },
  })) as RemoveNonce<T> & { blockSize?: number; tagLength?: number };
  // Auto-nonce wrappers still preserve the wrapped payload geometry.
  if ('blockSize' in fn) res.blockSize = (fn as any).blockSize;
  if ('tagLength' in fn) res.tagLength = (fn as any).tagLength;
  return res as TRet<RemoveNonce<T>>;
}

/** `Uint8Array.of()` return type helper for TS 5.9. */
export type Uint8ArrayBuffer = TRet<Uint8Array>;