/*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
import { sha256 } from '@noble/hashes/sha256';
import { createCurve } from './_shortw_utils.js';
import { createHasher } from './abstract/hash-to-curve.js';
import { Field } from './abstract/modular.js';
import { mapToCurveSimpleSWU } from './abstract/weierstrass.js';

// NIST secp256r1 aka p256
// https://www.secg.org/sec2-v2.pdf, https://neuromancer.sk/std/nist/P-256

const Fp = Field(BigInt('0xffffffff00000001000000000000000000000000ffffffffffffffffffffffff'));
const CURVE_A = Fp.create(BigInt('-3'));
const CURVE_B = BigInt('0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b');

// prettier-ignore
export const p256 = createCurve({
  a: CURVE_A, // Equation params: a, b
  b: CURVE_B,
  Fp, // Field: 2n**224n * (2n**32n-1n) + 2n**192n + 2n**96n-1n
  // Curve order, total count of valid points in the field
  n: BigInt('0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551'),
  // Base (generator) point (x, y)
  Gx: BigInt('0x6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296'),
  Gy: BigInt('0x4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5'),
  h: BigInt(1),
  lowS: false,
} as const, sha256);
export const secp256r1 = p256;

const mapSWU = /* @__PURE__ */ (() =>
  mapToCurveSimpleSWU(Fp, {
    A: CURVE_A,
    B: CURVE_B,
    Z: Fp.create(BigInt('-10')),
  }))();

const htf = /* @__PURE__ */ (() =>
  createHasher(secp256r1.ProjectivePoint, (scalars: bigint[]) => mapSWU(scalars[0]), {
    DST: 'P256_XMD:SHA-256_SSWU_RO_',
    encodeDST: 'P256_XMD:SHA-256_SSWU_NU_',
    p: Fp.ORDER,
    m: 1,
    k: 128,
    expand: 'xmd',
    hash: sha256,
  }))();
export const hashToCurve = /* @__PURE__ */ (() => htf.hashToCurve)();
export const encodeToCurve = /* @__PURE__ */ (() => htf.encodeToCurve)();