// Writes packages/runtime/src/scr_cipher_info.h from the running Node's
// crypto.getCipherInfo: one record per cipher, the names (lowercase) and nids
// that find it, and the keyLength and ivLength options each accepts. The
// candidate names are getCiphers() and `openssl list -cipher-algorithms`
// (OpenSSL's aliases and its legacy-provider ciphers, which getCiphers()
// leaves out). Run with the pinned Node: node scripts/gen-cipher-info.mjs
import crypto from "node:crypto";
import { execFileSync } from "node:child_process";
import fs from "node:fs";

const listed = execFileSync("openssl", ["list", "-cipher-algorithms"], { encoding: "utf8" })
  .match(/[A-Za-z0-9][A-Za-z0-9._-]*/g)
  .filter((word) => !["Legacy", "Provided", "default", "legacy", "base", "fips"].includes(word));
const candidates = new Set([...crypto.getCiphers(), ...listed]);
for (let nid = 1; nid < 1400; nid++) {
  const info = crypto.getCipherInfo(nid);
  if (info) candidates.add(info.name);
}

function ivRule(name, info) {
  const accepted = [];
  for (let v = 0; v <= 70; v++) if (crypto.getCipherInfo(name, { ivLength: v })) accepted.push(v);
  const large = !!crypto.getCipherInfo(name, { ivLength: 100000 });
  const own = info.ivLength ?? 0;
  if (accepted.length === 0) return "SC_INFO_NONE";
  if (accepted.length === 1 && accepted[0] === own && !large) return "SC_INFO_EXACT";
  if (accepted.join() === "7,8,9,10,11,12,13" && !large) return "SC_INFO_CCM";
  if (accepted.join() === [...Array(15)].map((_, i) => i + 1).join() && !large)
    return "SC_INFO_OCB";
  if (accepted.length === 71 && large) return "SC_INFO_ANY";
  throw new Error(`unclassified ivLength rule for ${name}: ${accepted}`);
}
function keyRule(name, info) {
  const accepted = [];
  for (let k = 0; k <= 80; k++) if (crypto.getCipherInfo(name, { keyLength: k })) accepted.push(k);
  if (accepted.length === 0) return "SC_INFO_NONE";
  if (accepted.length === 1 && accepted[0] === info.keyLength) return "SC_INFO_EXACT";
  throw new Error(`unclassified keyLength rule for ${name}: ${accepted}`);
}

const records = [];
const recordIndex = new Map();
function recordOf(name, info) {
  const key = JSON.stringify(info);
  let index = recordIndex.get(key);
  const rules = [keyRule(name, info), ivRule(name, info)];
  if (index === undefined) {
    index = records.length;
    records.push({ info, rules });
    recordIndex.set(key, index);
  } else if (records[index].rules.join() !== rules.join()) {
    throw new Error(`rules differ for ${name}`);
  }
  return index;
}

const names = [];
for (const name of [...candidates].map((n) => n.toLowerCase()).sort()) {
  if (names.length && names.at(-1)[0] === name) continue;
  const info = crypto.getCipherInfo(name);
  if (info) names.push([name, recordOf(name, info)]);
}
const nids = [];
for (let nid = 1; nid < 1400; nid++) {
  const info = crypto.getCipherInfo(nid);
  if (info) nids.push([nid, recordOf(info.name, info)]);
}

const str = (s) => (s === undefined ? "NULL" : JSON.stringify(s));
const num = (n) => (n === undefined ? -1 : n);
let out = `/* Generated by scripts/gen-cipher-info.mjs from Node ${process.version}'s
 * crypto.getCipherInfo: every cipher OpenSSL names, with the fields Node
 * reports (-1 or NULL for a field it leaves out) and the keyLength and
 * ivLength options each accepts. Do not edit. */
#ifndef SCR_CIPHER_INFO_H
#define SCR_CIPHER_INFO_H

enum { SC_INFO_NONE, SC_INFO_EXACT, SC_INFO_CCM, SC_INFO_OCB, SC_INFO_ANY };

typedef struct {
  const char *mode;
  const char *name;
  int nid;
  int block_size;
  int iv_length;
  int key_length;
  unsigned char key_rule;
  unsigned char iv_rule;
} ScCipherInfo;

static const ScCipherInfo sc_cipher_infos[] = {
`;
for (const { info, rules } of records)
  out += `  {${str(info.mode)}, ${str(info.name)}, ${num(info.nid)}, ${num(info.blockSize)}, ${num(info.ivLength)}, ${info.keyLength}, ${rules[0]}, ${rules[1]}},\n`;
out += `};

/* Lowercase names, sorted, with their record. */
static const struct {
  const char *name;
  unsigned short info;
} sc_cipher_info_names[] = {
`;
for (const [name, index] of names) out += `  {${JSON.stringify(name)}, ${index}},\n`;
out += `};

/* Nids, ascending, with their record. */
static const struct {
  unsigned short nid;
  unsigned short info;
} sc_cipher_info_nids[] = {
`;
for (const [nid, index] of nids) out += `  {${nid}, ${index}},\n`;
out += `};

#endif
`;
for (const { info } of records) {
  const keys = Object.keys(info).join();
  const expected = ["mode", "name", "nid", "blockSize", "ivLength", "keyLength"]
    .filter((k) => k in info)
    .join();
  if (keys !== expected) throw new Error(`unexpected key order ${keys}`);
}
fs.writeFileSync(new URL("../packages/runtime/src/scr_cipher_info.h", import.meta.url), out);
console.log(records.length, "records,", names.length, "names,", nids.length, "nids");