#!/usr/bin/env node

import { createECDH, randomBytes } from "node:crypto";
import {
  accessSync,
  chmodSync,
  constants,
  existsSync,
  mkdirSync,
  readFileSync,
  writeFileSync,
} from "node:fs";
import { homedir } from "node:os";
import { dirname, join } from "node:path";
import { spawnSync } from "node:child_process";
import { fileURLToPath } from "node:url";

const identityName = "Github Manager";
const relayUrl = process.env.BUZZ_RELAY_URL || "https://buzz.gdk.so";
const configHome =
  process.env.XDG_CONFIG_HOME || join(homedir(), ".config");
const buzzHome =
  process.env.GOOSE_BUZZ_HOME || join(configHome, "goose", "buzz");
const identityDirectory = join(buzzHome, "github-manager");
const privateKeyPath = join(identityDirectory, "private-key.nsec");
const publicKeyPath = join(identityDirectory, "public-key.npub");
const publicKeyHexPath = join(identityDirectory, "public-key.hex");
const profileCreatedPath = join(identityDirectory, "profile-created");
const keyPaths = [privateKeyPath, publicKeyPath, publicKeyHexPath];
const avatarPath = join(
  dirname(fileURLToPath(import.meta.url)),
  "assets",
  "GithubManager.png",
);

const existingKeyPaths = keyPaths.filter(existsSync);
let nsec;
let npub;
let publicKeyHex;
if (existingKeyPaths.length > 0) {
  if (existingKeyPaths.length !== keyPaths.length) {
    console.error(
      `Refusing to change the incomplete Github Manager key pair in ${identityDirectory}`,
    );
    process.exit(1);
  }

  chmodSync(identityDirectory, 0o700);
  for (const keyPath of keyPaths) {
    chmodSync(keyPath, 0o600);
  }

  nsec = readFileSync(privateKeyPath, "utf8").trim();
  npub = readFileSync(publicKeyPath, "utf8").trim();
  publicKeyHex = readFileSync(publicKeyHexPath, "utf8").trim();
  console.log(`Github Manager keys already exist: ${npub}`);
  console.log(`Keys: ${identityDirectory}`);
  if (existsSync(profileCreatedPath)) {
    chmodSync(profileCreatedPath, 0o600);
    console.log("No key or profile changes were made.");
    process.exit(0);
  }
  console.log("The profile marker is missing; recreating the Buzz profile.");
} else {
  mkdirSync(identityDirectory, { recursive: true, mode: 0o700 });
  chmodSync(identityDirectory, 0o700);

  const { privateKey, publicKey } = generateKeyPair();
  publicKeyHex = publicKey.toString("hex");
  nsec = bech32Encode("nsec", privateKey);
  npub = bech32Encode("npub", publicKey);

  writeSecret(privateKeyPath, nsec);
  writeSecret(publicKeyPath, npub);
  writeSecret(publicKeyHexPath, publicKeyHex);

  console.log(`Generated ${identityName}: ${npub}`);
  console.log(`Public key (hex): ${publicKeyHex}`);
  console.log(`Keys: ${identityDirectory}`);
}

const buzz = findBuzz();
const buzzEnvironment = {
  ...process.env,
  BUZZ_PRIVATE_KEY: nsec,
};
const uploadResult = spawnSync(
  buzz,
  ["--relay", relayUrl, "upload", "file", "--file", avatarPath],
  {
    encoding: "utf8",
    env: buzzEnvironment,
  },
);

if (uploadResult.error) {
  console.error("The Github Manager avatar was not uploaded.");
  console.error(`Could not run Buzz: ${uploadResult.error.message}`);
  process.exit(1);
}

if (uploadResult.status !== 0) {
  console.error("The Github Manager avatar was not uploaded.");
  process.stderr.write(uploadResult.stderr);
  process.exit(uploadResult.status || 1);
}

let avatarUrl;
try {
  avatarUrl = JSON.parse(uploadResult.stdout).url;
} catch {
  console.error("Buzz returned an invalid response after uploading the avatar.");
  process.exit(1);
}

if (!avatarUrl) {
  console.error("Buzz did not return a URL for the uploaded avatar.");
  process.exit(1);
}

const profileResult = spawnSync(
  buzz,
  [
    "--relay",
    relayUrl,
    "users",
    "set-profile",
    "--name",
    identityName,
    "--avatar",
    avatarUrl,
  ],
  {
    encoding: "utf8",
    env: buzzEnvironment,
  },
);

if (profileResult.error) {
  console.error("The Buzz profile was not created.");
  console.error(`Could not run Buzz: ${profileResult.error.message}`);
  process.exit(1);
}

if (profileResult.status !== 0) {
  console.error("The Buzz profile was not created.");
  process.stderr.write(profileResult.stderr);
  process.exit(profileResult.status || 1);
}

writeSecret(profileCreatedPath, new Date().toISOString());

if (profileResult.stdout) {
  process.stdout.write(profileResult.stdout);
}
console.log(`Created the ${identityName} Buzz profile.`);

function writeSecret(path, value) {
  writeFileSync(path, `${value}\n`, { flag: "wx", mode: 0o600 });
  chmodSync(path, 0o600);
}

function generateKeyPair() {
  while (true) {
    const privateKey = randomBytes(32);
    const ecdh = createECDH("secp256k1");

    try {
      ecdh.setPrivateKey(privateKey);
      const compressedPublicKey = ecdh.getPublicKey(undefined, "compressed");
      return {
        privateKey,
        publicKey: compressedPublicKey.subarray(1),
      };
    } catch {
      continue;
    }
  }
}

function findBuzz() {
  if (process.env.BUZZ_BIN) {
    return process.env.BUZZ_BIN;
  }

  const bundledBuzz = "/Applications/Buzz.app/Contents/MacOS/buzz";
  try {
    accessSync(bundledBuzz, constants.X_OK);
    return bundledBuzz;
  } catch {
    return "buzz";
  }
}

function bech32Encode(prefix, bytes) {
  const alphabet = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
  const words = convertBits(bytes, 8, 5);
  const checksumInput = [
    ...expandPrefix(prefix),
    ...words,
    0,
    0,
    0,
    0,
    0,
    0,
  ];
  const checksum = polymod(checksumInput) ^ 1;
  const checksumWords = Array.from(
    { length: 6 },
    (_, index) => (checksum >> (5 * (5 - index))) & 31,
  );

  return `${prefix}1${[...words, ...checksumWords]
    .map((word) => alphabet[word])
    .join("")}`;
}

function convertBits(bytes, fromBits, toBits) {
  let accumulator = 0;
  let bitCount = 0;
  const result = [];
  const mask = (1 << toBits) - 1;

  for (const byte of bytes) {
    accumulator = (accumulator << fromBits) | byte;
    bitCount += fromBits;

    while (bitCount >= toBits) {
      bitCount -= toBits;
      result.push((accumulator >> bitCount) & mask);
    }
  }

  if (bitCount > 0) {
    result.push((accumulator << (toBits - bitCount)) & mask);
  }

  return result;
}

function expandPrefix(prefix) {
  return [
    ...Array.from(prefix, (character) => character.charCodeAt(0) >> 5),
    0,
    ...Array.from(prefix, (character) => character.charCodeAt(0) & 31),
  ];
}

function polymod(values) {
  const generators = [
    0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3,
  ];
  let checksum = 1;

  for (const value of values) {
    const top = checksum >>> 25;
    checksum = ((checksum & 0x1ffffff) << 5) ^ value;

    for (let index = 0; index < generators.length; index += 1) {
      if ((top >> index) & 1) {
        checksum ^= generators[index];
      }
    }
  }

  return checksum;
}