#!/usr/bin/env node

/**
 * PDS Setup Script
 *
 * Registers a did:plc, initializes the PDS, and notifies the relay.
 * Zero dependencies - uses Node.js built-ins only.
 *
 * Usage: node scripts/setup.js --handle alice --pds https://your-pds.workers.dev
 */

import { webcrypto } from 'node:crypto';
import { writeFileSync } from 'node:fs';

// === ARGUMENT PARSING ===

function parseArgs() {
  const args = process.argv.slice(2);
  const opts = {
    handle: null,
    pds: null,
    plcUrl: 'https://plc.directory',
    relayUrl: 'https://bsky.network',
  };

  for (let i = 0; i < args.length; i++) {
    if (args[i] === '--handle' && args[i + 1]) {
      opts.handle = args[++i];
    } else if (args[i] === '--pds' && args[i + 1]) {
      opts.pds = args[++i];
    } else if (args[i] === '--plc-url' && args[i + 1]) {
      opts.plcUrl = args[++i];
    } else if (args[i] === '--relay-url' && args[i + 1]) {
      opts.relayUrl = args[++i];
    }
  }

  if (!opts.pds) {
    console.error(
      'Usage: node scripts/setup.js --pds <pds-url> [--handle <subdomain>]',
    );
    console.error('');
    console.error('Options:');
    console.error(
      '  --pds         PDS URL (e.g., "https://atproto-pds.chad-53c.workers.dev")',
    );
    console.error(
      '  --handle      Subdomain handle (e.g., "alice") - optional, uses bare hostname if omitted',
    );
    console.error(
      '  --plc-url     PLC directory URL (default: https://plc.directory)',
    );
    console.error('  --relay-url   Relay URL (default: https://bsky.network)');
    process.exit(1);
  }

  return opts;
}

// === KEY GENERATION ===

async function generateP256Keypair() {
  const keyPair = await webcrypto.subtle.generateKey(
    { name: 'ECDSA', namedCurve: 'P-256' },
    true,
    ['sign', 'verify'],
  );

  // Export private key as raw 32 bytes
  const privateJwk = await webcrypto.subtle.exportKey(
    'jwk',
    keyPair.privateKey,
  );
  const privateBytes = base64UrlDecode(privateJwk.d);

  // Export public key as uncompressed point (65 bytes)
  const publicRaw = await webcrypto.subtle.exportKey('raw', keyPair.publicKey);
  const publicBytes = new Uint8Array(publicRaw);

  // Compress public key to 33 bytes
  const compressedPublic = compressPublicKey(publicBytes);

  return {
    privateKey: privateBytes,
    publicKey: compressedPublic,
    cryptoKey: keyPair.privateKey,
  };
}

function compressPublicKey(uncompressed) {
  // uncompressed is 65 bytes: 0x04 + x(32) + y(32)
  const x = uncompressed.slice(1, 33);
  const y = uncompressed.slice(33, 65);
  const prefix = (y[31] & 1) === 0 ? 0x02 : 0x03;
  const compressed = new Uint8Array(33);
  compressed[0] = prefix;
  compressed.set(x, 1);
  return compressed;
}

function base64UrlDecode(str) {
  const base64 = str.replace(/-/g, '+').replace(/_/g, '/');
  const binary = atob(base64);
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < binary.length; i++) {
    bytes[i] = binary.charCodeAt(i);
  }
  return bytes;
}

function bytesToHex(bytes) {
  return Array.from(bytes)
    .map((b) => b.toString(16).padStart(2, '0'))
    .join('');
}

// === DID:KEY ENCODING ===

// Multicodec prefix for P-256 public key (0x1200)
const P256_MULTICODEC = new Uint8Array([0x80, 0x24]);

function publicKeyToDidKey(compressedPublicKey) {
  // did:key format: "did:key:" + multibase(base58btc) of multicodec + key
  const keyWithCodec = new Uint8Array(
    P256_MULTICODEC.length + compressedPublicKey.length,
  );
  keyWithCodec.set(P256_MULTICODEC);
  keyWithCodec.set(compressedPublicKey, P256_MULTICODEC.length);

  return `did:key:z${base58btcEncode(keyWithCodec)}`;
}

function base58btcEncode(bytes) {
  const ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

  // Count leading zeros
  let zeros = 0;
  for (const b of bytes) {
    if (b === 0) zeros++;
    else break;
  }

  // Convert to base58
  const digits = [0];
  for (const byte of bytes) {
    let carry = byte;
    for (let i = 0; i < digits.length; i++) {
      carry += digits[i] << 8;
      digits[i] = carry % 58;
      carry = (carry / 58) | 0;
    }
    while (carry > 0) {
      digits.push(carry % 58);
      carry = (carry / 58) | 0;
    }
  }

  // Convert to string
  let result = '1'.repeat(zeros);
  for (let i = digits.length - 1; i >= 0; i--) {
    result += ALPHABET[digits[i]];
  }

  return result;
}

// === CBOR ENCODING (dag-cbor compliant for PLC operations) ===

function cborEncodeKey(key) {
  // Encode a string key to CBOR bytes (for sorting)
  const bytes = new TextEncoder().encode(key);
  const parts = [];
  const mt = 3 << 5; // major type 3 = text string
  if (bytes.length < 24) {
    parts.push(mt | bytes.length);
  } else if (bytes.length < 256) {
    parts.push(mt | 24, bytes.length);
  } else if (bytes.length < 65536) {
    parts.push(mt | 25, bytes.length >> 8, bytes.length & 0xff);
  }
  parts.push(...bytes);
  return new Uint8Array(parts);
}

function compareBytes(a, b) {
  // dag-cbor: bytewise lexicographic order of encoded keys
  const minLen = Math.min(a.length, b.length);
  for (let i = 0; i < minLen; i++) {
    if (a[i] !== b[i]) return a[i] - b[i];
  }
  return a.length - b.length;
}

function cborEncode(value) {
  const parts = [];

  function encode(val) {
    if (val === null) {
      parts.push(0xf6);
    } else if (typeof val === 'string') {
      const bytes = new TextEncoder().encode(val);
      encodeHead(3, bytes.length);
      parts.push(...bytes);
    } else if (typeof val === 'number') {
      if (Number.isInteger(val) && val >= 0) {
        encodeHead(0, val);
      }
    } else if (val instanceof Uint8Array) {
      encodeHead(2, val.length);
      parts.push(...val);
    } else if (Array.isArray(val)) {
      encodeHead(4, val.length);
      for (const item of val) encode(item);
    } else if (typeof val === 'object') {
      // dag-cbor: sort keys by their CBOR-encoded bytes (length first, then lexicographic)
      const keys = Object.keys(val);
      const keysSorted = keys.sort((a, b) =>
        compareBytes(cborEncodeKey(a), cborEncodeKey(b)),
      );
      encodeHead(5, keysSorted.length);
      for (const key of keysSorted) {
        encode(key);
        encode(val[key]);
      }
    }
  }

  function encodeHead(majorType, length) {
    const mt = majorType << 5;
    if (length < 24) {
      parts.push(mt | length);
    } else if (length < 256) {
      parts.push(mt | 24, length);
    } else if (length < 65536) {
      parts.push(mt | 25, length >> 8, length & 0xff);
    }
  }

  encode(value);
  return new Uint8Array(parts);
}

// === HASHING ===

async function sha256(data) {
  const hash = await webcrypto.subtle.digest('SHA-256', data);
  return new Uint8Array(hash);
}

// === PLC OPERATIONS ===

async function signPlcOperation(operation, privateKey) {
  // Encode operation without sig field
  const { sig, ...opWithoutSig } = operation;
  const encoded = cborEncode(opWithoutSig);

  // Sign with P-256
  const signature = await webcrypto.subtle.sign(
    { name: 'ECDSA', hash: 'SHA-256' },
    privateKey,
    encoded,
  );

  // Convert to low-S form and base64url encode
  const sigBytes = ensureLowS(new Uint8Array(signature));
  return base64UrlEncode(sigBytes);
}

function ensureLowS(sig) {
  // P-256 order N
  const N = BigInt(
    '0xFFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551',
  );
  const halfN = N / 2n;

  const r = sig.slice(0, 32);
  const s = sig.slice(32, 64);

  // Convert s to BigInt
  let sInt = BigInt(`0x${bytesToHex(s)}`);

  // If s > N/2, replace with N - s
  if (sInt > halfN) {
    sInt = N - sInt;
    const newS = hexToBytes(sInt.toString(16).padStart(64, '0'));
    const result = new Uint8Array(64);
    result.set(r);
    result.set(newS, 32);
    return result;
  }

  return sig;
}

function hexToBytes(hex) {
  const bytes = new Uint8Array(hex.length / 2);
  for (let i = 0; i < hex.length; i += 2) {
    bytes[i / 2] = parseInt(hex.substr(i, 2), 16);
  }
  return bytes;
}

function base64UrlEncode(bytes) {
  const binary = String.fromCharCode(...bytes);
  return btoa(binary)
    .replace(/\+/g, '-')
    .replace(/\//g, '_')
    .replace(/=+$/, '');
}

async function createGenesisOperation(opts) {
  const { didKey, handle, pdsUrl, cryptoKey } = opts;

  // Build full handle: subdomain.pds-hostname, or just pds-hostname if no subdomain
  const pdsHost = new URL(pdsUrl).host;
  const fullHandle = handle ? `${handle}.${pdsHost}` : pdsHost;

  const operation = {
    type: 'plc_operation',
    rotationKeys: [didKey],
    verificationMethods: {
      atproto: didKey,
    },
    alsoKnownAs: [`at://${fullHandle}`],
    services: {
      atproto_pds: {
        type: 'AtprotoPersonalDataServer',
        endpoint: pdsUrl,
      },
    },
    prev: null,
  };

  // Sign the operation
  operation.sig = await signPlcOperation(operation, cryptoKey);

  return { operation, fullHandle };
}

async function deriveDidFromOperation(operation) {
  // DID is computed from the FULL operation INCLUDING the signature
  const encoded = cborEncode(operation);
  const hash = await sha256(encoded);
  // DID is base32 of first 15 bytes of hash (= 24 base32 chars)
  return `did:plc:${base32Encode(hash.slice(0, 15))}`;
}

function base32Encode(bytes) {
  const alphabet = 'abcdefghijklmnopqrstuvwxyz234567';
  let result = '';
  let bits = 0;
  let value = 0;

  for (const byte of bytes) {
    value = (value << 8) | byte;
    bits += 8;
    while (bits >= 5) {
      bits -= 5;
      result += alphabet[(value >> bits) & 31];
    }
  }

  if (bits > 0) {
    result += alphabet[(value << (5 - bits)) & 31];
  }

  return result;
}

// === PLC DIRECTORY REGISTRATION ===

async function registerWithPlc(plcUrl, did, operation) {
  const url = `${plcUrl}/${encodeURIComponent(did)}`;

  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(operation),
  });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`PLC registration failed: ${response.status} ${text}`);
  }

  return true;
}

// === PDS INITIALIZATION ===

async function initializePds(pdsUrl, did, privateKeyHex, handle) {
  const url = `${pdsUrl}/init?did=${encodeURIComponent(did)}`;

  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      did,
      privateKey: privateKeyHex,
      handle,
    }),
  });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`PDS initialization failed: ${response.status} ${text}`);
  }

  return response.json();
}

// === HANDLE REGISTRATION ===

async function registerHandle(pdsUrl, handle, did) {
  const url = `${pdsUrl}/register-handle`;

  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ handle, did }),
  });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`Handle registration failed: ${response.status} ${text}`);
  }

  return true;
}

// === RELAY NOTIFICATION ===

async function notifyRelay(relayUrl, pdsHostname) {
  const url = `${relayUrl}/xrpc/com.atproto.sync.requestCrawl`;

  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      hostname: pdsHostname,
    }),
  });

  // Relay might return 200 or 202, both are OK
  if (!response.ok && response.status !== 202) {
    const text = await response.text();
    console.warn(
      `  Warning: Relay notification returned ${response.status}: ${text}`,
    );
    return false;
  }

  return true;
}

// === CREDENTIALS OUTPUT ===

function saveCredentials(filename, credentials) {
  writeFileSync(filename, JSON.stringify(credentials, null, 2));
}

// === MAIN ===

async function main() {
  const opts = parseArgs();

  console.log('PDS Federation Setup');
  console.log('====================');
  console.log(`PDS: ${opts.pds}`);
  console.log('');

  // Step 1: Generate keypair
  console.log('Generating P-256 keypair...');
  const keyPair = await generateP256Keypair();
  const didKey = publicKeyToDidKey(keyPair.publicKey);
  console.log(`  did:key: ${didKey}`);
  console.log('');

  // Step 2: Create genesis operation
  console.log('Creating PLC genesis operation...');
  const { operation, fullHandle } = await createGenesisOperation({
    didKey,
    handle: opts.handle,
    pdsUrl: opts.pds,
    cryptoKey: keyPair.cryptoKey,
  });
  const did = await deriveDidFromOperation(operation);
  console.log(`  DID: ${did}`);
  console.log(`  Handle: ${fullHandle}`);
  console.log('');

  // Step 3: Register with PLC directory
  console.log(`Registering with ${opts.plcUrl}...`);
  await registerWithPlc(opts.plcUrl, did, operation);
  console.log('  Registered successfully!');
  console.log('');

  // Step 4: Initialize PDS
  console.log(`Initializing PDS at ${opts.pds}...`);
  const privateKeyHex = bytesToHex(keyPair.privateKey);
  await initializePds(opts.pds, did, privateKeyHex, fullHandle);
  console.log('  PDS initialized!');
  console.log('');

  // Step 4b: Register handle -> DID mapping (only for subdomain handles)
  if (opts.handle) {
    console.log(`Registering handle mapping...`);
    await registerHandle(opts.pds, opts.handle, did);
    console.log(`  Handle ${opts.handle} -> ${did}`);
    console.log('');
  }

  // Step 5: Notify relay
  const pdsHostname = new URL(opts.pds).host;
  console.log(`Notifying relay at ${opts.relayUrl}...`);
  const relayOk = await notifyRelay(opts.relayUrl, pdsHostname);
  if (relayOk) {
    console.log('  Relay notified!');
  }
  console.log('');

  // Step 6: Save credentials
  const credentials = {
    handle: fullHandle,
    did,
    privateKeyHex: bytesToHex(keyPair.privateKey),
    didKey,
    pdsUrl: opts.pds,
    createdAt: new Date().toISOString(),
  };

  const credentialsFile = `./credentials-${opts.handle || new URL(opts.pds).host}.json`;
  saveCredentials(credentialsFile, credentials);

  // Final output
  console.log('Setup Complete!');
  console.log('===============');
  console.log(`Handle: ${fullHandle}`);
  console.log(`DID: ${did}`);
  console.log(`PDS: ${opts.pds}`);
  console.log('');
  console.log(`Credentials saved to: ${credentialsFile}`);
  console.log('Keep this file safe - it contains your private key!');
}

main().catch((err) => {
  console.error('Error:', err.message);
  process.exit(1);
});