#!/usr/bin/env node
'use strict';

// I'm not proud of the way this code is written - it snowballed from a thought
// experiment into a full-fledged CLI, literally overnight (as it it's 4:30am
// right now), but I love what it accomplishes!

/*global Promise*/
var fs = require('fs');
var Rasha = require('rasha');
var Eckles = require('eckles');
var Keypairs = require('keypairs');
var pkg = require('../package.json');
var kpkg = require('keypairs/package.json');

// XXX
// TODO read from pipe as the first argument, if available
// XXX
var args = process.argv.slice(2);
var opts = { keys: [], jwts: [], jwss: [], payloads: [], names: [], filenames: [], files: [] };
var conflicts = {
  'namedCurve': 'modulusLength'
, 'public': 'private'
};
Object.keys(conflicts).forEach(function (k) {
  conflicts[conflicts[k]] = k;
});
function set(key, val) {
  if (opts[conflicts[key]]) {
    console.error("cannot set '" + key + "' to '" + val + "': '" + conflicts[key] + "' already set as '" + opts[conflicts[key]] + "'");
    process.exit(1);
  }
  if (opts[key]) {
    console.error("cannot set '" + key + "' to '" + val + "': already set as '" + opts[key] + "'");
    process.exit(1);
  }
  opts[key] = val;
}

// duck type all the things
// TODO segment off by actions (gen, sign, verify) and allow parse/convert or gen before sign
args.forEach(function (arg) {
  var larg = arg.toLowerCase().replace(/[^\w]/g, '');
  var narg = parseInt(arg, 10) || 0;
  if (narg.toString() !== arg) {
    // i.e. 2048.pem is a valid file name
    narg = false;
  }

  if ('help' === arg) {
    helpAndExit();
    return;
  }

  if ('version' === arg) {
    console.info('%s v%s (%s v%s)', pkg.name, pkg.version, kpkg.name, kpkg.version);
    process.exit(0);
    return;
  }

  if (setTimes(arg)) {
    return;
  }
  if (setIssuer(arg)) {
    return;
  }
  if (setSubject(arg)) {
    return;
  }

  if ('ecdsa' === larg || 'ec' === larg) {
    set('kty', "EC");
    if (opts.modulusLength) {
      console.error("EC keys do not have bit lengths such as '" + opts.modulusLength + "'. Choose either the P-256 or P-384 'curve' instead.");
      process.exit(1);
    }
  }
  if ('rsa' === larg) {
    set('kty', "RSA");
    if (opts.namedCurve) {
      console.error("RSA keys do not have curves such as '" + opts.namedCurve + "'. Choose a modulus bit length, such as 2048 instead.");
      process.exit(1);
    }
    return;
  }

  // P-384
  if (-1 !== ['256', 'p256', 'prime256v1', 'secp256r1'].indexOf(larg)) {
    set('namedCurve', "P-256");
    return;
  }

  // P-384
  if (-1 !== ['384', 'p384', 'secp384r1'].indexOf(larg)) {
    set('namedCurve', "P-384");
    return;
  }

  // RSA Modulus Length
  if (narg) {
    if (narg < 2048 || narg % 8 || narg > 8192) {
      console.error("RSA modulusLength must be >=2048, <=8192 and divisible by 8");
      process.exit(1);
    }
    set('modulusLength', narg);
    return;
  }

  // Booleans
  if (-1 !== [ 'private', 'public', 'nocompact', 'nofetch', 'debug', 'overwrite' ].indexOf(arg)) {
    set(arg, true);
    return;
  }
  if ('uncompressed' === arg) {
    set('uncompressed', true);
    return;
  }
  if (-1 !== [ 'gen', 'sign', 'verify', 'decode' ].indexOf(arg)) {
    set('action', arg);
    return;
  }

  // Key format and encoding
  if (-1 !== [ 'spki', 'pkix' ].indexOf(larg)) {
    set('pubFormat', 'spki');
    return;
  }
  // TODO add ssh private key support (it's already built in jwk-to-ssh)
  if ('ssh' === larg) {
    set('pubFormat', 'ssh');
    return;
  }
  if (-1 !== [ 'openssh', 'sec1', 'pkcs1', 'pkcs8' ].indexOf(larg)) {
    // pkcs1 can be public or private, it's ambiguous
    if (!opts.privFormat) {
      set('privFormat', larg);
      return;
    }

    if ('pkcs1' === larg || 'ssh' === larg) {
      set('pubFormat', larg);
      return;
    }
    if ('openssh' === larg) {
      console.warn("specifying 'openssh' twice? ...assuming that you meant 'ssh'");
      set('pubFormat', 'ssh');
      return;
    }
    if ('pkcs8' === larg) {
      console.warn("specifying 'pkcs8' twice? ...assuming that you meant 'spki' (pkix)");
      set('pubFormat', 'spki');
      return;
    }
    if ('sec1' === larg) {
      console.warn("specifying 'sec1' twice? ...assuming that you meant 'spki' (pkix)");
      set('pubFormat', 'spki');
      return;
    }
    return;
  }
  if ('jwk' === larg) {
    if (!opts.privFormat) {
      set('privFormat', larg);
    } else {
      set('pubFormat', larg);
    }
    return;
  }
  if ('pem' === larg || 'der' === larg || 'json' === larg) {
    if (!opts.privEncoding) {
      set('privEncoding', larg);
    } else {
      set('pubEncoding', larg);
    }
    return;
  }

  // Filename
  try {
    fs.accessSync(arg);
    opts.filenames.push(arg);
    opts.names.push({ taken: true, name: arg });
    if (!guessFile(arg)) {
      opts.files.push(arg);
    }
    return;
  } catch(e) { /* not keypath */ }

  // Test for JWK-ness / payload-ness
  if (guess(arg)) {
    return;
  }

  // Test for JWT-ness
  if (setJwt(arg)) {
    return;
  }

  // Possibly the output file
  if (opts.names.length < 3) {
    opts.names.push({ taken: false, name: arg });
    return;
  }
  // check if it's a valid output key

  console.error("too many arguments or didn't understand argument '" + arg + "'");
  if (opts.debug) {
    console.warn(opts);
  }
  process.exit(1);
});

function guessFile(filename) {
  try {
    // TODO der support
    var txt = fs.readFileSync(filename).toString('utf8');
    return guess(txt, filename);
  } catch(e) {
    return false;
  }
}

function guess(txt, filename) {
  try {
    var json = JSON.parse(txt);
    if (-1 !== [ 'RSA', 'EC' ].indexOf(json.kty)) {
      opts.keys.push({ raw: txt, jwk: json, filename: filename });
      return true;
    } else if (json.signature && json.payload && (json.header || json.protected)) {
      opts.jwss.push(json);
      return true;
    } else {
      opts.payloads.push(txt);
      return true;
    }
  } catch(e) {
    try {
      var jwk = Eckles.importSync({ pem: txt });
      // pem._string = txt;
      opts.keys.push({ jwk: jwk, pem: true, raw: txt });
      return true;
    } catch(e) {
      try {
        var jwk = Rasha.importSync({ pem: txt });
        // pem._string = txt;
        opts.keys.push({ jwk: jwk, pem: true, raw: txt });
        return true;
      } catch(e) {
        // ignore
      }
    }
  }
  return false;
}

// node bin/keypairs.js debug spki pem json pkcs1 ~/.ssh/id_rsa.pub foo.pem bar.pem 'abc.abc.abc' '{"kty":"EC"}' '{}' '{"signature":"x", "payload":"x", "header":"x"}' '{"signature":"x", "payload":"x", "protected":"x"}' verify
if (opts.debug) {
  console.warn(opts);
}

var kp;

if ('gen' === opts.action || (!opts.action && !opts.names.length)) {
  if (opts.names.length > 2) {
    console.error("there should only be two output files at most when generating keypairs");
    console.error(opts.names.map(function (t) { return t.name; }));
    process.exit(1);
    return;
  }

  kp = genKeypair();
} else if ('decode' === opts.action) {
  if (!opts.jwts.length) {
    console.error("no JWTs specified to decode");
    process.exit(1);
    return;
  }

  return Promise.all(opts.jwts.map(function (jwt, i) {
    try {
      var decoded = decodeJwt(jwt);
      console.info("Decoded #" + (i + 1) + ":");
      console.info(JSON.stringify(decoded, null, 2));
    } catch(e) {
      console.error("Failed to decode #" + (i + 1) + ":");
      console.error(e);
    }
  }));
} else if ('verify' === opts.action || (!opts.action && opts.jwts.length)) {
  if (!opts.jwts.length) {
    console.error("no JWTs specified to verify");
    process.exit(1);
    return;
  }

  return Promise.all(opts.jwts.map(function (jwt, i) {
    return require('keyfetch').verify({ jwt: jwt }).then(function (decoded) {
      console.info("Verified #" + (i + 1) + ":");
      console.info(JSON.stringify(decoded, null, 2));
    }).catch(function (err) {
      console.error("Failed to verify #" + (i + 1) + ":");
      console.error(err);
    });
  }));
} else {
  if (opts.names.length > 3) {
    console.error("there should only be one input file and up to two output files when converting keypairs");
    console.error(opts.names.map(function (t) { return t.name; }));
    process.exit(1);
    return;
  }
  var pair = readKeypair();
  pair._convert = true;
  kp = Promise.resolve(pair);
}

if ('sign' === opts.action) {
  return kp.then(function (pair) {
    var jwk = pair.private;
    if (!jwk || !jwk.d) {
      console.error("the first key was not a private key");
      console.error(opts.names.map(function (t) { return t.name; }));
      process.exit(1);
      return;
    }
    if (!opts.payloads.length) {
      opts.payloads.push('{}');
    }
    return Promise.all(opts.payloads.map(function (payload) {
      var claims = JSON.parse(payload);
      if (!claims.iss) { claims.iss = opts.issuer; }
      if (!claims.iss) { console.warn("No issuer given, token will not be verifiable"); }
      if (!claims.sub) { claims.sub = opts.sub; }
      if (!claims.exp) {
        if (!opts.expiresAt) { setTimes('15m'); }
        claims.exp = opts.expiresAt;
      }
      if (!claims.iat) { claims.iat = opts.issuedAt; }
      if (!claims.nbf) { claims.nbf = opts.nbf; }
      return Keypairs.signJwt({ jwk: pair.private, claims: claims }).then(function (jwt) {
        console.info(jwt);
      });
    }));
  });
} else {
  return kp.then(function (pair) {
    if (pair._convert) {
      return convertKeypair(pair);
    }
  });
}

function readKeypair() {
  // note that the jwk may be a string
  var keyopts = opts.keys.shift();
  var jwk = keyopts && keyopts.jwk;
  if (!jwk) {
    console.error("no keys could be parsed from the given arguments");
    console.error(opts.names.map(function (t) { return t.name; }));
    process.exit(1);
    return;
  }

  // omit the primary private key from the list of actual (or soon-to-be) files
  if (keyopts.filename) {
    opts.names = opts.names.filter(function (name) {
      return name.name !== keyopts.filename;
    });
  }

  var pair = { private: null, public: null, pem: keyopts.pem, raw: keyopts.raw };
  if (jwk.d) {
    pair.private = jwk;
  }
  pair.public = Keypairs._neuter({ jwk: jwk });
  return pair;
}

// Note: some of the conditions can be factored out
// this was all built in high-speed iterative during the 3ams+
function convertKeypair(pair) {
  //var pair = readKeypair();

  // XXX
  // TODO detect desired format via extension(s) (pem, der, json, jwk)
  // XXX

  var ps = [];
  // if it's private only, or if it's not public-only, produce the private key
  if (pair.private || !opts.public) {
    // if it came from pem (or is explicitly json), it should go to jwk
    // otherwise, if it came from jwk, it should go to pem
    if (((!opts.privEncoding && pair.pem) || 'json' === opts.privEncoding)
      && ((!opts.privFormat && pair.pem) || 'jwk' === opts.privFormat)) {
      ps.push(Promise.resolve(pair.private));
    } else {
      ps.push(Keypairs.export({ jwk: pair.private, format: opts.privFormat, encoding: opts.privEncoding }));
    }
  }

  // if it's not private key only, we want to produce the public key
  if (!opts.private) {
    if (opts.public) {
      // if it's public-only the ambigious options will fall to the private key
      // so we need to fix that
      if (!opts.pubFormat) { opts.pubFormat = opts.privFormat; }
      if (!opts.pubEncoding) { opts.pubEncoding = opts.privEncoding; }
    }

    // same as above - swap formats by default
    if (((!opts.pubEncoding && pair.pem) || 'json' === opts.pubEncoding)
      && ((!opts.pubFormat && pair.pem) || 'jwk' === opts.pubFormat)) {
      ps.push(Promise.resolve(pair.public));
    } else {
      ps.push(Keypairs.export({ jwk: pair.public, format: opts.pubFormat, encoding: opts.pubEncoding, public: true }));
    }
  }

  return Promise.all(ps).then(function (exported) {
    // start with the first key, annotating if it should be public
    var index = 0;
    var key = stringifyIfJson(index, opts.public);

    // re: opts.names
    // if we're only doing the public key we can end early
    // (if the source key was from a file and was in opts.names,
    // we're safe here because we already removed it earlier)

    if (opts.public) {
      if (opts.names.length) {
        writeFile(opts.names[index].name, key, !opts.public);
      } else {
        // output public keys to stderr
        printPublic(key);
      }
      // end <-- we're not outputting other keys
      return;
    }

    // private key stuff
    if (opts.names.length >= 1) {
      writeFile(opts.names[index].name, key, true);
    } else {
      printPrivate(key);
    }

    // pub key stuff
    // we have to output the private key,
    // but the public key can be derived at any time
    // so we don't need to put the same noise to the screen
    if (!opts.private && opts.names.length >= 2) {
      index = 1;
      key = stringifyIfJson(index, false);
      writeFile(opts.names[index].name, key, false);
    }

    return pair;

    function stringifyIfJson(i, pub) {
      if (exported[i].kty) {
        if (pub) {
          if (opts.expiresAt) { exported[i].exp = opts.expiresAt; }
          exported[i].use = "sig";
        }
        exported[i] = JSON.stringify(exported[i]);
      }
      return exported[i];
    }
  });
}

function genKeypair() {
  return Keypairs.generate({
    kty: opts.kty
  , modulusLength: opts.modulusLength
  , namedCurve: opts.namedCurve
  }).then(function (pair) {
    // always generate as jwk by default
    var ps = [];
    if ((!opts.privEncoding || 'json' === opts.privEncoding) && (!opts.privFormat || 'jwk' === opts.privFormat)) {
      ps.push(Promise.resolve(pair.private));
    } else {
      ps.push(Keypairs.export({ jwk: pair.private, format: opts.privFormat, encoding: opts.privEncoding }));
    }
    if ((!opts.pubEncoding || 'json' === opts.pubEncoding) && (!opts.pubFormat || 'jwk' === opts.pubFormat)) {
      ps.push(Promise.resolve(pair.public));
    } else {
      ps.push(Keypairs.export({ jwk: pair.public, format: opts.pubFormat, encoding: opts.pubEncoding, public: true }));
    }
    return Promise.all(ps).then(function (arr) {
      if (arr[0].kty) {
        arr[0] = JSON.stringify(arr[0]);
      }
      if (arr[1].kty) {
        if (opts.expiresAt) { arr[1].exp = opts.expiresAt; }
        arr[1].use = "sig";
        arr[1] = JSON.stringify(arr[1]);
      }
      if (!opts.names.length) {
        console.info(arr[0] + "\n");
        console.warn(arr[1] + "\n");
      }
      if (opts.names.length >= 1) {
        writeFile(opts.names[0].name, arr[0], true);
        if (!opts.private && opts.names.length >= 2) {
          writeFile(opts.names[1].name, arr[1]);
        }
      }

      return pair;
    });
  });
}

function writeFile(name, key, priv) {
  var overwrite;
  try {
    fs.accessSync(name);
    overwrite = opts.overwrite;
    if (!opts.overwrite) {
      if (priv) {
        // output private keys to stdout
        console.info(key + "\n");
      } else {
        // output public keys to stderr
        console.warn(key + "\n");
      }
      console.error("'" + name + "' exists! force overwrite with 'overwrite'");
      process.exit(1);
      return;
    }
  } catch(e) {
    // the file does not exist (or cannot be accessed)
  }
  fs.writeFileSync(name, key);
  if (overwrite) {
    console.info("Overwrote " + (priv ? "private" : "public") + " key at '" + name + "'");
  } else {
    console.info("Wrote " + (priv ? "private" : "public") + " key to '" + name + "'");
  }
}

function setJwt(arg) {
  try {
    var jwt = arg.match(/^([\w-]+)\.([\w-]+)\.([\w-]+)$/);
    // make sure header is a JWT header
    JSON.parse(Buffer.from(jwt[1], 'base64'));
    opts.jwts.push(arg);
    return true;
  } catch(e) {
    // ignore
  }
}

function setSubject(arg) {
  if (!/.+@[a-z0-9_-]+\.[a-z0-9_-]+/i.test(arg)) {
    return false;
  }

  opts.subject = arg;
  return false;
}

function setIssuer(arg) {
  if (!/^https?:\/\/[a-z0-9_-]+\.[a-z0-9_-]+/i.test(arg)) {
    return false;
  }

  try {
    new URL(arg);
    opts.issuer = arg.replace(/\/$/, '');
    return true;
  } catch(e) {
  }
  return false;
}

function setTimes(arg) {
  var t = arg.match(/^(\-?\d+)([dhms])$/i);
  if (!t || !t[0]) {
    return false;
  }

  var num = parseInt(t[1], 10);
  var unit = t[2];
  var mult = 1;
  opts.issuedAt = Math.round(Date.now()/1000);
  switch(unit) {
    // fancy fallthrough, what fun!
    case 'd':
      mult *= 24;
      /*falls through*/
    case 'h':
      mult *= 60;
      /*falls through*/
    case 'm':
      mult *= 60;
      /*falls through*/
    case 's':
      mult *= 1;
  }
  if (!opts.expiresIn) {
    opts.expiresIn = mult * num;
    opts.expiresAt = opts.issuedAt + opts.expiresIn;
  } else {
    opts.nbf = opts.issuedAt + (mult * num);
  }
  return true;
}

function decodeJwt(jwt) {
  var parts = jwt.split('.');
  return {
    header: JSON.parse(Buffer.from(parts[0], 'base64'))
  , payload: JSON.parse(Buffer.from(parts[1], 'base64'))
  , signature: parts[2] //Buffer.from(parts[2], 'base64')
  };
}

function printPrivate(key) {
  console.info(key + "\n");
}
function printPublic(key) {
  console.warn(key + "\n");
}

function helpAndExit() {
  console.info();
  console.info('## Generate Keys');
  console.info('keypairs gen [key-opts] [[private-format] [private-key-file]]  [[public-format] [public-key-file]]');
  console.info('\tkeypairs gen');
  console.info('\tkeypairs gen ec P-256');
  console.info('\tkeypairs gen rsa 2048');
  console.info('\tkeypairs gen key.json pub.json');
  console.info('\tkeypairs gen pem key.pem');
  console.info('\tkeypairs gen sec1 key.pem ssh id.pub');
  console.info();

  console.info('## Parse and Convert Keys');
  console.info('keypairs [key-file-or-string] [[private-format] [private-key-file]]  [[public-format] [public-key-file]]');
  console.info('\tkeypairs key.pem                               # PEM-to-JWK');
  console.info('\tkeypairs \'{"kty":"EC"...}\' key.pem             # JWK-to-PEM');
  console.info('\tkeypairs key.pem spki pub.pem                  # PEM-to-PEM');
  console.info('\tkeypairs id_rsa.pub spki                       # SSH-to-PEM');
  console.info('\tkeypairs key.pem ssh id_rsa.pub                # PEM-to-SSH');
  console.info('\tkeypairs key.json pem id_rsa ssh id_rsa.pub    # JWK-to-SSH');
  console.info('\tkeypairs id_rsa.pub pub.json                   # SSH-to-JWK');
  console.info();

  // XXX
  // TODO test fetch the public keys from the issuer url
  //      (report warning if not found or if kid is not thumbprint)
  // XXX
  console.info('## Sign JWTs');
  console.info('keypairs sign [key-file-or-string] [issuer-url] [subject-email] [claims-json] [exp] [nbf]');
  console.info('\tkeypairs sign key.pem \'{"iss":"https://example.com/"}\' 1h');
  console.info('\tkeypairs sign key.json https://example.com/ jon@gmail.com 15m');
  console.info('\tkeypairs sign \'{"kty":"RSA"...}\' https://example.com \'{"foo":"bar"}\'');
  console.info('\tkeypairs sign key.pem https://example.com/ 3d 30s');
  console.info('\tkeypairs sign key.pem https://example.com/ \'{"sub":"jon@gmail.com"}\'');
  console.info();

  console.info('## Decode JWTs (without verification)');
  console.info('keypairs decode [jwt-file-or-string]');
  console.info('\tkeypairs decode \'xxx.yyy.zzz\'');
  console.info('\tkeypairs decode token.jwt');
  console.info();

  console.info('## Verify JWTs (by fetching public key)');
  console.info('keypairs verify [jwt-file-or-string]');
  console.info('\tkeypairs verify \'xxx.yyy.zzz\'');
  console.info('\tkeypairs verify token.jwt');
  console.info();

  // XXX
  // TODO thumbprint
  // XXX

  console.info('-----');
  console.info();
  console.info('Keys Options:');
  console.info('\trsa 2048 3072 4096 8192');
  console.info('\tec P-256 P-384');
  console.info();
  console.info('Schemas: jwk, pkcs1, sec1, pkcs8, spki (pkix), ssh');
  console.info();
  console.info('Encodings: json, pem');
  process.exit(0);
}