'use strict'

const crypto = require('../../shims/crypto/index.js')

let cpuInfo
try {
  cpuInfo = require('cpu-features')()
} catch {}

const { bindingAvailable, CIPHER_INFO, MAC_INFO } = require('./crypto.js')

const eddsaSupported = (() => {
  if (typeof crypto.sign === 'function' && typeof crypto.verify === 'function') {
    const key =
      '-----BEGIN PRIVATE KEY-----\r\nMC4CAQAwBQYDK2VwBCIEIHKj+sVa9WcD' +
      '/q2DJUJaf43Kptc8xYuUQA4bOFj9vC8T\r\n-----END PRIVATE KEY-----'
    const data = Buffer.from('a')
    let sig
    let verified
    try {
      sig = crypto.sign(null, data, key)
      verified = crypto.verify(null, data, key, sig)
    } catch {}
    if (Buffer.isBuffer(sig) && sig.length === 64 && verified === true) return true
  }

  // Bare `bare-crypto`: PEM-based probe fails; sign/verify require Key objects.
  if (
    typeof crypto.generateKeyPair === 'function' &&
    typeof crypto.sign === 'function' &&
    typeof crypto.verify === 'function'
  ) {
    try {
      const { publicKey, privateKey } = crypto.generateKeyPair('ed25519')
      const data = Buffer.from('a')
      const sig = crypto.sign(null, data, privateKey)
      const verified = crypto.verify(null, data, publicKey, sig)
      const sigLen = sig && (sig.length ?? sig.byteLength)
      const sigOk =
        verified === true &&
        typeof sigLen === 'number' &&
        sigLen === 64 &&
        (Buffer.isBuffer(sig) || ArrayBuffer.isView(sig))
      if (sigOk) return true
    } catch {}
  }

  return false
})()

const curve25519Supported =
  typeof crypto.diffieHellman === 'function' &&
  typeof crypto.generateKeyPairSync === 'function' &&
  typeof crypto.createPublicKey === 'function'

const DEFAULT_KEX = [
  // https://tools.ietf.org/html/rfc5656#section-10.1
  'ecdh-sha2-nistp256',
  'ecdh-sha2-nistp384',
  'ecdh-sha2-nistp521',

  // https://tools.ietf.org/html/rfc4419#section-4
  'diffie-hellman-group-exchange-sha256',

  // https://tools.ietf.org/html/rfc8268
  'diffie-hellman-group14-sha256',
  'diffie-hellman-group15-sha512',
  'diffie-hellman-group16-sha512',
  'diffie-hellman-group17-sha512',
  'diffie-hellman-group18-sha512'
]
if (curve25519Supported) {
  DEFAULT_KEX.unshift('curve25519-sha256')
  DEFAULT_KEX.unshift('curve25519-sha256@libssh.org')
}
const SUPPORTED_KEX = DEFAULT_KEX.concat([
  // https://tools.ietf.org/html/rfc4419#section-4
  'diffie-hellman-group-exchange-sha1',

  'diffie-hellman-group14-sha1', // REQUIRED
  'diffie-hellman-group1-sha1' // REQUIRED
])

const DEFAULT_SERVER_HOST_KEY = [
  'ecdsa-sha2-nistp256',
  'ecdsa-sha2-nistp384',
  'ecdsa-sha2-nistp521',
  'rsa-sha2-512', // RFC 8332
  'rsa-sha2-256', // RFC 8332
  'ssh-rsa'
]
if (eddsaSupported) DEFAULT_SERVER_HOST_KEY.unshift('ssh-ed25519')
const SUPPORTED_SERVER_HOST_KEY = DEFAULT_SERVER_HOST_KEY.concat(['ssh-dss'])

const canUseCipher = (() => {
  const ciphers = crypto.getCiphers()
  return (name) => ciphers.includes(CIPHER_INFO[name].sslName)
})()
let DEFAULT_CIPHER = [
  // http://tools.ietf.org/html/rfc5647
  'aes128-gcm@openssh.com',
  'aes256-gcm@openssh.com',

  // http://tools.ietf.org/html/rfc4344#section-4
  'aes128-ctr',
  'aes192-ctr',
  'aes256-ctr'
]
if (cpuInfo && cpuInfo.flags && !cpuInfo.flags.aes) {
  // We know for sure the CPU does not support AES acceleration
  if (bindingAvailable) DEFAULT_CIPHER.unshift('chacha20-poly1305@openssh.com')
  else DEFAULT_CIPHER.push('chacha20-poly1305@openssh.com')
} else if (bindingAvailable && cpuInfo && cpuInfo.arch === 'x86') {
  // Places chacha20-poly1305 immediately after GCM ciphers since GCM ciphers
  // seem to outperform it on x86, but it seems to be faster than CTR ciphers
  DEFAULT_CIPHER.splice(4, 0, 'chacha20-poly1305@openssh.com')
} else {
  DEFAULT_CIPHER.push('chacha20-poly1305@openssh.com')
}
DEFAULT_CIPHER = DEFAULT_CIPHER.filter(canUseCipher)
const SUPPORTED_CIPHER = DEFAULT_CIPHER.concat(
  [
    'aes256-cbc',
    'aes192-cbc',
    'aes128-cbc',
    'blowfish-cbc',
    '3des-cbc',
    'aes128-gcm',
    'aes256-gcm',

    // http://tools.ietf.org/html/rfc4345#section-4:
    'arcfour256',
    'arcfour128',

    'cast128-cbc',
    'arcfour'
  ].filter(canUseCipher)
)

const canUseMAC = (() => {
  const hashes = crypto.getHashes()
  return (name) => hashes.includes(MAC_INFO[name].sslName)
})()
const DEFAULT_MAC = [
  'hmac-sha2-256-etm@openssh.com',
  'hmac-sha2-512-etm@openssh.com',
  'hmac-sha1-etm@openssh.com',
  'hmac-sha2-256',
  'hmac-sha2-512',
  'hmac-sha1'
].filter(canUseMAC)
const SUPPORTED_MAC = DEFAULT_MAC.concat(
  [
    'hmac-md5',
    'hmac-sha2-256-96', // first 96 bits of HMAC-SHA256
    'hmac-sha2-512-96', // first 96 bits of HMAC-SHA512
    'hmac-ripemd160',
    'hmac-sha1-96', // first 96 bits of HMAC-SHA1
    'hmac-md5-96' // first 96 bits of HMAC-MD5
  ].filter(canUseMAC)
)

const DEFAULT_COMPRESSION = [
  'none',
  'zlib@openssh.com', // ZLIB (LZ77) compression, except
  // compression/decompression does not start until after
  // successful user authentication
  'zlib' // ZLIB (LZ77) compression
]
const SUPPORTED_COMPRESSION = DEFAULT_COMPRESSION.concat([])

const COMPAT = {
  BAD_DHGEX: 1 << 0,
  OLD_EXIT: 1 << 1,
  DYN_RPORT_BUG: 1 << 2,
  BUG_DHGEX_LARGE: 1 << 3,
  IMPLY_RSA_SHA2_SIGALGS: 1 << 4
}

module.exports = {
  MESSAGE: {
    // Transport layer protocol -- generic (1-19)
    DISCONNECT: 1,
    IGNORE: 2,
    UNIMPLEMENTED: 3,
    DEBUG: 4,
    SERVICE_REQUEST: 5,
    SERVICE_ACCEPT: 6,
    EXT_INFO: 7, // RFC 8308

    // Transport layer protocol -- algorithm negotiation (20-29)
    KEXINIT: 20,
    NEWKEYS: 21,

    // Transport layer protocol -- key exchange method-specific (30-49)
    KEXDH_INIT: 30,
    KEXDH_REPLY: 31,

    KEXDH_GEX_GROUP: 31,
    KEXDH_GEX_INIT: 32,
    KEXDH_GEX_REPLY: 33,
    KEXDH_GEX_REQUEST: 34,

    KEXECDH_INIT: 30,
    KEXECDH_REPLY: 31,

    // User auth protocol -- generic (50-59)
    USERAUTH_REQUEST: 50,
    USERAUTH_FAILURE: 51,
    USERAUTH_SUCCESS: 52,
    USERAUTH_BANNER: 53,

    // User auth protocol -- user auth method-specific (60-79)
    USERAUTH_PASSWD_CHANGEREQ: 60,

    USERAUTH_PK_OK: 60,

    USERAUTH_INFO_REQUEST: 60,
    USERAUTH_INFO_RESPONSE: 61,

    // Connection protocol -- generic (80-89)
    GLOBAL_REQUEST: 80,
    REQUEST_SUCCESS: 81,
    REQUEST_FAILURE: 82,

    // Connection protocol -- channel-related (90-127)
    CHANNEL_OPEN: 90,
    CHANNEL_OPEN_CONFIRMATION: 91,
    CHANNEL_OPEN_FAILURE: 92,
    CHANNEL_WINDOW_ADJUST: 93,
    CHANNEL_DATA: 94,
    CHANNEL_EXTENDED_DATA: 95,
    CHANNEL_EOF: 96,
    CHANNEL_CLOSE: 97,
    CHANNEL_REQUEST: 98,
    CHANNEL_SUCCESS: 99,
    CHANNEL_FAILURE: 100

    // Reserved for client protocols (128-191)

    // Local extensions (192-155)
  },
  DISCONNECT_REASON: {
    HOST_NOT_ALLOWED_TO_CONNECT: 1,
    PROTOCOL_ERROR: 2,
    KEY_EXCHANGE_FAILED: 3,
    RESERVED: 4,
    MAC_ERROR: 5,
    COMPRESSION_ERROR: 6,
    SERVICE_NOT_AVAILABLE: 7,
    PROTOCOL_VERSION_NOT_SUPPORTED: 8,
    HOST_KEY_NOT_VERIFIABLE: 9,
    CONNECTION_LOST: 10,
    BY_APPLICATION: 11,
    TOO_MANY_CONNECTIONS: 12,
    AUTH_CANCELED_BY_USER: 13,
    NO_MORE_AUTH_METHODS_AVAILABLE: 14,
    ILLEGAL_USER_NAME: 15
  },
  DISCONNECT_REASON_STR: undefined,
  CHANNEL_OPEN_FAILURE: {
    ADMINISTRATIVELY_PROHIBITED: 1,
    CONNECT_FAILED: 2,
    UNKNOWN_CHANNEL_TYPE: 3,
    RESOURCE_SHORTAGE: 4
  },
  TERMINAL_MODE: {
    TTY_OP_END: 0, // Indicates end of options.
    VINTR: 1, // Interrupt character; 255 if none. Similarly for the
    //  other characters.  Not all of these characters are
    //  supported on all systems.
    VQUIT: 2, // The quit character (sends SIGQUIT signal on POSIX
    //  systems).
    VERASE: 3, // Erase the character to left of the cursor.
    VKILL: 4, // Kill the current input line.
    VEOF: 5, // End-of-file character (sends EOF from the
    //  terminal).
    VEOL: 6, // End-of-line character in addition to carriage
    //  return and/or linefeed.
    VEOL2: 7, // Additional end-of-line character.
    VSTART: 8, // Continues paused output (normally control-Q).
    VSTOP: 9, // Pauses output (normally control-S).
    VSUSP: 10, // Suspends the current program.
    VDSUSP: 11, // Another suspend character.
    VREPRINT: 12, // Reprints the current input line.
    VWERASE: 13, // Erases a word left of cursor.
    VLNEXT: 14, // Enter the next character typed literally, even if
    //  it is a special character
    VFLUSH: 15, // Character to flush output.
    VSWTCH: 16, // Switch to a different shell layer.
    VSTATUS: 17, // Prints system status line (load, command, pid,
    //  etc).
    VDISCARD: 18, // Toggles the flushing of terminal output.
    IGNPAR: 30, // The ignore parity flag.  The parameter SHOULD be 0
    //  if this flag is FALSE, and 1 if it is TRUE.
    PARMRK: 31, // Mark parity and framing errors.
    INPCK: 32, // Enable checking of parity errors.
    ISTRIP: 33, // Strip 8th bit off characters.
    INLCR: 34, // Map NL into CR on input.
    IGNCR: 35, // Ignore CR on input.
    ICRNL: 36, // Map CR to NL on input.
    IUCLC: 37, // Translate uppercase characters to lowercase.
    IXON: 38, // Enable output flow control.
    IXANY: 39, // Any char will restart after stop.
    IXOFF: 40, // Enable input flow control.
    IMAXBEL: 41, // Ring bell on input queue full.
    ISIG: 50, // Enable signals INTR, QUIT, [D]SUSP.
    ICANON: 51, // Canonicalize input lines.
    XCASE: 52, // Enable input and output of uppercase characters by
    //  preceding their lowercase equivalents with "\".
    ECHO: 53, // Enable echoing.
    ECHOE: 54, // Visually erase chars.
    ECHOK: 55, // Kill character discards current line.
    ECHONL: 56, // Echo NL even if ECHO is off.
    NOFLSH: 57, // Don't flush after interrupt.
    TOSTOP: 58, // Stop background jobs from output.
    IEXTEN: 59, // Enable extensions.
    ECHOCTL: 60, // Echo control characters as ^(Char).
    ECHOKE: 61, // Visual erase for line kill.
    PENDIN: 62, // Retype pending input.
    OPOST: 70, // Enable output processing.
    OLCUC: 71, // Convert lowercase to uppercase.
    ONLCR: 72, // Map NL to CR-NL.
    OCRNL: 73, // Translate carriage return to newline (output).
    ONOCR: 74, // Translate newline to carriage return-newline
    //  (output).
    ONLRET: 75, // Newline performs a carriage return (output).
    CS7: 90, // 7 bit mode.
    CS8: 91, // 8 bit mode.
    PARENB: 92, // Parity enable.
    PARODD: 93, // Odd parity, else even.
    TTY_OP_ISPEED: 128, // Specifies the input baud rate in bits per second.
    TTY_OP_OSPEED: 129 // Specifies the output baud rate in bits per second.
  },
  CHANNEL_EXTENDED_DATATYPE: {
    STDERR: 1
  },

  SIGNALS: [
    'ABRT',
    'ALRM',
    'FPE',
    'HUP',
    'ILL',
    'INT',
    'QUIT',
    'SEGV',
    'TERM',
    'USR1',
    'USR2',
    'KILL',
    'PIPE'
  ].reduce((cur, val) => ({ ...cur, [val]: 1 }), {}),

  COMPAT,
  COMPAT_CHECKS: [
    ['Cisco-1.25', COMPAT.BAD_DHGEX],
    [/^Cisco-1[.]/, COMPAT.BUG_DHGEX_LARGE],
    [/^[0-9.]+$/, COMPAT.OLD_EXIT], // old SSH.com implementations
    [/^OpenSSH_5[.][0-9]+/, COMPAT.DYN_RPORT_BUG],
    [/^OpenSSH_7[.]4/, COMPAT.IMPLY_RSA_SHA2_SIGALGS]
  ],

  // KEX proposal-related
  DEFAULT_KEX,
  SUPPORTED_KEX,
  DEFAULT_SERVER_HOST_KEY,
  SUPPORTED_SERVER_HOST_KEY,
  DEFAULT_CIPHER,
  SUPPORTED_CIPHER,
  DEFAULT_MAC,
  SUPPORTED_MAC,
  DEFAULT_COMPRESSION,
  SUPPORTED_COMPRESSION,

  curve25519Supported,
  eddsaSupported
}

module.exports.DISCONNECT_REASON_BY_VALUE = Array.from(
  Object.entries(module.exports.DISCONNECT_REASON)
).reduce((obj, [key, value]) => ({ ...obj, [value]: key }), {})