## Nim-Libp2p
## Copyright (c) 2021 Status Research & Development GmbH
## Licensed under either of
##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.

{.push raises: [Defect].}

import chronos
import ./utils

const
  SHA1DigestSize* = 20
  WSHeaderSize* = 12
  WSDefaultVersion* = 13
  WSDefaultFrameSize* = 1 shl 20 # 1mb
  WSMaxMessageSize* = 20 shl 20  # 20mb
  WSGuid* = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
  CRLF* = "\r\n"

type
  ReadyState* {.pure.} = enum
    Connecting = 0 # The connection is not yet open.
    Open = 1       # The connection is open and ready to communicate.
    Closing = 2    # The connection is in the process of closing.
    Closed = 3     # The connection is closed or couldn't be opened.

  Opcode* {.pure.} = enum
    ## 4 bits. Defines the interpretation of the "Payload data".
    Cont = 0x0   ## Denotes a continuation frame.
    Text = 0x1   ## Denotes a text frame.
    Binary = 0x2 ## Denotes a binary frame.
    # 3-7 are reserved for further non-control frames.
    Close = 0x8  ## Denotes a connection close.
    Ping = 0x9   ## Denotes a ping.
    Pong = 0xa   ## Denotes a pong.
    # B-F are reserved for further control frames.

  HeaderFlag* {.pure, size: sizeof(uint8).} = enum
    rsv3
    rsv2
    rsv1
    fin

  HeaderFlags* = set[HeaderFlag]

  MaskKey* = array[4, char]

  Frame* = ref object
    fin*: bool                 ## Indicates that this is the final fragment in a message.
    rsv1*: bool                ## MUST be 0 unless negotiated that defines meanings
    rsv2*: bool                ## MUST be 0
    rsv3*: bool                ## MUST be 0
    opcode*: Opcode            ## Defines the interpretation of the "Payload data".
    mask*: bool                ## Defines whether the "Payload data" is masked.
    data*: seq[byte]           ## Payload data
    maskKey*: MaskKey          ## Masking key
    length*: uint64            ## Message size.
    consumed*: uint64          ## how much has been consumed from the frame

  Status* {.pure.} = enum
    # 0-999 not used
    Fulfilled = 1000
    GoingAway = 1001
    ProtocolError = 1002
    CannotAccept = 1003
    # 1004 reserved
    NoStatus = 1005         # use by clients
    ClosedAbnormally = 1006 # use by clients
    Inconsistent = 1007
    PolicyError = 1008
    TooLarge = 1009
    NoExtensions = 1010
    UnexpectedError = 1011
    ReservedCode = 3999     # use by clients
                            # 3000-3999 reserved for libs
                            # 4000-4999 reserved for applications

  ControlCb* = proc(data: openArray[byte] = [])
    {.gcsafe, raises: [Defect].}

  CloseResult* = tuple
    code: Status
    reason: string

  CloseCb* = proc(code: Status, reason: string):
    CloseResult {.gcsafe, raises: [Defect].}

  Extension* = ref object of RootObj
    name*: string

  WebSocket* = ref object of RootObj
    extensions: seq[Extension] # extension active for this session
    version*: uint
    key*: string
    proto*: string
    readyState*: ReadyState
    masked*: bool # send masked packets
    binary*: bool # is payload binary?
    rng*: Rng
    frameSize*: int
    onPing*: ControlCb
    onPong*: ControlCb
    onClose*: CloseCb

  WebSocketError* = object of CatchableError
  WSMalformedHeaderError* = object of WebSocketError
  WSFailedUpgradeError* = object of WebSocketError
  WSVersionError* = object of WebSocketError
  WSProtoMismatchError* = object of WebSocketError
  WSMaskMismatchError* = object of WebSocketError
  WSHandshakeError* = object of WebSocketError
  WSOpcodeMismatchError* = object of WebSocketError
  WSRsvMismatchError* = object of WebSocketError
  WSWrongUriSchemeError* = object of WebSocketError
  WSMaxMessageSizeError* = object of WebSocketError
  WSClosedError* = object of WebSocketError
  WSSendError* = object of WebSocketError
  WSPayloadTooLarge* = object of WebSocketError
  WSReserverdOpcodeError* = object of WebSocketError
  WSFragmentedControlFrameError* = object of WebSocketError
  WSInvalidCloseCodeError* = object of WebSocketError
  WSPayloadLengthError* = object of WebSocketError
  WSInvalidOpcodeError* = object of WebSocketError

proc `name=`*(self: Extension, name: string) =
  raiseAssert "Can't change extensions name!"

method decode*(self: Extension, frame: Frame): Future[Frame] {.base, async.} =
  raiseAssert "Not implemented!"

method encode*(self: Extension, frame: Frame): Future[Frame] {.base, async.} =
  raiseAssert "Not implemented!"