!import "base.tri"      !Local
!import "io.tri"        !Local

-- Socket primitives for the IO driver.
-- All actions return a Result tree (see lib/base.tri):
--   ok value  -- pair true (pair value t)
--   err msg   -- pair false (pair msg t)

socket      = pair 70 t
closeSocket = sock : pair 71 sock
bindSocket  = sock addr port : pair 72 (pair sock (pair addr port))
listen      = sock backlog   : pair 73 (pair sock backlog)
accept      = sock           : pair 74 sock
connect     = sock addr port : pair 75 (pair sock (pair addr port))
recv        = sock maxBytes  : pair 76 (pair sock maxBytes)
send        = sock bytes     : pair 77 (pair sock bytes)
getSocketName = sock         : pair 78 sock

-- ---------------------------------------------------------------------------
-- Convenience helpers
-- ---------------------------------------------------------------------------

onSocket = (action errCase okCase :
  bind action (result :
    matchResult errCase okCase result))

-- Create a listening socket bound to an address and port.
-- Returns ok listenSocket or err message.
listenSocket = addr port backlog :
  bind (socket) (result :
    matchResult
      (err rest : pure (err "socket creation failed"))
      (sock rest :
        bind (bindSocket sock addr port) (bindResult :
          matchResult
            (err rest : pure (err "bind failed"))
            (_ rest :
              bind (listen sock backlog) (listenResult :
                matchResult
                  (err rest : pure (err "listen failed"))
                  (_ rest : pure (ok sock))
                  listenResult))
            bindResult))
      result)

-- Accept a connection and return (clientSocket, peerAddr).
-- The returned peerAddr is a string like "127.0.0.1:8080".
onAccept = (sock errCase okCase :
  bind (accept sock) (result :
    matchResult errCase okCase result))

-- Receive all available bytes up to maxBytes.
onRecv = (sock maxBytes errCase okCase :
  bind (recv sock maxBytes) (result :
    matchResult errCase okCase result))

-- Send bytes and return number of bytes sent.
onSend = (sock bytes errCase okCase :
  bind (send sock bytes) (result :
    matchResult errCase okCase result))

-- Close a socket, ignoring errors.
closeSocket_ = sock : bind (closeSocket sock) (_ : pure t)