package zmq

import "core:c"
import "core:os"

foreign import lib "system:zmq"

Context :: distinct rawptr
Socket :: distinct rawptr

@(default_calling_convention = "c", link_prefix = "zmq_")
foreign lib {
	// TODO: Try to access errno directly
	errno :: proc() -> c.int ---

	ctx_new :: proc() -> Context ---
	@(link_name = "zmq_ctx_term")
	_ctx_term :: proc(ctx: Context) -> c.int ---
	@(link_name = "zmq_socket")
	_socket :: proc(ctx: Context, type: Socket_Type) -> Socket ---
	@(link_name = "zmq_close")
	_close :: proc(s: Socket) -> c.int ---
	@(link_name = "zmq_bind")
	_bind :: proc(s: Socket, addr: cstring) -> c.int ---
	@(link_name = "zmq_connect")
	_connect :: proc(s: Socket, addr: cstring) -> c.int ---
	@(link_name = "zmq_send")
	_send :: proc(s: Socket, buf: rawptr, len: c.size_t, flags: Flags) -> c.int ---

	@(link_name = "zmq_send_const")
	_send_const :: proc(s: Socket, buf: rawptr, len: c.size_t, flags: Flags) -> c.int ---

	@(link_name = "zmq_recv")
	_recv :: proc(s: Socket, buf: rawptr, len: c.size_t, flags: Flags) -> c.int ---
	@(link_name = "zmq_poll")
	_poll :: proc(items: rawptr, nitems: c.int, timeout: c.long) -> c.int ---
	@(link_name = "zmq_strerror")
	_strerror :: proc(errnum: c.int) -> cstring ---
	@(link_name = "zmq_version")
	_version :: proc(major, minor, patch: ^c.int) ---
}

Socket_Type :: enum c.int {
	PAIR   = 0,
	PUB    = 1,
	SUB    = 2,
	REQ    = 3,
	REP    = 4,
	DEALER = 5,
	ROUTER = 6,
	PULL   = 7,
	PUSH   = 8,
	XPUB   = 9,
	XSUB   = 10,
	STREAM = 11,
}

Flag :: enum c.int {
	DONTWAIT,
	SNDMORE,
}

Flags :: bit_set[Flag;c.int]

NoBlock :: Flags{.DONTWAIT}

// zmq_poll event flags (zmq.h ZMQ_POLLIN etc.). bit_set uses enum values as
// bit indices, so these are positions (0..3), not the ZMQ_POLL* masks (1,2,4,8):
// {.POLLIN} -> bit 0 -> mask 1 == ZMQ_POLLIN, {.POLLOUT} -> bit 1 -> mask 2, etc.
Poll_Event :: enum c.short {
	POLLIN  = 0,
	POLLOUT = 1,
	POLLERR = 2,
	POLLPRI = 3,
}
Poll_Events :: bit_set[Poll_Event;c.short]

// Mirrors C zmq_pollitem_t (16 B: ptr / int / short / short).
// socket non-nil => poll the ØMQ socket; otherwise poll fd.
Poll_Item :: struct {
	socket:  Socket,
	fd:      c.int,
	events:  Poll_Events,
	revents: Poll_Events,
}

Error :: union #shared_nil {
	os.Platform_Error,
	ZMQ_Error,
}

strerror :: proc(e: Error) -> cstring {
	switch v in e {
	case os.Platform_Error:
		return _strerror(c.int(v))
	case ZMQ_Error:
		return _strerror(denormalize_from_zmq(c.int(v)))
	case:
		return _strerror(0)
	}
}

version :: proc() -> (major, minor, patch: int) {
	ma, mi, pa: c.int = 0, 0, 0
	_version(&ma, &mi, &pa)
	return int(ma), int(mi), int(pa)
}

ctx_term :: proc(ctx: Context) -> Error {
	return _ctx_term(ctx) == 0 ? nil : last_error()
}

socket :: proc(ctx: Context, type: Socket_Type) -> (s: Socket, err: Error) {
	s = _socket(ctx, type)

	if s == nil {
		err = last_error()
	}

	return s, err
}

close :: proc(s: Socket) -> Error {
	return _close(s) == 0 ? nil : last_error()
}

bind :: proc(s: Socket, addr: cstring) -> Error {
	return _bind(s, addr) == 0 ? nil : last_error()
}

connect :: proc(s: Socket, addr: cstring) -> Error {
	return _connect(s, addr) == 0 ? nil : last_error()
}

send :: proc {
	send_bytes,
	send_const_string,
	send_string,
}

send_bytes :: proc(s: Socket, buf: []u8, flags: Flags = {}) -> (int, Error) {
	n := _send(s, rawptr(&buf[0]), c.size_t(len(buf)), flags)
	if n < 0 {
		return -1, last_error()
	}
	return int(n), nil
}

send_string :: proc(s: Socket, buf: string, flags: Flags = {}) -> (int, Error) {
	return send_bytes(s, transmute([]u8)buf, flags)
}

send_const :: proc {
	send_const_bytes,
	send_const_string,
}

// buf must have @(rodata) or global lifetime.
send_const_bytes :: proc(s: Socket, buf: []byte, flags: Flags = {}) -> (int, Error) {
	n := _send_const(s, rawptr(&buf[0]), c.size_t(len(buf)), flags)
	if n < 0 {
		return -1, last_error()
	}

	return int(n), nil
}

send_const_string :: proc(s: Socket, $str: string, flags: Flags = {}) -> (int, Error) {
	return send_const_bytes(s, transmute([]byte)str, flags)
}

recv :: proc(s: Socket, buf: []u8, flags: Flags = Flags{}) -> (int, Error) {
	n := _recv(s, rawptr(&buf[0]), c.size_t(len(buf)), flags)
	if n < 0 {
		return -1, last_error()
	}
	return int(n), nil
}

// timeout_ms -1 = block forever, 0 = non-blocking.
poll :: proc(items: []Poll_Item, timeout_ms: c.long) -> (int, Error) {
	n := _poll(rawptr(&items[0]), c.int(len(items)), timeout_ms)
	if n < 0 {
		return -1, last_error()
	}
	return int(n), nil
}