module net

import time
import io
import strings

pub const (
	tcp_default_read_timeout  = 30 * time.second
	tcp_default_write_timeout = 30 * time.second
)

[heap]
pub struct TcpConn {
pub mut:
	sock TcpSocket
mut:
	handle         int
	write_deadline time.Time
	read_deadline  time.Time
	read_timeout   time.Duration
	write_timeout  time.Duration
	is_blocking    bool
}

pub fn dial_tcp(address string) !&TcpConn {
	addrs := resolve_addrs_fuzzy(address, .tcp) or {
		return error('${err.msg()}; could not resolve address ${address} in dial_tcp')
	}

	// Keep track of dialing errors that take place
	mut errs := []IError{}

	// Very simple dialer
	for addr in addrs {
		mut s := new_tcp_socket(addr.family()) or {
			return error('${err.msg()}; could not create new tcp socket in dial_tcp')
		}
		s.connect(addr) or {
			errs << err
			// Connection failed
			s.close() or { continue }
			continue
		}

		return &TcpConn{
			sock: s
			read_timeout: net.tcp_default_read_timeout
			write_timeout: net.tcp_default_write_timeout
		}
	}

	// Once we've failed now try and explain why we failed to connect
	// to any of these addresses
	mut err_builder := strings.new_builder(1024)
	err_builder.write_string('dial_tcp failed for address ${address}\n')
	err_builder.write_string('tried addrs:\n')
	for i := 0; i < errs.len; i++ {
		addr := addrs[i]
		why := errs[i]
		err_builder.write_string('\t${addr}: ${why}\n')
	}

	// failed
	return error(err_builder.str())
}

// bind local address and dial.
pub fn dial_tcp_with_bind(saddr string, laddr string) !&TcpConn {
	addrs := resolve_addrs_fuzzy(saddr, .tcp) or {
		return error('${err.msg()}; could not resolve address ${saddr} in dial_tcp_with_bind')
	}

	// Very simple dialer
	for addr in addrs {
		mut s := new_tcp_socket(addr.family()) or {
			return error('${err.msg()}; could not create new tcp socket in dial_tcp_with_bind')
		}
		s.bind(laddr) or {
			s.close() or { continue }
			continue
		}
		s.connect(addr) or {
			// Connection failed
			s.close() or { continue }
			continue
		}

		return &TcpConn{
			sock: s
			read_timeout: net.tcp_default_read_timeout
			write_timeout: net.tcp_default_write_timeout
		}
	}
	// failed
	return error('dial_tcp_with_bind failed for address ${saddr}')
}

pub fn (mut c TcpConn) close() ! {
	$if trace_tcp ? {
		eprintln('    TcpConn.close | c.sock.handle: ${c.sock.handle:6}')
	}
	c.sock.close()!
}

pub fn (c TcpConn) read_ptr(buf_ptr &u8, len int) !int {
	mut res := wrap_read_result(C.recv(c.sock.handle, voidptr(buf_ptr), len, 0))!
	$if trace_tcp ? {
		eprintln('<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} len: ${len} | res: ${res}')
	}
	if res > 0 {
		$if trace_tcp_data_read ? {
			eprintln(
				'<<< TcpConn.read_ptr  | 1 data.len: ${res:6} | hex: ${unsafe { buf_ptr.vbytes(res) }.hex()} | data: ' +
				unsafe { buf_ptr.vstring_with_len(res) })
		}
		return res
	}
	code := error_code()
	if code == int(error_ewouldblock) {
		c.wait_for_read()!
		res = wrap_read_result(C.recv(c.sock.handle, voidptr(buf_ptr), len, 0))!
		$if trace_tcp ? {
			eprintln('<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} len: ${len} | res: ${res}')
		}
		$if trace_tcp_data_read ? {
			if res > 0 {
				eprintln(
					'<<< TcpConn.read_ptr  | 2 data.len: ${res:6} | hex: ${unsafe { buf_ptr.vbytes(res) }.hex()} | data: ' +
					unsafe { buf_ptr.vstring_with_len(res) })
			}
		}
		return socket_error(res)
	} else {
		wrap_error(code)!
	}
	return error('none')
}

pub fn (c TcpConn) read(mut buf []u8) !int {
	return c.read_ptr(buf.data, buf.len) or {
		return io.NotExpected{
			cause: 'unexpected error in `read_ptr` function'
			code: -1
		}
	}
}

pub fn (mut c TcpConn) read_deadline() !time.Time {
	if c.read_deadline.unix == 0 {
		return c.read_deadline
	}
	return error('none')
}

// write_ptr blocks and attempts to write all data
pub fn (mut c TcpConn) write_ptr(b &u8, len int) !int {
	$if trace_tcp_sock_handle ? {
		eprintln('>>> TcpConn.write_ptr | c: ${ptr_str(c)} | c.sock.handle: ${c.sock.handle} | b: ${ptr_str(b)} | len: ${len}')
	}
	$if trace_tcp ? {
		eprintln(
			'>>> TcpConn.write_ptr | c.sock.handle: ${c.sock.handle} | b: ${ptr_str(b)} len: ${len} |\n' +
			unsafe { b.vstring_with_len(len) })
	}
	$if trace_tcp_data_write ? {
		eprintln(
			'>>> TcpConn.write_ptr | data.len: ${len:6} | hex: ${unsafe { b.vbytes(len) }.hex()} | data: ' +
			unsafe { b.vstring_with_len(len) })
	}
	unsafe {
		mut ptr_base := &u8(b)
		mut total_sent := 0
		for total_sent < len {
			ptr := ptr_base + total_sent
			remaining := len - total_sent
			mut sent := C.send(c.sock.handle, ptr, remaining, msg_nosignal)
			$if trace_tcp_data_write ? {
				eprintln('>>> TcpConn.write_ptr | data chunk, total_sent: ${total_sent:6}, remaining: ${remaining:6}, ptr: ${voidptr(ptr):x} => sent: ${sent:6}')
			}
			if sent < 0 {
				code := error_code()
				if code == int(error_ewouldblock) {
					c.wait_for_write()!
					continue
				} else {
					wrap_error(code)!
				}
			}
			total_sent += sent
		}
		return total_sent
	}
}

// write blocks and attempts to write all data
pub fn (mut c TcpConn) write(bytes []u8) !int {
	return c.write_ptr(bytes.data, bytes.len)
}

// write_string blocks and attempts to write all data
pub fn (mut c TcpConn) write_string(s string) !int {
	return c.write_ptr(s.str, s.len)
}

pub fn (mut c TcpConn) set_read_deadline(deadline time.Time) {
	c.read_deadline = deadline
}

pub fn (mut c TcpConn) write_deadline() !time.Time {
	if c.write_deadline.unix == 0 {
		return c.write_deadline
	}
	return error('none')
}

pub fn (mut c TcpConn) set_write_deadline(deadline time.Time) {
	c.write_deadline = deadline
}

pub fn (c &TcpConn) read_timeout() time.Duration {
	return c.read_timeout
}

pub fn (mut c TcpConn) set_read_timeout(t time.Duration) {
	c.read_timeout = t
}

pub fn (c &TcpConn) write_timeout() time.Duration {
	return c.write_timeout
}

pub fn (mut c TcpConn) set_write_timeout(t time.Duration) {
	c.write_timeout = t
}

[inline]
pub fn (c TcpConn) wait_for_read() ! {
	return wait_for_read(c.sock.handle, c.read_deadline, c.read_timeout)
}

[inline]
pub fn (mut c TcpConn) wait_for_write() ! {
	return wait_for_write(c.sock.handle, c.write_deadline, c.write_timeout)
}

// set_sock initialises the c.sock field. It should be called after `.accept_only()!`.
// Note: just use `.accept()!`. In most cases it is simpler, and calls `.set_sock()!` for you.
pub fn (mut c TcpConn) set_sock() ! {
	c.sock = tcp_socket_from_handle(c.handle)!
	$if trace_tcp ? {
		eprintln('    TcpListener.accept | << new_sock.handle: ${c.handle:6}')
	}
}

// peer_addr retrieves the ip address and port number used by the peer
pub fn (c &TcpConn) peer_addr() !Addr {
	return peer_addr_from_socket_handle(c.sock.handle)
}

// peer_ip retrieves the ip address used by the peer, and returns it as a string
pub fn (c &TcpConn) peer_ip() !string {
	return c.peer_addr()!.str()
}

pub fn (c &TcpConn) addr() !Addr {
	return c.sock.address()
}

pub fn (c TcpConn) str() string {
	s := c.sock.str().replace('\n', ' ').replace('  ', ' ')
	return 'TcpConn{ write_deadline: ${c.write_deadline}, read_deadline: ${c.read_deadline}, read_timeout: ${c.read_timeout}, write_timeout: ${c.write_timeout}, sock: ${s} }'
}

pub struct TcpListener {
pub mut:
	sock TcpSocket
mut:
	accept_timeout  time.Duration
	accept_deadline time.Time
}

[params]
pub struct ListenOptions {
pub:
	dualstack bool = true
	backlog   int  = 128
}

pub fn listen_tcp(family AddrFamily, saddr string, options ListenOptions) !&TcpListener {
	mut s := new_tcp_socket(family) or { return error('${err.msg()}; could not create new socket') }
	s.set_dualstack(options.dualstack) or {}

	addrs := resolve_addrs(saddr, family, .tcp) or {
		return error('${err.msg()}; could not resolve address ${saddr}')
	}
	// TODO(logic to pick here)
	addr := addrs[0]

	// cast to the correct type
	alen := addr.len()
	socket_error_message(C.bind(s.handle, voidptr(&addr), alen), 'binding to ${saddr} failed')!
	socket_error_message(C.listen(s.handle, options.backlog), 'listening on ${saddr} with maximum backlog pending queue of ${options.backlog}, failed')!
	return &TcpListener{
		sock: s
		accept_deadline: no_deadline
		accept_timeout: infinite_timeout
	}
}

// accept a tcp connection from an external source to the listener `l`.
pub fn (mut l TcpListener) accept() !&TcpConn {
	mut res := l.accept_only()!
	res.set_sock()!
	return res
}

// accept_only accepts a tcp connection from an external source to the listener `l`.
// Unlike `accept`, `accept_only` *will not call* `.set_sock()!` on the result,
// and is thus faster.
//
// Note: you *need* to call `.set_sock()!` manually, before using the
// connection after calling `.accept_only()!`, but that does not have to happen
// in the same thread that called `.accept_only()!`.
// The intention of this API, is to have a more efficient way to accept
// connections, that are later processed by a thread pool, while the main
// thread remains active, so that it can accept other connections.
// See also vlib/vweb/vweb.v .
//
// If you do not need that, just call `.accept()!` instead, which will call
// `.set_sock()!` for you.
pub fn (mut l TcpListener) accept_only() !&TcpConn {
	$if trace_tcp ? {
		eprintln('    TcpListener.accept | l.sock.handle: ${l.sock.handle:6}')
	}

	mut new_handle := C.accept(l.sock.handle, 0, 0)
	if new_handle <= 0 {
		l.wait_for_accept()!
		new_handle = C.accept(l.sock.handle, 0, 0)
		if new_handle == -1 || new_handle == 0 {
			return error('accept failed')
		}
	}

	return &TcpConn{
		handle: new_handle
		read_timeout: net.tcp_default_read_timeout
		write_timeout: net.tcp_default_write_timeout
	}
}

pub fn (c &TcpListener) accept_deadline() !time.Time {
	if c.accept_deadline.unix != 0 {
		return c.accept_deadline
	}
	return error('invalid deadline')
}

pub fn (mut c TcpListener) set_accept_deadline(deadline time.Time) {
	c.accept_deadline = deadline
}

pub fn (c &TcpListener) accept_timeout() time.Duration {
	return c.accept_timeout
}

pub fn (mut c TcpListener) set_accept_timeout(t time.Duration) {
	c.accept_timeout = t
}

pub fn (mut c TcpListener) wait_for_accept() ! {
	return wait_for_read(c.sock.handle, c.accept_deadline, c.accept_timeout)
}

pub fn (mut c TcpListener) close() ! {
	c.sock.close()!
}

pub fn (c &TcpListener) addr() !Addr {
	return c.sock.address()
}

struct TcpSocket {
	Socket
}

fn new_tcp_socket(family AddrFamily) !TcpSocket {
	handle := socket_error(C.socket(family, SocketType.tcp, 0))!
	mut s := TcpSocket{
		handle: handle
	}
	$if trace_tcp ? {
		eprintln('    new_tcp_socket | s.handle: ${s.handle:6}')
	}

	// TODO(emily):
	// we shouldnt be using ioctlsocket in the 21st century
	// use the non-blocking socket option instead please :)

	// TODO(emily):
	// Move this to its own function on the socket
	s.set_option_int(.reuse_addr, 1)!

	$if !net_blocking_sockets ? {
		$if windows {
			t := u32(1) // true
			socket_error(C.ioctlsocket(handle, fionbio, &t))!
		} $else {
			socket_error(C.fcntl(handle, C.F_SETFL, C.fcntl(handle, C.F_GETFL) | C.O_NONBLOCK))!
		}
	}
	return s
}

fn tcp_socket_from_handle(sockfd int) !TcpSocket {
	mut s := TcpSocket{
		handle: sockfd
	}
	$if trace_tcp ? {
		eprintln('    tcp_socket_from_handle | s.handle: ${s.handle:6}')
	}
	// s.set_option_bool(.reuse_addr, true)?
	s.set_option_int(.reuse_addr, 1)!
	s.set_dualstack(true) or {
		// Not ipv6, we dont care
	}
	$if !net_blocking_sockets ? {
		$if windows {
			t := u32(1) // true
			socket_error(C.ioctlsocket(sockfd, fionbio, &t))!
		} $else {
			socket_error(C.fcntl(sockfd, C.F_SETFL, C.fcntl(sockfd, C.F_GETFL) | C.O_NONBLOCK))!
		}
	}
	return s
}

// tcp_socket_from_handle_raw is similar to tcp_socket_from_handle, but it does not modify any socket options
pub fn tcp_socket_from_handle_raw(sockfd int) TcpSocket {
	mut s := TcpSocket{
		handle: sockfd
	}
	$if trace_tcp ? {
		eprintln('    tcp_socket_from_handle_raw | s.handle: ${s.handle:6}')
	}
	return s
}

pub fn (mut s TcpSocket) set_option_bool(opt SocketOption, value bool) ! {
	// TODO reenable when this `in` operation works again
	// if opt !in opts_can_set {
	// 	return err_option_not_settable
	// }
	// if opt !in opts_bool {
	// 	return err_option_wrong_type
	// }
	x := int(value)
	socket_error(C.setsockopt(s.handle, C.SOL_SOCKET, int(opt), &x, sizeof(int)))!
}

pub fn (mut s TcpSocket) set_dualstack(on bool) ! {
	x := int(!on)
	socket_error(C.setsockopt(s.handle, C.IPPROTO_IPV6, int(SocketOption.ipv6_only), &x,
		sizeof(int)))!
}

pub fn (mut s TcpSocket) set_option_int(opt SocketOption, value int) ! {
	socket_error(C.setsockopt(s.handle, C.SOL_SOCKET, int(opt), &value, sizeof(int)))!
}

// bind a local rddress for TcpSocket
pub fn (mut s TcpSocket) bind(addr string) ! {
	addrs := resolve_addrs(addr, AddrFamily.ip, .tcp) or {
		return error('${err.msg()}; could not resolve address ${addr}')
	}

	// TODO(logic to pick here)
	a := addrs[0]

	// cast to the correct type
	alen := a.len()
	socket_error_message(C.bind(s.handle, voidptr(&a), alen), 'binding to ${addr} failed') or {
		return err
	}
}

fn (mut s TcpSocket) close() ! {
	shutdown(s.handle)
	return close(s.handle)
}

fn (mut s TcpSocket) @select(test Select, timeout time.Duration) !bool {
	return @select(s.handle, test, timeout)
}

const (
	connect_timeout = 5 * time.second
)

fn (mut s TcpSocket) connect(a Addr) ! {
	$if !net_blocking_sockets ? {
		res := C.connect(s.handle, voidptr(&a), a.len())
		if res == 0 {
			return
		}
		ecode := error_code()
		// On nix non-blocking sockets we expect einprogress
		// On windows we expect res == -1 && error_code() == ewouldblock
		if (is_windows && ecode == int(error_ewouldblock))
			|| (!is_windows && res == -1 && ecode == int(error_einprogress)) {
			// The  socket  is  nonblocking and the connection cannot be completed
			// immediately.  (UNIX domain sockets failed with EAGAIN instead.)
			// It is possible to select(2) or poll(2) for completion by selecting
			// the socket for  writing.   After  select(2) indicates  writability,
			// use getsockopt(2) to read the SO_ERROR option at level SOL_SOCKET to
			// determine whether connect() completed successfully (SO_ERROR is zero) or
			// unsuccessfully (SO_ERROR is one of the usual error codes  listed  here,
			// ex‐ plaining the reason for the failure).
			write_result := s.@select(.write, net.connect_timeout)!
			err := 0
			len := sizeof(err)
			xyz := C.getsockopt(s.handle, C.SOL_SOCKET, C.SO_ERROR, &err, &len)
			if xyz == 0 && err == 0 {
				return
			}
			if write_result {
				if xyz == 0 {
					wrap_error(err)!
					return
				}
				return
			}
			return err_timed_out
		}
		wrap_error(ecode)!
		return
	} $else {
		x := C.connect(s.handle, voidptr(&a), a.len())
		socket_error(x)!
	}
}