package notify

import (
	"context"
	"errors"
	"net"
	"os"
	"time"
)

var _ net.Conn = (*streamHandle)(nil)

func streamLocalAddrSnapshot(logical *LogicalConn, transport *TransportConn) net.Addr {
	if logical != nil {
		if conn := logical.transportSnapshot(); conn != nil && conn.LocalAddr() != nil {
			return conn.LocalAddr()
		}
		server := logical.Server()
		if common, ok := server.(*ServerCommon); ok {
			if common.listener != nil && common.listener.Addr() != nil {
				return common.listener.Addr()
			}
			if udp := common.serverUDPListenerSnapshot(); udp != nil && udp.LocalAddr() != nil {
				return udp.LocalAddr()
			}
		}
	}
	if transport != nil {
		return transportLocalAddrSnapshot(transport)
	}
	return nil
}

func streamRemoteAddrSnapshot(logical *LogicalConn, transport *TransportConn) net.Addr {
	if transport != nil && transport.RemoteAddr() != nil {
		return transport.RemoteAddr()
	}
	if logical != nil {
		return logical.RemoteAddr()
	}
	return nil
}

func transportLocalAddrSnapshot(transport *TransportConn) net.Addr {
	if transport == nil {
		return nil
	}
	logical := transport.LogicalConn()
	if logical == nil {
		return nil
	}
	conn := logical.transportSnapshot()
	if conn == nil || conn.LocalAddr() == nil {
		return nil
	}
	if transport.TransportGeneration() != 0 && transport.TransportGeneration() != logical.transportGenerationSnapshot() {
		return nil
	}
	return conn.LocalAddr()
}

func signalStreamDeadlineChangeLocked(ch *chan struct{}) {
	if ch == nil {
		return
	}
	current := *ch
	if current != nil {
		close(current)
	}
	*ch = make(chan struct{})
}

func streamEffectiveDeadline(now time.Time, timeout time.Duration, explicit time.Time) time.Time {
	deadline := explicit
	if timeout > 0 {
		timeoutDeadline := now.Add(timeout)
		if deadline.IsZero() || timeoutDeadline.Before(deadline) {
			deadline = timeoutDeadline
		}
	}
	return deadline
}

func streamDeadlineChanged(ch <-chan struct{}) bool {
	if ch == nil {
		return false
	}
	select {
	case <-ch:
		return true
	default:
		return false
	}
}

func normalizeStreamDeadlineError(err error) error {
	switch {
	case err == nil:
		return nil
	case errors.Is(err, context.DeadlineExceeded):
		return os.ErrDeadlineExceeded
	default:
		return err
	}
}