#ifndef LLARP_EV_H
#define LLARP_EV_H

#include <util/buffer.hpp>
#include <util/time.hpp>
#include <tuntap.h>

#ifdef _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#include <wspiapi.h>
#else
#include <netinet/in.h>
#include <sys/socket.h>
#include <net/net_if.hpp>
#endif

#include <memory>

#include <cstdint>
#include <cstdlib>

#if !defined(WIN32)
#include <uv.h>
#endif

/**
 * ev.h
 *
 * event handler (cross platform high performance event system for IO)
 */

#define EV_TICK_INTERVAL 10

// forward declare
struct llarp_threadpool;

struct llarp_ev_loop;

namespace llarp
{
  class Logic;
}

using llarp_ev_loop_ptr = std::shared_ptr< llarp_ev_loop >;

/// make an event loop using our baked in event loop on Windows
/// make an event loop using libuv otherwise.
llarp_ev_loop_ptr
llarp_make_ev_loop();

// run mainloop
void
llarp_ev_loop_run_single_process(llarp_ev_loop_ptr ev,
                                 std::shared_ptr< llarp::Logic > logic);

/// get the current time on the event loop
llarp_time_t
llarp_ev_loop_time_now_ms(const llarp_ev_loop_ptr &ev);

/// stop event loop and wait for it to complete all jobs
void
llarp_ev_loop_stop(const llarp_ev_loop_ptr &ev);

/// list of packets we recv'd
/// forward declared
struct llarp_pkt_list;

/// UDP handling configuration
struct llarp_udp_io
{
  /// set after added
  int fd;
  void *user;
  void *impl;
  struct llarp_ev_loop *parent;

  /// called every event loop tick after reads
  void (*tick)(struct llarp_udp_io *);
  /// sockaddr * is the source address
  void (*recvfrom)(struct llarp_udp_io *, const struct sockaddr *,
                   ManagedBuffer);
  /// set by parent
  int (*sendto)(struct llarp_udp_io *, const struct sockaddr *, const byte_t *,
                size_t);
};

/// get all packets recvieved last tick
/// return true if we got packets return false if we didn't
bool
llarp_ev_udp_recvmany(struct llarp_udp_io *udp, struct llarp_pkt_list *pkts);

/// add UDP handler
int
llarp_ev_add_udp(struct llarp_ev_loop *ev, struct llarp_udp_io *udp,
                 const struct sockaddr *src);

/// send a UDP packet
int
llarp_ev_udp_sendto(struct llarp_udp_io *udp, const struct sockaddr *to,
                    const llarp_buffer_t &pkt);

/// close UDP handler
int
llarp_ev_close_udp(struct llarp_udp_io *udp);

// forward declare
struct llarp_tcp_acceptor;

/// a single tcp connection
struct llarp_tcp_conn
{
  /// user data
  void *user;
  /// private implementation
  void *impl;
  /// parent loop (dont set me)
  struct llarp_ev_loop *loop;
  /// handle read event
  void (*read)(struct llarp_tcp_conn *, const llarp_buffer_t &);
  //// set by parent
  ssize_t (*write)(struct llarp_tcp_conn *, const byte_t *, size_t sz);
  /// set by parent
  bool (*is_open)(struct llarp_tcp_conn *);
  /// handle close event (free-ing is handled by event loop)
  void (*closed)(struct llarp_tcp_conn *);
  /// explict close by user (set by parent)
  void (*close)(struct llarp_tcp_conn *);
  /// handle event loop tick
  void (*tick)(struct llarp_tcp_conn *);
};

/// queue async write a buffer in full
/// return if we queued it or not
bool
llarp_tcp_conn_async_write(struct llarp_tcp_conn *, const llarp_buffer_t &);

/// close a tcp connection
void
llarp_tcp_conn_close(struct llarp_tcp_conn *);

/// handles outbound connections to 1 endpoint
struct llarp_tcp_connecter
{
  /// remote address family
  int af;
  /// remote address string
  char remote[512];
  /// userdata pointer
  void *user;
  /// private implementation (dont set me)
  void *impl;
  /// parent event loop (dont set me)
  struct llarp_ev_loop *loop;
  /// handle outbound connection made
  void (*connected)(struct llarp_tcp_connecter *, struct llarp_tcp_conn *);
  /// handle outbound connection error
  void (*error)(struct llarp_tcp_connecter *);
};

/// async try connecting to a remote connection 1 time
void
llarp_tcp_async_try_connect(struct llarp_ev_loop *l,
                            struct llarp_tcp_connecter *tcp);

/// handles inbound connections
struct llarp_tcp_acceptor
{
  /// userdata pointer
  void *user;
  /// internal implementation
  void *impl;
  /// parent event loop (dont set me)
  struct llarp_ev_loop *loop;
  /// handle event loop tick
  void (*tick)(struct llarp_tcp_acceptor *);
  /// handle inbound connection
  void (*accepted)(struct llarp_tcp_acceptor *, struct llarp_tcp_conn *);
  /// handle after server socket closed (free-ing is handled by event loop)
  void (*closed)(struct llarp_tcp_acceptor *);
  /// set by impl
  void (*close)(struct llarp_tcp_acceptor *);
};

/// bind to an address and start serving async
/// return false if failed to bind
/// return true on success
bool
llarp_tcp_serve(struct llarp_ev_loop *loop, struct llarp_tcp_acceptor *t,
                const sockaddr *bindaddr);

/// close and stop accepting connections
void
llarp_tcp_acceptor_close(struct llarp_tcp_acceptor *);

#ifdef _WIN32
#define IFNAMSIZ (16)
#endif

struct llarp_fd_promise;

/// wait until the fd promise is set
int
llarp_fd_promise_wait_for_value(struct llarp_fd_promise *promise);

struct llarp_tun_io
{
  // TODO: more info?
  char ifaddr[128];
  // windows only
  uint32_t dnsaddr;
  int netmask;
  char ifname[IFNAMSIZ + 1];

  void *user;
  void *impl;

  /// functor for getting a promise that returns the vpn fd
  /// dont set me if you don't know how to use this
  struct llarp_fd_promise *(*get_fd_promise)(struct llarp_tun_io *);

  struct llarp_ev_loop *parent;
  /// called when we are able to write right before we write
  /// this happens after reading packets
  void (*before_write)(struct llarp_tun_io *);
  /// called every event loop tick after reads
  void (*tick)(struct llarp_tun_io *);
  void (*recvpkt)(struct llarp_tun_io *, const llarp_buffer_t &);
  /// set by parent
  bool (*writepkt)(struct llarp_tun_io *, const byte_t *, size_t);
};

/// create tun interface with network interface name ifname
/// returns true on success otherwise returns false
bool
llarp_ev_add_tun(struct llarp_ev_loop *ev, struct llarp_tun_io *tun);

/// async write a packet on tun interface
/// returns true if queued, returns false on drop
bool
llarp_ev_tun_async_write(struct llarp_tun_io *tun, const llarp_buffer_t &);

#endif