#ifndef HOST_H
#define HOST_H

#include "sys.h"
#include "sock.h"

#define HOST_CHANNEL_ID_NIL (struct host_channel_id) { .gen = 0, .idx = 0 }
#define HOST_CHANNEL_ID_ALL (struct host_channel_id) { .gen = U32_MAX, .idx = U32_MAX }

struct buddy_ctx;
struct host_snd_packet;
struct host_channel_lookup_bin;
struct host_rcv_buffer;

enum host_cmd_kind {
    HOST_CMD_KIND_NONE,

    HOST_CMD_KIND_TRY_CONNECT,
    HOST_CMD_KIND_CONNECT_SUCCESS,
    HOST_CMD_KIND_DISCONNECT,
    HOST_CMD_KIND_HEARTBEAT,
    HOST_CMD_KIND_WRITE
};

enum host_event_kind {
    HOST_EVENT_KIND_NONE,

    HOST_EVENT_KIND_CHANNEL_OPENED,
    HOST_EVENT_KIND_CHANNEL_CLOSED,
    HOST_EVENT_KIND_MSG
};

enum host_write_flag {
    HOST_WRITE_FLAG_NONE = 0,

    HOST_WRITE_FLAG_RELIABLE = (1 << 0)
};

struct host_cmd {
    enum host_cmd_kind kind;
    struct host_channel_id channel_id;

    u16 heartbeat_id;
    u16 heartbeat_ack_id;

    b32 write_reliable;
    struct string write_msg;


    struct host_cmd *next;
};

struct host_event {
    enum host_event_kind kind;
    struct host_channel_id channel_id;
    struct string msg;

    struct host_event *next;
};

struct host_event_list {
    struct host_event *first;
    struct host_event *last;
};

struct host {
    struct arena *arena;

    struct sock *sock;

    struct buddy_ctx *buddy;  /* For storing msg assembler data */

    struct arena *cmd_arena;
    struct host_cmd *first_cmd;
    struct host_cmd *last_cmd;
    struct host_cmd *first_free_cmd;

    struct arena *channel_arena;
    struct host_channel *channels;
    struct host_channel *first_free_channel;
    u64 num_channels_reserved;

    struct host_snd_packet *first_free_packet;                                  /* Allocated in `arena` */
    struct host_msg_assembler *first_free_msg_assembler;                        /* Allocated in `arena` */

    struct host_channel_lookup_bin *channel_lookup_bins;                        /* Allocated in `arena` */
    u64 num_channel_lookup_bins;

    struct host_msg_assembler_lookup_bin *msg_assembler_lookup_bins;            /* Allocated in `arena` */
    u64 num_msg_assembler_lookup_bins;

    /* Double buffer for incoming data */
    struct sys_mutex *rcv_buffer_write_mutex;
    struct host_rcv_buffer *rcv_buffer_read;
    struct host_rcv_buffer *rcv_buffer_write;

    u64 bytes_received;
    u64 bytes_sent;

    struct atomic_i32 receiver_thread_shutdown_flag;
    struct sys_thread *receiver_thread;
};

/* ========================== *
 * Startup
 * ========================== */

struct host_startup_receipt { i32 _; };
struct host_startup_receipt host_startup(struct sock_startup_receipt *sock_sr);

/* ========================== *
 * Host
 * ========================== */

struct host *host_alloc(u16 listen_port);

void host_release(struct host *host);

/* ========================== *
 * Queue
 * ========================== */

void host_queue_connect_to_address(struct host *host, struct sock_address connect_address);

void host_queue_disconnect(struct host *host, struct host_channel_id channel_id);

void host_queue_write(struct host *host, struct host_channel_id channel_id, struct string msg, u32 flags);

/* ========================== *
 * Info
 * ========================== */

i64 host_get_channel_last_rtt_ns(struct host *host, struct host_channel_id channel_id);
INLINE b32 host_channel_id_eq(struct host_channel_id a, struct host_channel_id b) { return a.idx == b.idx && a.gen == b.gen; }
INLINE b32 host_channel_id_is_nil(struct host_channel_id id) { return id.gen == 0 && id.idx == 0; }

/* ========================== *
 * Update
 * ========================== */

struct host_event_list host_update_begin(struct arena *arena, struct host *host);
void host_update_end(struct host *host);

#endif