#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/prctl.h>

#include "logo.h"
#include "stat.h"
#include "stellar.h"
#include "config.h"
#include "packet_private.h"
#include "packet_io.h"
#include "timestamp.h"
#include "id_generator.h"
#include "ip_reassembly.h"
#include "session_manager.h"
#include "plugin_manager.h"

#define STELLAR_LOG_STATE(format, ...) LOG_STATE("stellar", format, ##__VA_ARGS__)
#define STELLAR_LOG_ERROR(format, ...) LOG_ERROR("stellar", format, ##__VA_ARGS__)
#define STELLAR_LOG_DEBUG(format, ...) LOG_DEBUG("stellar", format, ##__VA_ARGS__)

struct thread_ctx
{
    pthread_t tid;
    uint16_t idx;
    uint64_t is_runing;
    struct ip_reassembly *ip_mgr;
    struct session_manager *sess_mgr;
};

struct stellar_runtime
{
    uint64_t need_exit;
    struct stellar_stat *stat;
    struct packet_io *packet_io;
    struct plugin_manager *plug_mgr;
    struct thread_ctx threads[MAX_THREAD_NUM];
};
struct stellar_runtime __runtime;
struct stellar_runtime *runtime = &__runtime;

struct stellar_config __config;
struct stellar_config *config = &__config;

static const char *log_config_file = "./conf/log.toml";
static const char *stellar_config_file = "./conf/stellar.toml";

/******************************************************************************
 * util
 ******************************************************************************/

static void signal_handler(int signo)
{
    if (signo == SIGINT)
    {
        STELLAR_LOG_STATE("SIGINT received, notify threads to exit !!!");
        ATOMIC_SET(&runtime->need_exit, 1);
    }

    if (signo == SIGQUIT)
    {
        STELLAR_LOG_STATE("SIGQUIT received, notify threads to exit !!!");
        ATOMIC_SET(&runtime->need_exit, 1);
    }

    if (signo == SIGTERM)
    {
        STELLAR_LOG_STATE("SIGTERM received, notify threads to exit !!!");
        ATOMIC_SET(&runtime->need_exit, 1);
    }

    if (signo == SIGHUP)
    {
        STELLAR_LOG_STATE("SIGHUP received, reload log level !!!");
        log_reload_level(log_config_file);
    }
}

static void execute_packet_action(struct packet_io *packet_io, struct session *sess, struct packet *pkt, uint16_t thr_idx)
{
    int is_ctrl = packet_is_ctrl(pkt);
    int need_drop = packet_need_drop(pkt);

    if (sess != NULL)
    {
        enum session_stat stat_pkt;
        enum session_stat stat_byte;
        if (need_drop)
        {
            stat_pkt = is_ctrl ? STAT_CTRL_PKTS_DROP : STAT_RAW_PKTS_DROP;
            stat_byte = is_ctrl ? STAT_CTRL_BYTES_DROP : STAT_RAW_BYTES_DROP;
        }
        else
        {
            stat_pkt = is_ctrl ? STAT_CTRL_PKTS_TX : STAT_RAW_PKTS_TX;
            stat_byte = is_ctrl ? STAT_CTRL_BYTES_TX : STAT_RAW_BYTES_TX;
        }

        session_inc_stat(sess, session_get_current_direction(sess), stat_pkt, 1);
        session_inc_stat(sess, session_get_current_direction(sess), stat_byte, packet_get_len(pkt));
        session_set_current_packet(sess, NULL);
        session_set_current_direction(sess, SESSION_DIRECTION_NONE);
    }

    if (need_drop)
    {
        packet_io_drop(packet_io, thr_idx, pkt, 1);
    }
    else
    {
        packet_io_egress(packet_io, thr_idx, pkt, 1);
    }
}

/******************************************************************************
 * thread
 ******************************************************************************/

static inline void thread_set_name(const char *thd_symbol, uint16_t thd_idx)
{
    char thd_name[16];
    snprintf(thd_name, sizeof(thd_name), "%s:%d", thd_symbol, thd_idx);
    prctl(PR_SET_NAME, (unsigned long long)thd_name, NULL, NULL, NULL);
}

static inline void stellar_thread_cron(struct thread_ctx *thr_ctx)
{
    thread_local uint64_t last = 0;
    if (timestamp_get_msec() - last > 2000)
    {
        struct thread_stat thr_stat = {
            ip_reassembly_get_stat(thr_ctx->ip_mgr),
            session_manager_get_stat(thr_ctx->sess_mgr),
        };
        stellar_peek_thr_stat(runtime->stat, &thr_stat, thr_ctx->idx);
        last = timestamp_get_msec();
    }
}

static void *work_thread(void *arg)
{
    int nr_recv;
    uint64_t now = 0;
    uint16_t thr_idx = 0;
    void *plugin_ctx;
    struct packet *pkt;
    struct packet packets[RX_BURST_MAX];
    struct session *sess;
    struct session *evicted_sess;
    struct session *expired_sess;
    struct packet_io *packet_io = runtime->packet_io;
    struct plugin_manager *plug_mgr = runtime->plug_mgr;
    struct thread_ctx *thr_ctx = (struct thread_ctx *)arg;
    struct ip_reassembly *ip_reass = thr_ctx->ip_mgr;
    struct session_manager *sess_mgr = thr_ctx->sess_mgr;
    thr_idx = thr_ctx->idx;

    if (packet_io_init(packet_io, thr_idx) != 0)
    {
        STELLAR_LOG_ERROR("unable to init marsio thread");
        return NULL;
    }

    ATOMIC_SET(&thr_ctx->is_runing, 1);
    thread_set_name("stellar", thr_idx);
    STELLAR_LOG_STATE("worker thread %d runing", thr_idx);

    while (ATOMIC_READ(&runtime->need_exit) == 0)
    {
        now = timestamp_get_msec(); // TODO
        nr_recv = packet_io_ingress(packet_io, thr_idx, packets, RX_BURST_MAX);
        if (nr_recv == 0)
        {
            goto idle_tasks;
        }

        for (int i = 0; i < nr_recv; i++)
        {
            sess = NULL;
            pkt = &packets[i];

            plugin_manager_dispatch_packet(plug_mgr, pkt);
            if (packet_is_fragment(pkt))
            {
                struct packet *defraged_pkt = ip_reassembly_packet(ip_reass, pkt, now);
                if (defraged_pkt == NULL)
                {
                    goto fast_path;
                }
                else
                {
                    pkt = defraged_pkt;
                    plugin_manager_dispatch_packet(plug_mgr, pkt);
                }
            }

            sess = session_manager_lookup_session(sess_mgr, pkt);
            if (sess == NULL)
            {
                sess = session_manager_new_session(sess_mgr, pkt, now);
                if (sess == NULL)
                {
                    goto fast_path;
                }
                plugin_ctx = plugin_manager_new_ctx(sess);
                session_set_user_data(sess, plugin_ctx);
            }
            else
            {
                if (session_manager_update_session(sess_mgr, sess, pkt, now) == -1)
                {
                    goto fast_path;
                }
            }
            plugin_manager_dispatch_session(plug_mgr, sess, pkt);

        fast_path:
            execute_packet_action(packet_io, sess, pkt, thr_idx);
        }

    idle_tasks:
        // nr_recv packet atmost trigger nr_recv session evict
        for (int i = 0; i < nr_recv; i++)
        {
            evicted_sess = session_manager_get_evicted_session(sess_mgr);
            if (evicted_sess)
            {
                plugin_ctx = session_get_user_data(evicted_sess);
                plugin_manager_free_ctx(plugin_ctx);
                session_manager_free_session(sess_mgr, evicted_sess);
            }
        }

        while ((expired_sess = session_manager_get_expired_session(sess_mgr, now)))
        {
            plugin_ctx = session_get_user_data(expired_sess);
            plugin_manager_free_ctx(plugin_ctx);
            session_manager_free_session(sess_mgr, expired_sess);
        }
        ip_reassembly_expire(ip_reass, now);

        stellar_thread_cron(thr_ctx);

        // TODO
        // plugin_manager_cron();
        // poll_non_packet_events();
        // packet_io_yield();
    }

    ATOMIC_SET(&thr_ctx->is_runing, 0);
    STELLAR_LOG_STATE("worker thread %d exit !!!", thr_idx);

    return NULL;
}

static int stellar_thread_init(struct stellar_runtime *ctx, uint8_t nr_threads)
{
    uint64_t now = timestamp_get_msec();
    for (uint8_t i = 0; i < nr_threads; i++)
    {
        struct thread_ctx *thr_ctx = &ctx->threads[i];
        thr_ctx->idx = i;
        thr_ctx->is_runing = 0;
        thr_ctx->sess_mgr = session_manager_new(&config->sess_mgr_opts, now);
        if (thr_ctx->sess_mgr == NULL)
        {
            STELLAR_LOG_ERROR("unable to create session manager");
            return -1;
        }
        thr_ctx->ip_mgr = ip_reassembly_new(&config->ip_opts);
        if (thr_ctx->ip_mgr == NULL)
        {
            STELLAR_LOG_ERROR("unable to create ip reassemble manager");
            return -1;
        }
    }

    return 0;
}

static void stellar_thread_clean(struct stellar_runtime *ctx, uint8_t nr_threads)
{
    for (uint8_t i = 0; i < nr_threads; i++)
    {
        struct thread_ctx *thr_ctx = &ctx->threads[i];
        if (ATOMIC_READ(&thr_ctx->is_runing) == 0)
        {
            STELLAR_LOG_STATE("wait worker thread %d free context", i);
            session_manager_free(thr_ctx->sess_mgr);
            ip_reassembly_free(thr_ctx->ip_mgr);
        }
    }
}

static int stellar_thread_run(struct stellar_runtime *ctx, uint8_t nr_threads)
{
    for (uint8_t i = 0; i < nr_threads; i++)
    {
        struct thread_ctx *thr_ctx = &ctx->threads[i];
        if (pthread_create(&thr_ctx->tid, NULL, work_thread, (void *)thr_ctx) < 0)
        {
            STELLAR_LOG_ERROR("unable to create worker thread, error %d: %s", errno, strerror(errno));
            return -1;
        }
    }

    return 0;
}

static void stellar_thread_join(struct stellar_runtime *ctx, uint8_t nr_threads)
{
    for (uint8_t i = 0; i < nr_threads; i++)
    {
        struct thread_ctx *thr_ctx = &ctx->threads[i];
        while (ATOMIC_READ(&thr_ctx->is_runing) == 1)
        {
            STELLAR_LOG_STATE("wait worker thread %d stop", i);
            sleep(1);
        }
    }
}

/******************************************************************************
 * main
 ******************************************************************************/

int main(int argc, char **argv)
{
    uint8_t nr_threads;
    uint64_t last_stat = 0;
    struct io_stat *io_stat;
    memset(runtime, 0, sizeof(struct stellar_runtime));
    memset(config, 0, sizeof(struct stellar_config));
    timestamp_update();

    signal(SIGINT, signal_handler);
    signal(SIGQUIT, signal_handler);
    signal(SIGTERM, signal_handler);
    signal(SIGHUP, signal_handler);

    if (log_init(log_config_file) != 0)
    {
        STELLAR_LOG_ERROR("unable to init log");
        goto error_out;
    }
    STELLAR_LOG_STATE("start stellar (version: %s)\n %s", __stellar_version, logo_str);

    if (stellar_config_load(stellar_config_file, config) != 0)
    {
        STELLAR_LOG_ERROR("unable to load config file");
        goto error_out;
    }
    stellar_config_print(config);
    nr_threads = config->io_opts.nr_threads;

    if (id_generator_init(config->dev_opts.base, config->dev_opts.offset) != 0)
    {
        STELLAR_LOG_ERROR("unable to init id generator");
        goto error_out;
    }

    runtime->stat = stellar_stat_new(nr_threads);
    if (runtime->stat == NULL)
    {
        STELLAR_LOG_ERROR("unable to create stellar stat");
        goto error_out;
    }

    runtime->plug_mgr = plugin_manager_new();
    if (runtime->plug_mgr == NULL)
    {
        STELLAR_LOG_ERROR("unable to create plugin manager");
        goto error_out;
    }

    runtime->packet_io = packet_io_new(&config->io_opts);
    if (runtime->packet_io == NULL)
    {
        STELLAR_LOG_ERROR("unable to create packet io");
        goto error_out;
    }

    if (stellar_thread_init(runtime, nr_threads) != 0)
    {
        STELLAR_LOG_ERROR("unable to init thread context");
        goto error_out;
    }

    if (stellar_thread_run(runtime, nr_threads) != 0)
    {
        STELLAR_LOG_ERROR("unable to create worker thread");
        goto error_out;
    }

    io_stat = packet_io_get_stat(runtime->packet_io);
    last_stat = timestamp_get_msec();
    while (!ATOMIC_READ(&runtime->need_exit))
    {
        timestamp_update();
        if (timestamp_get_msec() - last_stat > 2000)
        {
            stellar_peek_io_stat(runtime->stat, io_stat);
            stellar_stat_output(runtime->stat);
            last_stat = timestamp_get_msec();
        }

        usleep(5 * 1000);
    }

error_out:
    stellar_thread_join(runtime, nr_threads);
    stellar_thread_clean(runtime, nr_threads);
    packet_io_free(runtime->packet_io);
    plugin_manager_free(runtime->plug_mgr);
    stellar_stat_free(runtime->stat);
    STELLAR_LOG_STATE("stellar exit !!!\n");
    log_free();

    return 0;
}