#include <string.h>
#include <stdlib.h>
#include "tfe_utils.h"
#include "io_uring.h"

extern void *g_default_logger;

#if (SUPPORT_LIBURING)

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/uio.h>
#include <liburing.h>

enum ioevent
{
    IOEVENT_UNKNOWN = 0,
    IOEVENT_READ = 1,
    IOEVENT_WRITE = 2,
};

struct iobuffer
{
    struct iovec vec;
    enum ioevent event;
    struct iobuffer *next;
};

struct iobuffer_pool
{
    int buffer_size;
    int buffer_num;
    int buffer_used;
    int buffer_left;

    struct iobuffer *free_list;
};

struct io_uring_instance
{
    int cfg_ring_size;
    int cfg_buff_size;
    int cfg_flags;
    int cfg_sq_thread_idle; // milliseconds
    int cfg_enable_debug;

    int sockfd;
    int eventfd;

    struct io_uring ring;
    struct io_uring_params params;

    void *cb_args;
    io_uring_read_cb *read_cb;
    struct iobuffer_pool *pool;
};

/******************************************************************************
 *
 ******************************************************************************/

static const char *ioevent_tostring(enum ioevent event);

static struct iobuffer *iobuffer_create(int buffer_size);
static void iobuffer_destory(struct iobuffer *buffer);

struct iobuffer_pool *iobuffer_pool_create(int buffer_size, int buffer_num);
void iobuffer_pool_destory(struct iobuffer_pool *pool);
void iobuffer_pool_print(struct iobuffer_pool *pool);

struct iobuffer *iobuffer_pool_pop(struct iobuffer_pool *pool);
void iobuffer_pool_push(struct iobuffer_pool *pool, struct iobuffer *buffer);

struct io_uring_instance *io_uring_instance_create(int sockfd, int eventfd, int ring_size, int buff_size, int flags, int sq_thread_idle, int enable_debug);
void io_uring_instance_destory(struct io_uring_instance *instance);

static int io_uring_read(struct io_uring_instance *instance, struct iobuffer *buffer);
int io_uring_write(struct io_uring_instance *instance, const char *data, int len);

int io_uring_set_read_cb(struct io_uring_instance *instance, io_uring_read_cb *read_cb, void *cb_args);
int io_uring_polling(struct io_uring_instance *instance);

/******************************************************************************
 *
 ******************************************************************************/

static const char *ioevent_tostring(enum ioevent event)
{
    switch (event)
    {
    case IOEVENT_READ:
        return "read";
    case IOEVENT_WRITE:
        return "write";
    case IOEVENT_UNKNOWN: /* fall passthrough */
    default:
        return "unknown";
    }
}

static struct iobuffer *iobuffer_create(int buffer_size)
{
    struct iobuffer *buffer = (struct iobuffer *)calloc(1, sizeof(struct iobuffer));
    if (buffer == NULL)
    {
        goto error_out;
    }
    buffer->vec.iov_len = buffer_size;
    buffer->vec.iov_base = (void *)calloc(buffer->vec.iov_len, sizeof(char));
    if (buffer->vec.iov_base == NULL)
    {
        goto error_out;
    }
    buffer->event = IOEVENT_UNKNOWN;
    buffer->next = NULL;

    return buffer;

error_out:
    iobuffer_destory(buffer);
    return NULL;
}

static void iobuffer_destory(struct iobuffer *buffer)
{
    if (buffer)
    {
        if (buffer->vec.iov_base)
        {
            free(buffer->vec.iov_base);
            buffer->vec.iov_base = NULL;
        }

        free(buffer);
        buffer = NULL;
    }
}

struct iobuffer_pool *iobuffer_pool_create(int buffer_size, int buffer_num)
{
    struct iobuffer *head = NULL;
    struct iobuffer *tail = NULL;
    struct iobuffer *node = NULL;
    struct iobuffer_pool *pool = (struct iobuffer_pool *)calloc(1, sizeof(struct iobuffer_pool));
    if (pool == NULL)
    {
        goto error_out;
    }

    pool->buffer_size = buffer_size;
    pool->buffer_used = 0;

    for (int i = 0; i < buffer_num; i++)
    {
        node = iobuffer_create(pool->buffer_size);
        if (node == NULL)
        {
            goto error_out;
        }

        if (head == NULL)
        {
            head = node;
            tail = node;
        }
        else
        {
            tail->next = node;
            tail = node;
        }
        pool->buffer_left++;
        pool->buffer_num++;
    }
    pool->free_list = head;

    return pool;

error_out:
    iobuffer_pool_destory(pool);
    return NULL;
}

void iobuffer_pool_destory(struct iobuffer_pool *pool)
{
    if (pool)
    {
        struct iobuffer *next = NULL;
        struct iobuffer *node = pool->free_list;
        while (node)
        {
            next = node->next;
            iobuffer_destory(node);
            node = next;
        }

        free(pool);
        pool = NULL;
    }
}

void iobuffer_pool_print(struct iobuffer_pool *pool)
{
    if (pool)
    {
        printf("    pool->buffer_size : %d\n", pool->buffer_size);
        printf("    pool->buffer_num  : %d\n", pool->buffer_num);
        printf("    pool->buffer_used : %d\n", pool->buffer_used);
        printf("    pool->buffer_left : %d\n", pool->buffer_left);
        printf("    pool->free_list   : \n");

        struct iobuffer *node = pool->free_list;
        while (node)
        {
            printf("        node       : %p\n", node);
            printf("        node->next : %p\n", node->next);
            node = node->next;
        }
        printf("\n");
    }
}

struct iobuffer *iobuffer_pool_pop(struct iobuffer_pool *pool)
{
    struct iobuffer *buffer = NULL;
    if (pool == NULL)
    {
        assert(0);
        return NULL;
    }

    if (pool->buffer_left <= 0)
    {
        buffer = iobuffer_create(pool->buffer_size);
        if (buffer)
        {
            pool->buffer_used++;
            return buffer;
        }
        else
        {
            return NULL;
        }
    }

    if (pool->free_list == NULL)
    {
        assert(0);
        return NULL;
    }

    buffer = pool->free_list;
    pool->free_list = buffer->next;
    buffer->next = NULL;
    pool->buffer_used++;
    pool->buffer_left--;

    return buffer;
}

void iobuffer_pool_push(struct iobuffer_pool *pool, struct iobuffer *buffer)
{
    if (pool == NULL || buffer == NULL)
    {
        return;
    }

    if (pool->buffer_left >= pool->buffer_num)
    {
        iobuffer_destory(buffer);
        pool->buffer_used--;
        return;
    }

    buffer->event = IOEVENT_UNKNOWN;
    buffer->next = pool->free_list;
    pool->free_list = buffer;
    pool->buffer_left++;
    pool->buffer_used--;
}

/*
 * ring_size      : 1024
 * buff_size      : 2048
 * flags          : 0
 *                  IORING_SETUP_IOPOLL(1U << 0)     io_context is polled
 *                  IORING_SETUP_SQPOLL(1U << 1)     SQ poll thread
 *                  IORING_SETUP_SQ_AFF(1U << 2)     sq_thread_cpu is valid
 *                  ORING_SETUP_CQSIZE(1U << 3)      app defines CQ size
 *                  IORING_SETUP_CLAMP(1U << 4)      clamp SQ/CQ ring sizes
 *                  IORING_SETUP_ATTACH_WQ(1U << 5)  attach to existing wq
 *                  IORING_SETUP_R_DISABLED(1U << 6) start with ring disabled
 *                  IORING_SETUP_SUBMIT_ALL(1U << 7) continue submit on error
 * sq_thread_idle : 0
 */
struct io_uring_instance *io_uring_instance_create(int sockfd, int eventfd, int ring_size, int buff_size, int flags, int sq_thread_idle, int enable_debug)
{
    int ret;
    struct io_uring_instance *instance = (struct io_uring_instance *)calloc(1, sizeof(struct io_uring_instance));
    if (instance == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to create io_uring instance, %s", strerror(errno));
        return NULL;
    }

    instance->sockfd = sockfd;
    instance->eventfd = eventfd;
    instance->cfg_ring_size = ring_size;
    instance->cfg_buff_size = buff_size;
    instance->cfg_flags = flags;
    instance->cfg_sq_thread_idle = sq_thread_idle;
    instance->cfg_enable_debug = enable_debug;

    instance->pool = iobuffer_pool_create(instance->cfg_buff_size, instance->cfg_ring_size);
    if (instance->pool == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to create io buffer pool, %s", strerror(errno));
        goto error_out;
    }

    /*
     * 参考资料：https://unixism.net/loti/tutorial/sq_poll.html#sq-poll
     *
     * 执行下面命令进行验证 IORING_SETUP_SQPOLL:
     * sudo bpftrace -e 'tracepoint:io_uring:io_uring_submit_sqe {printf("%s(%d)\n", comm, pid);}'
     */
    if (instance->cfg_flags)
    {
        instance->params.flags |= instance->cfg_flags;
    }

    if (instance->cfg_sq_thread_idle)
    {
        instance->params.sq_thread_idle = instance->cfg_sq_thread_idle; // milliseconds
    }

    ret = io_uring_queue_init_params(ring_size, &instance->ring, &instance->params);
    if (ret)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to init io_uring queue params, %s", strerror(-ret));
        goto error_out;
    }

    if (instance->eventfd > 0)
    {
        ret = io_uring_register_eventfd(&instance->ring, instance->eventfd);
        if (ret)
        {
            TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to register eventfd for io_uring, %s", strerror(-ret));
            goto error_out;
        }
    }

    return instance;

error_out:
    io_uring_instance_destory(instance);
    return NULL;
}

void io_uring_instance_destory(struct io_uring_instance *instance)
{
    if (instance)
    {
        io_uring_queue_exit(&instance->ring);
        iobuffer_pool_destory(instance->pool);
        free(instance);
        instance = NULL;
    }
}

// return  0 : success
// reutrn -1 : error
static int io_uring_read(struct io_uring_instance *instance, struct iobuffer *buffer)
{
    struct io_uring_sqe *sqe = io_uring_get_sqe(&instance->ring);
    if (sqe == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to get io_uring sqe, io_uring submission queue is full, drop read type");
        return -1;
    }

    buffer->event = IOEVENT_READ;
    io_uring_prep_readv(sqe, instance->sockfd, &buffer->vec, 1, 0);
    io_uring_sqe_set_data(sqe, buffer);

    if (unlikely(instance->cfg_enable_debug))
    {
        TFE_LOG_DEBUG(g_default_logger, "IO_URING: submit read entry: sockfd: %02d sqe: %p user_data: %p iov_base: %p iovec_len: %04ld",
                      instance->sockfd, sqe, (void *)sqe->user_data, buffer->vec.iov_base, buffer->vec.iov_len);
    }
    io_uring_submit(&instance->ring);

    return 0;
}

// return  0 : success
// reutrn -1 : error
int io_uring_write(struct io_uring_instance *instance, const char *data, int len)
{
    struct io_uring_sqe *sqe = io_uring_get_sqe(&instance->ring);
    if (sqe == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to get io_uring sqe, io_uring submission queue is full, drop write type");
        return -1;
    }

    if (len > instance->cfg_buff_size)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: the length of the sent data [%d] is greater than the capacity of the io_uring buffer [%d]", len, instance->cfg_buff_size);
        return -1;
    }

    struct iobuffer *buffer = iobuffer_pool_pop(instance->pool);
    if (buffer == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: cannot get fixed buffer");
        return -1;
    }

    buffer->event = IOEVENT_WRITE;
    buffer->vec.iov_len = len;
    memcpy(buffer->vec.iov_base, data, len);
    io_uring_prep_writev(sqe, instance->sockfd, &buffer->vec, 1, 0);
    io_uring_sqe_set_data(sqe, buffer);

    if (unlikely(instance->cfg_enable_debug))
    {
        TFE_LOG_DEBUG(g_default_logger, "IO_URING: submit write entry: sockfd: %02d sqe: %p user_data: %p iov_base: %p iovec_len: %04ld",
                      instance->sockfd, sqe, (void *)sqe->user_data, buffer->vec.iov_base, buffer->vec.iov_len);
    }
    io_uring_submit(&instance->ring);

    return 0;
}

// return  0 : success
// reutrn -1 : error
int io_uring_set_read_cb(struct io_uring_instance *instance, io_uring_read_cb *read_cb, void *cb_args)
{
    if (instance->read_cb)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: cannot register read callback multiple times");
        return -1;
    }

    instance->read_cb = read_cb;
    instance->cb_args = cb_args;

    struct iobuffer *buffer = iobuffer_pool_pop(instance->pool);
    if (buffer == NULL)
    {
        TFE_LOG_ERROR(g_default_logger, "IO_URING: cannot get fixed buffer");
        return -1;
    }

    if (io_uring_read(instance, buffer) == -1)
    {
        iobuffer_pool_push(instance->pool, buffer);
        return -1;
    }

    return 0;
}

// returns the number of processed entrys
int io_uring_polling(struct io_uring_instance *instance)
{
    int ret = 0;
    int total = 0;
    struct io_uring_cqe *cqes[MAX_BATCH_CQE_NUM];
    struct io_uring_cqe *cqe = NULL;
    struct iobuffer *buffer = NULL;

    void *cb_args = instance->cb_args;
    struct io_uring *ring = &instance->ring;
    struct iobuffer_pool *pool = instance->pool;
    io_uring_read_cb *read_cb = instance->read_cb;
    int enable_debug = instance->cfg_enable_debug;

    while (1)
    {
        ret = io_uring_peek_batch_cqe(ring, cqes, MAX_BATCH_CQE_NUM);
        if (ret <= 0)
        {
            return total;
        }

        total += ret;
        for (int i = 0; i < ret; i++)
        {
            cqe = cqes[i];
            if (cqe == NULL || (void *)cqe->user_data == NULL)
            {
                // TFE_LOG_ERROR(g_default_logger, "IO_URING: unable to get io_uring cqe, null is return");
                continue;
            }

            buffer = (struct iobuffer *)cqe->user_data;
            if (unlikely(enable_debug))
            {
                TFE_LOG_DEBUG(g_default_logger, "IO_URING: handle %s entry: sockfd: %02d cqe: %p user_data: %p iov_base: %p iovec_len: %04ld cqe->res: %04d",
                              ioevent_tostring(buffer->event), instance->sockfd, cqe, (void *)buffer, buffer->vec.iov_base, buffer->vec.iov_len, cqe->res);
            }
            switch (buffer->event)
            {
            case IOEVENT_READ:
                if (cqe->res > 0)
                {
                    if (read_cb)
                    {
                        read_cb((const char *)buffer->vec.iov_base, cqe->res, cb_args);
                    }
                }
                cqe->user_data = 0;
                io_uring_cqe_seen(ring, cqe);
                io_uring_read(instance, buffer);
                break;
            case IOEVENT_WRITE:
                if (cqe->res < 0)
                {
                    TFE_LOG_ERROR(g_default_logger, "IO_URING: handle %s entry: sockfd: %02d (%d, %s)",
                                  ioevent_tostring(buffer->event), instance->sockfd, -cqe->res, strerror(-cqe->res));
                }
                iobuffer_pool_push(pool, buffer);
                cqe->user_data = 0;
                io_uring_cqe_seen(ring, cqe);
                break;
            default:
                iobuffer_pool_push(pool, buffer);
                cqe->user_data = 0;
                io_uring_cqe_seen(ring, cqe);
                break;
            }
        }

        if (ret < MAX_BATCH_CQE_NUM)
        {
            return total;
        }
    }
}
#else
struct io_uring_instance
{
};

struct io_uring_instance *io_uring_instance_create(int sockfd, int eventfd, int ring_size, int buff_size, int flags, int sq_thread_idle, int enable_debug)
{
    TFE_LOG_ERROR(g_default_logger, "IO_URING: feature not support on current system");
    return NULL;
}

void io_uring_instance_destory(struct io_uring_instance *instance)
{
    TFE_LOG_ERROR(g_default_logger, "IO_URING: feature not support on current system");
}

int io_uring_set_read_cb(struct io_uring_instance *instance, io_uring_read_cb *read_cb, void *cb_arg)
{
    TFE_LOG_ERROR(g_default_logger, "IO_URING: feature not support on current system");
    return -1;
}

int io_uring_write(struct io_uring_instance *instance, const char *data, int len)
{
    TFE_LOG_ERROR(g_default_logger, "IO_URING: feature not support on current system");
    return -1;
}

int io_uring_polling(struct io_uring_instance *instance)
{
    TFE_LOG_ERROR(g_default_logger, "IO_URING: feature not support on current system");
    return 0;
}
#endif