#include "diskuring.h"
#include "memory/alloc_dispatch.h"
#include <poll.h>
#include <sys/eventfd.h>

void task_init(task_t *t)
{
    pthread_mutex_init(&t->m, NULL);
    pthread_cond_init(&t->cv, NULL);
    t->done = 0;
    t->res = 0;
    t->next = NULL;
}

void task_finish(task_t *t, int res)
{
    pthread_mutex_lock(&t->m);
    t->res = res;
    t->done = 1;
    pthread_cond_broadcast(&t->cv);
    pthread_mutex_unlock(&t->m);
}

int task_wait(task_t *t)
{
    pthread_mutex_lock(&t->m);
    while (!t->done)
        pthread_cond_wait(&t->cv, &t->m);
    int r = t->res;
    pthread_mutex_unlock(&t->m);
    return r;
}

void task_destroy(task_t *t)
{
    pthread_mutex_destroy(&t->m);
    pthread_cond_destroy(&t->cv);
    if (t->iovs) {
        for (int i = 0; i < t->iovcnt; i++) {
            if (t->iovs[i].iov_base) {
                kvs_free(t->iovs[i].iov_base);
            }
        }
        kvs_free(t->iovs);
    }

    kvs_free(t);
}

static void queue_push(iouring_ctx_t *ctx, task_t *t)
{
    pthread_mutex_lock(&ctx->q_m);
    if (ctx->q_tail)
        ctx->q_tail->next = t;
    else
        ctx->q_head = t;
    ctx->q_tail = t;
    pthread_cond_signal(&ctx->q_cv);
    pthread_mutex_unlock(&ctx->q_m);
}

static task_t *queue_pop_all(iouring_ctx_t *ctx)
{
    pthread_mutex_lock(&ctx->q_m);
    while (!ctx->stop && ctx->q_head == NULL)
    {
        pthread_cond_wait(&ctx->q_cv, &ctx->q_m);
    }
    task_t *list = ctx->q_head;
    ctx->q_head = ctx->q_tail = NULL;
    pthread_mutex_unlock(&ctx->q_m);
    return list;
}

static void *worker_main(void *arg)
{
    iouring_ctx_t *ctx = (iouring_ctx_t *)arg;

    while (!ctx->stop)
    {

        // 1. 阻塞等任务（这里睡觉）
        task_t *list = queue_pop_all(ctx);
        if (!list)
            continue;

        // 2. 提交所有任务
        task_t *t;
        int submit_cnt = 0;

        for (t = list; t; t = t->next)
        {
            struct io_uring_sqe *sqe = io_uring_get_sqe(&ctx->ring);
            if (!sqe)
                break;

            io_uring_prep_writev(sqe, t->fd, t->iovs, t->iovcnt, t->off);
            sqe->user_data = (uint64_t)(uintptr_t)t;
            submit_cnt++;
        }

        io_uring_submit(&ctx->ring);

        // 3. 等全部完成
        for (int i = 0; i < submit_cnt; ++i)
        {
            struct io_uring_cqe *cqe;
            io_uring_wait_cqe(&ctx->ring, &cqe);

            task_t *done = (task_t *)(uintptr_t)cqe->user_data;
            task_finish(done, cqe->res);

            // todo: 失败应该通知主线程，提供一个链表，把失败的taskpush进去。主线程用定时器任务定时处理失败信息然后destory。
            // 暂时用打印说明失败
            if(done->res < 0){
                printf("uring failed: fd:%d, offset:%ld\n", done->fd, done->off);
            }
            task_destroy(done);

            io_uring_cqe_seen(&ctx->ring, cqe);
        }
    }

    return NULL;
}

int iouring_register_fd(iouring_ctx_t *ctx, int fd) {
    int fds[1] = {fd};
    int ret = io_uring_register_files(&ctx->ring, fds, 1);
    return ret;
}

int iouring_init(iouring_ctx_t *ctx, unsigned entries)
{
    memset(ctx, 0, sizeof(*ctx));
    pthread_mutex_init(&ctx->q_m, NULL);
    pthread_cond_init(&ctx->q_cv, NULL);

    struct io_uring_params params;
    memset(&params, 0, sizeof(params));
    int ret = io_uring_queue_init_params(entries, &ctx->ring, &params);
    if (ret < 0)
        return ret;

    ret = pthread_create(&ctx->th, NULL, worker_main, ctx);
    if (ret != 0)
    {
        io_uring_queue_exit(&ctx->ring);
        return -ret;
    }
    return 0;
}

void iouring_shutdown(iouring_ctx_t *ctx)
{
    pthread_mutex_lock(&ctx->q_m);
    ctx->stop = 1;
    pthread_cond_broadcast(&ctx->q_cv);
    pthread_mutex_unlock(&ctx->q_m);

    pthread_join(ctx->th, NULL);
    io_uring_queue_exit(&ctx->ring);

    pthread_mutex_destroy(&ctx->q_m);
    pthread_cond_destroy(&ctx->q_cv);
}

task_t* submit_write(iouring_ctx_t *ctx, int fd, void **bufs, size_t *lens, int count, off_t off){
    if (!bufs || !lens || count <= 0) return NULL;

    task_t *t = (task_t *)kvs_malloc(sizeof(task_t));
    task_init(t);
    t->op = TASK_WRITE;
    t->fd = fd;
    t->off = off;

    t->iovs =  (struct iovec *)kvs_malloc(sizeof(struct iovec) * count);
    if(!t->iovs) {
        kvs_free(t);
        return NULL;
    }

    for(int i = 0;i < count; ++ i){
        size_t len = lens[i];
        void *buf = kvs_malloc(len);
        if(!buf){
            for(int j = 0; j < i; ++j){
                if(t->iovs[j].iov_base) kvs_free(t->iovs[j].iov_base);
            }
            kvs_free(t->iovs);
            kvs_free(t);
            return NULL;
        }
        memcpy(buf, bufs[i], len);
        t->iovs[i].iov_base = buf;
        t->iovs[i].iov_len = len;
    }

    t->iovcnt = count;
    
    queue_push(ctx, t);
    return t;
}