#include <stdio.h>
#include <stdlib.h>
#include <uv.h>

static int bufsize = 1000;

typedef struct {
    uv_fs_t req;
    uv_file fd;
    uv_buf_t buf;
} fs_req_t;

void after_fs_read(uv_fs_t *req);

void after_fs_write(uv_fs_t *req) {
    fs_req_t *wr = (fs_req_t*) req;
    if (req->result < 0) {
        fprintf(stderr, "Write error: %s\n", uv_strerror(req->result));
    } else {
        fs_req_t* rr = (fs_req_t *) malloc(sizeof(fs_req_t));
        rr->fd = wr->fd;
        rr->buf = uv_buf_init((char *) malloc(bufsize), bufsize);
        uv_fs_read(uv_default_loop(), &rr->req, rr->fd, rr->buf.base, rr->buf.len, -1, after_fs_read);
    }
    uv_fs_req_cleanup(&wr->req);
    free(wr->buf.base);
    free(wr);
}

void after_fs_read(uv_fs_t *req) {
    fs_req_t *rr = (fs_req_t*) req;
    if (req->result < 0) {
        fprintf(stderr, "Read error: %s\n", uv_strerror(req->result));
    } else if (req->result == 0) {
        uv_fs_t close_req;
        // synchronous
        uv_fs_close(uv_default_loop(), &close_req, rr->fd, NULL);
    } else {
        fs_req_t* wr = (fs_req_t *) malloc(sizeof(fs_req_t));
        wr->fd = rr->fd;
        wr->buf = rr->buf;
        uv_fs_write(uv_default_loop(), &wr->req, 1, wr->buf.base, rr->req.result, -1, after_fs_write);
    }
    uv_fs_req_cleanup(&rr->req);
    free(rr);
}

void after_fs_open(uv_fs_t *req) {
    if (req->result < 0) {
        fprintf(stderr, "error opening file: %d\n", uv_strerror(req->result));
    } else {
        fs_req_t *rr = (fs_req_t *) malloc(sizeof(fs_req_t));
        rr->fd = req->result;
        rr->buf = uv_buf_init((char *) malloc(bufsize), bufsize);
        uv_fs_read(uv_default_loop(), &rr->req, rr->fd, rr->buf.base, rr->buf.len, -1, after_fs_read);
    }
    uv_fs_req_cleanup(req);
}

int main(int argc, char **argv) {
    uv_fs_t open_req;
    uv_fs_open(uv_default_loop(), &open_req, argv[1], O_RDONLY, 0, after_fs_open);
    return uv_run(uv_default_loop(), UV_RUN_DEFAULT);
}