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#include <errno.h>

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#include <string.h>

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#include <stdlib.h>

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#include "evfuse.h"

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#include "lib/log.h"

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struct evfuse {

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    // our mountpoint

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    char *mountpoint;

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    // the /dev/fuse fd/channel that we get from fuse_mount

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    struct fuse_chan *chan;

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    // the session that we use to process the fuse stuff

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    struct fuse_session *session;

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    // the event that we use to receive requests

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    struct event *ev;

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    // what our receive-message length is

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    size_t recv_size;

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    // the buffer that we use to receive events

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    char *recv_buf;

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};

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// prototypes

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void evfuse_close (struct evfuse *ctx);

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static void _evfuse_ev_read (evutil_socket_t fd, short what, void *arg) {

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    struct evfuse *ctx = arg;

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    struct fuse_chan *ch = ctx->chan;

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    int res;

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    // loop until we complete a recv

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    do {

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        // a new fuse_req is available

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        res = fuse_chan_recv(&ch, ctx->recv_buf, ctx->recv_size);

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    } while (res == -EINTR);

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    if (res == 0)

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        ERROR("fuse_chan_recv gave EOF");

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    if (res < 0 && res != -EAGAIN)

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        ERROR("fuse_chan_recv failed: %s", strerror(-res));

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    if (res > 0) {

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        DEBUG("got %d bytes from /dev/fuse", res);

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        // received a fuse_req, so process it

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        fuse_session_process(ctx->session, ctx->recv_buf, res, ch);

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    }

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    // reschedule

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    if (event_add(ctx->ev, NULL))

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        PERROR("event_add");

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    // ok, wait for the next event

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    return;

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error:

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    // close, but don't free

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    evfuse_close(ctx);

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}

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struct evfuse *evfuse_new (struct event_base *evbase, struct fuse_args *args, struct fuse_lowlevel_ops *llops, void *cb_data) {

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    struct evfuse *ctx = NULL;

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    int multithreaded, foreground;

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    // allocate our context

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    if ((ctx = calloc(1, sizeof(*ctx))) == NULL)

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        ERROR("calloc");

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    // parse the commandline for the mountpoint

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    if (fuse_parse_cmdline(args, &ctx->mountpoint, &multithreaded, &foreground) == -1)

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        ERROR("fuse_parse_cmdline");

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    // mount it

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    if ((ctx->chan = fuse_mount(ctx->mountpoint, args)) == NULL)

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        PERROR("fuse_mount_common");

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    // the receive buffer stufff

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    ctx->recv_size = fuse_chan_bufsize(ctx->chan);

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    // allocate the recv buffer

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    if ((ctx->recv_buf = malloc(ctx->recv_size)) == NULL)

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        ERROR("malloc");

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    // allocate a low-level session

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    if ((ctx->session = fuse_lowlevel_new(args, llops, sizeof(*llops), cb_data)) == NULL)

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        PERROR("fuse_lowlevel_new");

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    // add the channel to the session

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    // this isn't strictly necessary, but let's do it anyways

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    fuse_session_add_chan(ctx->session, ctx->chan);

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    // now, we can start listening for events on the channel

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    if ((ctx->ev = event_new(evbase, fuse_chan_fd(ctx->chan), EV_READ, &_evfuse_ev_read, ctx)) == NULL)

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        ERROR("event_new");

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    if (event_add(ctx->ev, NULL))

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        PERROR("event_add");

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    // and then we wait

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    return ctx;

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error:

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    evfuse_free(ctx);

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    return NULL;

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}

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void evfuse_close (struct evfuse *ctx) {

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    if (ctx->ev) {

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        // remove our event

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        if (event_del(ctx->ev))

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            PWARNING("event_del");

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        ctx->ev = NULL;

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    }

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    if (ctx->session) {

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        // remove the chan

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        fuse_session_remove_chan(ctx->chan);

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        // destroy the session

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        fuse_session_destroy(ctx->session);

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        ctx->session = NULL;

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    }

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    if (ctx->chan) {

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        // unmount

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        fuse_unmount(ctx->mountpoint, ctx->chan);

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        ctx->chan = NULL;

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    }

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    // free

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    free(ctx->recv_buf); ctx->recv_buf = NULL;

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    free(ctx->mountpoint); ctx->mountpoint = NULL;

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}

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void evfuse_free (struct evfuse *ctx) {

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    if (ctx) {

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        evfuse_close(ctx);

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        free(ctx);

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    }

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}

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