/***
  Copyright (c) 2004-2006 Lennart Poettering

  Permission is hereby granted, free of charge, to any person
  obtaining a copy of this software and associated documentation files
  (the "Software"), to deal in the Software without restriction,
  including without limitation the rights to use, copy, modify, merge,
  publish, distribute, sublicense, and/or sell copies of the Software,
  and to permit persons to whom the Software is furnished to do so,
  subject to the following conditions:

  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <string.h>
#include <limits.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <pthread.h>
#include <inttypes.h>
#include <limits.h>

#include <ne_props.h>
#include <ne_uri.h>
#include <ne_session.h>
#include <ne_utils.h>
#include <ne_socket.h>
#include <ne_auth.h>
#include <ne_dates.h>
#include <ne_basic.h>

#include "filecache.h"
#include "statcache.h"
#include "fusedav.h"
#include "session.h"

struct file_info {
    char *filename;
    int fd;
    off_t server_length, length, present;

    int readable;
    int writable;

    int modified;

    int ref, dead;

    pthread_mutex_t mutex;

    /* This field is locked by files_mutex, not by file_info->mutex */
    struct file_info *next;
};

static struct file_info *files = NULL;
static pthread_mutex_t files_mutex = PTHREAD_MUTEX_INITIALIZER;

static int file_cache_sync_unlocked(struct file_info *fi);

void* file_cache_get(const char *path) {
    struct file_info *f, *r = NULL;

    pthread_mutex_lock(&files_mutex);

    for (f = files; f; f = f->next) {

        pthread_mutex_lock(&f->mutex);
        if (!f->dead && f->filename && !strcmp(path, f->filename)) {
            f->ref++;
            r = f;
        }
        pthread_mutex_unlock(&f->mutex);

        if (r)
            break;
    }

    pthread_mutex_unlock(&files_mutex);
    return f;
}

static void file_cache_free_unlocked(struct file_info *fi) {
    assert(fi && fi->dead && fi->ref == 0);

    free(fi->filename);

    if (fi->fd >= 0)
        close(fi->fd);

    pthread_mutex_destroy(&fi->mutex);
    free(fi);
}

void file_cache_unref(void *f) {
    struct file_info *fi = f;
    assert(fi);

    pthread_mutex_lock(&fi->mutex);

    assert(fi->ref >= 1);
    fi->ref--;

    if (!fi->ref && fi->dead) {
        file_cache_sync_unlocked(fi);
        file_cache_free_unlocked(fi);
    }

    pthread_mutex_unlock(&fi->mutex);
}

static void file_cache_unlink(struct file_info *fi) {
    struct file_info *s, *prev;
    assert(fi);

    pthread_mutex_lock(&files_mutex);

    for (s = files, prev = NULL; s; s = s->next) {
        if (s == fi) {
            if (prev)
                prev->next = s->next;
            else
                files = s->next;

            break;
        }

        prev = s;
    }

    pthread_mutex_unlock(&files_mutex);
}

int file_cache_close(void *f) {
    struct file_info *fi = f;
    int r = 0;
    assert(fi);

    file_cache_unlink(f);

    pthread_mutex_lock(&fi->mutex);
    fi->dead = 1;
    pthread_mutex_unlock(&fi->mutex);

    return r;
}

void* file_cache_open(const char *path, int flags) {
    struct file_info *fi = NULL;
    char tempfile[PATH_MAX];
    const char *length = NULL;
    ne_request *req = NULL;
    ne_session *session;

    if (!(session = session_get(1))) {
        errno = EIO;
        goto fail;
    }

    if ((fi = file_cache_get(path))) {
        if (flags & O_RDONLY || flags & O_RDWR) fi->readable = 1;
        if (flags & O_WRONLY || flags & O_RDWR) fi->writable = 1;
        return fi;
    }

    fi = malloc(sizeof(struct file_info));
    memset(fi, 0, sizeof(struct file_info));
    fi->fd = -1;

    fi->filename = strdup(path);

    snprintf(tempfile, sizeof(tempfile), "%s/fusedav-cache-XXXXXX", "/tmp");
    if ((fi->fd = mkstemp(tempfile)) < 0)
        goto fail;
    unlink(tempfile);

    req = ne_request_create(session, "HEAD", path);
    assert(req);

    if (ne_request_dispatch(req) != NE_OK) {
        fprintf(stderr, "HEAD failed: %s\n", ne_get_error(session));
        errno = ENOENT;
        goto fail;
    }

    if (!(length = ne_get_response_header(req, "Content-Length")))
        /* dirty hack, since Apache doesn't send the file size if the file is empty */
        fi->server_length = fi->length = 0;
    else
        fi->server_length = fi->length = atoi(length);

    ne_request_destroy(req);

    if (flags & O_RDONLY || flags & O_RDWR) fi->readable = 1;
    if (flags & O_WRONLY || flags & O_RDWR) fi->writable = 1;

    pthread_mutex_init(&fi->mutex, NULL);

    pthread_mutex_lock(&files_mutex);
    fi->next = files;
    files = fi;
    pthread_mutex_unlock(&files_mutex);

    fi->ref = 1;

    return fi;

fail:

    if (req)
        ne_request_destroy(req);

    if (fi) {
        if (fi->fd >= 0)
            close(fi->fd);
        free(fi->filename);
        free(fi);
    }

    return NULL;
}

static int load_up_to_unlocked(struct file_info *fi, off_t l) {

    ne_content_range64 range;
    ne_session *session;

    assert(fi);

    if (!(session = session_get(1))) {
        errno = EIO;
        return -1;
    }

    if (l > fi->server_length)
        l = fi->server_length;

    if (l <= fi->present)
        return 0;

    if (lseek(fi->fd, fi->present, SEEK_SET) != fi->present)
        return -1;

    range.start = fi->present;
    range.end = l-1;
    range.total = 0;

    if (ne_get_range64(session, fi->filename, &range, fi->fd) != NE_OK) {
        fprintf(stderr, "GET failed: %s\n", ne_get_error(session));
        errno = ENOENT;
        return -1;
    }

    fi->present = l;
    return 0;
}

int file_cache_read(void *f, char *buf, size_t size, off_t offset) {
    struct file_info *fi = f;
    ssize_t r = -1;

    assert(fi && buf && size);

    pthread_mutex_lock(&fi->mutex);

    if (load_up_to_unlocked(fi, offset+size) < 0)
        goto finish;

    if ((r = pread(fi->fd, buf, size, offset)) < 0)
        goto finish;

finish:

    pthread_mutex_unlock(&fi->mutex);

    return r;
}

int file_cache_write(void *f, const char *buf, size_t size, off_t offset) {
    struct file_info *fi = f;
    ssize_t r = -1;

    assert (fi);

    pthread_mutex_lock(&fi->mutex);

    if (!fi->writable) {
        errno = EBADF;
        goto finish;
    }

    if (load_up_to_unlocked(fi, offset) < 0)
        goto finish;

    if ((r = pwrite(fi->fd, buf, size, offset)) < 0)
        goto finish;

    if (offset+size > fi->present)
        fi->present = offset+size;

    if (offset+size > fi->length)
        fi->length = offset+size;

    fi->modified = 1;

finish:
    pthread_mutex_unlock(&fi->mutex);

    return r;
}

int file_cache_truncate(void *f, off_t s) {
    struct file_info *fi = f;
    int r;

    assert(fi);

    pthread_mutex_lock(&fi->mutex);

    fi->length = s;
    r = ftruncate(fi->fd, fi->length);

    pthread_mutex_unlock(&fi->mutex);

    return r;
}

int file_cache_sync_unlocked(struct file_info *fi) {
    int r = -1;
    ne_session *session;

    assert(fi);

    if (!fi->writable) {
        errno = EBADF;
        goto finish;
    }

    if (!fi->modified) {
        r = 0;
        goto finish;
    }

    if (load_up_to_unlocked(fi, (off_t) -1) < 0)
        goto finish;

    if (lseek(fi->fd, 0, SEEK_SET) == (off_t)-1)
        goto finish;

    if (!(session = session_get(1))) {
        errno = EIO;
        goto finish;
    }

    if (ne_put(session, fi->filename, fi->fd)) {
        fprintf(stderr, "PUT failed: %s\n", ne_get_error(session));
        errno = ENOENT;
        goto finish;
    }

    stat_cache_invalidate(fi->filename);
    dir_cache_invalidate_parent(fi->filename);

    r = 0;

finish:

    return r;
}

int file_cache_sync(void *f) {
    struct file_info *fi = f;
    int r = -1;
    assert(fi);

    pthread_mutex_lock(&fi->mutex);
    r = file_cache_sync_unlocked(fi);
    pthread_mutex_unlock(&fi->mutex);

    return r;
}

int file_cache_close_all(void) {
    int r = 0;

    pthread_mutex_lock(&files_mutex);

    while (files) {
        struct file_info *fi = files;

        pthread_mutex_lock(&fi->mutex);
        fi->ref++;
        pthread_mutex_unlock(&fi->mutex);

        pthread_mutex_unlock(&files_mutex);
        file_cache_close(fi);
        file_cache_unref(fi);
        pthread_mutex_lock(&files_mutex);
    }

    pthread_mutex_unlock(&files_mutex);

    return r;
}

off_t file_cache_get_size(void *f) {
    struct file_info *fi = f;

    assert(fi);

    return fi->length;
}