/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "AP_Filesystem.h"

#if HAVE_FILESYSTEM_SUPPORT

static AP_Filesystem fs;

#if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
#include "AP_Filesystem_FATFS.h"
static AP_Filesystem_FATFS fs_local;
#endif
#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX || CONFIG_HAL_BOARD == HAL_BOARD_SITL
#include "AP_Filesystem_posix.h"
static AP_Filesystem_Posix fs_local;
#endif

#ifdef HAL_HAVE_AP_ROMFS_EMBEDDED_H
#include "AP_Filesystem_ROMFS.h"
static AP_Filesystem_ROMFS fs_romfs;
#endif

/*
  mapping from filesystem prefix to backend
 */
const AP_Filesystem::Backend AP_Filesystem::backends[] = {
    { nullptr, fs_local },
#ifdef HAL_HAVE_AP_ROMFS_EMBEDDED_H
    { "@ROMFS/", fs_romfs },
#endif
};

#define MAX_FD_PER_BACKEND 256U
#define NUM_BACKENDS ARRAY_SIZE(backends)
#define LOCAL_BACKEND backends[0];
#define BACKEND_IDX(backend) (&(backend) - &backends[0])

/*
  find backend by path
 */
const AP_Filesystem::Backend &AP_Filesystem::backend_by_path(const char *&path) const
{
    for (uint8_t i=1; i<NUM_BACKENDS; i++) {
        const uint8_t plen = strlen(backends[i].prefix);
        if (strncmp(path, backends[i].prefix, plen) == 0) {
            path += plen;
            return backends[i];
        }
    }
    // default to local filesystem
    return LOCAL_BACKEND;
}

/*
  return backend by file descriptor
 */
const AP_Filesystem::Backend &AP_Filesystem::backend_by_fd(int &fd) const
{
    if (fd < 0 || uint32_t(fd) >= NUM_BACKENDS*MAX_FD_PER_BACKEND) {
        return LOCAL_BACKEND;
    }
    const uint8_t idx = uint32_t(fd) / MAX_FD_PER_BACKEND;
    fd -= idx * MAX_FD_PER_BACKEND;
    return backends[idx];
}

int AP_Filesystem::open(const char *fname, int flags)
{
    const Backend &backend = backend_by_path(fname);
    int fd = backend.fs.open(fname, flags);
    if (fd < 0) {
        return -1;
    }
    if (uint32_t(fd) >= MAX_FD_PER_BACKEND) {
        backend.fs.close(fd);
        errno = ERANGE;
        return -1;
    }
    // offset fd so we can recognise the backend
    const uint8_t idx = (&backend - &backends[0]);
    fd += idx * MAX_FD_PER_BACKEND;
    return fd;
}

int AP_Filesystem::close(int fd)
{
    const Backend &backend = backend_by_fd(fd);
    return backend.fs.close(fd);
}

ssize_t AP_Filesystem::read(int fd, void *buf, size_t count)
{
    const Backend &backend = backend_by_fd(fd);
    return backend.fs.read(fd, buf, count);
}

ssize_t AP_Filesystem::write(int fd, const void *buf, size_t count)
{
    const Backend &backend = backend_by_fd(fd);
    return backend.fs.write(fd, buf, count);
}

int AP_Filesystem::fsync(int fd)
{
    const Backend &backend = backend_by_fd(fd);
    return backend.fs.fsync(fd);
}

off_t AP_Filesystem::lseek(int fd, off_t offset, int seek_from)
{
    const Backend &backend = backend_by_fd(fd);
    return backend.fs.lseek(fd, offset, seek_from);
}

int AP_Filesystem::stat(const char *pathname, struct stat *stbuf)
{
    const Backend &backend = backend_by_path(pathname);
    return backend.fs.stat(pathname, stbuf);
}

int AP_Filesystem::unlink(const char *pathname)
{
    const Backend &backend = backend_by_path(pathname);
    return backend.fs.unlink(pathname);
}

int AP_Filesystem::mkdir(const char *pathname)
{
    const Backend &backend = backend_by_path(pathname);
    return backend.fs.mkdir(pathname);
}

AP_Filesystem::DirHandle *AP_Filesystem::opendir(const char *pathname)
{
    const Backend &backend = backend_by_path(pathname);
    DirHandle *h = new DirHandle;
    if (!h) {
        return nullptr;
    }
    h->dir = backend.fs.opendir(pathname);
    if (h->dir == nullptr) {
        delete h;
        return nullptr;
    }
    h->fs_index = BACKEND_IDX(backend);
    return h;
}

struct dirent *AP_Filesystem::readdir(DirHandle *dirp)
{
    if (!dirp) {
        return nullptr;
    }
    const Backend &backend = backends[dirp->fs_index];
    return backend.fs.readdir(dirp->dir);
}

int AP_Filesystem::closedir(DirHandle *dirp)
{
    if (!dirp) {
        return -1;
    }
    const Backend &backend = backends[dirp->fs_index];
    int ret = backend.fs.closedir(dirp->dir);
    delete dirp;
    return ret;
}

// return free disk space in bytes
int64_t AP_Filesystem::disk_free(const char *path)
{
    const Backend &backend = backend_by_path(path);
    return backend.fs.disk_free(path);
}

// return total disk space in bytes
int64_t AP_Filesystem::disk_space(const char *path)
{
    const Backend &backend = backend_by_path(path);
    return backend.fs.disk_space(path);
}


/*
  set mtime on a file
 */
bool AP_Filesystem::set_mtime(const char *filename, const time_t mtime_sec)
{
    const Backend &backend = backend_by_path(filename);
    return backend.fs.set_mtime(filename, mtime_sec);
}

namespace AP
{
AP_Filesystem &FS()
{
    return fs;
}
}
#endif