/*
  * Copyright (c) 2013 Lukasz Marek <lukasz.m.luki@gmail.com>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <fcntl.h>

 #define LIBSSH_STATIC

 #include <libssh/sftp.h>
 #include "libavutil/avstring.h"
 #include "libavutil/opt.h"

 #include "libavutil/attributes.h"

 #include "libavformat/avio.h"

 #include "avformat.h"
 #include "internal.h"
 #include "url.h"
 
 typedef struct {
     const AVClass *class;
     ssh_session session;
     sftp_session sftp;
     sftp_file file;

     sftp_dir dir;

     int64_t filesize;
     int rw_timeout;
     int trunc;

     char *priv_key;

 } LIBSSHContext;
 

 static av_cold int libssh_create_ssh_session(LIBSSHContext *libssh, const char* hostname, unsigned int port)
 {
     static const int verbosity = SSH_LOG_NOLOG;
 
     if (!(libssh->session = ssh_new())) {
         av_log(libssh, AV_LOG_ERROR, "SSH session creation failed: %s\n", ssh_get_error(libssh->session));
         return AVERROR(ENOMEM);
     }
     ssh_options_set(libssh->session, SSH_OPTIONS_HOST, hostname);
     ssh_options_set(libssh->session, SSH_OPTIONS_PORT, &port);
     ssh_options_set(libssh->session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
     if (libssh->rw_timeout > 0) {
         long timeout = libssh->rw_timeout * 1000;
         ssh_options_set(libssh->session, SSH_OPTIONS_TIMEOUT_USEC, &timeout);
     }
 

     if (ssh_options_parse_config(libssh->session, NULL) < 0) {
         av_log(libssh, AV_LOG_WARNING, "Could not parse the config file.\n");
     }
 

     if (ssh_connect(libssh->session) != SSH_OK) {
         av_log(libssh, AV_LOG_ERROR, "Connection failed: %s\n", ssh_get_error(libssh->session));
         return AVERROR(EIO);
     }
 
     return 0;
 }
 

 static av_cold int libssh_authentication(LIBSSHContext *libssh, const char *user, const char *password)
 {
     int authorized = 0;
     int auth_methods;
 
     if (user)
         ssh_options_set(libssh->session, SSH_OPTIONS_USER, user);
 

     if (ssh_userauth_none(libssh->session, NULL) == SSH_AUTH_SUCCESS)
         return 0;
 

     auth_methods = ssh_userauth_list(libssh->session, NULL);
 
     if (auth_methods & SSH_AUTH_METHOD_PUBLICKEY) {
         if (libssh->priv_key) {
             ssh_string pub_key;
             ssh_private_key priv_key;
             int type;
             if (!ssh_try_publickey_from_file(libssh->session, libssh->priv_key, &pub_key, &type)) {
                 priv_key = privatekey_from_file(libssh->session, libssh->priv_key, type, password);
                 if (ssh_userauth_pubkey(libssh->session, NULL, pub_key, priv_key) == SSH_AUTH_SUCCESS) {
                     av_log(libssh, AV_LOG_DEBUG, "Authentication successful with selected private key.\n");
                     authorized = 1;
                 }
             } else {
                 av_log(libssh, AV_LOG_DEBUG, "Invalid key is provided.\n");
                 return AVERROR(EACCES);
             }
         } else if (ssh_userauth_autopubkey(libssh->session, password) == SSH_AUTH_SUCCESS) {
             av_log(libssh, AV_LOG_DEBUG, "Authentication successful with auto selected key.\n");
             authorized = 1;
         }
     }
 

     if (!authorized && password && (auth_methods & SSH_AUTH_METHOD_PASSWORD)) {

         if (ssh_userauth_password(libssh->session, NULL, password) == SSH_AUTH_SUCCESS) {
             av_log(libssh, AV_LOG_DEBUG, "Authentication successful with password.\n");
             authorized = 1;
         }
     }
 
     if (!authorized) {
         av_log(libssh, AV_LOG_ERROR, "Authentication failed.\n");
         return AVERROR(EACCES);
     }
 
     return 0;
 }
 

 static av_cold int libssh_create_sftp_session(LIBSSHContext *libssh)
 {
     if (!(libssh->sftp = sftp_new(libssh->session))) {
         av_log(libssh, AV_LOG_ERROR, "SFTP session creation failed: %s\n", ssh_get_error(libssh->session));
         return AVERROR(ENOMEM);
     }
 
     if (sftp_init(libssh->sftp) != SSH_OK) {
         av_log(libssh, AV_LOG_ERROR, "Error initializing sftp session: %s\n", ssh_get_error(libssh->session));
         return AVERROR(EIO);
     }
 
     return 0;
 }
 

 static av_cold int libssh_open_file(LIBSSHContext *libssh, int flags, const char *file)
 {
     int access;
 
     if ((flags & AVIO_FLAG_WRITE) && (flags & AVIO_FLAG_READ)) {
         access = O_CREAT | O_RDWR;
         if (libssh->trunc)
             access |= O_TRUNC;
     } else if (flags & AVIO_FLAG_WRITE) {
         access = O_CREAT | O_WRONLY;
         if (libssh->trunc)
             access |= O_TRUNC;
     } else
         access = O_RDONLY;
 
     /* 0666 = -rw-rw-rw- = read+write for everyone, minus umask */
     if (!(libssh->file = sftp_open(libssh->sftp, file, access, 0666))) {
         av_log(libssh, AV_LOG_ERROR, "Error opening sftp file: %s\n", ssh_get_error(libssh->session));
         return AVERROR(EIO);
     }
 
     return 0;
 }
 

 static av_cold void libssh_stat_file(LIBSSHContext *libssh)
 {
     sftp_attributes stat;
 
     if (!(stat = sftp_fstat(libssh->file))) {
         av_log(libssh, AV_LOG_WARNING, "Cannot stat remote file.\n");
         libssh->filesize = -1;
     } else {
         libssh->filesize = stat->size;
         sftp_attributes_free(stat);
     }
 }
 

 static av_cold int libssh_close(URLContext *h)

 {

     LIBSSHContext *libssh = h->priv_data;

     if (libssh->file) {

         sftp_close(libssh->file);

         libssh->file = NULL;
     }
     if (libssh->sftp) {

         sftp_free(libssh->sftp);

         libssh->sftp = NULL;
     }

     if (libssh->session) {
         ssh_disconnect(libssh->session);
         ssh_free(libssh->session);

         libssh->session = NULL;

     }
     return 0;
 }
 

 static av_cold int libssh_connect(URLContext *h, const char *url, char *path, size_t path_size)

 {

     LIBSSHContext *libssh = h->priv_data;

     char proto[10], hostname[1024], credencials[1024];
     int port = 22, ret;

     const char *user = NULL, *pass = NULL;
     char *end = NULL;
 
     av_url_split(proto, sizeof(proto),
                  credencials, sizeof(credencials),
                  hostname, sizeof(hostname),
                  &port,

                  path, path_size,

                  url);
 

     if (!(*path))
         av_strlcpy(path, "/", path_size);
 

     // a port of 0 will use a port from ~/.ssh/config or the default value 22
     if (port < 0 || port > 65535)
         port = 0;

     if ((ret = libssh_create_ssh_session(libssh, hostname, port)) < 0)

         return ret;

     user = av_strtok(credencials, ":", &end);
     pass = av_strtok(end, ":", &end);
 

     if ((ret = libssh_authentication(libssh, user, pass)) < 0)

         return ret;

     if ((ret = libssh_create_sftp_session(libssh)) < 0)

         return ret;
 
     return 0;
 }
 
 static av_cold int libssh_open(URLContext *h, const char *url, int flags)
 {
     int ret;
     LIBSSHContext *libssh = h->priv_data;
     char path[MAX_URL_SIZE];
 
     if ((ret = libssh_connect(h, url, path, sizeof(path))) < 0)

         goto fail;
 

     if ((ret = libssh_open_file(libssh, flags, path)) < 0)

         goto fail;
 

     libssh_stat_file(libssh);

 
     return 0;
 
   fail:
     libssh_close(h);
     return ret;
 }
 
 static int64_t libssh_seek(URLContext *h, int64_t pos, int whence)
 {

     LIBSSHContext *libssh = h->priv_data;

     int64_t newpos;
 

     if (libssh->filesize == -1 && (whence == AVSEEK_SIZE || whence == SEEK_END)) {

         av_log(h, AV_LOG_ERROR, "Error during seeking.\n");
         return AVERROR(EIO);
     }
 
     switch(whence) {
     case AVSEEK_SIZE:

         return libssh->filesize;

     case SEEK_SET:
         newpos = pos;
         break;
     case SEEK_CUR:

         newpos = sftp_tell64(libssh->file) + pos;

         break;
     case SEEK_END:

         newpos = libssh->filesize + pos;

         break;
     default:
         return AVERROR(EINVAL);
     }
 

     if (newpos < 0) {
         av_log(h, AV_LOG_ERROR, "Seeking to nagative position.\n");
         return AVERROR(EINVAL);
     }
 

     if (sftp_seek64(libssh->file, newpos)) {

         av_log(h, AV_LOG_ERROR, "Error during seeking.\n");
         return AVERROR(EIO);
     }
 
     return newpos;
 }
 
 static int libssh_read(URLContext *h, unsigned char *buf, int size)
 {

     LIBSSHContext *libssh = h->priv_data;

     int bytes_read;
 

     if ((bytes_read = sftp_read(libssh->file, buf, size)) < 0) {
         av_log(libssh, AV_LOG_ERROR, "Read error.\n");

         return AVERROR(EIO);
     }

     return bytes_read ? bytes_read : AVERROR_EOF;

 }
 
 static int libssh_write(URLContext *h, const unsigned char *buf, int size)
 {

     LIBSSHContext *libssh = h->priv_data;

     int bytes_written;
 

     if ((bytes_written = sftp_write(libssh->file, buf, size)) < 0) {
         av_log(libssh, AV_LOG_ERROR, "Write error.\n");

         return AVERROR(EIO);
     }
     return bytes_written;
 }
 

 static int libssh_open_dir(URLContext *h)
 {
     LIBSSHContext *libssh = h->priv_data;
     int ret;
     char path[MAX_URL_SIZE];
 
     if ((ret = libssh_connect(h, h->filename, path, sizeof(path))) < 0)
         goto fail;
 
     if (!(libssh->dir = sftp_opendir(libssh->sftp, path))) {
         av_log(libssh, AV_LOG_ERROR, "Error opening sftp dir: %s\n", ssh_get_error(libssh->session));
         ret = AVERROR(EIO);
         goto fail;
     }
 
     return 0;
 
   fail:
     libssh_close(h);
     return ret;
 }
 
 static int libssh_read_dir(URLContext *h, AVIODirEntry **next)
 {
     LIBSSHContext *libssh = h->priv_data;
     sftp_attributes attr = NULL;
     AVIODirEntry *entry;
 
     *next = entry = ff_alloc_dir_entry();
     if (!entry)
         return AVERROR(ENOMEM);
 
     do {
         if (attr)
             sftp_attributes_free(attr);
         attr = sftp_readdir(libssh->sftp, libssh->dir);
         if (!attr) {
             av_freep(next);
             if (sftp_dir_eof(libssh->dir))
                 return 0;
             return AVERROR(EIO);
         }
     } while (!strcmp(attr->name, ".") || !strcmp(attr->name, ".."));
 
     entry->name = av_strdup(attr->name);
     entry->group_id = attr->gid;
     entry->user_id = attr->uid;
     entry->size = attr->size;
     entry->access_timestamp = INT64_C(1000000) * attr->atime;
     entry->modification_timestamp = INT64_C(1000000) * attr->mtime;
     entry->filemode = attr->permissions & 0777;
     switch(attr->type) {
     case SSH_FILEXFER_TYPE_REGULAR:
         entry->type = AVIO_ENTRY_FILE;
         break;
     case SSH_FILEXFER_TYPE_DIRECTORY:
         entry->type = AVIO_ENTRY_DIRECTORY;
         break;
     case SSH_FILEXFER_TYPE_SYMLINK:
         entry->type = AVIO_ENTRY_SYMBOLIC_LINK;
         break;
     case SSH_FILEXFER_TYPE_SPECIAL:
         /* Special type includes: sockets, char devices, block devices and pipes.
            It is probably better to return unknown type, to not confuse anybody. */
     case SSH_FILEXFER_TYPE_UNKNOWN:
     default:
         entry->type = AVIO_ENTRY_UNKNOWN;
     }
     sftp_attributes_free(attr);
     return 0;
 }
 
 static int libssh_close_dir(URLContext *h)
 {
     LIBSSHContext *libssh = h->priv_data;
     if (libssh->dir)
         sftp_closedir(libssh->dir);
     libssh->dir = NULL;
     libssh_close(h);
     return 0;
 }
 

 static int libssh_delete(URLContext *h)
 {
     int ret;
     LIBSSHContext *libssh = h->priv_data;
     sftp_attributes attr = NULL;
     char path[MAX_URL_SIZE];
 
     if ((ret = libssh_connect(h, h->filename, path, sizeof(path))) < 0)
         goto cleanup;
 
     if (!(attr = sftp_stat(libssh->sftp, path))) {
         ret = AVERROR(sftp_get_error(libssh->sftp));
         goto cleanup;
     }
 
     if (attr->type == SSH_FILEXFER_TYPE_DIRECTORY) {
         if (sftp_rmdir(libssh->sftp, path) < 0) {
             ret = AVERROR(sftp_get_error(libssh->sftp));
             goto cleanup;
         }
     } else {
         if (sftp_unlink(libssh->sftp, path) < 0) {
             ret = AVERROR(sftp_get_error(libssh->sftp));
             goto cleanup;
         }
     }
 
     ret = 0;
 
 cleanup:
     if (attr)
         sftp_attributes_free(attr);
     libssh_close(h);
     return ret;
 }
 
 static int libssh_move(URLContext *h_src, URLContext *h_dst)
 {
     int ret;
     LIBSSHContext *libssh = h_src->priv_data;
     char path_src[MAX_URL_SIZE], path_dst[MAX_URL_SIZE];
     char hostname_src[1024], hostname_dst[1024];
     char credentials_src[1024], credentials_dst[1024];
     int port_src = 22, port_dst = 22;
 
     av_url_split(NULL, 0,
                  credentials_src, sizeof(credentials_src),
                  hostname_src, sizeof(hostname_src),
                  &port_src,
                  path_src, sizeof(path_src),
                  h_src->filename);
 
     av_url_split(NULL, 0,
                  credentials_dst, sizeof(credentials_dst),
                  hostname_dst, sizeof(hostname_dst),
                  &port_dst,
                  path_dst, sizeof(path_dst),
                  h_dst->filename);
 
     if (strcmp(credentials_src, credentials_dst) ||
             strcmp(hostname_src, hostname_dst) ||
             port_src != port_dst) {
         return AVERROR(EINVAL);
     }
 
     if ((ret = libssh_connect(h_src, h_src->filename, path_src, sizeof(path_src))) < 0)
         goto cleanup;
 
     if (sftp_rename(libssh->sftp, path_src, path_dst) < 0) {
         ret = AVERROR(sftp_get_error(libssh->sftp));
         goto cleanup;
     }
 
     ret = 0;
 
 cleanup:
     libssh_close(h_src);
     return ret;
 }
 

 #define OFFSET(x) offsetof(LIBSSHContext, x)
 #define D AV_OPT_FLAG_DECODING_PARAM
 #define E AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
     {"timeout", "set timeout of socket I/O operations", OFFSET(rw_timeout), AV_OPT_TYPE_INT, {.i64 = -1}, -1, INT_MAX, D|E },
     {"truncate", "Truncate existing files on write", OFFSET(trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },

     {"private_key", "set path to private key", OFFSET(priv_key), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, D|E },

     {NULL}
 };
 
 static const AVClass libssh_context_class = {
     .class_name     = "libssh",
     .item_name      = av_default_item_name,
     .option         = options,
     .version        = LIBAVUTIL_VERSION_INT,
 };
 

 const URLProtocol ff_libssh_protocol = {

     .name                = "sftp",
     .url_open            = libssh_open,
     .url_read            = libssh_read,
     .url_write           = libssh_write,
     .url_seek            = libssh_seek,
     .url_close           = libssh_close,

     .url_delete          = libssh_delete,
     .url_move            = libssh_move,

     .url_open_dir        = libssh_open_dir,
     .url_read_dir        = libssh_read_dir,
     .url_close_dir       = libssh_close_dir,

     .priv_data_size      = sizeof(LIBSSHContext),
     .priv_data_class     = &libssh_context_class,
     .flags               = URL_PROTOCOL_FLAG_NETWORK,
 };