/*
  * 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 "avformat.h"
 #include "internal.h"
 #include "url.h"
 
 typedef struct {
     const AVClass *class;
     ssh_session session;
     sftp_session sftp;
     sftp_file file;
     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_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);
 
     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 && (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);
     if (libssh->sftp)
         sftp_free(libssh->sftp);
     if (libssh->session) {
         ssh_disconnect(libssh->session);
         ssh_free(libssh->session);

     }
     return 0;
 }
 

 static av_cold int libssh_open(URLContext *h, const char *url, int flags)

 {

     LIBSSHContext *libssh = h->priv_data;

     char proto[10], path[MAX_URL_SIZE], 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, sizeof(path),
                  url);
 
     if (port <= 0 || port > 65535)
         port = 22;
 

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

         goto fail;

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

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

         goto fail;

     if ((ret = libssh_create_sftp_session(libssh)) < 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;
 }
 
 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;
 }
 
 #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,
 };
 
 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,
     .priv_data_size      = sizeof(LIBSSHContext),
     .priv_data_class     = &libssh_context_class,
     .flags               = URL_PROTOCOL_FLAG_NETWORK,
 };