/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2011-2016 - Daniel De Matteis
 *
 *  RetroArch 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 Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch 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 RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <time.h>

#ifdef _WIN32
#include <direct.h>
#else
#include <unistd.h>
#endif
#include <errno.h>

#include <compat/strl.h>
#include <retro_assert.h>
#include <lists/string_list.h>
#include <streams/file_stream.h>
#include <rthreads/rthreads.h>
#include <file/file_path.h>

#include "../core.h"
#include "../file_path_special.h"
#include "../configuration.h"
#include "../msg_hash.h"
#include "../runloop.h"
#include "../verbosity.h"
#include "tasks_internal.h"

/* TODO/FIXME - turn this into actual task */

static struct string_list *task_save_files = NULL;

typedef struct ram_type ram_type_t;

struct ram_type
{
   const char *path;
   int type;
};

struct save_state_buf
{
   void* data;
   char path[PATH_MAX_LENGTH];
   size_t size;
};

/* Holds the previous saved state
 * Can be restored to disk with undo_save_state(). */
static struct save_state_buf undo_save_buf;

/* Holds the data from before a load_state() operation
 * Can be restored with undo_load_state(). */
static struct save_state_buf undo_load_buf;

struct sram_block
{
   unsigned type;
   void *data;
   size_t size;
};

#ifdef HAVE_THREADS
typedef struct autosave autosave_t;

/* Autosave support. */
struct autosave_st
{
   autosave_t **list;
   unsigned num;
};

struct autosave
{
   volatile bool quit;
   slock_t *lock;

   slock_t *cond_lock;
   scond_t *cond;
   sthread_t *thread;

   void *buffer;
   const void *retro_buffer;
   const char *path;
   size_t bufsize;
   unsigned interval;
};

static struct autosave_st autosave_state;

/**
 * autosave_thread:
 * @data            : pointer to autosave object
 *
 * Callback function for (threaded) autosave.
 **/
static void autosave_thread(void *data)
{
   bool first_log   = true;
   autosave_t *save = (autosave_t*)data;

   while (!save->quit)
   {
      bool differ;

      slock_lock(save->lock);
      differ = memcmp(save->buffer, save->retro_buffer,
            save->bufsize) != 0;
      if (differ)
         memcpy(save->buffer, save->retro_buffer, save->bufsize);
      slock_unlock(save->lock);

      if (differ)
      {
         /* Should probably deal with this more elegantly. */
         FILE *file = fopen(save->path, "wb");

         if (file)
         {
            bool failed = false;

            /* Avoid spamming down stderr ... */
            if (first_log)
            {
               RARCH_LOG("Autosaving SRAM to \"%s\", will continue to check every %u seconds ...\n",
                     save->path, save->interval);
               first_log = false;
            }
            else
               RARCH_LOG("SRAM changed ... autosaving ...\n");

            failed |= fwrite(save->buffer, 1, save->bufsize, file)
               != save->bufsize;
            failed |= fflush(file) != 0;
            failed |= fclose(file) != 0;
            if (failed)
               RARCH_WARN("Failed to autosave SRAM. Disk might be full.\n");
         }
      }

      slock_lock(save->cond_lock);

      if (!save->quit)
         scond_wait_timeout(save->cond, save->cond_lock,
               save->interval * 1000000LL);

      slock_unlock(save->cond_lock);
   }
}

/**
 * autosave_new:
 * @path            : path to autosave file
 * @data            : pointer to buffer
 * @size            : size of @data buffer
 * @interval        : interval at which saves should be performed.
 *
 * Create and initialize autosave object.
 *
 * Returns: pointer to new autosave_t object if successful, otherwise
 * NULL.
 **/
static autosave_t *autosave_new(const char *path,
      const void *data, size_t size,
      unsigned interval)
{
   autosave_t *handle   = (autosave_t*)calloc(1, sizeof(*handle));
   if (!handle)
      goto error;

   handle->bufsize      = size;
   handle->interval     = interval;
   handle->path         = path;
   handle->buffer       = malloc(size);
   handle->retro_buffer = data;

   if (!handle->buffer)
      goto error;

   memcpy(handle->buffer, handle->retro_buffer, handle->bufsize);

   handle->lock         = slock_new();
   handle->cond_lock    = slock_new();
   handle->cond         = scond_new();

   handle->thread       = sthread_create(autosave_thread, handle);

   return handle;

error:
   if (handle)
      free(handle);
   return NULL;
}

/**
 * autosave_free:
 * @handle          : pointer to autosave object
 *
 * Frees autosave object.
 **/
static void autosave_free(autosave_t *handle)
{
   if (!handle)
      return;

   slock_lock(handle->cond_lock);
   handle->quit = true;
   slock_unlock(handle->cond_lock);
   scond_signal(handle->cond);
   sthread_join(handle->thread);

   slock_free(handle->lock);
   slock_free(handle->cond_lock);
   scond_free(handle->cond);

   free(handle->buffer);
   free(handle);
}

/**
 * autosave_lock:
 *
 * Lock autosave.
 **/
void autosave_lock(void)
{
   unsigned i;

   for (i = 0; i < autosave_state.num; i++)
   {
      if (autosave_state.list[i])
         slock_lock(autosave_state.list[i]->lock);
   }
}

/**
 * autosave_unlock:
 *
 * Unlocks autosave.
 **/
void autosave_unlock(void)
{
   unsigned i;

   for (i = 0; i < autosave_state.num; i++)
   {
      if (autosave_state.list[i])
         slock_unlock(autosave_state.list[i]->lock);
   }
}

void autosave_init(void)
{
   unsigned i;
   autosave_t **list    = NULL;
   settings_t *settings = config_get_ptr();

   if (settings->autosave_interval < 1 || !task_save_files)
      return;

   list = (autosave_t**)calloc(task_save_files->size,
               sizeof(*autosave_state.list));
   if (!list)
      return;

   autosave_state.list = list;
   autosave_state.num  = task_save_files->size;

   for (i = 0; i < task_save_files->size; i++)
   {
      retro_ctx_memory_info_t mem_info;
      const char *path = task_save_files->elems[i].data;
      unsigned    type = task_save_files->elems[i].attr.i;

      mem_info.id = type;

      core_get_memory(&mem_info);

      if (mem_info.size <= 0)
         continue;

      autosave_state.list[i] = autosave_new(path,
            mem_info.data,
            mem_info.size,
            settings->autosave_interval);

      if (!autosave_state.list[i])
         RARCH_WARN("%s\n", msg_hash_to_str(MSG_AUTOSAVE_FAILED));
   }
}

void autosave_deinit(void)
{
   unsigned i;

   for (i = 0; i < autosave_state.num; i++)
      autosave_free(autosave_state.list[i]);

   if (autosave_state.list)
      free(autosave_state.list);

   autosave_state.list     = NULL;
   autosave_state.num      = 0;
}
#endif

static unsigned content_allocate_save_blocks(struct sram_block *blocks)
{
   unsigned i;
   unsigned num_blocks       = 0;
   settings_t *settings      = config_get_ptr();

   /* Checking of SRAM overwrite, the backing up of it and
      flushing. */
   if (settings->block_sram_overwrite && task_save_files
         && task_save_files->size)
   {
      RARCH_LOG("%s.\n",
            msg_hash_to_str(MSG_BLOCKING_SRAM_OVERWRITE));
      blocks = (struct sram_block*)
         calloc(task_save_files->size, sizeof(*blocks));

      if (blocks)
      {
         num_blocks = task_save_files->size;
         for (i = 0; i < num_blocks; i++)
            blocks[i].type = task_save_files->elems[i].attr.i;
      }
   }

   for (i = 0; i < num_blocks; i++)
   {
      retro_ctx_memory_info_t    mem_info;

      mem_info.id = blocks[i].type;
      core_get_memory(&mem_info);

      blocks[i].size = mem_info.size;
   }

   for (i = 0; i < num_blocks; i++)
      if (blocks[i].size)
         blocks[i].data = malloc(blocks[i].size);

   /* Backup current SRAM which is overwritten by unserialize. */
   for (i = 0; i < num_blocks; i++)
   {
      if (blocks[i].data)
      {
         retro_ctx_memory_info_t    mem_info;
         void *dst       = NULL;
         const void *src = NULL;

         mem_info.id = blocks[i].type;

         core_get_memory(&mem_info);

         src = mem_info.data;
         dst = blocks[i].data;
         if (src)
            memcpy(dst, src, blocks[i].size);
      }
   }

   return num_blocks;
}

static void content_flush_save_blocks(struct sram_block *blocks,
      unsigned num_blocks)
{
   unsigned i;

   /* Flush back. */
   for (i = 0; i < num_blocks; i++)
   {
      if (blocks[i].data)
      {
         retro_ctx_memory_info_t    mem_info;
         const void *src = NULL;
         void *dst       = NULL;

         mem_info.id = blocks[i].type;

         core_get_memory(&mem_info);

         src = blocks[i].data;
         dst = mem_info.data;
         if (dst)
            memcpy(dst, src, blocks[i].size);
      }
   }

   for (i = 0; i < num_blocks; i++)
      free(blocks[i].data);
   free(blocks);
}

/**
 * undo_load_state:
 * Revert to the state before a state was loaded.
 *
 * Returns: true if successful, false otherwise.
 **/
bool content_undo_load_state(void)
{
   retro_ctx_serialize_info_t serial_info;
   size_t temp_data_size;
   bool ret                  = false;
   void* temp_data           = NULL;
   unsigned num_blocks       = 0;
   struct sram_block *blocks = NULL;
   settings_t *settings      = config_get_ptr();

   RARCH_LOG("%s: \"%s\".\n",
         msg_hash_to_str(MSG_LOADING_STATE),
         undo_load_buf.path);

   RARCH_LOG("%s: %u %s.\n",
         msg_hash_to_str(MSG_STATE_SIZE),
         undo_load_buf.size,
         msg_hash_to_str(MSG_BYTES));

   num_blocks             = content_allocate_save_blocks(blocks);
   
   /* We need to make a temporary copy of the buffer, to allow the swap below */
   temp_data              = malloc(undo_load_buf.size);
   temp_data_size         = undo_load_buf.size;
   memcpy(temp_data, undo_load_buf.data, undo_load_buf.size);

   serial_info.data_const = temp_data;
   serial_info.size       = temp_data_size;

   /* Swap the current state with the backup state. This way, we can undo
   what we're undoing */
   content_save_state("RAM", false);

   ret                    = core_unserialize(&serial_info);

   /* Clean up the temporary copy */
   free(temp_data);
   temp_data              = NULL;

   content_flush_save_blocks(blocks, num_blocks);

   if (!ret)
   {
      RARCH_ERR("%s \"%s\".\n",
         msg_hash_to_str(MSG_FAILED_TO_UNDO_LOAD_STATE),
         undo_load_buf.path);
   } 

   return ret;
}

/**
 * undo_save_state:
 * Reverts the last save operation
 *
 * Returns: true if successful, false otherwise.
 **/
bool content_undo_save_state(void)
{
   bool ret = filestream_write_file(undo_save_buf.path,
         undo_save_buf.data, undo_save_buf.size);

   /* Wipe the save file buffer as it's intended to be one use only */
   undo_save_buf.path[0] = '\0';
   undo_save_buf.size    = 0;
   if (undo_save_buf.data)
   {
      free(undo_save_buf.data);
      undo_save_buf.data = NULL;
   }

   if (!ret)
   {
      RARCH_ERR("%s \"%s\".\n",
         msg_hash_to_str(MSG_FAILED_TO_UNDO_SAVE_STATE),
         undo_save_buf.path);
   }

   return ret;
}


/* TODO/FIXME - turn this into actual task */

/**
 * save_state:
 * @path      : path of saved state that shall be written to.
 * @save_to_disk: If false, saves the state onto undo_load_buf.
 * Save a state from memory to disk.
 *
 * Returns: true if successful, false otherwise.
 **/
bool content_save_state(const char *path, bool save_to_disk)
{
   retro_ctx_serialize_info_t serial_info;
   retro_ctx_size_info_t info;
   bool ret    = false;
   void *data  = NULL;

   core_serialize_size(&info);

   RARCH_LOG("%s: \"%s\".\n",
         msg_hash_to_str(MSG_SAVING_STATE),
         path);

   if (info.size == 0)
      return false;

   data = malloc(info.size);

   if (!data)
      return false;

   RARCH_LOG("%s: %d %s.\n",
         msg_hash_to_str(MSG_STATE_SIZE),
         (int)info.size,
         msg_hash_to_str(MSG_BYTES));

   serial_info.data = data;
   serial_info.size = info.size;
   ret              = core_serialize(&serial_info);

   if (ret)
   {
      if (save_to_disk)
      {
         if (path_file_exists(path))
         {
            /* Before overwritting the savestate file, load it into a buffer
            to allow undo_save_state() to work */
            /* TODO/FIXME - Use msg_hash_to_str here */
            RARCH_LOG("%s\n",
               "File already exists. Saving to backup buffer...");

            content_load_state(path, true);
         }

         ret = filestream_write_file(path, data, info.size);
      }
      
      else 
      {
         /* save_to_disk is false, which means we are saving the state
         in undo_load_buf to allow content_undo_load_state() to restore it */

         /* If we were holding onto an old state already, clean it up first */
         if (undo_load_buf.data)
         {
            free(undo_load_buf.data);
            undo_load_buf.data = NULL;
         }

         undo_load_buf.data = malloc(info.size);
         if (!undo_load_buf.data)
         {
            free(data);
            return false;
         }

         memcpy(undo_load_buf.data, data, info.size);
         undo_load_buf.size = info.size;
         strlcpy(undo_load_buf.path, path, sizeof(undo_load_buf.path));
      }
   }
   else
   {
      RARCH_ERR("%s \"%s\".\n",
            msg_hash_to_str(MSG_FAILED_TO_SAVE_STATE_TO),
            path);
   }

   free(data);

   return ret;
}

/**
 * content_load_state:
 * @path      : path that state will be loaded from.
 * @load_to_backup_buffer: If true, the state will be loaded into undo_save_buf.
 * Load a state from disk to memory.
 *
 * Returns: true if successful, false otherwise.
 *
 *
 **/
bool content_load_state(const char *path, bool load_to_backup_buffer)
{
   unsigned i;
   ssize_t size;
   retro_ctx_serialize_info_t serial_info;
   unsigned num_blocks       = 0;
   void *buf                 = NULL;
   struct sram_block *blocks = NULL;
   settings_t *settings      = config_get_ptr();
   bool ret                  = filestream_read_file(path, &buf, &size);

   RARCH_LOG("%s: \"%s\".\n",
         msg_hash_to_str(MSG_LOADING_STATE),
         path);

   if (!ret || size < 0)
      goto error;

   RARCH_LOG("%s: %u %s.\n",
         msg_hash_to_str(MSG_STATE_SIZE),
         (unsigned)size,
         msg_hash_to_str(MSG_BYTES));

   /* This means we're backing up the file in memory, so content_undo_save_state()
   can restore it */
   if (load_to_backup_buffer)
   {
      /* If we were previously backing up a file, let go of it first */
      if (undo_save_buf.data)
      {
         free(undo_save_buf.data);
         undo_save_buf.data = NULL;
      }

      undo_save_buf.data = malloc(size);
      if (!undo_save_buf.data)
         goto error;

      memcpy(undo_save_buf.data, buf, size);
      undo_save_buf.size = size;
      strlcpy(undo_save_buf.path, path, sizeof(undo_save_buf.path));

      free(buf);
      return true;
   }

   num_blocks             = content_allocate_save_blocks(blocks);

   serial_info.data_const = buf;
   serial_info.size       = size;
   
   /* Backup the current state so we can undo this load */
   content_save_state("RAM", false);

   ret                    = core_unserialize(&serial_info);

   content_flush_save_blocks(blocks, num_blocks);
   
   if (!ret)
      goto error;

   free(buf);

   return true;

error:
   RARCH_ERR("%s \"%s\".\n",
         msg_hash_to_str(MSG_FAILED_TO_LOAD_STATE),
         path);
   free(buf);
   return false;
}

bool content_rename_state(const char *origin, const char *dest)
{
   int ret = 0;
   if (path_file_exists(dest))
      unlink(dest);

   ret = rename (origin, dest);
   if (!ret)
      return true;

   RARCH_LOG("Error %d renaming file %s\n", ret, origin);
   return false;
}

/*
* 
* TODO/FIXME: Figure out when and where this should be called.
* As it is, when e.g. closing Gambatte, we get the same printf message 4 times.
*
*/
bool content_reset_savestate_backups(void)
{
   RARCH_LOG("Resetting undo buffers.\n");

   if (undo_save_buf.data)
   {
      free(undo_save_buf.data);
      undo_save_buf.data = NULL;
   }

   undo_save_buf.path[0] = '\0';
   undo_save_buf.size    = 0;

   if (undo_load_buf.data)
   {
      free(undo_load_buf.data);
      undo_load_buf.data = NULL;
   }

   undo_load_buf.path[0] = '\0';
   undo_load_buf.size    = 0;

   return true;
}

bool content_undo_load_buf_is_empty(void)
{
   return undo_load_buf.data == NULL || undo_load_buf.size == 0;
}

bool content_undo_save_buf_is_empty(void)
{
   return undo_save_buf.data == NULL || undo_save_buf.size == 0;
}

static bool content_get_memory(retro_ctx_memory_info_t *mem_info,
      ram_type_t *ram, unsigned slot)
{
   ram->type = task_save_files->elems[slot].attr.i;
   ram->path = task_save_files->elems[slot].data;

   mem_info->id  = ram->type;

   core_get_memory(mem_info);

   if (!mem_info->data || mem_info->size == 0)
      return false;

   return true;
}

/**
 * content_load_ram_file:
 * @path             : path of RAM state that will be loaded from.
 * @type             : type of memory
 *
 * Load a RAM state from disk to memory.
 */
bool content_load_ram_file(unsigned slot)
{
   ssize_t rc;
   ram_type_t ram;
   retro_ctx_memory_info_t mem_info;
   void *buf        = NULL;

   if (!content_get_memory(&mem_info, &ram, slot))
      return false;

   if (!filestream_read_file(ram.path, &buf, &rc))
      return false;

   if (rc > 0)
   {
      if (rc > (ssize_t)mem_info.size)
      {
         RARCH_WARN("SRAM is larger than implementation expects, "
               "doing partial load (truncating %u %s %s %u).\n",
               (unsigned)rc,
               msg_hash_to_str(MSG_BYTES),
               msg_hash_to_str(MSG_TO),
               (unsigned)mem_info.size);
         rc = mem_info.size;
      }
      memcpy(mem_info.data, buf, rc);
   }

   if (buf)
      free(buf);

   return true;
}

/**
 * content_save_ram_file:
 * @path             : path of RAM state that shall be written to.
 * @type             : type of memory
 *
 * Save a RAM state from memory to disk.
 *
 */
bool content_save_ram_file(unsigned slot)
{
   ram_type_t ram;
   retro_ctx_memory_info_t mem_info;

   if (!content_get_memory(&mem_info, &ram, slot))
      return false;


   RARCH_LOG("%s #%u %s \"%s\".\n",
         msg_hash_to_str(MSG_SAVING_RAM_TYPE),
         ram.type,
         msg_hash_to_str(MSG_TO),
         ram.path);

   if (!filestream_write_file(ram.path, mem_info.data, mem_info.size))
   {
      RARCH_ERR("%s.\n",
            msg_hash_to_str(MSG_FAILED_TO_SAVE_SRAM));
      RARCH_WARN("Attempting to recover ...\n");

      /* In case the file could not be written to, 
       * the fallback function 'dump_to_file_desperate'
       * will be called. */
      if (!dump_to_file_desperate(mem_info.data, mem_info.size, ram.type))
      {
         RARCH_WARN("Failed ... Cannot recover save file.\n");
      }
      return false;
   }

   RARCH_LOG("%s \"%s\".\n",
         msg_hash_to_str(MSG_SAVED_SUCCESSFULLY_TO),
         ram.path);

   return true;
}

bool event_save_files(void)
{
   unsigned i;
   global_t  *global         = global_get_ptr();

   if (!global || !task_save_files || !global->sram.use)
      return false;

   for (i = 0; i < task_save_files->size; i++)
      content_save_ram_file(i);

   return true;
}

bool event_load_save_files(void)
{
   unsigned i;
   global_t *global = global_get_ptr();

   if (!global)
      return false;
   if (!task_save_files || global->sram.load_disable)
      return false;

   for (i = 0; i < task_save_files->size; i++)
      content_load_ram_file(i);

   return true;
}

void path_init_savefile_rtc(void)
{
   union string_list_elem_attr attr;
   char savefile_name_rtc[PATH_MAX_LENGTH] = {0};
   global_t                        *global = global_get_ptr();

   attr.i = RETRO_MEMORY_SAVE_RAM;
   string_list_append(task_save_files, global->name.savefile, attr);

   /* Infer .rtc save path from save ram path. */
   attr.i = RETRO_MEMORY_RTC;
   fill_pathname(savefile_name_rtc,
         global->name.savefile,
         file_path_str(FILE_PATH_RTC_EXTENSION),
         sizeof(savefile_name_rtc));
   string_list_append(task_save_files, savefile_name_rtc, attr);
}

void path_deinit_savefile(void)
{
   if (task_save_files)
      string_list_free(task_save_files);
   task_save_files = NULL;
}

void path_init_savefile_new(void)
{
   task_save_files = string_list_new();
   retro_assert(task_save_files);
}

void *savefile_ptr_get(void)
{
   return task_save_files;
}