/*
  Copyright 2009 Nathan Phillip Brink, Ethan Zonca, Matthew Orlando

  This file is a part of DistRen.

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

  DistRen 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 Affero General Public License for more details.

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

*/

/* This file contains the code which both processes (renders) jobs as a slave, and the code which distributes frames to slaves after receiving them from the client portion of the codebase. */

#include "execio.h"
#include "options.h"
#include "distrenjob.h"
#include "protocol.h"
#include "slavefuncs.h"

#include <confuse.h>
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <unistd.h> /* getopt */
#include <time.h>
#include <sys/stat.h>

/* ******************* Structs ************************ */

// Gets config info from confs
struct distrend_config
{
  cfg_t *mycfg;
  struct options_common *options;
  struct distrend_listen **listens; /*< Null terminated array of structs */
  char *datadir;
};



/*
 frame[frame] Status Assignments:
  "NULL" - don't render me
  "0" - canceled
  "1" - unassigned
  "2" - assigned to slave
  "3" - completed by slave and uploaded
*/

struct general_info {
  short int jobs_in_queue; //
  unsigned short int free_clients;
  unsigned short int rendering_clients;//
  unsigned short int total_finished_jobs; //
  unsigned int total_frames_rendered; //
  unsigned int highest_jobnum;
} general_info;



/*
  internally defined funcs's prototypes
*/
void distrenjob_remove(struct distrenjob **head, struct distrenjob *bj);

struct distrenjob *distrenjob_get(struct distrenjob *head, jobnum_t jobnum);
void distrenjob_enqueue(struct distrenjob *head, struct distrenjob *job);

/* Global Vars, try to cut down on these */
jobnum_t jobnum = 0; // The next job number to create in the queue
int hcfjob; // Highest consecutively finished job
int highest_jobnum; // The job number of the most recently created job, this is used when creating new jobs


/* ********************** Functions ************************* */

/** Dumps all data in RAM to an xml file (such as current jobs, etc) which is parsed by start_data. Remember to invoke this before shutting down! */
int xml_dump()
{
  return 0;
}
/**
   Performs command stored in a client's request.
*/
int distrend_do()
{
  return 0;
}
/**
   Accepts a client's connection
 */
void distrend_accept()
{

}
/**
   Frees the action
*/
void distrend_action_free()
{

}
/**
   Start listening
*/
void distrend_listen()
{

}
/**
   Stop listening
*/
void distrend_unlisten()
{

}
/**
   This is probably just a placeholder for remotio
*/
void remotio_send_to_client()
{
	// I am futile!
}

/** Fill variables after crash / shutdown from XML dumps */
int start_data(){
  struct stat buffer;
  if(stat(SYSCONFDIR "/data.xml", &buffer) == 0){

    // @TODO: retrieve total_finished_jobs and total_finished_frames from xml file

    fprintf(stderr,"Parsing XML files and restoring previous state...\n");
    return 1;
  }
  else{
    general_info.total_finished_jobs = 0;
    general_info.total_frames_rendered = 0;
    fprintf(stderr,"Can't find XML dump, starting up fresh.\n");
    return 2;
  }
  free(&buffer); // @TODO: Is this pointless?
}

/** Finish-Setter: Sets a frame to the "completed" status.*/
void finish_frame(struct distrenjob *distrenjob, int frame){
  distrenjob->frameset[frame].status = 2;
  distrenjob->frameset[frame].time_to_render = (clock() - distrenjob[jobnum].frameset[frame].start_time); // Consider changing time-to-render to time-for-frame or something?
  distrenjob->avg_render_time = ((distrenjob->avg_render_time*(distrenjob->completed_frames - 1)) + distrenjob->frameset[frame].time_to_render)/distrenjob->completed_frames;
  distrenjob->completed_frames++;
  general_info.total_frames_rendered++; // Increase total frames var for stats
}


/**
   creates a structure from starting data, then calls another function to actually add that struct to the queue
*/
void prepare_distrenjob(struct frameset *head, int type, char *name, char *submitter, char *email, int priority, int start_frame, int end_frame)
{
  int counter2;
  int counter;

  struct distrenjob *distrenjob;

  distrenjob->type = 1;
  distrenjob->name = name;
  distrenjob->submitter = submitter;
  distrenjob->email = email;
  distrenjob->priority = priority;
  distrenjob->frameset = malloc(end_frame - start_frame + 1);
  distrenjob->total_frames = (end_frame - start_frame + 1); // sets the total number of frames in animation for status purposes

  /* @TODO: what does this do? frameset array is declared above */
  /*
  distrenjob->frameset = malloc(sizeof(struct frameset) * numframes);
  if(!job->frameset)
    fprintf(stderr, "Error allocating memory\n");
  */

  /* prepares all the frames by setting that status to "unassigned" */
  counter2 = start_frame;
  for(counter = 0; counter <= (end_frame- start_frame + 1); counter++){
    distrenjob->frameset[counter].num = counter2;
    distrenjob->frameset[counter].status = 0;

    counter2++;
  }

  /* @TODO: change frame_num_struct_builder to add_blendjob_to_queue */
  distrenjob_enqueue(head, distrenjob);

  general_info.jobs_in_queue++;
}

/** -- OLD -- Queuer: Adds files to the queue
int queue(struct distrenjob *distrenjob, int type, char *name, char *submitter, char *email, int priority, int mode, int spp, struct frameset *frameset) {
  // Type: 1 = blender, add more types later
  // jobnum is the next available job number
  if(type == 1){
    distrenjob->name = name;
    distrenjob->submitter = submitter;
    distrenjob->email = email;
    distrenjob->priority = priority;
    distrenjob->frameset = frameset;
  }
  else{
    // Throw error.
    fprintf(stderr,"You tried to queue a job type that isn't supported by this version of DistRen.\nI have no idea how this would happen, but it just did.\n");
    return 0; // fail
  }
jobnum++; // Advance the jobnumber for the next queued job
return 0; // OK
}*/


/* distrenjob_enqueue: This function adds the job to the queue based on its priority */
void distrenjob_enqueue(struct distrenjob *head, struct distrenjob *job) {
  struct distrenjob *prev_job = head; // create pointer to previous job
  struct distrenjob *current_job;     // create pointer to current_job (which job is being compared to)

  // iterate through linked list of jobs
  for(current_job = head; current_job != NULL; current_job = current_job->next){
    if(current_job == NULL){ // if it has reached the end of the list, add job there
      current_job = job;
      break;
    }
    else if(job->priority < current_job->priority){ // if job's priority is less than current_job's priority, insert job
      prev_job->next = job;                        // keep in mind 1 is the highest priority given to jobs, head has a
      job->next = current_job;                     // priority of zero so it will always be before other jobs
      break;
    }

    prev_job = current_job;
  } /* for(current_job) */
}

/**
   @arg head I may end up changing the head if job == head
 */
void change_job_priority(struct distrenjob *head, struct distrenjob *job, int new_priority){
  distrenjob_remove(head, job);
  job->priority = new_priority;
  struct distrenjob *current_job;
  struct distrenjob *prev_job = head;

  if(job->frameset[0].status == 0){ // if job was not yet started
    distrenjob_enqueue(head, job);
  }
  else{ // if job has already been started then place it before the jobs with the same priority
    // iterate through linked list of jobs
    for(current_job = head; current_job != NULL; current_job = current_job->next){
      if(current_job == NULL){ // if it has reached the end of the list, add job there
        current_job = job;
        break;
      }
      else if(job->priority <= current_job->priority){ // if job's priority is less than or equal to current_job's priority, insert job
        prev_job->next = job;                        // keep in mind 1 is the highest priority given to jobs, head has a
        job->next = current_job;                     // priority of zero so it will always be before other jobs
        break;
      }

      prev_job = current_job;
    }
  }
}

/**
  Frame Finder: matches your computer up with a lovely frame to render
  TODO: Major issue here, the client needs to know the frame number, AND the job number!
  Notice that this function starts by looking at the oldest job first

	TODO: Link this up with the main() function to check if there are frames available or not and provide jobnum/framenum to the client

  @return 0 success, other: error
*/
/*@TODO: change frame_finder to job_finder */
int frame_finder(struct distrenjob *head, struct distrenjob **job, struct frameset **frame)
{
  int your_frame = 0;  // your_frame is an integer value that will be given to the client as the frame number to render
  short int your_job_type = 0;
  unsigned short int found;

  struct distrenjob *distrenjob_ptr;

  found = 0;

  while(!found)
  {
    /* iterate through jobs from first to last */
    for(distrenjob_ptr = head->next; !found && !distrenjob_ptr; distrenjob_ptr = distrenjob_ptr->next)
      {
        if(distrenjob_ptr->is_job_done)
          distrenjob_ptr->type = your_job_type;
      }

    found = 0;
    // check the job type to see if the job is avaliable to be worked on
    switch(your_job_type)
    {
      case 1: // blender
        for(your_frame; !found; your_frame++)
          {
            if(distrenjob_ptr->frameset[your_frame].status == 0)
              {
                found = 1;
                distrenjob_ptr->frameset[your_frame].status = 1;
                distrenjob_ptr->frameset[your_frame].start_time = clock();
                break;
              }
          }
    }
  } // end of while statement... job must be found or linked list must be ended to get out of here
      if(!found)
        {
          fprintf(stderr, "No more jobs to render\n");
          return 1;
        }

    // the actual frame number to be rendered by the client is start_frame + your_frame
    // @TODO: refine how we want to return data from this
    //struct framejob { distrenjob_ptr; distrenjob_ptr->(&frameset[your_frame])};

      /* should the job be removed now? ANSWER: well, if a computer decides not to return their frame then we lost our data... so its not done yet. */
      fprintf(stderr, "Job %d is finished, this is probably the place to call the job-removal function\n", distrenjob_ptr->jobnum);
      /* @TODO: At this point, all slaves should be instructed to delete the source data for this job. */

  return 0;
}

/** Checks for dead, laggy, or stale slaves */
void blend_frame_watchdog(struct distrenjob *distrenjob_head)
{
  unsigned short int watchdog_forgiveness; /*< seconds to wait on a frame before re-assigning it */
  struct distrenjob *distrenjob_ptr;
  unsigned int counter;

  watchdog_forgiveness = 1; /*< hours of forgiveness before frame is re-assigned @TODO: Make this more user-configurable (maybe per-job), 3 hours is a LONG time */
  distrenjob_ptr = distrenjob_head;

  for(distrenjob_ptr = distrenjob_head; distrenjob_ptr; distrenjob_ptr = distrenjob_ptr->next)
    /* iterate through jobs */

    for(counter = 0; counter < distrenjob_ptr->total_frames; counter ++)
      /* iterate through all frames for this job*/
      {
        if((distrenjob_ptr->frameset[counter].start_time + (watchdog_forgiveness * 3600)) < clock())
          /*
            If frame is not completed within the number of hours specified by watchdog_forgiveness
            Then change the frame status to unassigned
           */
          distrenjob_ptr->frameset[counter].status = 0;
      }

}

/**
   Finds a distrenjob struct based on the jobnum
   @arg jobnum job number to search for
   @return NULL on job doesn't exist
 */
struct distrenjob *distrenjob_get(struct distrenjob *head, jobnum_t jobnum)
{
  struct distrenjob *distrenjob_ptr;

  /*
    The conditions of the for loop will leave distrenjob_ptr at NULL if the end of the list is reached. It will leave it pointing to the correct job if it is found.
   */
  for(distrenjob_ptr = head;
      distrenjob_ptr
        && distrenjob_ptr->jobnum != jobnum;
      distrenjob_ptr = distrenjob_ptr->next);

  return distrenjob_ptr;
}


/**
   Removes a distrenjob from the distrenjob linked list.

   @arg head a double pointer. the head pointer will have to be changed if distrenjob == *head. Thus, make sure that the pointer points to the pointer to the head that all functions use. (I'm going to come back to this and misunderstand myself ;-))
 */
void distrenjob_remove(struct distrenjob **head, struct distrenjob *bj)
{
  struct distrenjob *previous_distrenjob;

  if(bj == *head)
    *head = bj->next;
  else
    {

      for(previous_distrenjob = *head;
        previous_distrenjob
          && previous_distrenjob->next != bj; /*< stop on the distrenjob that comes before bj */
          previous_distrenjob = previous_distrenjob->next)
	/* all of the action is in the definition of the for loop itself */;

      /*
	This removes references to bj from the linked list. I.E., we now skip bj when iterating through the list
       */
      previous_distrenjob->next = bj->next;
    }
}


/* Grabs config info from confs */
int distrend_do_config(int argc, char *argv[], struct distrend_config **config)
{
  cfg_opt_t myopts_listen[] =
    {
      CFG_SIMPLE_STR("type", NULL),
      CFG_SIMPLE_STR("path", NULL),
      CFG_SIMPLE_INT("port", NULL),
      CFG_END()
    };
  cfg_opt_t myopts[] =
    {
      CFG_SEC("listen",  /* this must be imported into struct listens (which must still be declared) */
          myopts_listen,
          CFGF_MULTI),
      CFG_SIMPLE_STR("datadir", NULL),
      CFG_END()
    };

  struct distrenjob *distrenjob;

  int tmp;

  xmlinit();
  /*
   * test xml2distrenjob()
   */
  tmp = xml2distrenjob(&distrenjob, "distrenjob.xml.example");
  if(tmp)
    fprintf(stderr, "xml2distrenjob() returned %d. Try to cd to distren/doc if you want to test out the xml2distrenjob() function. (This will only fix this error if the error is due to an inability of the xml library to access distrenjob.xml.example)\n", tmp);
  else
    fprintf(stderr, "using email ``%s'' for user ``%s'' -- reading in XML files and pulling data from them using libxml2+XPath works!!!\n", distrenjob->email, distrenjob->submitter);

  fprintf(stderr, "%s:%d running config\n", __FILE__, __LINE__);

  *config = malloc(sizeof(struct distrend_config));
  myopts[1].simple_value = &(*config)->datadir;

  options_init(argc, argv, &(*config)->mycfg, myopts, "server", &(*config)->options);

  fprintf(stderr, "using %s as datadir\n", (*config)->datadir);

  xmlcleanup();
  return 0;
}
int distrend_config_free(struct distrend_config *config)
{
  options_free(config->options);
  free(config);

  return 0;
}


/* ************************** Main ************************* */

int main(int argc, char *argv[])
{

  /* @TODO: Put some arg-grabbing code here */

  struct distrenjob head;
  head.priority = 0; // make head have the highest priority

  int cont;
  struct distrend_listenset *listenset;
  struct distrend_config *config;

  enum clientstatus
  {
    CLIENTSTATUS_UNINITIALIZED = 0,
    CLIENTSTATUS_BUSY = 1,
    CLIENTSTATUS_IDLE = 2
  } clientstatus;

  cont = 1;
  memset(&head, '\0', sizeof(struct distrenjob));

  start_data(); // Starts fresh or loads data from xml dump. Should we grab the return?

  distrend_do_config(argc, argv, &config);

  distrend_listen(&listenset, config);
  /* This is called the "main loop" */
  while(cont)
    {
      struct distren_action *action;
      int clientsays; /*< temporary example variable, will be replaced when we can handle messages */

      distrend_accept(&action);
      cont = distrend_do(action);

      /* Make the following code more event-driven */
      status_report_generator(&head);
      blend_frame_watchdog(&head);


      struct frameset *frame;
      struct distrenjob *job;

      /* If the client is idle, must be modified for climbing through linked list of clients (client->clientnum) */
      if(clientstatus == CLIENTSTATUS_IDLE)
	{
	  int returnnum = frame_finder(&head, &job, &frame); // Finds a frame to render
	  if(returnnum)
	    {
	      fprintf(stderr,"No frames are available to render at this time. Idling...\n");
	      sleep(10);
	    }
	  else
	    /* returnnum == 0 */
	    remotio_send_to_client(frame->num, job->jobnum); // Pseudo-sends data to client
	}

      /* If the client states that they finished the frame */
      	if(clientsays == DISTREN_REQUEST_DONEFRAME){
      	  clientstatus = CLIENTSTATUS_IDLE; // Sets the client back to idle
      	  finish_frame(&head, frame->num); // @TODO: Check that finish_frame really gets the jobnum somehow
      	}

      distrend_action_free(action);
    }

  distrend_unlisten(listenset);
  distrend_config_free(config);

  return 0;
}