/* scheduler.c */

#include "asm.h"
#include "message.h"
#include "process.h"
#include "scheduler.h"
#include "string.h"
#include "tty3.h"
#include "user.h"

int get_running() {
  int i;
  for (i = 0; i < PROCESSES; i++) {
    if (PCB_list[i].status == RUNNING) { return i; }
  }
  return -1;
}

void hold(int pid) {
  int id = pid - 1;
  int check_value = PCB_list[id].toggle;
  while(PCB_list[id].toggle == check_value)
    ;
}

void revive(int pid) {
  int id = pid - 1;
  if (receive_message() && PCB_list[id].current_message.priority == CRASH_PRIO) {
    int crashed_pid = string_to_int(PCB_list[id].current_message.data);
    int crashed_id = crashed_pid - 1;
    char program[MAX_STR_LEN];
    char argv[2][MAX_STR_LEN];
    string_memcpy(program, PCB_list[crashed_id].name);
    string_memcpy(argv[0], PCB_list[crashed_id].arg_1);
    string_memcpy(argv[1], PCB_list[crashed_id].arg_2);
    terminate(crashed_pid);
    int new_pid = new_p(program, argv);
    PCB_list[new_pid - 1].supervisor_pid = pid;
    print_string("The program [");
    print_string(program);
    print_string("] was revived.\n");
  }
}

void check_crashes() {
  int i;
  for (i = 0; i < PROCESSES; i++) {
    if (PCB_list[i].status == CRASHED && PCB_list[i].supervisor_pid) {
      int pid = i + 1;
      char mess[MAX_STR_LEN];
      int_to_string(mess, pid);
      send_message(mess, CRASH_PRIO, PCB_list[i].supervisor_pid);
      PCB_list[i].supervisor_pid = -1;
    }
  }
}

void do_delay() {
  int i;
  for (i = 0; i < PROCESSES; i++) {
    if (PCB_list[i].status == DELAYED) {
      PCB_list[i].delay_time--;
      if (PCB_list[i].delay_time == 0)
        { PCB_list[i].status = WAITING; }
    }
  }
}

void increase_wait() {
  int i;
  for (i = 0; i < PROCESSES; i++) {
    if (PCB_list[i].status == WAITING) { PCB_list[i].wait_time++; }
  }
}

int get_highest_process() {
  int highest_priority = 0;
  int highest_process = -1;
  int i;
  for (i = 0; i < PROCESSES; i++) {
    if (PCB_list[i].status == WAITING) {
      if (PCB_list[i].priority > highest_priority) {
        highest_priority = PCB_list[i].priority;
        highest_process = i;
      }
      else if
        (PCB_list[i].priority == highest_priority &&
         PCB_list[i].wait_time >= PCB_list[highest_process].wait_time)
        {   highest_process = i; }
    }
  }
  return highest_process;
}

void select_process() {
  int running = get_running();
  if (running != -1) { PCB_list[running].status = WAITING; }
  int new_running = get_highest_process();
  if (new_running != -1) {
    PCB_list[new_running].status = RUNNING;
    PCB_list[new_running].wait_time = 0;
  }
}