#include "sched.h"
#include "terminal.h"
#include "task.h"
#include "interrupts.h"

Scheduler scheduler;

void Scheduler::do_it(registers *regs) {
	schedule(regs);
}
int Scheduler::addTask(Task* t) {
  if(t==0) {
      PANIC("Added bad task");
  }
  if(!t->page_dir.is_set()) {
	con->putval("invalid page directory for task",ntasks+1);
	con->putval("Set as: ",t->page_dir.physical_address);
      PANIC("INVALID PAGE DIRECTORY");
  }
  t->pid=ntasks++;
  t->setNext(head);
  head=t;
  return t->pid;
}

Task* Scheduler::removeTask(int pid) {
	PANIC("NOT CALLED");
  Task* r = head;
  if(!head) return 0;
  if(head->pid==pid) {
      head=head->getNext();
  } else {
    Task* prev = head;
    r=head->getNext();
    while(r!=0) {
      if(r->pid==pid) {
	prev->setNext(r->getNext());
	r->setNext(0);
	break;
      }
      prev=r;
      r=r->getNext();
    }
  }
  return r; // do bugger all for now.
}

void Scheduler::schedule(registers *regs) {
// 	return;
//con->print("In Scheduler\n");
//static int count=0;
//if(currTask) {con->print("WWWWWWWWWWWWWWWWWWWWWWWWWWWWWW"); hang(); }
//con->putval("In scheduler - head=",head);
//con->putval("Number of tasks=",ntasks);
//con->putval("current task:",currTask);
// 	con->print("\n");
//  for(Task* t=head;t!=0;t=t->getNext()) {
// // 	 if(t->pid==2) {
//  		 con->print("PID: ");
// 		 con->puthex(t->pid);
// 		 con->print("-state: ");
// 		 con->puthex(t->_state);
// 		 con->putval("-Task: ",t);
// // 		 if(t->_state==Task::EXITED)
// // 			 PANIC("FOO");
//  	 }
// 	//con->putval("Task: ",t);
// }
 //IRQHandler::dump_registers(*regs);
// con->putval("Head = ",head);
// u32 ss = regs->ss;
    //if(!head || firstTask.page_dir ==0) {
	// this will become the idle thread once it's prepared.
	//	firstTask.setup(regs->eip,PageDirectory::current,regs->useresp,0);
//		addTask(&firstTask);
  //  }

		if(currTask==0) {
 			con->print("\n***First scheduler invocation!\n ");
			currTask=head;
		} else {
//     		con->putval("Switching from task ",currTask->pid);
       		currTask->store_regs(regs);
		}
// 		PANIC("HERE");
		if(currTask->_state==Task::RUNNING)
			currTask->setState(Task::RUNNABLE);
		Task* nextTask=currTask;
// con->print("Starting search.....");
		if(nextTask==nextTask->getNext())
			PANIC("Circular list in scheduler...");

		// go around the list looking for the next runnable task.
		do {
			Task*prev=nextTask;
			nextTask=nextTask->getNext();
			if(nextTask==0) {
				nextTask=head;
				continue;
			} // remove a dead one if we pass it.
			if(nextTask->_state==Task::EXITED) {
				if(prev==0) {
					head=nextTask->getNext();
				} else {
					prev->setNext(nextTask->getNext());
				}
				nextTask->page_dir.switch_to_this();
				nextTask->page_dir.destroy();
				delete nextTask;

			}
// 			con->putval("\n\nXXXXXX--------------task    ",nextTask);
//  			con->putval("\nXXXXXX--------------pid     ",nextTask->pid);
//  			con->putval("XXXXXX--------------state   ",nextTask->_state);
// 			con->putval("XXXXXX--------------next    ",nextTask->getNext());

		} while(nextTask->_state!=Task::RUNNABLE);
// 		do {
// if(nextTask==nextTask->next)
// 	PANIC("Circular list in scheduler...");
// // 			con->putval("\n\nXXXXXX--------------task    ",nextTask);
//  			con->putval("\nXXXXXX--------------pid     ",nextTask->pid);
//  			con->putval("XXXXXX--------------state   ",nextTask->_state);
// 			con->putval("XXXXXX--------------next    ",nextTask->next);
// 			if(nextTask!=0)
// 				nextTask=nextTask->next;
// 			if(nextTask==0)
// 				nextTask=head;
// 		} while(nextTask->_state!=Task::RUNNABLE);
     nextTask->restore_regs(regs);
	currTask=nextTask;


	/*con->print("Task has state: ");
switch(currTask->state) {
case Task::RUNNABLE: con->print("Runnable\n");break;
case Task::BLOCKED: con->print("BLOCKED\n"); break;
default: con->print("OTHER\n");
}*/
	if(currTask->_state!=Task::RUNNABLE) {
		PANIC("Task to run is not runnable!");
	}
	currTask->setState(Task::RUNNING);
// 	if(currTask->pid==1) {
// 		con->print("IDLE THREAD\n");
// 	} else {
//   		con->putval("next task is:",(nextTask->pid));
//   		con->putval("next EIP is:",regs->eip);
//  		con->putval("PGDIR: ",currTask->page_dir.physical_address);
// 	}

      currTask->page_dir.switch_to_this();
//  	  if(currTask->pid!=4)
//       con->putval("Switching to task ",currTask->pid);

    return;
}