// vim: set noet ts=4 sw=4:

#include "scheduler.h"

#include "../arch/core.h"
#include "../debug/assert.h"  // IWYU pragma: keep

Scheduler::Scheduler() {}

Thread *Scheduler::getNext() {
	Thread *next = readylist.dequeue();
	if (next == nullptr) {
		next = &idleThread;
	}

	assert(next != nullptr && "No thread available!");
	return next;
}

void Scheduler::schedule() { dispatcher.go(getNext()); }

void Scheduler::ready(Thread *that) {
	assert(that != nullptr && "nullptr pointer not allowed for ready list!");

	assert(static_cast<Thread *>(&idleThread) != that &&
		   "IdleThread must not be placed in ready list!");

	readylist.enqueue(*that);
}

void Scheduler::resume(bool ready) {
	Thread *me = dispatcher.active();
	assert(me != nullptr && "Pointer to active thread should never be nullptr");

	// Be careful, never put the idle thread into the ready list
	bool is_idle_thread = static_cast<Thread *>(&idleThread) == me;

	if (ready && readylist.is_empty()) {
		return;
	} else if (!is_idle_thread) {
		if (ready) readylist.enqueue(*me);
	}

	dispatcher.dispatch(getNext());
}

void Scheduler::exit() {
	Thread *next = getNext();

	dispatcher.dispatch(next);
}

void Scheduler::kill(Thread *that) {
	if (dispatcher.active() == that) {
		exit();
	}

	readylist.remove(that);
}

bool Scheduler::isEmpty() const { return readylist.is_empty(); }