#include <kernel/machine/cpu.h>
#include <kernel/printk.h>
#include <kernel/sched.h>
#include <kernel/syscall.h>
#include <kernel/vm-region.h>

extern kern_status_t sys_task_exit(int status)
{
	while (1) {
		printk("sys_exit(%d)", status);
		milli_sleep(1000);
	}

	return KERN_UNIMPLEMENTED;
}

kern_status_t sys_task_create(
	kern_handle_t parent_handle,
	const char *name,
	size_t name_len,
	kern_handle_t *out_task,
	kern_handle_t *out_address_space)
{
	unsigned long flags;
	struct task *self = current_task();

	if (name_len && !validate_access_r(self, name, name_len)) {
		return KERN_MEMORY_FAULT;
	}

	if (!validate_access_w(self, out_task, sizeof *out_task)) {
		return KERN_MEMORY_FAULT;
	}

	if (!validate_access_w(
		    self,
		    out_address_space,
		    sizeof *out_address_space)) {
		return KERN_MEMORY_FAULT;
	}

	struct object *parent_obj;
	handle_flags_t parent_flags;
	task_lock_irqsave(self, &flags);
	kern_status_t status = task_resolve_handle(
		self,
		parent_handle,
		&parent_obj,
		&parent_flags);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, flags);
		return status;
	}

	object_ref(parent_obj);
	struct task *parent = task_cast(parent_obj);

	struct handle *child_handle_slot = NULL, *space_handle_slot = NULL;
	kern_handle_t child_handle, space_handle;
	status = handle_table_alloc_handle(
		self->t_handles,
		&child_handle_slot,
		&child_handle);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, flags);
		return status;
	}

	status = handle_table_alloc_handle(
		self->t_handles,
		&space_handle_slot,
		&space_handle);
	if (status != KERN_OK) {
		handle_table_free_handle(self->t_handles, child_handle);
		task_unlock_irqrestore(self, flags);
		return status;
	}

	task_unlock_irqrestore(self, flags);

	struct task *child = task_create(name, name_len);
	if (!child) {
		object_unref(parent_obj);

		task_lock_irqsave(self, &flags);
		handle_table_free_handle(self->t_handles, child_handle);
		handle_table_free_handle(self->t_handles, space_handle);
		task_unlock_irqrestore(self, flags);

		return KERN_NO_MEMORY;
	}

	task_lock_irqsave(parent, &flags);
	task_add_child(parent, child);
	task_unlock_irqrestore(parent, flags);

	child_handle_slot->h_object = &child->t_base;
	space_handle_slot->h_object = &child->t_address_space->vr_base;

	object_add_handle(&child->t_base);
	object_add_handle(&child->t_address_space->vr_base);

	object_unref(parent_obj);

	*out_task = child_handle;
	*out_address_space = space_handle;

	return KERN_OK;
}

kern_status_t sys_task_create_thread(
	kern_handle_t task,
	virt_addr_t ip,
	virt_addr_t sp,
	uintptr_t *args,
	size_t nr_args,
	kern_handle_t *out_thread)
{
	unsigned long flags;
	struct task *self = current_task();

	if (!validate_access_r(self, args, nr_args * sizeof(uintptr_t))) {
		return KERN_MEMORY_FAULT;
	}

	if (!validate_access_w(self, out_thread, sizeof *out_thread)) {
		return KERN_MEMORY_FAULT;
	}

	struct object *target_obj;
	handle_flags_t target_flags;
	task_lock_irqsave(self, &flags);
	kern_status_t status
		= task_resolve_handle(self, task, &target_obj, &target_flags);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, flags);
		return status;
	}

	object_ref(target_obj);
	struct task *target = task_cast(target_obj);

	struct handle *target_handle = NULL;
	kern_handle_t out_handle;
	status = handle_table_alloc_handle(
		self->t_handles,
		&target_handle,
		&out_handle);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, flags);
		return status;
	}

	task_unlock_irqrestore(self, flags);
	task_lock_irqsave(target, &flags);

	struct thread *thread = task_create_thread(target);
	if (!thread) {
		object_unref(target_obj);
		task_unlock_irqrestore(target, flags);

		task_lock_irqsave(self, &flags);
		handle_table_free_handle(self->t_handles, out_handle);
		task_unlock_irqrestore(self, flags);
		return KERN_NO_MEMORY;
	}

	thread_init_user(thread, ip, sp, args, nr_args);
	target_handle->h_object = &thread->thr_base;
	object_add_handle(&thread->thr_base);

	task_unlock_irqrestore(target, flags);

	*out_thread = out_handle;
	return KERN_OK;
}

kern_status_t sys_thread_start(kern_handle_t thread_handle)
{
	unsigned long flags;
	struct task *self = current_task();

	struct object *thread_obj;
	handle_flags_t thread_flags;
	task_lock_irqsave(self, &flags);
	kern_status_t status = task_resolve_handle(
		self,
		thread_handle,
		&thread_obj,
		&thread_flags);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, flags);
		return status;
	}

	object_ref(thread_obj);
	struct thread *thread = thread_cast(thread_obj);
	task_unlock_irqrestore(self, flags);

	schedule_thread_on_cpu(thread);

	return KERN_OK;
}