#include <kernel/channel.h>
#include <kernel/port.h>
#include <kernel/printk.h>
#include <kernel/sched.h>
#include <kernel/syscall.h>
#include <kernel/vm-region.h>

kern_status_t sys_channel_create(unsigned int id, kern_handle_t *out)
{
	struct task *self = current_task();
	if (!validate_access_w(self, out, sizeof *out)) {
		return KERN_MEMORY_FAULT;
	}

	struct channel *channel = channel_create();
	if (!channel) {
		return KERN_NO_MEMORY;
	}

	unsigned long irq_flags;
	task_lock_irqsave(self, &irq_flags);

	if (task_get_channel(self, id)) {
		task_unlock_irqrestore(self, irq_flags);
		return KERN_NAME_EXISTS;
	}

	kern_handle_t handle;
	kern_status_t status
		= task_open_handle(self, &channel->c_base, 0, &handle);
	if (status != KERN_OK) {
		task_unlock_irqrestore(self, irq_flags);
		object_unref(&channel->c_base);
		return status;
	}

	task_add_channel(self, channel, id);
	task_unlock_irqrestore(self, irq_flags);

	*out = handle;
	return KERN_OK;
}

kern_status_t sys_port_create(kern_handle_t *out)
{
	struct task *self = current_task();
	if (!validate_access_w(self, out, sizeof *out)) {
		return KERN_MEMORY_FAULT;
	}

	struct port *port = port_create();
	if (!port) {
		return KERN_NO_MEMORY;
	}

	unsigned long irq_flags;
	task_lock_irqsave(self, &irq_flags);

	kern_handle_t handle;
	kern_status_t status
		= task_open_handle(self, &port->p_base, 0, &handle);
	task_unlock_irqrestore(self, irq_flags);

	if (status != KERN_OK) {
		object_unref(&port->p_base);
		return status;
	}

	*out = handle;
	return KERN_OK;
}

kern_status_t sys_port_connect(
	kern_handle_t port_handle,
	tid_t task_id,
	unsigned int channel_id)
{
	unsigned long flags;

	struct task *self = current_task();
	task_lock_irqsave(self, &flags);

	struct object *port_obj = NULL;
	handle_flags_t port_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		port_handle,
		&port_obj,
		&port_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(port_obj);
	struct port *port = port_cast(port_obj);
	task_unlock_irqrestore(self, flags);

	struct task *remote_task = task_from_tid(task_id);
	if (!remote_task) {
		return KERN_NO_ENTRY;
	}

	task_lock_irqsave(remote_task, &flags);

	struct channel *remote = task_get_channel(remote_task, channel_id);
	if (!remote) {
		task_unlock_irqrestore(remote_task, flags);
		return KERN_NO_ENTRY;
	}

	object_ref(&remote->c_base);
	task_unlock_irqrestore(remote_task, flags);

	port_lock_irqsave(port, &flags);
	status = port_connect(port, remote);
	port_unlock_irqrestore(port, flags);
	object_unref(port_obj);
	object_unref(&remote->c_base);

	return KERN_OK;
}

kern_status_t sys_port_disconnect(kern_handle_t port_handle)
{
	unsigned long flags;

	struct task *self = current_task();
	task_lock_irqsave(self, &flags);

	struct object *port_obj = NULL;
	handle_flags_t port_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		port_handle,
		&port_obj,
		&port_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(port_obj);
	task_unlock_irqrestore(self, flags);

	struct port *port = port_cast(port_obj);
	if (!port) {
		object_unref(port_obj);
		return KERN_INVALID_ARGUMENT;
	}

	object_unref(port_obj);
	port_lock_irqsave(port, &flags);
	status = port_disconnect(port);
	port_unlock_irqrestore(port, flags);

	return status;
}

static bool validate_iovec(
	struct task *task,
	const kern_iovec_t *iov,
	size_t count,
	bool rw)
{
	if (!validate_access_r(task, iov, count * sizeof(*iov))) {
		return false;
	}

	for (size_t i = 0; i < count; i++) {
		bool ok = false;
		const kern_iovec_t *vec = &iov[i];
		if (rw) {
			ok = validate_access_w(task, vec->io_base, vec->io_len);
		} else {
			ok = validate_access_r(task, vec->io_base, vec->io_len);
		}

		if (!ok) {
			return false;
		}
	}

	return true;
}

static bool validate_msg(struct task *task, const kern_msg_t *msg, bool rw)
{
	if (!msg) {
		return false;
	}

	vm_prot_t flags;
	if (rw) {
		flags = VM_PROT_WRITE | VM_PROT_USER;
	} else {
		flags = VM_PROT_READ | VM_PROT_USER;
	}

	if (!validate_access(task, msg, sizeof *msg, flags)) {
		return false;
	}

	if (!validate_iovec(task, msg->msg_data, msg->msg_data_count, rw)) {
		return false;
	}

	size_t handle_buffer_len
		= msg->msg_handles_count * sizeof(*msg->msg_handles);
	if (!validate_access(
		    task,
		    msg->msg_handles,
		    handle_buffer_len,
		    flags)) {
		return false;
	}

	return true;
}

kern_status_t sys_msg_send(
	kern_handle_t port_handle,
	const kern_msg_t *msg,
	kern_msg_t *out_reply)
{
	struct task *self = current_task();

	if (!validate_msg(self, msg, false)) {
		return KERN_MEMORY_FAULT;
	}

	if (!validate_msg(self, out_reply, true)) {
		return KERN_MEMORY_FAULT;
	}

	unsigned long flags;

	task_lock_irqsave(self, &flags);

	struct object *port_obj = NULL;
	handle_flags_t port_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		port_handle,
		&port_obj,
		&port_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(port_obj);
	task_unlock_irqrestore(self, flags);

	struct port *port = port_cast(port_obj);
	if (!port) {
		object_unref(port_obj);
		return KERN_INVALID_ARGUMENT;
	}

	port_lock_irqsave(port, &flags);
	status = port_send_msg(port, msg, out_reply, &flags);
	port_unlock_irqrestore(port, flags);
	object_unref(port_obj);

	return status;
}

kern_status_t sys_msg_recv(kern_handle_t channel_handle, kern_msg_t *out_msg)
{
	struct task *self = current_task();

	if (!validate_msg(self, out_msg, true)) {
		return KERN_MEMORY_FAULT;
	}

	unsigned long flags;

	task_lock_irqsave(self, &flags);

	struct object *channel_obj = NULL;
	handle_flags_t channel_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		channel_handle,
		&channel_obj,
		&channel_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(channel_obj);
	task_unlock_irqrestore(self, flags);

	struct channel *channel = channel_cast(channel_obj);
	if (!channel) {
		object_unref(channel_obj);
		return KERN_INVALID_ARGUMENT;
	}

	channel_lock_irqsave(channel, &flags);
	status = channel_recv_msg(channel, out_msg, &flags);
	channel_unlock_irqrestore(channel, flags);
	object_unref(channel_obj);

	return status;
}

kern_status_t sys_msg_reply(
	kern_handle_t channel_handle,
	msgid_t id,
	const kern_msg_t *reply)
{
	struct task *self = current_task();

	if (!validate_msg(self, reply, true)) {
		return KERN_MEMORY_FAULT;
	}

	unsigned long flags;

	task_lock_irqsave(self, &flags);

	struct object *channel_obj = NULL;
	handle_flags_t channel_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		channel_handle,
		&channel_obj,
		&channel_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(channel_obj);
	task_unlock_irqrestore(self, flags);

	struct channel *channel = channel_cast(channel_obj);
	if (!channel) {
		object_unref(channel_obj);
		return KERN_INVALID_ARGUMENT;
	}

	channel_lock_irqsave(channel, &flags);
	status = channel_reply_msg(channel, id, reply, &flags);
	channel_unlock_irqrestore(channel, flags);
	object_unref(channel_obj);

	return status;
}

kern_status_t sys_msg_read(
	kern_handle_t channel_handle,
	msgid_t id,
	size_t offset,
	const kern_iovec_t *iov,
	size_t iov_count,
	size_t *nr_read)
{
	struct task *self = current_task();

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

	if (!validate_iovec(self, iov, iov_count, true)) {
		return KERN_MEMORY_FAULT;
	}

	unsigned long flags;

	task_lock_irqsave(self, &flags);

	struct object *channel_obj = NULL;
	handle_flags_t channel_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		channel_handle,
		&channel_obj,
		&channel_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(channel_obj);
	task_unlock_irqrestore(self, flags);

	struct channel *channel = channel_cast(channel_obj);
	if (!channel) {
		object_unref(channel_obj);
		return KERN_INVALID_ARGUMENT;
	}

	channel_lock_irqsave(channel, &flags);
	status = channel_read_msg(
		channel,
		id,
		offset,
		self->t_address_space,
		iov,
		iov_count,
		nr_read);
	channel_unlock_irqrestore(channel, flags);
	object_unref(channel_obj);

	return status;
}

kern_status_t sys_msg_write(
	kern_handle_t channel_handle,
	msgid_t id,
	size_t offset,
	const kern_iovec_t *iov,
	size_t iov_count,
	size_t *nr_written)
{
	struct task *self = current_task();

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

	if (!validate_iovec(self, iov, iov_count, false)) {
		return KERN_MEMORY_FAULT;
	}

	unsigned long flags;

	task_lock_irqsave(self, &flags);

	struct object *channel_obj = NULL;
	handle_flags_t channel_handle_flags = 0;
	kern_status_t status = task_resolve_handle(
		self,
		channel_handle,
		&channel_obj,
		&channel_handle_flags);
	if (status != KERN_OK) {
		return status;
	}

	/* add a reference to the port object to make sure it isn't deleted
	 * while we're using it */
	object_ref(channel_obj);
	task_unlock_irqrestore(self, flags);

	struct channel *channel = channel_cast(channel_obj);
	if (!channel) {
		object_unref(channel_obj);
		return KERN_INVALID_ARGUMENT;
	}

	channel_lock_irqsave(channel, &flags);
	status = channel_write_msg(
		channel,
		id,
		offset,
		self->t_address_space,
		iov,
		iov_count,
		nr_written);
	channel_unlock_irqrestore(channel, flags);
	object_unref(channel_obj);

	return status;
}