#include <mango/status.h>
#include <string.h>
#include <xpc/buffer.h>
#include <xpc/msg.h>

kern_status_t xpc_buffer_read(
	const xpc_buffer_t *buf,
	size_t offset,
	void *out,
	size_t max,
	size_t *nr_read)
{
	if ((buf->buf_flags & (XPC_BUFFER_F_IN | XPC_BUFFER_F_REMOTE))
	    != (XPC_BUFFER_F_IN | XPC_BUFFER_F_REMOTE)) {
		return KERN_BAD_STATE;
	}

	if (offset >= buf->buf_len) {
		if (nr_read) {
			*nr_read = 0;
		}

		return KERN_OK;
	}

	size_t to_read = max;
	if (offset + to_read > buf->buf_len) {
		to_read = buf->buf_len - offset;
	}

	kern_status_t status = xpc_msg_read(
		buf->buf_origin,
		buf->buf_offset + offset,
		out,
		to_read,
		nr_read);
	if (status != KERN_OK) {
		return status;
	}

	return KERN_OK;
}

kern_status_t xpc_buffer_write(
	xpc_buffer_t *buf,
	size_t offset,
	const void *in,
	size_t len,
	size_t *nr_written)
{
	if (!(buf->buf_flags & XPC_BUFFER_F_OUT)) {
		return KERN_BAD_STATE;
	}

	if (offset >= buf->buf_max) {
		if (nr_written) {
			*nr_written = 0;
		}

		return KERN_OK;
	}

	size_t to_write = len;
	if (offset + to_write > buf->buf_max) {
		to_write = buf->buf_max - offset;
	}

	if (!(buf->buf_flags & XPC_BUFFER_F_REMOTE)) {
		memcpy(buf->buf_ptr, in, to_write);
		*nr_written = to_write;
		return KERN_OK;
	}

	return xpc_msg_write(
		buf->buf_origin,
		buf->buf_offset + offset,
		in,
		to_write,
		nr_written);
}

xpc_status_t xpc_buffer_readv(
	const xpc_buffer_t *buf,
	size_t offset,
	kern_iovec_t *iov,
	size_t nr_iov,
	size_t *nr_read)
{
	if (!(buf->buf_flags & XPC_BUFFER_F_IN)) {
		return KERN_BAD_STATE;
	}

	/* TODO limit to buffer bounds */

	if (!(buf->buf_flags & XPC_BUFFER_F_REMOTE)) {
		/* TODO */
		return KERN_UNIMPLEMENTED;
	}

	return xpc_msg_readv(
		buf->buf_origin,
		buf->buf_offset + offset,
		iov,
		nr_iov,
		nr_read);
}

xpc_status_t xpc_buffer_writev(
	xpc_buffer_t *buf,
	size_t offset,
	kern_iovec_t *iov,
	size_t nr_iov,
	size_t *nr_written)
{
	if (!(buf->buf_flags & XPC_BUFFER_F_OUT)) {
		return KERN_BAD_STATE;
	}

	/* TODO limit to buffer bounds */

	if (!(buf->buf_flags & XPC_BUFFER_F_REMOTE)) {
		/* TODO */
		return KERN_UNIMPLEMENTED;
	}

	return xpc_msg_writev(
		buf->buf_origin,
		buf->buf_offset + offset,
		iov,
		nr_iov,
		nr_written);
}

xpc_status_t xpc_buffer_length(const xpc_buffer_t *s)
{
	return s->buf_len;
}

xpc_status_t xpc_buffer_capacity(const xpc_buffer_t *s)
{
	return s->buf_max;
}