#include "hip-prv.h"

#include <stdlib.h>
#include <string.h>

struct hip_chan_t
{
	hip_t* hip;

	int closed;

	hip_oow_t unit_size;
	hip_oow_t buf_size;

	hip_uint8_t* buf;
	hip_uint8_t* endptr;
	hip_uint8_t* readptr;
	hip_uint8_t* writeptr;

	hip_uctx_link_t sendq; // list of senders waiting on this channel
	hip_uctx_link_t recvq; // list of receivers waiting on this channel
};

hip_chan_t* hip_chan_open(hip_t* hip, hip_oow_t buf_size)
{
	hip_chan_t* c;

	c = (hip_chan_t*)malloc(HIP_SIZEOF(*c) + buf_size);
	if (HIP_UNLIKELY(!c)) return HIP_NULL;

	memset(c, 0, HIP_SIZEOF(*c));
	c->hip = hip;
	c->closed = 0;
	c->buf_size = buf_size;
	c->buf = (hip_uint8_t*)(c + 1);
	c->endptr = 0;
	c->readptr = 0;
	c->writeptr = 0;

	HIP_LIST_INIT(&c->recvq);
	HIP_LIST_INIT(&c->sendq);

	return c;
}

void hip_chan_close(hip_chan_t* c)
{
	free(c);
}

int hip_chan_send(hip_chan_t* c, const void* ptr, hip_oow_t len)
{
	hip_uctx_t* self;
	int ret;

	self = UCTX_FROM_LINK(c->hip->running);

// TODO: IS BUFFER EMPTY

	if (!HIP_LIST_IS_EMPTY(&c->recvq)) /* there is a receving routine */
	{
		hip_uctx_link_t* x;
		hip_uctx_t* xx;

		/* remove the receiving routine from the queue and make it runnable */
		x = HIP_LIST_HEAD(&c->recvq);
		HIP_LIST_UNCHAIN(x);
		HIP_LIST_ADD_BACK(x, &c->hip->runnables);

		xx = UCTX_FROM_LINK(x);

		if (len > xx->chan_data_len) len = xx->chan_data_len;
		memcpy(xx->chan_data_ptr, ptr, len);
		*(xx->chan_ret_ptr) = len; /* manipulate the return value of the receiver */

		hip_yield(c->hip); /* let other routines go first */
		return len;
	}


	/* remember the data holder and places the current running routine in the send queue */
	self->chan_data_ptr = (hip_uint8_t*)ptr;
	self->chan_data_len = len;
	self->chan_ret_ptr = &ret; /* remember the pointer to the return value holder to be set by the receiver */
	HIP_LIST_ADD_BACK(c->hip->running, &c->sendq);

	hip_switch(c->hip);
	return ret;
}

int hip_chan_recv(hip_chan_t* c, void* ptr, hip_oow_t len)
{
	hip_uctx_t* self;
	int ret;

	self = UCTX_FROM_LINK(c->hip->running);

	/* TODO: IS THERE DATA IN BUFFER ? */

	if (!HIP_LIST_IS_EMPTY(&c->sendq)) /* there is a sending routine */
	{
		hip_uctx_link_t* x;
		hip_uctx_t* xx;

		/* remove the sending routine from the queue and make it runnable */
		x = HIP_LIST_HEAD(&c->sendq);
		HIP_LIST_UNCHAIN(x);
		HIP_LIST_ADD_BACK(x, &c->hip->runnables);

		xx = UCTX_FROM_LINK(x);

		/* copy the data from the sending routine's buffer */
		if (len > xx->chan_data_len) len = xx->chan_data_len; /* TODO: do something else instead of simple truncation */
		memcpy(ptr, xx->chan_data_ptr, len);
		*(xx->chan_data_ptr) = len; /* manipulate the return value of the sender */

		hip_yield(c->hip); /* let other routines go first */
		return len;
	}

	/* remember the data holder and place the calling routine in the receive queue */
	self->chan_data_ptr = ptr;
	self->chan_data_len = len;
	self->chan_ret_ptr = &ret; /* remember the pointer to the return value holder to be set by the sender */
	HIP_LIST_ADD_BACK(c->hip->running, &c->recvq);

	hip_switch(c->hip); /* switch to the scheduler */
	return ret;
}