#include "quakedef.h"
#include "meshqueue.h"

cvar_t r_meshqueue_entries = {CVAR_SAVE, "r_meshqueue_entries", "16"};
cvar_t r_meshqueue_immediaterender = {0, "r_meshqueue_immediaterender", "0"};
cvar_t r_meshqueue_sort = {0, "r_meshqueue_sort", "0"};

typedef struct meshqueue_s
{
	struct meshqueue_s *next;
	void (*callback)(void *data1, int data2);
	void *data1;
	int data2;
	float dist;
}
meshqueue_t;

float mqt_viewplanedist;
meshqueue_t *mq_array, *mqt_array, *mq_listhead;
int mq_count, mqt_count;
int mq_total, mqt_total;

mempool_t *meshqueuemempool;

void R_MeshQueue_Init(void)
{
	Cvar_RegisterVariable(&r_meshqueue_entries);
	Cvar_RegisterVariable(&r_meshqueue_immediaterender);
	Cvar_RegisterVariable(&r_meshqueue_sort);

	meshqueuemempool = Mem_AllocPool("R_MeshQueue");
	mq_total = 0;
	mqt_total = 1000;
	mq_array = NULL;
	mqt_array = NULL;
}

static void R_MeshQueue_Render(void)
{
	meshqueue_t *mq;
	for (mq = mq_listhead;mq;mq = mq->next)
		mq->callback(mq->data1, mq->data2);
	mq_count = 0;
	mq_listhead = NULL;
}

static void R_MeshQueue_EnlargeTransparentArray(int newtotal)
{
	meshqueue_t *newarray;
	newarray = Mem_Alloc(meshqueuemempool, newtotal * sizeof(meshqueue_t));
	if (mqt_array)
	{
		memcpy(newarray, mqt_array, mqt_total * sizeof(meshqueue_t));
		Mem_Free(mqt_array);
	}
	mqt_array = newarray;
	mqt_total = newtotal;
}

void R_MeshQueue_Add(void (*callback)(void *data1, int data2), void *data1, int data2)
{
	meshqueue_t *mq, **mqnext;
	if (r_meshqueue_immediaterender.integer)
	{
		callback(data1, data2);
		return;
	}
	if (mq_count >= mq_total)
		R_MeshQueue_Render();
	mq = &mq_array[mq_count++];
	mq->callback = callback;
	mq->data1 = data1;
	mq->data2 = data2;

	// bubble-insert sort into meshqueue
	mqnext = &mq_listhead;
	if (r_meshqueue_sort.integer)
	{
		for(;;)
		{
			if (*mqnext)
			{
				if (mq->callback == (*mqnext)->callback)
				{
					if (mq->data1 == (*mqnext)->data1)
					{
						if (mq->data2 <= (*mqnext)->data2)
							break;
					}
					else if (mq->data1 < (*mqnext)->data1)
						break;
				}
				else if (mq->callback < (*mqnext)->callback)
					break;
			}
			else
				break;
			mqnext = &(*mqnext)->next;
		}
	}
	mq->next = *mqnext;
	*mqnext = mq;
}

void R_MeshQueue_AddTransparent(vec3_t center, void (*callback)(void *data1, int data2), void *data1, int data2)
{
	meshqueue_t *mq;
	if (mqt_count >= mqt_total)
		R_MeshQueue_EnlargeTransparentArray(mqt_total + 100);
	mq = &mqt_array[mqt_count++];
	mq->callback = callback;
	mq->data1 = data1;
	mq->data2 = data2;
	mq->dist = DotProduct(center, vpn) - mqt_viewplanedist;
	mq->next = NULL;
}

static void R_MeshQueue_RenderTransparent(void)
{
	int i;
	int hashdist;
	meshqueue_t *mqt;
	meshqueue_t *hash[4096];
	memset(hash, 0, 4096 * sizeof(meshqueue_t *));
	for (i = 0, mqt = mqt_array;i < mqt_count;i++, mqt++)
	{
		// generate index
		hashdist = (int) (mqt->dist);
		hashdist = bound(0, hashdist, 4095);
		// reversed to simplify render loop
		hashdist = 4095 - hashdist;
		// link into hash chain
		mqt->next = hash[hashdist];
		hash[hashdist] = mqt;
	}
	for (i = 0;i < 4096;i++)
		if (hash[i])
			for (mqt = hash[i];mqt;mqt = mqt->next)
				R_MeshQueue_Add(mqt->callback, mqt->data1, mqt->data2);
	mqt_count = 0;
}

void R_MeshQueue_BeginScene(void)
{
	if (r_meshqueue_entries.integer < 1)
		Cvar_SetValueQuick(&r_meshqueue_entries, 1);
	if (r_meshqueue_entries.integer > 65536)
		Cvar_SetValueQuick(&r_meshqueue_entries, 65536);

	if (mq_total != r_meshqueue_entries.integer || mq_array == NULL)
	{
		mq_total = r_meshqueue_entries.integer;
		if (mq_array)
			Mem_Free(mq_array);
		mq_array = Mem_Alloc(meshqueuemempool, mq_total * sizeof(meshqueue_t));
	}

	if (mqt_array == NULL)
		mqt_array = Mem_Alloc(meshqueuemempool, mqt_total * sizeof(meshqueue_t));

	mq_count = 0;
	mqt_count = 0;
	mq_listhead = NULL;
	mqt_viewplanedist = DotProduct(r_origin, vpn);
}

void R_MeshQueue_EndScene(void)
{
	if (mqt_count)
		R_MeshQueue_RenderTransparent();
	if (mq_count)
		R_MeshQueue_Render();
}