#include "pruning.h"

static void        genptable_bfs(PruneData *pd, int d, Move *ms);
static void        genptable_branch(PruneData *pd, uint64_t i, int d, Move *m);
static void        ptable_update(PruneData *pd, Cube cube, int m);
static void        ptable_update_index(PruneData *pd, uint64_t ind, int m);
static int         ptableval_index(PruneData *pd, uint64_t ind);
static bool        read_ptable_file(PruneData *pd);
static bool        write_ptable_file(PruneData *pd);

PruneData
pd_eofb_HTM = {
	.filename = "pt_eofb_HTM",
	.coord    = &coord_eofb,
	.moveset  = moveset_HTM,
};

PruneData
pd_coud_HTM = {
	.filename = "pt_coud_HTM",
	.coord    = &coord_coud,
	.moveset  = moveset_HTM,
};

PruneData
pd_cornershtr_HTM = {
	.filename = "pt_cornershtr_HTM",
	.coord    = &coord_cornershtr,
	.moveset  = moveset_HTM,
};

PruneData
pd_corners_HTM = {
	.filename = "pt_corners_HTM",
	.coord    = &coord_corners,
	.moveset  = moveset_HTM,
};

PruneData
pd_drud_sym16_HTM = {
	.filename = "pt_drud_sym16_HTM",
	.coord    = &coord_drud_sym16,
	.moveset  = moveset_HTM,
};

PruneData
pd_drud_eofb = {
	.filename = "pt_drud_eofb",
	.coord    = &coord_drud_eofb,
	.moveset  = moveset_eofb,
};

PruneData
pd_drudfin_noE_sym16_drud = {
	.filename = "pt_drudfin_noE_sym16_drud",
	.coord    = &coord_drudfin_noE_sym16,
	.moveset  = moveset_drud,
};

PruneData
pd_htr_drud = {
	.filename = "pt_htr_drud",
	.coord    = &coord_htr_drud,
	.moveset  = moveset_drud,
};

PruneData
pd_htrfin_htr = {
	.filename = "pt_htrfin_htr",
	.coord    = &coord_htrfin,
	.moveset  = moveset_htr,
};

PruneData
pd_khuge_HTM = {
	.filename = "pt_khuge_HTM",
	.coord    = &coord_khuge,
	.moveset  = moveset_HTM,
};

void
genptable(PruneData *pd)
{
	Move ms[NMOVES];
	int d;
	uint64_t j, oldn;

	if (pd->generated)
		return;

	/* TODO: check if memory is enough, otherwise maybe exit gracefully? */
	pd->ptable = malloc(ptablesize(pd) * sizeof(uint8_t));

	if (read_ptable_file(pd)) {
		pd->generated = true;
		return;
	}
	pd->generated = true;

	fprintf(stderr, "Cannot load %s, generating it\n", pd->filename); 

	moveset_to_list(pd->moveset, ms);

	/* We use 4 bits per value, so any distance >= 15 is set to 15 */
	for (j = 0; j < pd->coord->max; j++)
		ptable_update_index(pd, j, 15);

	for (j = 0; j < pd->coord->max; j++)
		if (ptableval_index(pd, j) != 15) {
			printf("Error, non-max value at index %lu!\n", j);
			break;
		}
	printf("Table set, ready to start\n");

	ptable_update(pd, (Cube){0}, 0);
	pd->n = 1;
	oldn = 0;
	fprintf(stderr, "Depth %d done, generated %lu\t(%lu/%lu)\n",
		0, pd->n - oldn, pd->n, pd->coord->max);
	oldn = 1;
	for (d = 0; d < 15 && pd->n < pd->coord->max; d++) {
		genptable_bfs(pd, d, ms);
		fprintf(stderr, "Depth %d done, generated %lu\t(%lu/%lu)\n",
			d+1, pd->n - oldn, pd->n, pd->coord->max);
		oldn = pd->n;
	}

	if (!write_ptable_file(pd))
		fprintf(stderr, "Error writing ptable file\n");
}

static void
genptable_bfs(PruneData *pd, int d, Move *ms)
{
	uint64_t i;

	for (i = 0; i < pd->coord->max; i++)
		if (ptableval_index(pd, i) == d)
			genptable_branch(pd, i, d, ms);
}

static void
genptable_branch(PruneData *pd, uint64_t ind, int d, Move *ms)
{
	int i, j;
	Cube ci, cc, c;

	/*
	 * This is the only line of the whole program where we REALLY need an
	 * anti-indexer function. We could get rid of it if only we could save
	 * a cube object for each index value as we go, but then we would need
	 * an incredible amount of memory to generate each ptable: assuming
	 * fields in struct cube are 32 bit ints that would take 88 times the
	 * memory of the table to be generated, more than 120Gb for
	 * ptable_khuge for example!
	 */
	ci = pd->coord->cube(ind);

	for (i = 0; i < pd->coord->ntrans; i++) {
		/* For simplicity trans[] is NULL when ntrans = 1 */
		c = i == 0 ? ci :
			     apply_trans(pd->coord->trans[i], ci);
		for (j = 0; ms[j] != NULLMOVE; j++) {
			cc = apply_move(ms[j], c);
			if (ptableval(pd, cc) > d+1)
				ptable_update(pd, cc, d+1);
		}
	}
}

void
print_ptable(PruneData *pd)
{
	uint64_t i, a[16];
	
	for (i = 0; i < 16; i++)
		a[i] = 0;

	if (!pd->generated)
		genptable(pd);

	for (i = 0; i < pd->coord->max; i++)
		a[ptableval_index(pd, i)]++;
		
	fprintf(stderr, "Values for table %s\n", pd->filename);
	for (i = 0; i < 16; i++)
		printf("%2lu\t%10lu\n", i, a[i]);
}

uint64_t
ptablesize(PruneData *pd)
{
	return (pd->coord->max + 1) / 2;
}

static void
ptable_update(PruneData *pd, Cube cube, int n)
{
	uint64_t ind = pd->coord->index(cube);
	ptable_update_index(pd, ind, n);
}

static void
ptable_update_index(PruneData *pd, uint64_t ind, int n)
{
	uint8_t oldval2 = pd->ptable[ind/2];
	int other = (ind % 2) ? oldval2 % 16 : oldval2 / 16;

	pd->ptable[ind/2] = (ind % 2) ? 16*n + other : 16*other + n;
	pd->n++;
}

int
ptableval(PruneData *pd, Cube cube)
{
	return ptableval_index(pd, pd->coord->index(cube));
}

static int
ptableval_index(PruneData *pd, uint64_t ind)
{
	if (!pd->generated)
		genptable(pd);

	return (ind % 2) ? pd->ptable[ind/2] / 16 : pd->ptable[ind/2] % 16;
}

static bool
read_ptable_file(PruneData *pd)
{
	init_env();

	FILE *f;
	char fname[strlen(tabledir)+100];
	uint64_t r;

	strcpy(fname, tabledir);
	strcat(fname, "/");
	strcat(fname, pd->filename);

	if ((f = fopen(fname, "rb")) == NULL)
		return false;

	r = fread(pd->ptable, sizeof(uint8_t), ptablesize(pd), f);
	fclose(f);

	return r == ptablesize(pd);
}

static bool
write_ptable_file(PruneData *pd)
{
	init_env();

	FILE *f;
	char fname[strlen(tabledir)+100];
	uint64_t written;

	strcpy(fname, tabledir);
	strcat(fname, "/");
	strcat(fname, pd->filename);

	if ((f = fopen(fname, "wb")) == NULL)
		return false;

	written = fwrite(pd->ptable, sizeof(uint8_t), ptablesize(pd), f);
	fclose(f);

	return written == ptablesize(pd);
}