// -*- mode: c; tab-width: 8; indent-tabs-mode: 1; st-rulers: [70] -*-
// vim: ts=8 sw=8 ft=c noet

#include <decaf/sha512.h>

/*
 * Erlang NIF functions
 */

static ERL_NIF_TERM
libdecaf_sha2_512_2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	ErlNifBinary in;
	unsigned long outlen;

	if (argc != 2 || !enif_inspect_binary(env, argv[0], &in)
			|| !enif_get_ulong(env, argv[1], &outlen)
			|| outlen > 64) {
		return enif_make_badarg(env);
	}

	if (in.size <= MAX_PER_SLICE) {
		ERL_NIF_TERM out;
		unsigned char *buf = enif_make_new_binary(env, outlen, &out);

		(void) sha512_hash(buf, outlen, in.data, in.size);

		return out;
	}

	libdecaf_priv_data_t *priv_data = (libdecaf_priv_data_t *)(enif_priv_data(env));
	ErlNifResourceType *resource_type = priv_data->sha2_512_ctx;
	void *resource = enif_alloc_resource(resource_type, sizeof(sha512_ctx_t));
	struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(resource);
	(void) sha512_init(ctx);

	ERL_NIF_TERM newargv[5];

	newargv[0] = argv[0];					/* In */
	newargv[1] = argv[1];					/* Outlen */
	newargv[2] = enif_make_ulong(env, MAX_PER_SLICE);	/* MaxPerSlice */
	newargv[3] = enif_make_ulong(env, 0);			/* Offset */
	newargv[4] = enif_make_resource(env, resource);		/* Context */

	(void) enif_release_resource(resource);

	return enif_schedule_nif(env, "sha2_512", 0, libdecaf_sha2_512_5, 5, newargv);
}

static ERL_NIF_TERM
libdecaf_sha2_512_5(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	ErlNifBinary in;
	unsigned long outlen;
	unsigned long max_per_slice;
	unsigned long offset;
	libdecaf_priv_data_t *priv_data = (libdecaf_priv_data_t *)(enif_priv_data(env));
	ErlNifResourceType *resource_type = priv_data->sha2_512_ctx;
	void *resource;

	if (argc != 5 || !enif_inspect_binary(env, argv[0], &in)
			|| !enif_get_ulong(env, argv[1], &outlen)
			|| !enif_get_ulong(env, argv[2], &max_per_slice)
			|| !enif_get_ulong(env, argv[3], &offset)
			|| !enif_get_resource(env, argv[4], resource_type, &resource)) {
		return enif_make_badarg(env);
	}

	struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(resource);

	struct timeval start;
	struct timeval stop;
	struct timeval slice;
	unsigned long end;
	unsigned long i;
	int percent;
	int total = 0;

	end = offset + max_per_slice;

	if (end > in.size) {
		end = in.size;
	}

	i = offset;

	while (i < in.size) {
		(void) gettimeofday(&start, NULL);
		(void) sha512_update(ctx, (uint8_t *)(in.data) + i, end - i);
		i = end;
		if (i == in.size) {
			break;
		}
		(void) gettimeofday(&stop, NULL);
		/* determine how much of the timeslice was used */
		timersub(&stop, &start, &slice);
		percent = (int)((slice.tv_sec*1000000+slice.tv_usec)/10);
		total += percent;
		if (percent > 100) {
			percent = 100;
		} else if (percent == 0) {
			percent = 1;
		}
		if (enif_consume_timeslice(env, percent)) {
			/* the timeslice has been used up, so adjust our max_per_slice byte count based on the processing we've done, then reschedule to run again */
			max_per_slice = i - offset;
			if (total > 100) {
				int m = (int)(total/100);
				if (m == 1) {
					max_per_slice -= (unsigned long)(max_per_slice*(total-100)/100);
				} else {
					max_per_slice = (unsigned long)(max_per_slice/m);
				}
			}
			ERL_NIF_TERM newargv[5];
			newargv[0] = argv[0];					/* In */
			newargv[1] = argv[1];					/* Outlen */
			newargv[2] = enif_make_ulong(env, max_per_slice);	/* MaxPerSlice */
			newargv[3] = enif_make_ulong(env, i);			/* Offset */
			newargv[4] = argv[4];					/* Context */
			return enif_schedule_nif(env, "sha2_512", 0, libdecaf_sha2_512_5, argc, newargv);
		}
		end += max_per_slice;
		if (end > in.size) {
			end = in.size;
		}
	}

	ERL_NIF_TERM out;
	unsigned char *buf = enif_make_new_binary(env, outlen, &out);

	(void) sha512_final(ctx, buf, outlen);
	(void) sha512_destroy(ctx);

	return out;
}

static ERL_NIF_TERM
libdecaf_sha2_512_init_0(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	if (argc != 0) {
		return enif_make_badarg(env);
	}

	ERL_NIF_TERM out;
	unsigned char *buf = enif_make_new_binary(env, sizeof(sha512_ctx_t), &out);
	struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(buf);

	(void) sha512_init(ctx);

	return enif_make_tuple2(env, ATOM_sha2_512, out);
}

static ERL_NIF_TERM
libdecaf_sha2_512_update_2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	int arity;
	const ERL_NIF_TERM *state;
	ErlNifBinary state_bin;
	ErlNifBinary in;

	if (argc != 2 || !enif_get_tuple(env, argv[0], &arity, &state)
		|| arity != 2
		|| state[0] != ATOM_sha2_512
		|| !enif_inspect_binary(env, state[1], &state_bin)
		|| state_bin.size != sizeof(sha512_ctx_t)
		|| !enif_inspect_binary(env, argv[1], &in)) {
		return enif_make_badarg(env);
	}

	if (in.size <= MAX_PER_SLICE) {
		ERL_NIF_TERM out;
		unsigned char *buf = enif_make_new_binary(env, state_bin.size, &out);
		(void) memcpy(buf, state_bin.data, state_bin.size);
		struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(buf);

		(void) sha512_update(ctx, in.data, in.size);

		return enif_make_tuple2(env, ATOM_sha2_512, out);
	}

	libdecaf_priv_data_t *priv_data = (libdecaf_priv_data_t *)(enif_priv_data(env));
	ErlNifResourceType *resource_type = priv_data->sha2_512_ctx;
	void *resource = enif_alloc_resource(resource_type, state_bin.size);
	(void) memcpy(resource, state_bin.data, state_bin.size);

	ERL_NIF_TERM newargv[4];

	newargv[0] = argv[1];					/* In */
	newargv[1] = enif_make_ulong(env, MAX_PER_SLICE);	/* MaxPerSlice */
	newargv[2] = enif_make_ulong(env, 0);			/* Offset */
	newargv[3] = enif_make_resource(env, resource);		/* Context */

	(void) enif_release_resource(resource);

	return enif_schedule_nif(env, "sha2_512_update", 0, libdecaf_sha2_512_update_4, 4, newargv);
}

static ERL_NIF_TERM
libdecaf_sha2_512_update_4(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	ErlNifBinary in;
	unsigned long max_per_slice;
	unsigned long offset;
	libdecaf_priv_data_t *priv_data = (libdecaf_priv_data_t *)(enif_priv_data(env));
	ErlNifResourceType *resource_type = priv_data->sha2_512_ctx;
	void *resource;

	if (argc != 4 || !enif_inspect_binary(env, argv[0], &in)
			|| !enif_get_ulong(env, argv[1], &max_per_slice)
			|| !enif_get_ulong(env, argv[2], &offset)
			|| !enif_get_resource(env, argv[3], resource_type, &resource)) {
		return enif_make_badarg(env);
	}

	struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(resource);

	struct timeval start;
	struct timeval stop;
	struct timeval slice;
	unsigned long end;
	unsigned long i;
	int percent;
	int total = 0;

	end = offset + max_per_slice;

	if (end > in.size) {
		end = in.size;
	}

	i = offset;

	while (i < in.size) {
		(void) gettimeofday(&start, NULL);
		(void) sha512_update(ctx, (uint8_t *)(in.data) + i, end - i);
		i = end;
		if (i == in.size) {
			break;
		}
		(void) gettimeofday(&stop, NULL);
		/* determine how much of the timeslice was used */
		timersub(&stop, &start, &slice);
		percent = (int)((slice.tv_sec*1000000+slice.tv_usec)/10);
		total += percent;
		if (percent > 100) {
			percent = 100;
		} else if (percent == 0) {
			percent = 1;
		}
		if (enif_consume_timeslice(env, percent)) {
			/* the timeslice has been used up, so adjust our max_per_slice byte count based on the processing we've done, then reschedule to run again */
			max_per_slice = i - offset;
			if (total > 100) {
				int m = (int)(total/100);
				if (m == 1) {
					max_per_slice -= (unsigned long)(max_per_slice*(total-100)/100);
				} else {
					max_per_slice = (unsigned long)(max_per_slice/m);
				}
			}
			ERL_NIF_TERM newargv[4];
			newargv[0] = argv[0];					/* In */
			newargv[1] = enif_make_ulong(env, max_per_slice);	/* MaxPerSlice */
			newargv[2] = enif_make_ulong(env, i);			/* Offset */
			newargv[3] = argv[3];					/* Context */
			return enif_schedule_nif(env, "sha2_512_update", 0, libdecaf_sha2_512_update_4, argc, newargv);
		}
		end += max_per_slice;
		if (end > in.size) {
			end = in.size;
		}
	}

	ERL_NIF_TERM out;
	unsigned char *buf = enif_make_new_binary(env, sizeof(sha512_ctx_t), &out);
	(void) memcpy(buf, resource, sizeof(sha512_ctx_t));

	return enif_make_tuple2(env, ATOM_sha2_512, out);
}

static ERL_NIF_TERM
libdecaf_sha2_512_final_2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
	int arity;
	const ERL_NIF_TERM *state;
	ErlNifBinary state_bin;
	unsigned long outlen;

	if (argc != 2 || !enif_get_tuple(env, argv[0], &arity, &state)
		|| arity != 2
		|| state[0] != ATOM_sha2_512
		|| !enif_inspect_binary(env, state[1], &state_bin)
		|| state_bin.size != sizeof(sha512_ctx_t)
		|| !enif_get_ulong(env, argv[1], &outlen)
		|| outlen > 64) {
		return enif_make_badarg(env);
	}

	libdecaf_priv_data_t *priv_data = (libdecaf_priv_data_t *)(enif_priv_data(env));
	ErlNifResourceType *resource_type = priv_data->sha2_512_ctx;
	void *resource = enif_alloc_resource(resource_type, state_bin.size);
	(void) memcpy(resource, state_bin.data, state_bin.size);
	struct sha512_ctx_s *ctx = (struct sha512_ctx_s *)(resource);
	ERL_NIF_TERM out;
	unsigned char *buf = enif_make_new_binary(env, outlen, &out);

	(void) sha512_final(ctx, buf, outlen);
	(void) sha512_destroy(ctx);
	(void) enif_release_resource(resource);

	return out;
}