#include <bearssl.h>
#include <sodium.h>

#include "apk_crypto.h"

// Union tag is in apk_digest_ctx->alg
union digest_state {
	crypto_hash_sha256_state sha256;
	crypto_hash_sha512_state sha512;
	br_sha1_context sha1;
	br_md5_context md5;
};

static const char *apk_digest_str[] = {
    [APK_DIGEST_NONE]       = "none",
    [APK_DIGEST_MD5]        = "md5",
    [APK_DIGEST_SHA1]       = "sha1",
    [APK_DIGEST_SHA256_160] = "sha256-160",
    [APK_DIGEST_SHA256]     = "sha256",
    [APK_DIGEST_SHA512]     = "sha512",
};

const char *apk_digest_alg_str(uint8_t alg)
{
	const char *alg_str = "unknown";
	if (alg < ARRAY_SIZE(apk_digest_str))
		alg_str = apk_digest_str[alg];
	return alg_str;
}

int apk_digest_alg_len(uint8_t alg)
{
	switch (alg) {
	case APK_DIGEST_MD5:
		return 16;
	case APK_DIGEST_SHA1:
		return 20;
	case APK_DIGEST_SHA256_160:
		return 20;
	case APK_DIGEST_SHA256:
		return 32;
	case APK_DIGEST_SHA512:
		return 64;
	default:
		return 0;
	}
}

uint8_t apk_digest_alg_by_len(int len)
{
	switch (len) {
	case 0:
		return APK_DIGEST_NONE;
	case 16:
		return APK_DIGEST_MD5;
	case 20:
		return APK_DIGEST_SHA1;
	case 32:
		return APK_DIGEST_SHA256;
	case 64:
		return APK_DIGEST_SHA512;
	default:
		return APK_DIGEST_NONE;
	}
}

uint8_t apk_digest_alg_from_csum(int csum)
{
	switch (csum) {
	case APK_CHECKSUM_NONE:
		return APK_DIGEST_NONE;
	case APK_CHECKSUM_MD5:
		return APK_DIGEST_MD5;
	case APK_CHECKSUM_SHA1:
		return APK_DIGEST_SHA1;
	default:
		return APK_DIGEST_NONE;
	}
}

uint8_t apk_digest_from_blob(struct apk_digest *d, apk_blob_t b)
{
	d->alg = apk_digest_alg_by_len(b.len);
	d->len = 0;

	if (d->alg != APK_DIGEST_NONE) {
		d->len = b.len;
		memcpy(d->data, b.ptr, d->len);
	}

	return d->alg;
}

int apk_digest_calc(struct apk_digest *d, uint8_t alg, const void *ptr, size_t sz)
{
	union digest_state state;

	switch (alg) {
	case APK_DIGEST_SHA256:
	case APK_DIGEST_SHA256_160:
		crypto_hash_sha256(d->data, ptr, sz);
		break;
	case APK_DIGEST_SHA512:
		crypto_hash_sha512(d->data, ptr, sz);
		break;
	case APK_DIGEST_NONE:
		break;
	case APK_DIGEST_MD5:
		br_md5_init(&state.md5);
		br_md5_update(&state.md5, ptr, sz);
		br_md5_out(&state.md5, d->data);
		break;
	case APK_DIGEST_SHA1:
		br_sha1_init(&state.sha1);
		br_sha1_update(&state.sha1, ptr, sz);
		br_sha1_out(&state.sha1, d->data);
		break;
	default:
		return -APKE_CRYPTO_NOT_SUPPORTED;
	}

	d->alg = alg;
	d->len = apk_digest_alg_len(d->alg);

	return 0;
}

int apk_digest_ctx_init(struct apk_digest_ctx *dctx, uint8_t alg)
{
	union digest_state *state;

	dctx->impl = malloc(sizeof(union digest_state));
	if (dctx->impl == NULL) {
		return -ENOMEM;
	}

	state = (union digest_state *) dctx->impl;

	dctx->alg = alg;
	switch (alg) {
	case APK_DIGEST_SHA256:
	case APK_DIGEST_SHA256_160:
		crypto_hash_sha256_init(&state->sha256);
		break;
	case APK_DIGEST_SHA512:
		crypto_hash_sha512_init(&state->sha512);
		break;
	case APK_DIGEST_MD5:
		br_md5_init(&state->md5);
		break;
	case APK_DIGEST_SHA1:
		br_sha1_init(&state->sha1);
		break;
	case APK_DIGEST_NONE:
		break;
	default:
		free(dctx->impl);
		return -APKE_CRYPTO_NOT_SUPPORTED;
	}

	return 0;
}

int apk_digest_ctx_reset(struct apk_digest_ctx *dctx, uint8_t alg)
{
	apk_digest_ctx_free(dctx);
	return apk_digest_ctx_init(dctx, alg);
}

void apk_digest_ctx_free(struct apk_digest_ctx *dctx)
{
	if (dctx->impl == NULL) {
		return;
	}

	switch (dctx->alg) {
	case APK_DIGEST_NONE:
	case APK_DIGEST_MD5:
	case APK_DIGEST_SHA1:
	case APK_DIGEST_SHA256:
	case APK_DIGEST_SHA512:
	case APK_DIGEST_SHA256_160:
		free(dctx->impl);
		dctx->impl = NULL;
		break;
	default:
		/* illegal state, don't touch impl? */
		return;
	}
}

int apk_digest_ctx_update(struct apk_digest_ctx *dctx, const void *ptr, size_t sz)
{
	union digest_state *state = (union digest_state *) dctx->impl;

	switch (dctx->alg) {
	case APK_DIGEST_SHA256:
	case APK_DIGEST_SHA256_160:
		crypto_hash_sha256_update(&state->sha256, ptr, sz);
		break;
	case APK_DIGEST_SHA512:
		crypto_hash_sha512_update(&state->sha512, ptr, sz);
		break;
	case APK_DIGEST_MD5:
		br_md5_update(&state->md5, ptr, sz);
		break;
	case APK_DIGEST_SHA1:
		br_sha1_update(&state->sha1, ptr, sz);
		break;
	case APK_DIGEST_NONE:
		break;
	default:
		return -APKE_CRYPTO_NOT_SUPPORTED;
	}

	return 0;
}

int apk_digest_ctx_final(struct apk_digest_ctx *dctx, struct apk_digest *d)
{
	union digest_state *state = (union digest_state *) dctx->impl;

	switch (dctx->alg) {
	case APK_DIGEST_SHA256:
	case APK_DIGEST_SHA256_160:
		crypto_hash_sha256_final(&state->sha256, d->data);
		break;
	case APK_DIGEST_SHA512:
		crypto_hash_sha512_final(&state->sha512, d->data);
		break;
	case APK_DIGEST_MD5:
		br_md5_out(&state->md5, d->data);
		break;
	case APK_DIGEST_SHA1:
		br_sha1_out(&state->sha1, d->data);
		break;
	case APK_DIGEST_NONE:
		break;
	default:
		return -APKE_CRYPTO_NOT_SUPPORTED;
	}

	d->alg = dctx->alg;
	d->len = apk_digest_alg_len(d->alg);

	return 0;
}