/*
 * Copyright 2020, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "EicCbor.h"

void eicCborInit(EicCbor* cbor, uint8_t* buffer, size_t bufferSize) {
  eicMemSet(cbor, '\0', sizeof(EicCbor));
  cbor->size = 0;
  cbor->bufferSize = bufferSize;
  cbor->buffer = buffer;
  cbor->digestType = EIC_CBOR_DIGEST_TYPE_SHA256;
  eicOpsSha256Init(&cbor->digester.sha256);
}

void eicCborInitHmacSha256(EicCbor* cbor, uint8_t* buffer, size_t bufferSize,
                           const uint8_t* hmacKey, size_t hmacKeySize) {
  eicMemSet(cbor, '\0', sizeof(EicCbor));
  cbor->size = 0;
  cbor->bufferSize = bufferSize;
  cbor->buffer = buffer;
  cbor->digestType = EIC_CBOR_DIGEST_TYPE_HMAC_SHA256;
  eicOpsHmacSha256Init(&cbor->digester.hmacSha256, hmacKey, hmacKeySize);
}

void eicCborEnableSecondaryDigesterSha256(EicCbor* cbor, EicSha256Ctx* sha256) {
  cbor->secondaryDigesterSha256 = sha256;
}

void eicCborFinal(EicCbor* cbor, uint8_t digest[EIC_SHA256_DIGEST_SIZE]) {
  switch (cbor->digestType) {
    case EIC_CBOR_DIGEST_TYPE_SHA256:
      eicOpsSha256Final(&cbor->digester.sha256, digest);
      break;
    case EIC_CBOR_DIGEST_TYPE_HMAC_SHA256:
      eicOpsHmacSha256Final(&cbor->digester.hmacSha256, digest);
      break;
  }
}

void eicCborAppend(EicCbor* cbor, const uint8_t* data, size_t size) {
  switch (cbor->digestType) {
    case EIC_CBOR_DIGEST_TYPE_SHA256:
      eicOpsSha256Update(&cbor->digester.sha256, data, size);
      break;
    case EIC_CBOR_DIGEST_TYPE_HMAC_SHA256:
      eicOpsHmacSha256Update(&cbor->digester.hmacSha256, data, size);
      break;
  }
  if (cbor->secondaryDigesterSha256 != NULL) {
    eicOpsSha256Update(cbor->secondaryDigesterSha256, data, size);
  }

  if (cbor->size >= cbor->bufferSize) {
    cbor->size += size;
    return;
  }

  size_t numBytesLeft = cbor->bufferSize - cbor->size;
  size_t numBytesToCopy = size;
  if (numBytesToCopy > numBytesLeft) {
    numBytesToCopy = numBytesLeft;
  }
  eicMemCpy(cbor->buffer + cbor->size, data, numBytesToCopy);

  cbor->size += size;
}

size_t eicCborAdditionalLengthBytesFor(size_t size) {
  if (size < 24) {
    return 0;
  } else if (size <= 0xff) {
    return 1;
  } else if (size <= 0xffff) {
    return 2;
  } else if (size <= 0xffffffff) {
    return 4;
  }
  return 8;
}

void eicCborBegin(EicCbor* cbor, int majorType, uint64_t size) {
  uint8_t data[9];

  if (size < 24) {
    data[0] = (majorType << 5) | size;
    eicCborAppend(cbor, data, 1);
  } else if (size <= 0xff) {
    data[0] = (majorType << 5) | 24;
    data[1] = size;
    eicCborAppend(cbor, data, 2);
  } else if (size <= 0xffff) {
    data[0] = (majorType << 5) | 25;
    data[1] = size >> 8;
    data[2] = size & 0xff;
    eicCborAppend(cbor, data, 3);
  } else if (size <= 0xffffffff) {
    data[0] = (majorType << 5) | 26;
    data[1] = (size >> 24) & 0xff;
    data[2] = (size >> 16) & 0xff;
    data[3] = (size >> 8) & 0xff;
    data[4] = size & 0xff;
    eicCborAppend(cbor, data, 5);
  } else {
    data[0] = (majorType << 5) | 27;
    data[1] = (((uint64_t)size) >> 56) & 0xff;
    data[2] = (((uint64_t)size) >> 48) & 0xff;
    data[3] = (((uint64_t)size) >> 40) & 0xff;
    data[4] = (((uint64_t)size) >> 32) & 0xff;
    data[5] = (((uint64_t)size) >> 24) & 0xff;
    data[6] = (((uint64_t)size) >> 16) & 0xff;
    data[7] = (((uint64_t)size) >> 8) & 0xff;
    data[8] = ((uint64_t)size) & 0xff;
    eicCborAppend(cbor, data, 9);
  }
}

void eicCborAppendByteString(EicCbor* cbor, const uint8_t* data,
                             size_t dataSize) {
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, dataSize);
  eicCborAppend(cbor, data, dataSize);
}

void eicCborAppendString(EicCbor* cbor, const char* str, size_t strLength) {
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_STRING, strLength);
  eicCborAppend(cbor, (const uint8_t*)str, strLength);
}

void eicCborAppendStringZ(EicCbor* cbor, const char* str) {
  eicCborAppendString(cbor, str, eicStrLen(str));
}

void eicCborAppendSimple(EicCbor* cbor, uint8_t simpleValue) {
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_SIMPLE, simpleValue);
}

void eicCborAppendBool(EicCbor* cbor, bool value) {
  uint8_t simpleValue =
      value ? EIC_CBOR_SIMPLE_VALUE_TRUE : EIC_CBOR_SIMPLE_VALUE_FALSE;
  eicCborAppendSimple(cbor, simpleValue);
}

void eicCborAppendSemantic(EicCbor* cbor, uint64_t value) {
  size_t encoded = value;
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_SEMANTIC, encoded);
}

void eicCborAppendUnsigned(EicCbor* cbor, uint64_t value) {
  uint64_t encoded = value;
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_UNSIGNED, encoded);
}

void eicCborAppendNumber(EicCbor* cbor, int64_t value) {
  if (value < 0) {
    uint64_t encoded = -1 - value;
    eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_NEGATIVE, encoded);
  } else {
    eicCborAppendUnsigned(cbor, value);
  }
}

void eicCborAppendArray(EicCbor* cbor, size_t numElements) {
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_ARRAY, numElements);
}

void eicCborAppendMap(EicCbor* cbor, size_t numPairs) {
  eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_MAP, numPairs);
}

bool eicCborCalcAccessControl(EicCbor* cborBuilder, int id,
                              const uint8_t* readerCertificate,
                              size_t readerCertificateSize,
                              bool userAuthenticationRequired,
                              uint64_t timeoutMillis, uint64_t secureUserId) {
  size_t numPairs = 1;
  if (readerCertificateSize > 0) {
    numPairs += 1;
  }
  if (userAuthenticationRequired) {
    numPairs += 2;
    if (secureUserId > 0) {
      numPairs += 1;
    }
  }
  eicCborAppendMap(cborBuilder, numPairs);
  eicCborAppendStringZ(cborBuilder, "id");
  eicCborAppendUnsigned(cborBuilder, id);
  if (readerCertificateSize > 0) {
    eicCborAppendStringZ(cborBuilder, "readerCertificate");
    eicCborAppendByteString(cborBuilder, readerCertificate,
                            readerCertificateSize);
  }
  if (userAuthenticationRequired) {
    eicCborAppendStringZ(cborBuilder, "userAuthenticationRequired");
    eicCborAppendBool(cborBuilder, userAuthenticationRequired);
    eicCborAppendStringZ(cborBuilder, "timeoutMillis");
    eicCborAppendUnsigned(cborBuilder, timeoutMillis);
    if (secureUserId > 0) {
      eicCborAppendStringZ(cborBuilder, "secureUserId");
      eicCborAppendUnsigned(cborBuilder, secureUserId);
    }
  }

  if (cborBuilder->size > cborBuilder->bufferSize) {
    eicDebug("Buffer for ACP CBOR is too small (%zd) - need %zd bytes",
             cborBuilder->bufferSize, cborBuilder->size);
    return false;
  }

  return true;
}

bool eicCborCalcEntryAdditionalData(
    const uint8_t* accessControlProfileIds, size_t numAccessControlProfileIds,
    const char* nameSpace, size_t nameSpaceLength, const char* name,
    size_t nameLength, uint8_t* cborBuffer, size_t cborBufferSize,
    size_t* outAdditionalDataCborSize,
    uint8_t additionalDataSha256[EIC_SHA256_DIGEST_SIZE]) {
  EicCbor cborBuilder;

  eicCborInit(&cborBuilder, cborBuffer, cborBufferSize);
  eicCborAppendMap(&cborBuilder, 3);
  eicCborAppendStringZ(&cborBuilder, "Namespace");
  eicCborAppendString(&cborBuilder, nameSpace, nameSpaceLength);
  eicCborAppendStringZ(&cborBuilder, "Name");
  eicCborAppendString(&cborBuilder, name, nameLength);
  eicCborAppendStringZ(&cborBuilder, "AccessControlProfileIds");
  eicCborAppendArray(&cborBuilder, numAccessControlProfileIds);
  for (size_t n = 0; n < numAccessControlProfileIds; n++) {
    eicCborAppendNumber(&cborBuilder, accessControlProfileIds[n]);
  }
  if (cborBuilder.size > cborBufferSize) {
    eicDebug(
        "Not enough space for additionalData - buffer is only %zd bytes, "
        "content is %zd",
        cborBufferSize, cborBuilder.size);
    return false;
  }
  if (outAdditionalDataCborSize != NULL) {
    *outAdditionalDataCborSize = cborBuilder.size;
  }
  eicCborFinal(&cborBuilder, additionalDataSha256);
  return true;
}