/**
 * Copyright (C) 2013 Regents of the University of California.
 * @author: Jeff Thompson <jefft0@remap.ucla.edu>
 * Derived from ContentObject.js by Meki Cheraoui.
 * See COPYING for copyright and distribution information.
 */

#include "binary-xml-encoder.h"
#include "binary-xml-decoder.h"
#include "binary-xml-name.h"
#include "binary-xml-publisher-public-key-digest.h"
#include "binary-xml-data.h"

static ndn_Error encodeSignature(struct ndn_Signature *signature, struct ndn_BinaryXmlEncoder *encoder)
{
  ndn_Error error;
  if ((error = ndn_BinaryXmlEncoder_writeElementStartDTag(encoder, ndn_BinaryXml_DTag_Signature)))
    return error;
  
  // TODO: Check if digestAlgorithm is the same as the default, and skip it, otherwise encode it as UDATA.

  if ((error = ndn_BinaryXmlEncoder_writeOptionalBlobDTagElement(encoder, ndn_BinaryXml_DTag_Witness, &signature->witness)))
    return error;

  // Require a signature.
  if ((error = ndn_BinaryXmlEncoder_writeBlobDTagElement(encoder, ndn_BinaryXml_DTag_SignatureBits, &signature->signature)))
    return error;
  
  if ((error = ndn_BinaryXmlEncoder_writeElementClose(encoder)))
    return error;
  
  return NDN_ERROR_success;    
}

static ndn_Error decodeSignature(struct ndn_Signature *signature, struct ndn_BinaryXmlDecoder *decoder)
{
  ndn_Error error;
  if ((error = ndn_BinaryXmlDecoder_readElementStartDTag(decoder, ndn_BinaryXml_DTag_Signature)))
    return error;
  
  /* TODO: digestAlgorithm as UDATA */ signature->digestAlgorithm.value = 0; signature->digestAlgorithm.length = 0;
  
  if ((error = ndn_BinaryXmlDecoder_readOptionalBinaryDTagElement
      (decoder, ndn_BinaryXml_DTag_Witness, 0, &signature->witness)))
    return error;
  
  // Require a signature.
  if ((error = ndn_BinaryXmlDecoder_readBinaryDTagElement
      (decoder, ndn_BinaryXml_DTag_SignatureBits, 0, &signature->signature)))
    return error;
  
  if ((error = ndn_BinaryXmlDecoder_readElementClose(decoder)))
    return error;
  
  return NDN_ERROR_success;
}

static ndn_Error encodeSignedInfo(struct ndn_Signature *signature, struct ndn_MetaInfo *metaInfo, struct ndn_BinaryXmlEncoder *encoder)
{
  if (metaInfo->type < 0)
    return NDN_ERROR_success;

  ndn_Error error;
  if ((error = ndn_BinaryXmlEncoder_writeElementStartDTag(encoder, ndn_BinaryXml_DTag_SignedInfo)))
    return error;

  // This will skip encoding if there is no publisherPublicKeyDigest.
  if ((error = ndn_encodeBinaryXmlPublisherPublicKeyDigest(&signature->publisherPublicKeyDigest, encoder)))
    return error;
  
  if ((error = ndn_BinaryXmlEncoder_writeOptionalTimeMillisecondsDTagElement
      (encoder, ndn_BinaryXml_DTag_Timestamp, metaInfo->timestampMilliseconds)))
    return error;
  
  if (!(metaInfo->type < 0 || metaInfo->type == ndn_ContentType_DATA)) {
    // Not the default of DATA, so we need to encode the type.
    struct ndn_Blob typeBytes;
    typeBytes.length = 3;
    if (metaInfo->type == ndn_ContentType_ENCR)
      typeBytes.value = "\x10\xD0\x91";
    else if (metaInfo->type == ndn_ContentType_GONE)
      typeBytes.value = "\x18\xE3\x44";
    else if (metaInfo->type == ndn_ContentType_KEY)
      typeBytes.value = "\x28\x46\x3F";
    else if (metaInfo->type == ndn_ContentType_LINK)
      typeBytes.value = "\x2C\x83\x4A";
    else if (metaInfo->type == ndn_ContentType_NACK)
      typeBytes.value = "\x34\x00\x8A";
    else
      return NDN_ERROR_unrecognized_ndn_ContentType;

    if ((error = ndn_BinaryXmlEncoder_writeBlobDTagElement(encoder, ndn_BinaryXml_DTag_Type, &typeBytes)))
      return error;
  }
  
  if ((error = ndn_BinaryXmlEncoder_writeOptionalUnsignedDecimalIntDTagElement
      (encoder, ndn_BinaryXml_DTag_FreshnessSeconds, metaInfo->freshnessSeconds)))
    return error;
  
  if ((error = ndn_BinaryXmlEncoder_writeOptionalBlobDTagElement
      (encoder, ndn_BinaryXml_DTag_FinalBlockID, &metaInfo->finalBlockID.value)))
    return error;
 
  // This will skip encoding if there is no key locator.
  if ((error = ndn_encodeBinaryXmlKeyLocator(&signature->keyLocator, encoder)))
    return error;
  
  if ((error = ndn_BinaryXmlEncoder_writeElementClose(encoder)))
    return error;
  
  return NDN_ERROR_success;  
}

static ndn_Error decodeSignedInfo(struct ndn_Signature *signature, struct ndn_MetaInfo *metaInfo, struct ndn_BinaryXmlDecoder *decoder)
{
  ndn_Error error;
  if ((error = ndn_BinaryXmlDecoder_readElementStartDTag(decoder, ndn_BinaryXml_DTag_SignedInfo)))
    return error;
  
  if ((error = ndn_decodeOptionalBinaryXmlPublisherPublicKeyDigest(&signature->publisherPublicKeyDigest, decoder)))
    return error;
  
  if (error= ndn_BinaryXmlDecoder_readOptionalTimeMillisecondsDTagElement
      (decoder, ndn_BinaryXml_DTag_Timestamp, &metaInfo->timestampMilliseconds))
    return error;
  
  struct ndn_Blob typeBytes;
  if ((error = ndn_BinaryXmlDecoder_readOptionalBinaryDTagElement
      (decoder, ndn_BinaryXml_DTag_Type, 0, &typeBytes)))
    return error;
  if (typeBytes.length == 0)
    // The default Type is DATA.
    metaInfo->type = ndn_ContentType_DATA;
  else if (typeBytes.length == 3) {
    // All the recognized content types are 3 bytes.
    if (ndn_memcmp(typeBytes.value, "\x0C\x04\xC0", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_DATA;
    else if (ndn_memcmp(typeBytes.value, "\x10\xD0\x91", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_ENCR;
    else if (ndn_memcmp(typeBytes.value, "\x18\xE3\x44", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_GONE;
    else if (ndn_memcmp(typeBytes.value, "\x28\x46\x3F", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_KEY;
    else if (ndn_memcmp(typeBytes.value, "\x2C\x83\x4A", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_LINK;
    else if (ndn_memcmp(typeBytes.value, "\x34\x00\x8A", typeBytes.length) == 0)
      metaInfo->type = ndn_ContentType_NACK;
    else
      return NDN_ERROR_unrecognized_ndn_ContentType;
  }
  else
    return NDN_ERROR_unrecognized_ndn_ContentType;
 
  if ((error = ndn_BinaryXmlDecoder_readOptionalUnsignedIntegerDTagElement
      (decoder, ndn_BinaryXml_DTag_FreshnessSeconds, &metaInfo->freshnessSeconds)))
    return error;

  if ((error = ndn_BinaryXmlDecoder_readOptionalBinaryDTagElement
      (decoder, ndn_BinaryXml_DTag_FinalBlockID, 0, &metaInfo->finalBlockID.value)))
    return error;

  if ((error = ndn_decodeOptionalBinaryXmlKeyLocator(&signature->keyLocator, decoder)))
    return error;
  
  if ((error = ndn_BinaryXmlDecoder_readElementClose(decoder)))
    return error;
  
  return NDN_ERROR_success;
}

ndn_Error ndn_encodeBinaryXmlData
  (struct ndn_Data *data, size_t *signedPortionBeginOffset, size_t *signedPortionEndOffset, struct ndn_BinaryXmlEncoder *encoder)
{
  ndn_Error error;
  if ((error = ndn_BinaryXmlEncoder_writeElementStartDTag(encoder, ndn_BinaryXml_DTag_ContentObject)))
    return error;
  
  if ((error = encodeSignature(&data->signature, encoder)))
    return error;
  
  *signedPortionBeginOffset = encoder->offset;

  if ((error = ndn_encodeBinaryXmlName(&data->name, encoder)))
    return error;
  
  if ((error = encodeSignedInfo(&data->signature, &data->metaInfo, encoder)))
    return error;

  if ((error = ndn_BinaryXmlEncoder_writeBlobDTagElement(encoder, ndn_BinaryXml_DTag_Content, &data->content)))
    return error;

  *signedPortionEndOffset = encoder->offset;

  if ((error = ndn_BinaryXmlEncoder_writeElementClose(encoder)))
    return error;
  
  return NDN_ERROR_success;
}

ndn_Error ndn_decodeBinaryXmlData
  (struct ndn_Data *data, size_t *signedPortionBeginOffset, size_t *signedPortionEndOffset, struct ndn_BinaryXmlDecoder *decoder)
{
  ndn_Error error;
  if ((error = ndn_BinaryXmlDecoder_readElementStartDTag(decoder, ndn_BinaryXml_DTag_ContentObject)))
    return error;

  int gotExpectedTag;
  if ((error = ndn_BinaryXmlDecoder_peekDTag(decoder, ndn_BinaryXml_DTag_Signature, &gotExpectedTag)))
    return error;
  if (gotExpectedTag) {
    if ((error = decodeSignature(&data->signature, decoder)))
      return error;
  }
  else
    ndn_Signature_initialize(&data->signature, data->signature.keyLocator.keyName.components, data->signature.keyLocator.keyName.maxComponents);
  
  *signedPortionBeginOffset = decoder->offset;
  
  if ((error = ndn_decodeBinaryXmlName(&data->name, decoder)))
    return error;
  
  if ((error = ndn_BinaryXmlDecoder_peekDTag(decoder, ndn_BinaryXml_DTag_SignedInfo, &gotExpectedTag)))
    return error;
  if (gotExpectedTag) {
    if ((error = decodeSignedInfo(&data->signature, &data->metaInfo, decoder)))
      return error;
  }
  else
    ndn_MetaInfo_initialize(&data->metaInfo);

  // Require a Content element, but set allowNull to allow a missing BLOB.
  if ((error = ndn_BinaryXmlDecoder_readBinaryDTagElement(decoder, ndn_BinaryXml_DTag_Content, 1, &data->content)))
    return error; 
  
  *signedPortionEndOffset = decoder->offset;

  if ((error = ndn_BinaryXmlDecoder_readElementClose(decoder)))
    return error;
  
  return NDN_ERROR_success;
}