#include <string.h>
#include <stdlib.h>

#include "libp2p/crypto/rsa.h"
#include "libp2p/crypto/sha256.h"
#include "libp2p/record/record.h"
#include "protobuf.h"
#include "mh/hashes.h"
#include "mh/multihash.h"


/**
 * Create a record with default settings
 * @returns the newly allocated record struct
 */
struct Libp2pRecord* libp2p_record_new() {
	struct Libp2pRecord* out = (struct Libp2pRecord*)malloc(sizeof(struct Libp2pRecord));
	if (out != NULL) {
		out->author = NULL;
		out->author_size = 0;
		out->key = NULL;
		out->key_size = 0;
		out->signature = NULL;
		out->signature_size = 0;
		out->time_received = NULL;
		out->time_received_size = 0;
		out->value = NULL;
		out->value_size = 0;
	}
	return out;
}

/**
 * Free the resources from a record struct
 * @param in the struct to free
 */
void libp2p_record_free(struct Libp2pRecord* in) {
	if (in != NULL) {
		if (in->author != NULL)
			free(in->author);
		if (in->key != NULL)
			free(in->key);
		if (in->signature != NULL)
			free(in->signature);
		if (in->time_received != NULL)
			free(in->time_received);
		if (in->value != NULL)
			free(in->value);
		free(in);
	}
}

/**
 * Protobuf a record, allocating memory
 * @param in the record to protobuf
 * @param buffer where to put the results
 * @param buffer_size the size of the results
 * @returns true(1) on success, false(0) otherwise
 */
int libp2p_record_protobuf_allocate_and_encode(const struct Libp2pRecord* in, unsigned char** buffer, size_t* buffer_size) {
	*buffer_size = libp2p_record_protobuf_encode_size(in);
	*buffer = malloc(*buffer_size);
	if (*buffer == NULL) {
		*buffer_size = 0;
		return 0;
	}
	int retVal = libp2p_record_protobuf_encode(in, *buffer, *buffer_size, buffer_size);
	if (retVal == 0) {
		free(*buffer);
		*buffer = NULL;
		*buffer_size = 0;
	}
	return retVal;
}

/**
 * Convert a Libp2pRecord into protobuf format
 * @param in the Libp2pRecord to convert
 * @param buffer where to store the protobuf
 * @param max_buffer_size the size of the allocated buffer
 * @param bytes_written the size written into buffer
 * @returns true(1) on success, otherwise false(0)
 */
int libp2p_record_protobuf_encode(const struct Libp2pRecord* in, unsigned char* buffer, size_t max_buffer_size, size_t* bytes_written) {
	// data & data_size
	size_t bytes_used = 0;
	*bytes_written = 0;
	int retVal = 0;
	// field 1
	retVal = protobuf_encode_length_delimited(1, WIRETYPE_LENGTH_DELIMITED, in->key, in->key_size, &buffer[*bytes_written], max_buffer_size - *bytes_written, &bytes_used);
	if (retVal == 0)
		return 0;
	*bytes_written += bytes_used;
	// field 2
	retVal = protobuf_encode_length_delimited(2, WIRETYPE_LENGTH_DELIMITED, (char*)in->value, in->value_size, &buffer[*bytes_written], max_buffer_size - *bytes_written, &bytes_used);
	if (retVal == 0)
		return 0;
	*bytes_written += bytes_used;
	// field 3
	retVal = protobuf_encode_length_delimited(3, WIRETYPE_LENGTH_DELIMITED, in->author, in->author_size, &buffer[*bytes_written], max_buffer_size - *bytes_written, &bytes_used);
	if (retVal == 0)
		return 0;
	*bytes_written += bytes_used;
	// field 4
	retVal = protobuf_encode_length_delimited(4, WIRETYPE_LENGTH_DELIMITED, (char*)in->signature, in->signature_size, &buffer[*bytes_written], max_buffer_size - *bytes_written, &bytes_used);
	if (retVal == 0)
		return 0;
	*bytes_written += bytes_used;
	// field 5
	retVal = protobuf_encode_length_delimited(5, WIRETYPE_LENGTH_DELIMITED, in->time_received, in->time_received_size, &buffer[*bytes_written], max_buffer_size - *bytes_written, &bytes_used);
	if (retVal == 0)
		return 0;
	*bytes_written += bytes_used;
	return 1;
}

/**
 * Generates an estimate of the buffer size needed to encode the struct
 * @param in the Libp2pRecord that you want to encode
 * @returns the approximate number of bytes required
 */
size_t libp2p_record_protobuf_encode_size(const struct Libp2pRecord* in) {
	size_t retVal = 0;
	if (in != NULL) {
		retVal = 11 + in->key_size;
		retVal += 11 + in->value_size;
		retVal += 11 + in->author_size;
		retVal += 11 + in->signature_size;
		retVal += 11 + in->time_received_size;
	}
	return retVal;
}

/**
 * Convert a protobuf byte array into a Libp2pRecord
 * @param in the byte array
 * @param in_size the size of the byte array
 * @param out a pointer to the new Libp2pRecord
 * @returns true(1) on success, otherwise false(0)
 */
int libp2p_record_protobuf_decode(const unsigned char* in, size_t in_size, struct Libp2pRecord** out) {
	size_t pos = 0;
	int retVal = 0;

	if ( (*out = libp2p_record_new()) == NULL)
		goto exit;

	while(pos < in_size) {
		size_t bytes_read = 0;
		int field_no;
		enum WireType field_type;
		if (!protobuf_decode_field_and_type(&in[pos], in_size, &field_no, &field_type, &bytes_read)) {
			goto exit;
		}
		pos += bytes_read;
		switch(field_no) {
			case (1): // key
				if (!protobuf_decode_string(&in[pos], in_size - pos, (char**)&((*out)->key), &bytes_read))
					goto exit;
				(*out)->key_size = strlen((*out)->key);
				pos += bytes_read;
				break;
			case (2): // value
				if (!protobuf_decode_length_delimited(&in[pos], in_size - pos, (char**)&((*out)->value), &((*out)->value_size), &bytes_read))
					goto exit;
				pos += bytes_read;
				break;
			case (3): // author
				if (!protobuf_decode_length_delimited(&in[pos], in_size - pos, (char**)&((*out)->author), &((*out)->author_size), &bytes_read))
					goto exit;
				pos += bytes_read;
				break;
			case (4): // signature
				if (!protobuf_decode_length_delimited(&in[pos], in_size - pos, (char**)&((*out)->signature), &((*out)->signature_size), &bytes_read))
					goto exit;
				pos += bytes_read;
				break;
			case (5): // time
				if (!protobuf_decode_length_delimited(&in[pos], in_size - pos, (char**)&((*out)->time_received), &((*out)->time_received_size), &bytes_read))
					goto exit;
				pos += bytes_read;
				break;
		}
	}

	retVal = 1;

exit:
	if (retVal == 0) {
		free(*out);
		*out = NULL;
	}
	return retVal;
}



/**
 * This method does all the hard stuff in one step. It fills a Libp2pRecord struct, and converts it into a protobuf
 * @param record a pointer to the protobuf results
 * @param rec_size the number of bytes used in the area pointed to by record
 * @param sk the private key used to sign
 * @param key the key in the Libp2pRecord
 * @param value the value in the Libp2pRecord
 * @param vlen the length of value
 * @param sign true(1) if you want to sign the data
 * @returns 0 on success, otherwise -1
 */
int libp2p_record_make_put_record (char** record_buf, size_t *rec_size, const struct RsaPrivateKey* sk, const char* key, const char* value, size_t vlen, int sign)
{
	int retVal = -1;
	size_t bytes_size = 0;
	unsigned char* bytes = NULL;
	unsigned char* sign_buf = NULL;
	unsigned char hash[32];

    // build the struct
    struct Libp2pRecord record;
    record.key = (char*)key;
    record.key_size = strlen(key);
    record.value = (unsigned char*)value;
    record.value_size = vlen;

    // clear the rest of the fields
    record.signature = NULL;
    record.signature_size = 0;
    //TODO: what should we put in the time field?
    record.time_received = NULL;
    record.time_received_size = 0;

    // build a hash of the author's public key
    libp2p_crypto_hashing_sha256((unsigned char*)sk->public_key_der, sk->public_key_length, &hash[0]);
    record.author = (char*)&hash[0];
    record.author_size = 32;

	bytes_size = record.key_size + record.value_size + record.author_size;
	bytes = malloc(bytes_size);
	if (bytes == NULL)
		goto exit;

    // build the signature
    if (sign) {
    	memcpy(&bytes[0], record.key, record.key_size);
    	memcpy(&bytes[record.key_size], record.value, record.value_size);
    	memcpy(&bytes[record.key_size + record.value_size], record.author, record.author_size);
        size_t sign_length = 0;
        if (!libp2p_crypto_rsa_sign ((struct RsaPrivateKey*)sk, (char*)bytes, bytes_size, &sign_buf, &sign_length))
        	goto exit;
        record.signature = sign_buf;
        record.signature_size = sign_length;
    }

    // now protobuf the struct
    size_t protobuf_size = libp2p_record_protobuf_encode_size(&record);
    *record_buf = malloc(protobuf_size);
    if (*record_buf == NULL)
    	goto exit;

    if (!libp2p_record_protobuf_encode(&record, (unsigned char*)*record_buf, protobuf_size, &protobuf_size))
    	goto exit;

    *rec_size = protobuf_size;

    // we're done here. Cleanup time.
    retVal = 0;

    exit:

	if (bytes != NULL)
		free(bytes);
	if (sign_buf != NULL)
		free(sign_buf);
	if (retVal == -1) {
		free(*record_buf);
		*record_buf = NULL;
	}

    return retVal;
}