/*
 * Mini Object Storage, (C) 2014 Minio, Inc.
 *
 * 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.
 */

package sha1

// #include <stdio.h>
// #include <stdint.h>
// void sha1_transform(int32_t *hash, const char* input, size_t num_blocks);
import "C"
import (
	gosha1 "crypto/sha1"
	"io"
)

/*
const (
	SHA1_BLOCKSIZE  = 64
	SHA1_DIGESTSIZE = 20
)


func Sha1(buffer []byte) ([]int32, error) {
	if cpu.HasAVX2() {
		var shbuf []int32
		var cbuffer *C.char

		shbuf = make([]int32, SHA1_DIGESTSIZE)
		var length = len(buffer)
		if length == 0 {
			return []int32{0}, errors.New("Invalid input")
		}

		rem := length % SHA1_BLOCKSIZE
		padded_len := length

		if rem > 0 {
			padded_len = length + (SHA1_BLOCKSIZE - rem)
		}

		rounds := padded_len / SHA1_BLOCKSIZE
		pad := padded_len - length
		if pad > 0 {
			s := make([]byte, pad)
			// Expand with new padded blocks to the byte array
			buffer = append(buffer, s...)
		}

		cshbuf := (*C.int32_t)(unsafe.Pointer(&shbuf[0]))
		cbuffer = (*C.char)(unsafe.Pointer(&buffer[0]))
		C.sha1_transform(cshbuf, cbuffer, C.size_t(rounds))

		return 0, nil
	}
}
*/
func Sum(reader io.Reader) ([]byte, error) {
	hash := gosha1.New()
	var err error
	for err == nil {
		length := 0
		byteBuffer := make([]byte, 1024*1024)
		length, err = reader.Read(byteBuffer)
		byteBuffer = byteBuffer[0:length]
		hash.Write(byteBuffer)
	}
	if err != io.EOF {
		return nil, err
	}
	return hash.Sum(nil), nil
}