/*
 * Copyright (C) 2016 The Android Open Source Project
 * Copyright (C) 2016 The CyanogenMod Project
 * Copyright (C) 2016 The Mokee 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 <stdio.h>
#include <string.h>

#include "hash.h"

SHA1Context sha;

/*
 * HASH method: SHA1
 */

uint64_t convert_hash_to_number() {
    uint64_t num = 0;
    num = ((uint64_t)sha.Message_Digest[0] << 32) + sha.Message_Digest[1];
    return num;
}

uint64_t hash_file(const char *file_path) {
    FILE * file;
    char str[MAX_FILE_LENGTH];
    int len = 0;
    file = fopen(file_path, "rb");
    if (!file)
        return 1;
    len = fread(str, sizeof(char), MAX_FILE_LENGTH, file);
    fclose(file);
    sha1_hash(str, len);
    return convert_hash_to_number();
}

uint64_t hash_string(const char *str) {
    sha1_hash(str, strlen(str));
    return convert_hash_to_number();
}

void SHA1Reset(SHA1Context *context){
    context->Length_Low             = 0;
    context->Length_High            = 0;
    context->Message_Block_Index    = 0;

    context->Message_Digest[0]      = 0x67452301;
    context->Message_Digest[1]      = 0xEFCDAB89;
    context->Message_Digest[2]      = 0x98BADCFE;
    context->Message_Digest[3]      = 0x10325476;
    context->Message_Digest[4]      = 0xC3D2E1F0;

    context->Computed   = 0;
    context->Corrupted  = 0;
}


int SHA1Result(SHA1Context *context){
    if (context->Corrupted) {
        return 0;
    }
    if (!context->Computed) {
        SHA1PadMessage(context);
        context->Computed = 1;
    }
    return 1;
}


void SHA1Input(SHA1Context *context,const char *message_array,unsigned length){
    if (!length) return;

    if (context->Computed || context->Corrupted){
        context->Corrupted = 1;
        return;
    }

    while(length-- && !context->Corrupted){
        context->Message_Block[context->Message_Block_Index++] = (*message_array & 0xFF);

        context->Length_Low += 8;

        context->Length_Low &= 0xFFFFFFFF;
        if (context->Length_Low == 0){
            context->Length_High++;
            context->Length_High &= 0xFFFFFFFF;
            if (context->Length_High == 0) context->Corrupted = 1;
        }

        if (context->Message_Block_Index == 64){
            SHA1ProcessMessageBlock(context);
        }
        message_array++;
    }
}

void SHA1ProcessMessageBlock(SHA1Context *context){
    const unsigned K[] = {0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6 };
    int         t;
    unsigned    temp;
    unsigned    W[80];
    unsigned    A, B, C, D, E;

    for(t = 0; t < 16; t++) {
    W[t] = ((unsigned) context->Message_Block[t * 4]) << 24;
    W[t] |= ((unsigned) context->Message_Block[t * 4 + 1]) << 16;
    W[t] |= ((unsigned) context->Message_Block[t * 4 + 2]) << 8;
    W[t] |= ((unsigned) context->Message_Block[t * 4 + 3]);
    }

    for(t = 16; t < 80; t++)  W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);

    A = context->Message_Digest[0];
    B = context->Message_Digest[1];
    C = context->Message_Digest[2];
    D = context->Message_Digest[3];
    E = context->Message_Digest[4];

    for(t = 0; t < 20; t++) {
        temp =  SHA1CircularShift(5,A) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 20; t < 40; t++) {
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 40; t < 60; t++) {
        temp = SHA1CircularShift(5,A) + ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 60; t < 80; t++) {
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    context->Message_Digest[0] = (context->Message_Digest[0] + A) & 0xFFFFFFFF;
    context->Message_Digest[1] = (context->Message_Digest[1] + B) & 0xFFFFFFFF;
    context->Message_Digest[2] = (context->Message_Digest[2] + C) & 0xFFFFFFFF;
    context->Message_Digest[3] = (context->Message_Digest[3] + D) & 0xFFFFFFFF;
    context->Message_Digest[4] = (context->Message_Digest[4] + E) & 0xFFFFFFFF;
    context->Message_Block_Index = 0;
}

void SHA1PadMessage(SHA1Context *context){
    if (context->Message_Block_Index > 55) {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 64)  context->Message_Block[context->Message_Block_Index++] = 0;
        SHA1ProcessMessageBlock(context);
        while(context->Message_Block_Index < 56) context->Message_Block[context->Message_Block_Index++] = 0;
    } else {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 56) context->Message_Block[context->Message_Block_Index++] = 0;
    }
    context->Message_Block[56] = (context->Length_High >> 24 ) & 0xFF;
    context->Message_Block[57] = (context->Length_High >> 16 ) & 0xFF;
    context->Message_Block[58] = (context->Length_High >> 8 ) & 0xFF;
    context->Message_Block[59] = (context->Length_High) & 0xFF;
    context->Message_Block[60] = (context->Length_Low >> 24 ) & 0xFF;
    context->Message_Block[61] = (context->Length_Low >> 16 ) & 0xFF;
    context->Message_Block[62] = (context->Length_Low >> 8 ) & 0xFF;
    context->Message_Block[63] = (context->Length_Low) & 0xFF;

    SHA1ProcessMessageBlock(context);
}

int sha1_hash(const char *source, int len){
    SHA1Reset(&sha);
    SHA1Input(&sha, source, len);

    if (!SHA1Result(&sha)){
        return -1;
    }
    return 0;
}