#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <xmmintrin.h>
#include <errno.h>
#include <immintrin.h>
#include <stdint.h>
#include <getopt.h>

// The file "testfile" should lead to this hash: fc982e558db259f298b43cd4c1241c66

void md2_checksum(size_t len, uint8_t* buf) {

}

void md2_hash(size_t len, const uint8_t buf[len], uint8_t out[16]) {

}

static uint8_t* read_file(const char* path, size_t* size) {
    // Read the contents of the file specified by path into a heap-allocated
    // buffer and return a pointer to that buffer.
    FILE* f = fopen(path, "r");
    if(f == NULL) {
        printf("Fopen error: %d\n", errno);
        fclose(f);
        return NULL;
    }

    struct stat statOfFile;
    int status = fstat(fileno(f), &statOfFile);
    if(status == -1) {
        printf("Fstat error: %d\n", errno);
        fclose(f);
        return NULL;
    };

    if((statOfFile.st_mode & S_IFMT) != S_IFREG){
        printf("File is not a regular file!\n");
        fclose(f);
        return NULL;
    }

    uint8_t* data = malloc(statOfFile.st_size);

    size_t bytesRead = fread(data, statOfFile.st_blksize, statOfFile.st_blocks, f);
    // Or: size_t bytesRead = fread(data, sizeof(char), statOfFile.st_size, f);
    if(bytesRead != 0 && !feof(f)) {
        printf("Error reading file!\n");
        fclose(f);
        return NULL;
    }

    fclose(f);

    (*size) = bytesRead;
    return data;
}

int stringToInt(char* string) {
    char* leftover = "";
    errno = 0;
    int x = strtold(string, &leftover);
    if(*leftover != '\0' || leftover == string) {
        errno = EINVAL;
        return -1;
    }
    if(errno == ERANGE) {
        printf("Number is too large or too small!\n");
        errno = EINVAL;
        return -1;
    }
    errno = 0;
    return x;
}

void help(char* progname) {
    fprintf(stderr, "usage: %s [-V implementation] [-B [repetitons]] [-h] [--help] file\n", progname);
}

int main(int argc, char** argv) {
     
    int opt;
    int implementationTosUse = 0;
    int doBenchmark = 0;
    int benchmarkingCycles = 1;

    while (1) {

        static struct option longOptions[] =
        {
            /* These options set a flag. */
            {"help", no_argument, NULL, 'h'},
            NULL
        };
        int longOptionIndex = 0;

        opt = getopt_long(argc, argv, "V:B::h", longOptions, &longOptionIndex);

        if(-1 == opt)
            break;

        switch (opt) {
        case 'B': 
            doBenchmark = 1;
            if(optarg != NULL) {
                benchmarkingCycles = stringToInt(optarg);
                if(errno == 0) break;
                fprintf(stderr, "%s: invalid argument, has to be int -- 'B' got '%s'\n", argv[0], optarg); 
                help(argv[0]);
                return EXIT_FAILURE;
            }
            break;
        case 'V': 
            implementationTosUse = stringToInt(optarg);
            if(errno == 0) break;
            fprintf(stderr, "%s: invalid argument, has to be int -- 'V' got '%s'\n", argv[0], optarg);
            help(argv[0]);
            return EXIT_FAILURE;

        case 'h':
            help(argv[0]);
            return EXIT_SUCCESS;

        default:
            help(argv[0]);
            return EXIT_FAILURE;
        }
    }

    char* filename = "";

    if(argc > optind) {
        filename = argv[optind];
    }
    else {
        fprintf(stderr, "%s: missing poisional argument -- 'file'\n", argv[0]);
        help(argv[0]);
        return EXIT_FAILURE;
    }

    printf("Hashing file: %s\nUsing implementation: %d, doing benchmark: %d, benchmark cycles: %d\n", filename, implementationTosUse, doBenchmark, benchmarkingCycles);

    return 0;
}