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

/* max size of arrays */
#define STRING_SIZE 64
#define NUM_STRINGS 100000

/* the number of threads */
int num_threads;

/* global variables, used to specify what to search for each thread */
char strings[NUM_STRINGS][STRING_SIZE];
int num_strings;
char target[STRING_SIZE];

/* the function called for each thread */
void* search_thread(void* idp) {
    /* get our thread id */
    int id = * (int*) idp;

    /* calculate the start and end points by evenly dividing the range */
    int start = (num_strings / num_threads) * id;
    int end = start + (num_strings / num_threads) - 1;

    /* the last thread needs to do all remaining ones */
    if (id == (num_threads - 1)) {
        end = num_strings;
    }

    /* search the array for the given string */
    int i;
    for (i = start; i < end; i++) {
        if (strstr(strings[i], target)) {
            printf("%s", strings[i]);
            printf(" matches ");
            printf("%s", target);
            printf(" on line ");
            printf("%d", i);
            printf("\n"); 
        }
    }

    return NULL;
}

/* the main thread loads up a file of strings and asks the user what to search for */
int main (int argc, char** argv) {
    /* get the number of threads */
    if (argc < 2) {
        printf("Pass the number of threads to use!\n");
        return 0;
    } else {
        num_threads = atoi(argv[1]);
    }

    /* read in the dictionary file! */
    FILE* fp = fopen("words.txt", "r");
    int i = 0;
    do {
        fscanf(fp, "%s", strings[i]);
        i++;
    } while (!feof(fp));
    num_strings = i;

    /* ask the user what to search for */
    printf("What text would you like to search for?\n");
    scanf("%s", target);

    /* an array of threads */
    pthread_t threads[num_threads];
    int ids[num_threads];

    /* spawn all threads */
    for (i = 0; i < num_threads; i++) {
        ids[i] = i;
        pthread_create(&threads[i], NULL, search_thread, &ids[i]);
    }

    /* join all threads */
    for (i = 0; i < num_threads; i++) {
        pthread_join(threads[i], NULL);
    }

    return 0;
}