/*
 * hashtable.c
 *
 * Computer Science 50, Fall 2011
 * section7
 *
 * Credit: Tommy MacWilliam (aka TMac)
 *
 * Create your very own hash table.
 */

#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// size of hashtable
#define SIZE 5

// function prototype
int hash_function(char *key);

int
main(void)
{
    // create a hash table
    char *hash_table[SIZE];
    
    // initalize the hash table with empty strings
    for (int i = 0; i < SIZE; i++)
        hash_table[i] = "";
    
    // put a sample key into the hash table
    int v = hash_function("CS50");
    hash_table[v] = "CS50";
    
    // declare a choice value
    char *choice;
    
    while(strcmp(choice, "quit") != 0)
    {
        // get user's choice
        printf("What do you want to do? ");
        choice = GetString();
        
        // print out all keys in the hash table
        if (strcmp(choice, "print") == 0)
            for (int j = 0; j < SIZE; j ++)
                printf("%d: %s\n", j, hash_table[j]);
        
        /* put a key into the table
           (Quick Quiz: how fast is this, asymptotically? */
        else if (strcmp(choice,"insert") == 0)
        {
            printf("Key please: ");
            string s = GetString();
            hash_table[hash_function(s)] = s;
        }
        
        /* get a key from the table
           (Quick Quiz: how fast is this, asymptotically? */
        else if (strcmp(choice, "lookup") == 0)
        {
            printf("Key please: ");
            string s = GetString();
            if (strcmp(hash_table[hash_function(s)], s) == 0)
                printf("It's here!\n");
            else
                printf("Couldn't find it.\n");
        }
    }
    
    // success!
    return 0;
}

/*
 * Maps a key to a value.
 */
int
hash_function(char *key)
{
    // initalize hash variable
    int hash = 0;
    
    /* calculate specific hash value
       (Quick Quiz: what is my hash function?) */
    for (int i = 0, n = strlen(key); i < n; i++) 
        hash += key[i];

    // return a value
    return hash % SIZE;
}