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

#define NSCRAMBLERS 4

struct scramble {
	char* (*run)(char*);
	char* (*undo)(char*);
};

char* shift(char *word){
	register size_t wordlen = strlen(word);
	char *shifted = malloc(sizeof(char) * (wordlen + 1));
	for(int i = 0; i < wordlen - 1; i++)
		shifted[i+1] = word[i];
	shifted[0] = word[wordlen - 1];
	shifted[wordlen] = 0;
	return shifted;
}

char* unshift(char *word){
	register size_t wordlen = strlen(word);
	char *shifted = malloc(sizeof(char) * (wordlen + 1));
	for(int i = 0; i < wordlen - 1; i++)
		shifted[i] = word[i+1];
	shifted[wordlen-1] = word[0];
	shifted[wordlen] = 0;
	return shifted;
}

char* reverse(char *word){
	register size_t wordlen = strlen(word);
	char *reversed = malloc(sizeof(char) * (wordlen + 1));
	for(int i = 0; i < wordlen; i++)
		reversed[wordlen - i - 1] = word[i];
	reversed[wordlen] = 0;
	return reversed;
}

char* firstlast(char *word){
	char *product = malloc(sizeof(char) * (strlen(word) + 1));
	strcpy(product, word);
	product[0] = word[strlen(word)-1];
	product[strlen(word) - 1] = word[0];
	return product;
}

char* copy(char *word){
	char *c = malloc(sizeof(char) * (strlen(word)+1));
	strcpy(c, word);
	return c;
}

const struct scramble shifts = {shift, unshift};
const struct scramble reverser = {reverse, reverse};
const struct scramble endswap = {firstlast, firstlast};
const struct scramble donothing = {copy, copy};

//char* (*list_of_scramblers[])(char*) = {reverse, firstlast, copy, shift};
struct scramble scramblers[] = {shifts, reverser, endswap, donothing};

char** scrambles(char* word){
	char **scramble_pointers = malloc(sizeof(char*) * NSCRAMBLERS);
	for(int i = 0; i < NSCRAMBLERS; i++)
		scramble_pointers[i] = scramblers[i].run(word);
	return scramble_pointers;
}

int main(){
	char ** sp = scrambles("giraffe");
	for(int i = 0; i < NSCRAMBLERS; i++)
		printf("sc[i] = %s\n", sp[i]);
	for(char **sc = sp; sc < sp + NSCRAMBLERS; sc++)
		puts(*sc);
	for(int i = 0; i < NSCRAMBLERS; i++){
		char *unscramble = scramblers[i].undo(sp[i]);
		printf("Unscramble %d:  %s\n", i, unscramble);
		free(unscramble);
	}


	for(int i = 0; i < NSCRAMBLERS; i++)
		free(sp[i]);
	free(sp);
	return 0;
}