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

struct {
    int* pegA;
    int* pegB;
    int* pegC;
    unsigned int blocks;
} state;

void initState();
void printState();
int hasWon();
void play();

int main() {
    printf("Towers of Hanoi\t~By Arc\n\n");
    printf("Enter number of layers to play with:\t");
    scanf("%d", &state.blocks);
    initState();
    while(!hasWon()) {
        system("clear||cls");
        printf("Towers of Hanoi\t~By Arc\n\n");
        printState();
        play();
    }
    system("clear||cls");
    printf("Towers of Hanoi\t~By Arc\n\n");
    printState();
    printf("Congratulations! You solved the puzzle!");
    //clean
    free(state.pegA);
    free(state.pegB);
    free(state.pegC);
    return 0;
}

void initState() {
    int i;
    state.pegA = (int*)calloc(state.blocks, sizeof(int));
    state.pegB = (int*)calloc(state.blocks, sizeof(int));
    state.pegC = (int*)calloc(state.blocks, sizeof(int));
    //populate pegA
    for(i = 0; (unsigned int)i < state.blocks; i++) {
        *(state.pegA + i) = i + 1;
    }
}
void printState() {
    int i;
    for(i = 0; (unsigned int)i < state.blocks; i++) {
        printf("%d\t%d\t%d\n", *(state.pegA + i), *(state.pegB + i), *(state.pegC + i));
    }
    printf("Peg A  Peg B  Peg C\n\n");
}
int hasWon() {
    int i;
    //check in pegB
    for(i = 0; (unsigned int)i < state.blocks; i++) {
        if (*(state.pegB + i) != i + 1) break;
    }
    if ((unsigned int)i == state.blocks) {
        return 1;
    }
    //check in pegC
    for(i = 0; (unsigned int)i < state.blocks; i++) {
        if (*(state.pegC + i) != i + 1) break;
    }
    if ((unsigned int)i == state.blocks) {
        return 1;
    }
    return 0;
}
void play() {
    int ch;
    int source, target;
    int *sourcePeg, *targetPeg;
    int i;
    int block = 0;
    int blockIndex = 0;
    //clean input stream
    while((ch = getchar()) != '\n' && ch != EOF);
    printf("Select a peg to move a block from (A/B/C):\nPeg ");
    source = getchar();
    if(source != 'A' && source != 'B' && source != 'C' && source != 'a' && source != 'b' && source != 'c') {
        printf("Invalid input. Please try again.\n");
        play();
    }
    //clean input stream
    while((ch = getchar()) != '\n' && ch != EOF);
    printf("Select a peg to move the block to (A/B/C):\nPeg ");
    target = getchar();
    if(target != 'A' && target != 'B' && target != 'C' && target != 'a' && target != 'b' && target != 'c') {
        printf("Invalid input. Please try again.\n");
        play();
    }
    else if (source == target) {
        printf("You cannot move to the same peg!\n");
        play();
    }
    if (source == 'A' || source == 'a') sourcePeg = state.pegA;
    else if (source == 'B' || source == 'b') sourcePeg = state.pegB;
    else sourcePeg = state.pegC;
    if (target == 'A' || target == 'a') targetPeg = state.pegA;
    else if (target == 'B' || target == 'b') targetPeg = state.pegB;
    else targetPeg = state.pegC;

    //remove from source
    for(i = 0; (unsigned int)i < state.blocks; i++) {
        if (*(sourcePeg + i) != 0) {
            block = *(sourcePeg + i);
            //*(sourcePeg + i) = 0;
            blockIndex = i;
            break;
        }
    }
    if (block == 0) {
        printf("Peg %c has no blocks!\n", source);
        play();
    }
    //stack on target
    if (*(targetPeg + state.blocks - 1) == 0) {
        *(targetPeg + state.blocks - 1) = block;
        *(sourcePeg + blockIndex) = 0;
    }
    else for(i = 0; (unsigned int)i < state.blocks; i++) {
        if(*(targetPeg + i) != 0 && block < *(targetPeg + i)) {
            *(targetPeg + i - 1) = block;
            //remove from source
            *(sourcePeg + blockIndex) = 0;
            break;
        }
        else if (*(targetPeg + i) != 0 && block > *(targetPeg + i)) {
            printf("Cannot place a bigger block on top of a smaller block!\n");
            play();
        }
    }
    //clean
    sourcePeg = NULL;
    targetPeg = NULL;
}