/******************************************************************************
 * This program solves the Tower of Hanoi
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

#undef NDEBUG

#include "Utils.hpp"
#include <algorithm>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>

using namespace Utils;
using namespace std;

static int NUM_DISKS = 0;
static vector<vector<int>> PEGS(3);
static int MOVE_NUMBER = 0;
static int PRINT_MOD = 1;

static void print_pegs() noexcept {
    cout << string("Move: ") + to_string(MOVE_NUMBER) << endl;
    for (auto i = 0; i < NUM_DISKS; ++i) {
        for (auto j = 0; j < 3; ++j) {
            int const DISK = PEGS[j][i];
            cout << (DISK == 0 ? "|" : to_string(DISK));
            cout << "   ";
        }
        cout << endl;
    }
    cout << "=========" << endl;
    cout << endl;
}

static void move(int source, int dest) noexcept {
    ++MOVE_NUMBER;
    int disk = 0;
    for (auto i = 0; i < NUM_DISKS; ++i) {
        if (PEGS[source][i] != 0) {
            disk = PEGS[source][i];
            PEGS[source][i] = 0;
            break;
        }
    }
    int pos = NUM_DISKS - 1;
    for (auto i = 0; i < NUM_DISKS; ++i) {
        if (PEGS[dest][i] != 0) {
            pos = i - 1;
            break;
        }
    }
    PEGS[dest][pos] = disk;
    if (MOVE_NUMBER % PRINT_MOD == 0) {
        print_pegs();
    }
}

static void solve(int num_disks, int source, int dest, int aux) noexcept {
    if (num_disks == 1) {
        move(source, dest);
    } else {
        solve(num_disks - 1, source, aux, dest);
        move(source, dest);
        solve(num_disks - 1, aux, dest, source);
    }
}

int main(int argc, char **argv) {
    if (argc != 2) {
        cout << "Syntax: " << argv[0] << " [disks]" << endl;
        exit(1);
    }
    NUM_DISKS = Utils::stoiWithDefault(string(argv[1]), 3);

    for (auto i = 0; i < 3; ++i) {
        vector<int> positions = {};
        for (auto j = 0; j < NUM_DISKS; ++j) {
            Utils::push(positions, 0);
        }
        PEGS[i] = positions;
    }
    for (auto i = 0; i < NUM_DISKS; ++i) {
        PEGS[0][i] = i + 1;
    }

    int const SOLUTION_STEPS = int(pow(2., NUM_DISKS) - 1.);
    PRINT_MOD = SOLUTION_STEPS / 5 + 2;
    PRINT_MOD -= PRINT_MOD % 5;
    PRINT_MOD = max(PRINT_MOD, 1);
    print_pegs();
    solve(NUM_DISKS, 0, 2, 1);
    if (MOVE_NUMBER % PRINT_MOD != 0) {
        print_pegs();
    }
    return 0;
}