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

int field[4][4] = {
    {0,0,0,0},
    {0,0,0,0},
    {0,0,0,0},
    {0,0,0,0}
};
int start1[2] = {0,0};
int start2[2] = {0,0};
int new1[2] = {0,0};

void printfield() {
    printf("\033[2j\033[H");
    for(int i = 0; i < 4; i++) {
        for(int j = 0; j < 4; j++) {
            printf("%7d ",field[i][j]);
        }
        printf("\n");
    }
}

int main(int argc, char* argv[]) {
    srand(time(NULL));
    start1[0] = rand() % 4; //only twos to start off with
    start1[1] = rand() % 4;
    start2[0] = rand() % 4;
    start2[1] = rand() % 4;
    while((start1[0] == start2[0]) && (start1[1] == start2[1])) {
        start2[0] = rand() % 4;
        start2[1] = rand() % 4;
    }
    field[start1[0]][start1[1]] = 2;
    field[start2[0]][start2[1]] = 2;
    printfield();

    while(1) {
        printfield();
        switch(getchar()) {
            case 10:
            case 13:
            case 27:
                continue;
            case 119: //w
                for(int i = 0; i < 4; i++) {
                    for(int j = 0; j < 4; j++) {
                        for(int k = 1; k < 4; k++) {
                            if(!field[k-1][i]) { //if one tile further than i is empty
                                field[k-1][i] = field[k][i]; //move i tile up
                                field[k][i] = 0; //clear i for closer tile
                            } else if(field[k-1][i] == field[k][i]) { //if one tile further than i is the same
                                field[k-1][i] = field[k-1][i] * 2; //double the tile one tile further than i
                                field[k][i] = 0; //clear i for close tile
                            }
                        }
                    }
                }
                break;
            case 97: //a
                for(int i = 0; i < 4; i++) {
                    for(int j = 0; j < 4; j++) {
                        for(int k = 1; k < 4; k++) {
                            if(!field[i][k-1]) {
                                field[i][k-1] = field[i][k];
                                field[i][k] = 0;
                            } else if(field[i][k-1] == field[i][k]) {
                                field[i][k-1] = field[i][k-1] * 2;
                                field[i][k] = 0;
                            }
                        }
                    }
                }
                break;
            case 115: //s
                for(int i = 0; i < 4; i++) {
                    for(int j = 0; j < 4; j++) {
                        for(int k = 2; k > -1; k--) {
                            if(!field[k+1][i]) {
                                field[k+1][i] = field[k][i];
                                field[k][i] = 0;
                            } else if(field[k+1][i] == field[k][i]) {
                                field[k+1][i] = field[k+1][i] * 2;
                                field[k][i] = 0;
                            }
                        }
                    }
                }
                break;
            case 100: //d
                for(int i = 0; i < 4; i++) {
                    for(int j = 0; j < 4; j++) {
                        for(int k = 2; k > -1; k--) {
                            if(!field[i][k+1]) {
                                field[i][k+1] = field[i][k];
                                field[i][k] = 0;
                            } else if(field[i][k+1] == field[i][k]) {
                                field[i][k+1] = field[i][k+1] * 2;
                                field[i][k] = 0;
                            }
                        }
                    }
                }
                break;
        }

        new1[0] = rand() % 4;
        new1[1] = rand() % 4;
        while(field[new1[0]][new1[1]]) {
            new1[0] = rand() % 4;
            new1[1] = rand() % 4;
        }
        field[new1[0]][new1[1]] = 2;

    }
    exit(0);
}