package com.Main;

import java.io.; import java.util.;

public class Main { public static void main(String[] args) throws IOException {

    String filePath = "src/org/example/snakeGame/board.txt";
    String statePath = "src/org/example/snakeGame/snake_state.txt";

    // Read grid
    List<String> lines = new ArrayList<>();
    try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
        String line;
        while ((line = br.readLine()) != null) {
            lines.add(line.replace(" ", ""));
        }
    }

    int rows = lines.size();
    int cols = lines.get(0).length();

    char[][] grid = new char[rows][cols];
    for (int r = 0; r < rows; r++) {
        grid[r] = lines.get(r).toCharArray();
    }

    LinkedList<int[]> snakeList = new LinkedList<>();

    File stateFile = new File(statePath);

    if (stateFile.exists()) {
        try (BufferedReader br = new BufferedReader(new FileReader(stateFile))) {
            String line;
            while ((line = br.readLine()) != null) {
                String[] p = line.split(",");
                int r = Integer.parseInt(p[0]);
                int c = Integer.parseInt(p[1]);
                snakeList.add(new int[]{r, c});
            }
        }

        // clear grid and rebuild snake
        for (int r = 0; r < rows; r++) {
            Arrays.fill(grid[r], '-');
        }
        for (int[] part : snakeList) {
            grid[part[0]][part[1]] = 'o';
        }

    } else {
        // first run
        for (int r = 0; r < rows; r++) {
            for (int c = 0; c < cols; c++) {
                if (grid[r][c] == 'o') {
                    snakeList.add(new int[]{r, c});
                }
            }
        }
    }

    // directions
    String[] dirs = {"up", "down", "left", "right"};
    int[][] moves = {
            {-1, 0}, {1, 0}, {0, -1}, {0, 1}
    };

    String direction = args[0];
    int steps = Integer.parseInt(args[1]);

    for (int step = 0; step < steps; step++) {
        int[] head = snakeList.getLast();
        int newRow = head[0];
        int newCol = head[1];

        for (int i = 0; i < dirs.length; i++) {
            if (direction.equals(dirs[i])) {
                newRow += moves[i][0];
                newCol += moves[i][1];
            }
        }

        // prevent reverse
        if (snakeList.size() > 1) {
            int[] neck = snakeList.get(snakeList.size() - 2);
            if (newRow == neck[0] && newCol == neck[1]) {
                System.out.println("Cannot reverse into itself.");
                break;
            }
        }

        // wall check
        if (newRow < 0 || newRow >= rows || newCol < 0 || newCol >= cols) {
            System.out.println("Hit the wall!");
            break;
        }

        // move
        snakeList.add(new int[]{newRow, newCol});
        grid[newRow][newCol] = 'o';

        int[] tail = snakeList.removeFirst();
        grid[tail[0]][tail[1]] = '-';
    }

    // print
    for (int r = 0; r < rows; r++) {
        for (int c = 0; c < cols; c++) {
            System.out.print(grid[r][c] + " ");
        }
        System.out.println();
    }

    try (BufferedWriter bw = new BufferedWriter(new FileWriter(filePath))) {
        for (int r = 0; r < rows; r++) {
            for (int c = 0; c < cols; c++) {
                bw.write(grid[r][c]);
                if (c < cols - 1) bw.write(" ");
            }
            bw.newLine();
        }
    }

    try (BufferedWriter bw = new BufferedWriter(new FileWriter(statePath))) {
        for (int[] part : snakeList) {
            bw.write(part[0] + "," + part[1]);
            bw.newLine();
        }
    }
}

}