import 'dart:math';
import 'package:flutter/material.dart';

class GameState extends ChangeNotifier {
  final int rows = 8;
  final int cols = 8;
  late List<List<int>> grid;
  int? selectedRow;
  int? selectedCol;

  GameState() {
    _initializeGrid();
  }

  void _initializeGrid() {
    grid = List.generate(
        rows, (i) => List.generate(cols, (j) => _randomElement()));
    _removeInitialMatches();
  }

  int _randomElement() {
    return Random().nextInt(6) + 1;
  }

  void _removeInitialMatches() {
    bool hasMatches;
    do {
      hasMatches = false;
      for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
          if (_hasMatch(i, j)) {
            grid[i][j] = _randomElement();
            hasMatches = true;
          }
        }
      }
    } while (hasMatches);
  }

  void selectElement(int row, int col) {
    if (selectedRow == null || selectedCol == null) {
      selectedRow = row;
      selectedCol = col;
    } else {
      if (_isAdjacent(selectedRow!, selectedCol!, row, col)) {
        swapElements(selectedRow!, selectedCol!, row, col);
        Future.delayed(const Duration(milliseconds: 300), () {
          if (!_checkMatches()) {
            swapElements(row, col, selectedRow!, selectedCol!);
          }
          selectedRow = null;
          selectedCol = null;
          notifyListeners();
        });
      } else {
        selectedRow = row;
        selectedCol = col;
      }
    }
    notifyListeners();
  }

  bool _isAdjacent(int row1, int col1, int row2, int col2) {
    return (row1 == row2 && (col1 - col2).abs() == 1) ||
        (col1 == col2 && (row1 - row2).abs() == 1);
  }

  void swapElements(int row1, int col1, int row2, int col2) {
    final temp = grid[row1][col1];
    grid[row1][col1] = grid[row2][col2];
    grid[row2][col2] = temp;
    notifyListeners();
  }

  bool _checkMatches() {
    final matches = <List<int>>[];
    for (int i = 0; i < rows; i++) {
      for (int j = 0; j < cols; j++) {
        if (_hasMatch(i, j)) {
          matches.add([i, j]);
        }
      }
    }

    if (matches.isNotEmpty) {
      for (final match in matches) {
        _removeMatchedElements(match[0], match[1]);
      }
      _applyGravity();
      Future.delayed(const Duration(milliseconds: 300), () {
        _fillEmptySpaces();
        _checkMatches();
      });
      return true;
    }
    return false;
  }

  bool _hasMatch(int row, int col) {
    final value = grid[row][col];
    if (value == 0) return false;

    int count = 1;
    for (int i = col + 1; i < cols && grid[row][i] == value; i++) count++;
    for (int i = col - 1; i >= 0 && grid[row][i] == value; i--) count++;
    if (count >= 3) return true;

    count = 1;
    for (int i = row + 1; i < rows && grid[i][col] == value; i++) count++;
    for (int i = row - 1; i >= 0 && grid[i][col] == value; i--) count++;
    return count >= 3;
  }

  void _removeMatchedElements(int row, int col) {
    final value = grid[row][col];

    int left = col;
    while (left > 0 && grid[row][left - 1] == value) left--;
    int right = col;
    while (right < cols - 1 && grid[row][right + 1] == value) right++;
    if (right - left + 1 >= 3) {
      for (int i = left; i <= right; i++) {
        grid[row][i] = 0;
      }
    }

    int top = row;
    while (top > 0 && grid[top - 1][col] == value) top--;
    int bottom = row;
    while (bottom < rows - 1 && grid[bottom + 1][col] == value) bottom++;
    if (bottom - top + 1 >= 3) {
      for (int i = top; i <= bottom; i++) {
        grid[i][col] = 0;
      }
    }
  }

  void _applyGravity() {
    for (int col = 0; col < cols; col++) {
      int emptyRow = rows - 1;
      for (int row = rows - 1; row >= 0; row--) {
        if (grid[row][col] != 0) {
          if (row != emptyRow) {
            grid[emptyRow][col] = grid[row][col];
            grid[row][col] = 0;
          }
          emptyRow--;
        }
      }
    }
  }

  void _fillEmptySpaces() {
    for (int col = 0; col < cols; col++) {
      for (int row = rows - 1; row >= 0; row--) {
        if (grid[row][col] == 0) {
          grid[row][col] = _randomElement();
        }
      }
    }
    notifyListeners();
  }
}