examples/mine_digger/lib/main.dart

// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:math';

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/painting.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';

// Classic minesweeper-inspired game. The mouse controls are standard
// except for left + right combo which is not implemented. For touch,
// the duration of the pointer determines probing versus flagging.
//
// There are only 3 classes to understand. MineDiggerApp, which is
// contains all the logic and two classes that describe the mines:
// CoveredMineNode and ExposedMineNode, none of them holding state.

// Colors for each mine count (0-8):
const List<Color> textColors = const <Color>[
  const Color(0xFF555555),
  const Color(0xFF0094FF), // blue
  const Color(0xFF13A023), // green
  const Color(0xFFDA1414), // red
  const Color(0xFF1E2347), // black
  const Color(0xFF7F0037), // dark red
  const Color(0xFF000000),
  const Color(0xFF000000),
  const Color(0xFF000000),
];

final List<TextStyle> textStyles = textColors.map((Color color) {
  return new TextStyle(color: color, fontWeight: bold, textAlign: TextAlign.center);
}).toList();

enum CellState { covered, exploded, cleared, flagged, shown }

class MineDigger extends StatefulComponent {
  MineDiggerState createState() => new MineDiggerState();
}

class MineDiggerState extends State<MineDigger> {
  static const int rows = 9;
  static const int cols = 9;
  static const int totalMineCount = 11;

  bool alive;
  bool hasWon;
  int detectedCount;

  // |cells| keeps track of the positions of the mines.
  List<List<bool>> cells;
  // |uiState| keeps track of the visible player progess.
  List<List<CellState>> uiState;

  void initState() {
    super.initState();
    resetGame();
  }

  void resetGame() {
    alive = true;
    hasWon = false;
    detectedCount = 0;
    // Initialize matrices.
    cells = new List<List<bool>>.generate(rows, (int row) {
      return new List<bool>.filled(cols, false);
    });
    uiState = new List<List<CellState>>.generate(rows, (int row) {
      return new List<CellState>.filled(cols, CellState.covered);
    });
    // Place the mines.
    Random random = new Random();
    int minesRemaining = totalMineCount;
    while (minesRemaining > 0) {
      int pos = random.nextInt(rows * cols);
      int row = pos ~/ rows;
      int col = pos % cols;
      if (!cells[row][col]) {
        cells[row][col] = true;
        minesRemaining--;
      }
    }
  }

  PointerEventListener _pointerDownHandlerFor(int posX, int posY) {
    return (PointerInputEvent event) {
      if (event.buttons == 1) {
        probe(posX, posY);
      } else if (event.buttons == 2) {
        flag(posX, posY);
      }
    };
  }

  Widget buildBoard() {
    bool hasCoveredCell = false;
    List<Row> flexRows = <Row>[];
    for (int iy = 0; iy < rows; iy++) {
      List<Widget> row = <Widget>[];
      for (int ix = 0; ix < cols; ix++) {
        CellState state = uiState[iy][ix];
        int count = mineCount(ix, iy);
        if (!alive) {
          if (state != CellState.exploded)
            state = cells[iy][ix] ? CellState.shown : state;
        }
        if (state == CellState.covered || state == CellState.flagged) {
          row.add(new GestureDetector(
            onTap: () {
              if (state == CellState.covered)
                probe(ix, iy);
            },
            onLongPress: () {
              userFeedback.performHapticFeedback(HapticFeedbackType.LONG_PRESS);
              flag(ix, iy);
            },
            child: new Listener(
              onPointerDown: _pointerDownHandlerFor(ix, iy),
              child: new CoveredMineNode(
                flagged: state == CellState.flagged,
                posX: ix,
                posY: iy
              )
            )
          ));
          if (state == CellState.covered) {
            // Mutating |hasCoveredCell| here is hacky, but convenient, same
            // goes for mutating |hasWon| below.
            hasCoveredCell = true;
          }
        } else {
          row.add(new ExposedMineNode(
            state: state,
            count: count
          ));
        }
      }
      flexRows.add(
        new Row(
          row,
          justifyContent: FlexJustifyContent.center,
          key: new ValueKey<int>(iy)
        )
      );
    }

    if (!hasCoveredCell) {
      // all cells uncovered. Are all mines flagged?
      if ((detectedCount == totalMineCount) && alive) {
        hasWon = true;
      }
    }

    return new Container(
      padding: new EdgeDims.all(10.0),
      margin: new EdgeDims.all(10.0),
      decoration: new BoxDecoration(backgroundColor: const Color(0xFF6B6B6B)),
      child: new Column(flexRows)
    );
  }

  Widget buildToolBar(BuildContext context) {
    String toolbarCaption = hasWon ?
      'Awesome!!' : alive ?
        'Mine Digger [$detectedCount-$totalMineCount]': 'Kaboom! [press here]';

    return new ToolBar(
      // FIXME: Strange to have the toolbar be tapable.
      center: new Listener(
        onPointerDown: handleToolbarPointerDown,
        child: new Text(toolbarCaption, style: Theme.of(context).text.title)
      )
    );
  }

  Widget build(BuildContext context) {
    // We build the board before we build the toolbar because we compute the win state during build step.
    Widget board = buildBoard();
    return new Title(
      title: 'Mine Digger',
      child: new Scaffold(
        toolBar: buildToolBar(context),
        body: new Container(
          child: new Center(child: board),
          decoration: new BoxDecoration(backgroundColor: Colors.grey[50])
        )
      )
    );
  }

  void handleToolbarPointerDown(PointerInputEvent event) {
    setState(() {
      resetGame();
    });
  }

  // User action. The user uncovers the cell which can cause losing the game.
  void probe(int x, int y) {
    if (!alive)
      return;
    if (uiState[y][x] == CellState.flagged)
      return;
    setState(() {
      // Allowed to probe.
      if (cells[y][x]) {
        // Probed on a mine --> dead!!
        uiState[y][x] = CellState.exploded;
        alive = false;
      } else {
        // No mine, uncover nearby if possible.
        cull(x, y);
      }
    });
  }

  // User action. The user is sure a mine is at this location.
  void flag(int x, int y) {
    setState(() {
      if (uiState[y][x] == CellState.flagged) {
        uiState[y][x] = CellState.covered;
        --detectedCount;
      } else {
        uiState[y][x] = CellState.flagged;
        ++detectedCount;
      }
    });
  }

  // Recursively uncovers cells whose totalMineCount is zero.
  void cull(int x, int y) {
    if (!inBoard(x, y))
      return;
    if (uiState[y][x] == CellState.cleared)
      return;
    uiState[y][x] = CellState.cleared;

    if (mineCount(x, y) > 0)
      return;

    cull(x - 1, y);
    cull(x + 1, y);
    cull(x, y - 1);
    cull(x, y + 1 );
    cull(x - 1, y - 1);
    cull(x + 1, y + 1);
    cull(x + 1, y - 1);
    cull(x - 1, y + 1);
  }

  int mineCount(int x, int y) {
    int count = 0;
    count += bombs(x - 1, y);
    count += bombs(x + 1, y);
    count += bombs(x, y - 1);
    count += bombs(x, y + 1 );
    count += bombs(x - 1, y - 1);
    count += bombs(x + 1, y + 1);
    count += bombs(x + 1, y - 1);
    count += bombs(x - 1, y + 1);
    return count;
  }

  int bombs(int x, int y) => inBoard(x, y) && cells[y][x] ? 1 : 0;

  bool inBoard(int x, int y) => x >= 0 && x < cols && y >= 0 && y < rows;
}

Widget buildCell(Widget child) {
  return new Container(
    padding: new EdgeDims.all(1.0),
    height: 27.0, width: 27.0,
    decoration: new BoxDecoration(backgroundColor: const Color(0xFFC0C0C0)),
    margin: new EdgeDims.all(2.0),
    child: child
  );
}

Widget buildInnerCell(Widget child) {
  return new Container(
    padding: new EdgeDims.all(1.0),
    margin: new EdgeDims.all(3.0),
    height: 17.0, width: 17.0,
    child: child
  );
}

class CoveredMineNode extends StatelessComponent {

  CoveredMineNode({ this.flagged, this.posX, this.posY });

  final bool flagged;
  final int posX;
  final int posY;

  Widget build(BuildContext context) {
    Widget text;
    if (flagged)
      text = buildInnerCell(new StyledText(elements : [textStyles[5], '\u2691']));

    Container inner = new Container(
      margin: new EdgeDims.all(2.0),
      height: 17.0, width: 17.0,
      decoration: new BoxDecoration(backgroundColor: const Color(0xFFD9D9D9)),
      child: text
    );

    return buildCell(inner);
  }
}

class ExposedMineNode extends StatelessComponent {

  ExposedMineNode({ this.state, this.count });

  final CellState state;
  final int count;

  Widget build(BuildContext context) {
    StyledText text;
    if (state == CellState.cleared) {
      // Uncovered cell with nearby mine count.
      if (count != 0)
        text = new StyledText(elements : [textStyles[count], '$count']);
    } else {
      // Exploded mine or shown mine for 'game over'.
      int color = state == CellState.exploded ? 3 : 0;
      text = new StyledText(elements : [textStyles[color], '\u2600']);
    }
    return buildCell(buildInnerCell(text));
  }
}

void main() {
  runApp(new MineDigger());
}