Dartchess

https://pub.dev/documentation/dartchess/latest/
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Dartchess is a Dart library that implements chess and chess variant rules with support for move...
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### Setup Class Constructors

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup-class.html

Information about how to create a Setup object.

```APIDOC
## Constructors

### `Setup(
  required Board board,
  Pockets? pockets,
  required Side turn,
  required SquareSet castlingRights,
  Square? epSquare,
  required int halfmoves,
  required int fullmoves,
  (int, int)? remainingChecks
)`

Creates a new Setup with the provided values.

### `Setup.parseFen(String fen)`

Parses a Forsyth-Edwards-Notation string and returns a Setup.

**Type:** factory
```

--------------------------------

### Setup Class Methods and Operators

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup-class.html

Available methods and operators for the Setup class.

```APIDOC
## Methods

### `noSuchMethod(Invocation invocation) → dynamic`

Invoked when a nonexistent method or property is accessed.
*inherited*

### `toString() → String`

A string representation of this object.
*inherited*

## Operators

### `operator ==(Object other) → bool`

The equality operator.
*override*
```

--------------------------------

### Setup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/Setup.html

Initializes a new Setup object with the specified board state, turn, castling rights, and move counters.

```APIDOC
## Setup Constructor

### Description
Creates a new Setup instance with the provided game state values.

### Parameters
- **board** (Board) - Required - The current state of the board.
- **pockets** (Pockets) - Optional - The contents of the pockets.
- **turn** (Side) - Required - The side whose turn it is to move.
- **castlingRights** (SquareSet) - Required - The current castling rights.
- **epSquare** (Square) - Optional - The en passant square, if applicable.
- **halfmoves** (int) - Required - The number of halfmoves played.
- **fullmoves** (int) - Required - The number of fullmoves played.
- **remainingChecks** ((int, int)) - Optional - The remaining checks for each side.
```

--------------------------------

### Setup Class Properties

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup-class.html

Details of the properties available on a Setup object.

```APIDOC
## Properties

- **board** → Board
  Piece positions on the board.
  *final*

- **castlingRights** → SquareSet
  Unmoved rooks positions used to determine castling rights.
  *final*

- **epSquare** → Square?
  En passant target square.
  *final*

- **fen** → String
  FEN representation of the setup.
  *no setter*

- **fullmoves** → int
  Current move number.
  *final*

- **halfmoves** → int
  Number of half-moves since the last capture or pawn move.
  *final*

- **hashCode** → int
  The hash code for this object.
  *no setter*
  *override*

- **pockets** → Pockets?
  Pockets in chess variants like Crazyhouse.
  *final*

- **remainingChecks** → (int, int)?
  Number of remainingChecks for white and black.
  *final*

- **runtimeType** → Type
  A representation of the runtime type of the object.
  *no setter*
  *inherited*

- **turn** → Side
  Side to move.
  *final*

- **turnLetter** → String
  FEN character for the side to move.
  *no setter*
```

--------------------------------

### Setup Class Constants

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup-class.html

Constants associated with the Setup class.

```APIDOC
## Constants

### `standard` → const Setup

Initial position setup.
```

--------------------------------

### Initialize Setup object

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/Setup.html

Defines the parameters required to instantiate a new Setup object for a chess game state.

```dart
const Setup({
  1. required Board board, 
  2. Pockets? pockets, 
  3. required Side turn, 
  4. required SquareSet castlingRights, 
  5. Square? epSquare, 
  6. required int halfmoves, 
  7. required int fullmoves, 
  8. (int, int)? remainingChecks, 

})
```

```dart
const Setup({
  required this.board,
  this.pockets,
  required this.turn,
  required this.castlingRights,
  this.epSquare,
  required this.halfmoves,
  required this.fullmoves,
  this.remainingChecks,
});
```

--------------------------------

### Initialize ThreeCheck from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/ThreeCheck/ThreeCheck.fromSetup.html

Creates a playable ThreeCheck position from a Setup object. Throws a PositionSetupException if the setup is invalid, unless ignoreImpossibleCheck is set to true.

```dart
factory ThreeCheck.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  if (setup.remainingChecks == null) {
    throw PositionSetupException.variant;
  } else {
    final pos = ThreeCheck(
      board: setup.board,
      turn: setup.turn,
      castles: Castles.fromSetup(setup),
      epSquare: _validEpSquare(setup),
      halfmoves: setup.halfmoves,
      fullmoves: setup.fullmoves,
      remainingChecks: setup.remainingChecks!,
    );
    pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
    return pos;
  }
}
```

--------------------------------

### Initialize Horde position from setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Horde/Horde.fromSetup.html

Creates a new Horde instance from a Setup object. Throws a PositionSetupException if the setup is invalid unless ignoreImpossibleCheck is true.

```dart
factory Horde.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Horde(
    board: setup.board,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Initialize RacingKings from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/RacingKings/RacingKings.fromSetup.html

Creates a new RacingKings instance from a Setup object. Throws a PositionSetupException if the setup is invalid unless ignoreImpossibleCheck is set to true.

```dart
factory RacingKings.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = RacingKings(
    board: setup.board,
    turn: setup.turn,
    castles: Castles.empty,
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Create Chess Position from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Chess/Chess.fromSetup.html

Use this factory constructor to set up a playable Chess position from a `Setup` object. It optionally allows skipping validity checks by passing `ignoreImpossibleCheck: true`. Throws `PositionSetupException` if the setup is invalid and checks are not ignored.

```dart
factory Chess.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Chess(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Crazyhouse Initial Constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Crazyhouse/initial-constant.html

The 'initial' constant defines the standard starting board setup for a Crazyhouse game, including pieces, turn, and game state.

```APIDOC
## Crazyhouse Initial Constant

### Description
The initial position of a Crazyhouse game.

### Implementation
```dart
static const initial = Crazyhouse(
  board: Board.standard,
  pockets: Pockets.empty,
  turn: Side.white,
  castles: Castles.standard,
  halfmoves: 0,
  fullmoves: 1,
);
```
```

--------------------------------

### Castles.fromSetup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Castles/Castles.fromSetup.html

Creates a Castles instance from a Setup object. It initializes castling rights based on the provided setup, considering rook positions relative to the king.

```APIDOC
## Castles.fromSetup Constructor

### Description
Creates a Castles instance from a Setup.

### Method
Factory Constructor

### Endpoint
N/A (Constructor)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (200)
N/A (Constructor returns an instance)

#### Response Example
N/A

### Implementation Details
This factory constructor iterates through each side (white and black) to determine castling rights. It identifies rooks on the back rank and checks their positions relative to the king to establish castling availability for both the king's and queen's sides.
```

--------------------------------

### ThreeCheck.fromSetup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/ThreeCheck-class.html

Factory method to initialize a playable ThreeCheck position from a setup configuration.

```APIDOC
## Factory ThreeCheck.fromSetup

### Description
Set up a playable ThreeCheck position from a provided setup object.

### Parameters
#### Request Body
- **setup** (Setup) - Required - The setup configuration.
- **ignoreImpossibleCheck** (bool?) - Optional - Flag to ignore impossible check states.
```

--------------------------------

### Define Standard Chess Initial Position

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Chess/initial-constant.html

This constant defines the standard starting board setup, turn, castling rights, and move counters for a chess game.

```dart
static const initial = Chess(
  board: Board.standard,
  turn: Side.white,
  castles: Castles.standard,
  halfmoves: 0,
  fullmoves: 1,
);
```

--------------------------------

### ThreeCheck.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/ThreeCheck/ThreeCheck.fromSetup.html

Sets up a playable ThreeCheck position from a given Setup object. It optionally accepts a boolean to ignore impossible check requirements. Throws a PositionSetupException if the Setup does not meet basic validity requirements.

```APIDOC
## ThreeCheck.fromSetup Factory Constructor

### Description
Sets up a playable ThreeCheck position from a given `Setup` object. It optionally accepts a boolean to ignore impossible check requirements. Throws a `PositionSetupException` if the `Setup` does not meet basic validity requirements.

### Method
`factory`

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
- **setup** (Setup) - Required - The setup object defining the initial board state.
- **ignoreImpossibleCheck** (bool?) - Optional - If true, skips the requirement for the setup to meet basic validity requirements regarding impossible checks.

### Request Example
```json
{
  "setup": {
    "board": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
    "turn": "w",
    "halfmoves": 0,
    "fullmoves": 1,
    "remainingChecks": null
  },
  "ignoreImpossibleCheck": false
}
```

### Response
#### Success Response (200)
- **ThreeCheck** (ThreeCheck) - An instance of the ThreeCheck class representing the configured game position.

#### Response Example
```json
{
  "board": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
  "turn": "w",
  "castles": {
    "wKingSide": true,
    "wQueenSide": true,
    "bKingSide": true,
    "bQueenSide": true
  },
  "epSquare": null,
  "halfmoves": 0,
  "fullmoves": 1,
  "remainingChecks": 0
}
```

### Error Handling
- **PositionSetupException**: Thrown if the `Setup` object does not meet basic validity requirements.
```

--------------------------------

### Chess.fromSetup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Chess/Chess.fromSetup.html

Initializes a new Chess instance based on a provided setup configuration.

```APIDOC
## Chess.fromSetup

### Description
Sets up a playable Chess position from a provided Setup object. Throws a PositionSetupException if the setup does not meet basic validity requirements.

### Parameters
#### Arguments
- **setup** (Setup) - Required - The configuration object containing board, pockets, turn, castles, epSquare, halfmoves, and fullmoves.
- **ignoreImpossibleCheck** (bool?) - Optional - If true, skips the requirement to check for impossible board states.

### Request Example
```dart
final setup = Setup(...);
final game = Chess.fromSetup(setup, ignoreImpossibleCheck: true);
```
```

--------------------------------

### Crazyhouse.fromSetup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Crazyhouse-class.html

Factory constructor to initialize a playable Crazyhouse position from a setup object.

```APIDOC
## Factory: Crazyhouse.fromSetup

### Description
Sets up a playable Crazyhouse position from a provided Setup object.

### Parameters
- **setup** (Setup) - Required - The setup configuration.
- **ignoreImpossibleCheck** (bool?) - Optional - Whether to ignore impossible check states.
```

--------------------------------

### Crazyhouse.fromSetup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Crazyhouse/Crazyhouse.fromSetup.html

Initializes a new Crazyhouse position based on the provided setup configuration.

```APIDOC
## Crazyhouse.fromSetup

### Description
Sets up a playable Crazyhouse position. Throws a PositionSetupException if the Setup does not meet basic validity requirements.

### Parameters
#### Arguments
- **setup** (Setup) - Required - The configuration object containing board state, pockets, turn, and move counters.

#### Named Parameters
- **ignoreImpossibleCheck** (bool?) - Optional - If true, skips the requirement to validate impossible check states.

### Implementation
```dart
factory Crazyhouse.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Crazyhouse(
    board: setup.board.withPromoted(setup.board.promoted
        .intersect(setup.board.occupied)
        .diff(setup.board.kings)
        .diff(setup.board.pawns)),
    pockets: setup.pockets ?? Pockets.empty,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```
```

--------------------------------

### Create Antichess Position from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Antichess/Antichess.fromSetup.html

Use this factory constructor to set up a playable Antichess position from a `Setup` object. It optionally allows skipping validity checks by passing `ignoreImpossibleCheck: true`. Throws `PositionSetupException` if the setup is invalid and checks are not ignored.

```dart
factory Antichess.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Antichess(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.empty,
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Crazyhouse.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Crazyhouse/Crazyhouse.fromSetup.html

Sets up a playable Crazyhouse position from a Setup object. Optionally ignores impossible check conditions. Throws PositionSetupException for invalid setups.

```dart
factory Crazyhouse.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Crazyhouse(
    board: setup.board.withPromoted(setup.board.promoted
        .intersect(setup.board.occupied)
        .diff(setup.board.kings)
        .diff(setup.board.pawns)),
    pockets: setup.pockets ?? Pockets.empty,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### GET /constants/standard

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/standard-constant.html

Retrieves the standard initial chess position configuration.

```APIDOC
## GET /constants/standard

### Description
Returns the default initial chess board setup, including piece placement, turn, castling rights, and move counters.

### Method
GET

### Endpoint
/constants/standard

### Response
#### Success Response (200)
- **board** (Board) - The standard initial board configuration.
- **turn** (Side) - The starting side, set to white.
- **castlingRights** (SquareSet) - Initial castling rights for all corners.
- **halfmoves** (int) - Initial halfmove count set to 0.
- **fullmoves** (int) - Initial fullmove count set to 1.

#### Response Example
{
  "board": "Board.standard",
  "turn": "Side.white",
  "castlingRights": "SquareSet.corners",
  "halfmoves": 0,
  "fullmoves": 1
}
```

--------------------------------

### Initialize Atomic Position from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Atomic/Atomic.fromSetup.html

Creates an Atomic position from a Setup object. Throws a PositionSetupException if the setup is invalid, unless ignoreImpossibleCheck is set to true.

```dart
factory Atomic.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Atomic(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Create Castles Instance from Setup

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Castles/Castles.fromSetup.html

Use this factory constructor to initialize Castles based on the current board setup and castling rights. It iterates through sides to identify potential castling moves.

```dart
factory Castles.fromSetup(Setup setup) {
  Castles castles = Castles.empty;
  final rooks = setup.castlingRights & setup.board.rooks;
  for (final side in Side.values) {
    final backrank = SquareSet.backrankOf(side);
    final king = setup.board.kingOf(side);
    if (king == null || !backrank.has(king)) continue;
    final backrankRooks = rooks & setup.board.bySide(side) & backrank;
    if (backrankRooks.first != null && backrankRooks.first! < king) {
      castles = 
          castles._add(side, CastlingSide.queen, king, backrankRooks.first!)
    }
    if (backrankRooks.last != null && king < backrankRooks.last!) {
      castles = 
          castles._add(side, CastlingSide.king, king, backrankRooks.last!)
    }
  }
  return castles;
}
```

--------------------------------

### RacingKings.fromSetup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/RacingKings/RacingKings.fromSetup.html

Initializes a new RacingKings position from a given setup configuration.

```APIDOC
## RacingKings.fromSetup

### Description
Sets up a playable RacingKings position. Throws a PositionSetupException if the Setup does not meet basic validity requirements.

### Parameters
#### Arguments
- **setup** (Setup) - Required - The configuration object containing board, turn, halfmoves, and fullmoves data.
- **ignoreImpossibleCheck** (bool) - Optional - If true, skips the impossible check validation requirement.

### Implementation
```dart
factory RacingKings.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = RacingKings(
    board: setup.board,
    turn: setup.turn,
    castles: Castles.empty,
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```
```

--------------------------------

### Get Initial Position for Chess Rule

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position/initialPosition.html

Use this method to retrieve the starting board state for a given chess rule. Ensure the Rule enum is imported.

```dart
static Position initialPosition(Rule rule) {
  switch (rule) {
    case Rule.chess:
      return Chess.initial;
    case Rule.antichess:
      return Antichess.initial;
    case Rule.atomic:
      return Atomic.initial;
    case Rule.kingofthehill:
      return KingOfTheHill.initial;
    case Rule.threecheck:
      return ThreeCheck.initial;
    case Rule.crazyhouse:
      return Crazyhouse.initial;
    case Rule.horde:
      return Horde.initial;
    case Rule.racingKings:
      return RacingKings.initial;
  }
}
```

--------------------------------

### KingOfTheHill.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/KingOfTheHill/KingOfTheHill.fromSetup.html

Sets up a playable KingOfTheHill position from a Setup object. Throws PositionSetupException for invalid setups. Optionally ignores impossible check validation.

```dart
factory KingOfTheHill.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = KingOfTheHill(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```

--------------------------------

### Atomic.fromSetup Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Atomic/Atomic.fromSetup.html

Initializes a playable Atomic position from a Setup object with optional validation settings.

```APIDOC
## Atomic.fromSetup

### Description
Sets up a playable Atomic position. Throws a PositionSetupException if the Setup does not meet basic validity requirements.

### Parameters
#### Arguments
- **setup** (Setup) - Required - The configuration object containing board, pockets, turn, and move data.

#### Named Parameters
- **ignoreImpossibleCheck** (bool?) - Optional - If true, skips the impossible check requirement during validation.

### Implementation
```dart
factory Atomic.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Atomic(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.fromSetup(setup),
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```
```

--------------------------------

### static Position setupPosition

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position/setupPosition.html

Creates a Position object from a provided Setup and Rule configuration.

```APIDOC
## static Position setupPosition

### Description
Creates a Position from a Setup and Rule. This method handles the instantiation of specific chess variants based on the provided rule set.

### Parameters
- **rule** (Rule) - Required - The chess rule set to apply (e.g., chess, antichess, atomic, etc.).
- **setup** (Setup) - Required - The configuration setup for the board.
- **ignoreImpossibleCheck** (bool?) - Optional - Flag to ignore impossible check states during position creation.

### Response
- **Position** - Returns a new Position instance corresponding to the selected rule set.
```

--------------------------------

### Position Static Methods

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position-class.html

Details the static methods for creating initial or setup positions.

```APIDOC
## Static Methods

### initialPosition

```dart
initialPosition(Rule rule)
```

Returns the initial Position for the corresponding Rule.

### setupPosition

```dart
setupPosition(Rule rule, Setup setup, {bool? ignoreImpossibleCheck})
```

Create a Position from a Setup and Rule.
```

--------------------------------

### Chess Class Constructors

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Chess-class.html

Details on how to create new Chess instances, either from scratch or from a setup configuration.

```APIDOC
## Chess Constructor

### Description
Creates a new Chess position with specified board, turn, castling rights, en passant square, and move counters.

### Parameters
- **board** (Board) - Required - Piece positions on the board.
- **pockets** (Pockets?) - Optional - Pockets for chess variants like Crazyhouse.
- **turn** (Side) - Required - The side to move.
- **castles** (Castles) - Required - Castling rights and unmoved rooks.
- **epSquare** (Square?) - Optional - The en passant target square.
- **halfmoves** (int) - Required - Number of half-moves since the last capture or pawn move.
- **fullmoves** (int) - Required - Current move number.

### Request Example
```dart
var chess = Chess(board: board, pockets: pockets, turn: Side.white, castles: castles, epSquare: epSquare, halfmoves: 0, fullmoves: 1);
```

## Chess.fromSetup Constructor

### Description
Sets up a playable Chess position from a given Setup configuration. Optionally ignores impossible check conditions.

### Parameters
- **setup** (Setup) - Required - The setup configuration for the chess position.
- **ignoreImpossibleCheck** (bool?) - Optional - If true, ignores impossible check conditions during setup.

### Request Example
```dart
var chess = Chess.fromSetup(setup);
```
```

--------------------------------

### Define PositionSetupException.empty constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/PositionSetupException/empty-constant.html

Represents an exception caused by an empty setup state.

```dart
static const empty = PositionSetupException(IllegalSetupCause.empty);
```

--------------------------------

### Implement Setup.parseFen constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/Setup.parseFen.html

This factory constructor parses a FEN string into a Setup object, throwing a FenException if the input format is invalid.

```dart
factory Setup.parseFen(String fen) {
  final parts = fen.split(RegExp(r'[\s_]+'));
  if (parts.isEmpty) throw const FenException(IllegalFenCause.format);

  // board and pockets
  final boardPart = parts.removeAt(0);
  Pockets? pockets;
  Board board;
  if (boardPart.endsWith(']')) {
    final pocketStart = boardPart.indexOf('[');
    if (pocketStart == -1) {
      throw const FenException(IllegalFenCause.format);
    }
    board = Board.parseFen(boardPart.substring(0, pocketStart));
    pockets = _parsePockets(
        boardPart.substring(pocketStart + 1, boardPart.length - 1));
  } else {
    final pocketStart = _nthIndexOf(boardPart, '/', 7);
    if (pocketStart == -1) {
      board = Board.parseFen(boardPart);
    } else {
      board = Board.parseFen(boardPart.substring(0, pocketStart));
      pockets = _parsePockets(boardPart.substring(pocketStart + 1));
    }
  }

  // turn
  Side turn;
  if (parts.isEmpty) {
    turn = Side.white;
  } else {
    final turnPart = parts.removeAt(0);
    if (turnPart == 'w') {
      turn = Side.white;
    } else if (turnPart == 'b') {
      turn = Side.black;
    } else {
      throw const FenException(IllegalFenCause.turn);
    }
  }

  // Castling
  SquareSet castlingRights;
  if (parts.isEmpty) {
    castlingRights = SquareSet.empty;
  } else {
    final castlingPart = parts.removeAt(0);
    castlingRights = _parseCastlingFen(board, castlingPart);
  }

  // En passant square
  Square? epSquare;
  if (parts.isNotEmpty) {
    final epPart = parts.removeAt(0);
    if (epPart != '-') {
      epSquare = Square.parse(epPart);
      if (epSquare == null) {
        throw const FenException(IllegalFenCause.enPassant);
      }
    }
  }

  // move counters or remainingChecks
  String? halfmovePart = parts.isNotEmpty ? parts.removeAt(0) : null;
  (int, int)? earlyRemainingChecks;
  if (halfmovePart != null && halfmovePart.contains('+')) {
    earlyRemainingChecks = _parseRemainingChecks(halfmovePart);
    halfmovePart = parts.isNotEmpty ? parts.removeAt(0) : null;
  }
  final halfmoves = halfmovePart != null ? _parseSmallUint(halfmovePart) : 0;
  if (halfmoves == null) {
    throw const FenException(IllegalFenCause.halfmoveClock);
  }

  final fullmovesPart = parts.isNotEmpty ? parts.removeAt(0) : null;
  final fullmoves =
      fullmovesPart != null ? _parseSmallUint(fullmovesPart) : 1;
  if (fullmoves == null) {
    throw const FenException(IllegalFenCause.fullmoveNumber);
  }

  final remainingChecksPart = parts.isNotEmpty ? parts.removeAt(0) : null;
  (int, int)? remainingChecks;
  if (remainingChecksPart != null) {
    if (earlyRemainingChecks != null) {
      throw const FenException(IllegalFenCause.remainingChecks);
    }
    remainingChecks = _parseRemainingChecks(remainingChecksPart);
  } else if (earlyRemainingChecks != null) {
    remainingChecks = earlyRemainingChecks;
  }

  if (parts.isNotEmpty) {
    throw const FenException(IllegalFenCause.format);
  }

  return Setup(
    board: board,
    pockets: pockets,
    turn: turn,
    castlingRights: castlingRights,
    epSquare: epSquare,
    halfmoves: halfmoves,
    fullmoves: fullmoves,
    remainingChecks: remainingChecks,
  );
}
```

--------------------------------

### operator == method

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/operator_equals.html

Defines the equality relation for the Setup class by comparing board state properties.

```APIDOC
## operator ==

### Description
Overrides the default equality operator to compare two Setup objects based on their internal state (board, turn, castling rights, en passant square, and move counters).

### Method
Operator Overload

### Parameters
#### Path Parameters
- **other** (Object) - Required - The object to compare against the current instance.

### Implementation
```dart
@override
bool operator ==(Object other) {
  return identical(this, other) ||
      other is Setup &&
          other.board == board &&
          other.turn == turn &&
          other.castlingRights == castlingRights &&
          other.epSquare == epSquare &&
          other.halfmoves == halfmoves &&
          other.fullmoves == fullmoves;
}
```

### Response
- **bool** - Returns true if the objects are identical or if all relevant state properties match.
```

--------------------------------

### Define Crazyhouse Initial Position

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Crazyhouse/initial-constant.html

Use this constant to initialize a Crazyhouse game with the standard starting setup. It defines the board, empty pockets, white's turn, standard castling rights, and initial move counts.

```dart
static const initial = Crazyhouse(
  board: Board.standard,
  pockets: Pockets.empty,
  turn: Side.white,
  castles: Castles.standard,
  halfmoves: 0,
  fullmoves: 1,
);
```

--------------------------------

### KingOfTheHill Initial Constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/KingOfTheHill/initial-constant.html

Defines the starting configuration for a KingOfTheHill game instance.

```APIDOC
## KingOfTheHill.initial

### Description
Represents the starting state of a KingOfTheHill game, initializing the board, turn, castling rights, and move counters.

### Implementation
```dart
static const initial = KingOfTheHill(
  board: Board.standard,
  turn: Side.white,
  castles: Castles.standard,
  halfmoves: 0,
  fullmoves: 1,
);
```
```

--------------------------------

### Get FEN String - DartChess

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position/fen.html

Retrieves the FEN string for the current chess position. This method ensures the position is legal, unlike FEN from direct setup. It requires the board, pockets, turn, castling rights, en passant square, halfmove clock, and fullmove number.

```dart
String get fen {
  return Setup(
    board: board,
    pockets: pockets,
    turn: turn,
    castlingRights: castles.castlingRights,
    epSquare: _legalEpSquare(),
    halfmoves: halfmoves,
    fullmoves: fullmoves,
  ).fen;
}
```

--------------------------------

### PositionSetupException.variant Constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/PositionSetupException/variant-constant.html

Provides the static constant for identifying illegal setup causes related to chess variants.

```APIDOC
## Constant: PositionSetupException.variant

### Description
A static constant representing a PositionSetupException triggered by an illegal chess variant configuration.

### Implementation
```dart
static const variant = PositionSetupException(IllegalSetupCause.variant);
```
```

--------------------------------

### ThreeCheck Initial Constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/ThreeCheck/initial-constant.html

The 'initial' constant defines the standard starting position for a ThreeCheck game.

```APIDOC
## ThreeCheck Initial Constant

### Description
The initial position of a ThreeCheck game.

### Implementation
```dart
static const initial = ThreeCheck(
  board: Board.standard,
  turn: Side.white,
  castles: Castles.standard,
  halfmoves: 0,
  fullmoves: 1,
  remainingChecks: _defaultRemainingChecks,
);
```
```

--------------------------------

### Horde.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Horde/Horde.fromSetup.html

Sets up a playable Horde position. Optionally pass `ignoreImpossibleCheck` to skip validity requirements.

```APIDOC
## Horde.fromSetup Factory Constructor

### Description
Sets up a playable Horde position. Throws a PositionSetupException if the Setup does not meet basic validity requirements. Optionally pass `ignoreImpossibleCheck` if you want to skip that requirement.

### Method
Factory Constructor

### Endpoint
N/A (Dart Class Method)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```dart
// Example usage (assuming Setup class is defined elsewhere)
// final setup = Setup(...);
// final hordePosition = Horde.fromSetup(setup, ignoreImpossibleCheck: true);
```

### Response
#### Success Response (Instance of Horde)
- **Horde** (Instance) - A new Horde position object.

#### Response Example
```dart
// Example of a successful response (Horde object)
// Horde(board: ..., turn: ..., ...)
```

### Error Handling
- **PositionSetupException**: Thrown if the `Setup` does not meet basic validity requirements.
```

--------------------------------

### Setup.parseFen Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/Setup.parseFen.html

Parses a Forsyth-Edwards-Notation string and returns a Setup object. The parser is relaxed and supports X-FEN, Shredder-FEN, and handles missing fields with default values.

```APIDOC
## Setup.parseFen Factory Constructor

### Description
Parses a Forsyth-Edwards-Notation string and returns a Setup object. The parser is relaxed, supporting X-FEN and Shredder-FEN for castling rights, and accepting missing FEN fields by filling them with default values.

### Method
Factory Constructor

### Parameters
#### Path Parameters
- **fen** (String) - Required - The Forsyth-Edwards-Notation string to parse.

### Request Example
```json
{
  "fen": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
}
```

### Response
#### Success Response (Setup Object)
- **board** (Board) - The board state.
- **pockets** (Pockets) - The pockets state (optional).
- **turn** (Side) - The current turn (white or black).
- **castlingRights** (SquareSet) - The castling rights.
- **epSquare** (Square) - The en passant square (optional).
- **halfmoves** (int) - The halfmove clock.
- **fullmoves** (int) - The fullmove number.
- **remainingChecks** (Tuple<int, int>) - The remaining checks (optional).

#### Response Example
```json
{
  "board": { ... },
  "pockets": { ... },
  "turn": "white",
  "castlingRights": { ... },
  "epSquare": null,
  "halfmoves": 0,
  "fullmoves": 1,
  "remainingChecks": null
}
```

### Throws
- **FenException** - If the provided FEN string is not valid, with specific causes like `IllegalFenCause.format`, `IllegalFenCause.turn`, `IllegalFenCause.enPassant`, `IllegalFenCause.halfmoveClock`, `IllegalFenCause.fullmoveNumber`, or `IllegalFenCause.remainingChecks`.
```

--------------------------------

### RacingKings Initial Constant

Source: https://pub.dev/documentation/dartchess/latest/dartchess/RacingKings/initial-constant.html

Defines the starting configuration for a RacingKings game, including board state, turn, and move counters.

```APIDOC
## RacingKings Initial Constant

### Description
Represents the starting position of a RacingKings game.

### Implementation
```dart
static const initial = RacingKings(
  board: Board.racingKings,
  turn: Side.white,
  castles: Castles.empty,
  halfmoves: 0,
  fullmoves: 1,
);
```
```

--------------------------------

### Side get opposite

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Side/opposite.html

Gets the opposite side (e.g., if the current side is white, it returns black, and vice versa).

```APIDOC
## Side get opposite

### Description
Gets the opposite side.

### Implementation
```dart
Side get opposite => this == Side.white ? Side.black : Side.white;
```
```

--------------------------------

### Static Method: startingPosition

Source: https://pub.dev/documentation/dartchess/latest/dartchess/PgnGame-class.html

Creates a chess position from PGN headers.

```APIDOC
## Static Method: startingPosition

### Description
Creates a Position object for a variant based on the provided PGN headers.

### Parameters
#### Query Parameters
- **headers** (PgnHeaders) - Required - The headers of the game.
- **ignoreImpossibleCheck** (bool) - Optional - Flag to ignore impossible check states.

### Response
#### Success Response (200)
- **Position** - The initialized chess position.
```

--------------------------------

### Get Material Count by Role

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Board/materialCount.html

Gets the number of pieces of each Role for the given Side. This implementation efficiently maps each role to its count.

```dart
IMap<Role, int> materialCount(Side side) => IMap.fromEntries(
    Role.values.map((role) => MapEntry(role, piecesOf(side, role).size)));
```

--------------------------------

### Get UCI Notation for a Move

Source: https://pub.dev/documentation/dartchess/latest/dartchess/NormalMove/uci.html

Returns the UCI notation for a chess move. Use this to get a standardized string representation of a move, including promotions.

```dart
@override
String get uci =>
    from.name + to.name + (promotion != null ? promotion!.letter : '');
```

--------------------------------

### File Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/File/File.html

Initializes a new File object representing a chessboard file index.

```APIDOC
## File Constructor

### Description
Gets the chessboard File from a file index between 0 and 7.

### Parameters
#### Path Parameters
- **value** (int) - Required - A file index between 0 and 7.

### Request Example
const File(0);
```

--------------------------------

### Create Empty PgnHeaders

Source: https://pub.dev/documentation/dartchess/latest/dartchess/PgnGame/emptyHeaders.html

Use this static method to create an empty map for PGN headers. No setup is required.

```dart
static PgnHeaders emptyHeaders() => <String, String>{};
```

--------------------------------

### Get Role Letter

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Role/letter.html

Gets the role letter in lowercase, as used for black pieces in FEN notation. This getter maps each Role enum value to its corresponding character.

```dart
String get letter => switch (this) {
      Role.pawn => 'p',
      Role.knight => 'n',
      Role.bishop => 'b',
      Role.rook => 'r',
      Role.queen => 'q',
      Role.king => 'k',
    };
```

--------------------------------

### Get Piece at Square - DartChess

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Board/pieceAt.html

Use this method to get the Piece at a specific Square. It returns null if no piece is present. Requires sideAt and roleAt methods to be available.

```dart
Piece? pieceAt(Square square) {
  final side = sideAt(square);
  if (side == null) {
    return null;
  }
  final role = roleAt(square)!;
  final prom = promoted.has(square);
  return Piece(color: side, role: role, promoted: prom);
}
```

--------------------------------

### Get Rook Square by Side and Castling Side

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Castles/rookOf.html

Use this method to get the Square of a specific rook. It requires the side (white/black) and castling side (queen/king) to identify the rook.

```dart
Square? rookOf(Side side, CastlingSide cs) => switch (side) {
      Side.white => switch (cs) {
          CastlingSide.queen => _whiteRookQueenSide,
          CastlingSide.king => _whiteRookKingSide,
        },
      Side.black => switch (cs) {
          CastlingSide.queen => _blackRookQueenSide,
          CastlingSide.king => _blackRookKingSide,
        },
    };
```

--------------------------------

### Implement withPromotion Method

Source: https://pub.dev/documentation/dartchess/latest/dartchess/NormalMove/withPromotion.html

Returns a copy of the move with a specified promotion role. Use when a pawn promotes to another piece.

```dart
NormalMove withPromotion(Role? promotion) =>
    NormalMove(from: from, to: to, promotion: promotion);
```

--------------------------------

### Antichess.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Antichess/Antichess.fromSetup.html

This factory constructor creates an Antichess position from a `Setup` object. It optionally accepts `ignoreImpossibleCheck` to bypass basic validity requirements.

```APIDOC
## Antichess.fromSetup

### Description
Sets up a playable Antichess position from a `Setup` object. Throws a `PositionSetupException` if the `Setup` does not meet basic validity requirements. Optionally pass `ignoreImpossibleCheck` if you want to skip that requirement.

### Method
Factory Constructor

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
None

### Response
#### Success Response (200)
An `Antichess` object representing the configured position.

#### Response Example
None

### Implementation Details
```dart
factory Antichess.fromSetup(Setup setup, {bool? ignoreImpossibleCheck}) {
  final pos = Antichess(
    board: setup.board,
    pockets: setup.pockets,
    turn: setup.turn,
    castles: Castles.empty,
    epSquare: _validEpSquare(setup),
    halfmoves: setup.halfmoves,
    fullmoves: setup.fullmoves,
  );
  pos.validate(ignoreImpossibleCheck: ignoreImpossibleCheck);
  return pos;
}
```
```

--------------------------------

### GET /rule

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position/rule.html

Retrieves the rule associated with the current position.

```APIDOC
## GET /rule

### Description
Retrieves the rule of the current position.

### Method
GET

### Endpoint
/rule

### Implementation
Rule get rule;
```

--------------------------------

### Create Position from PGN Headers

Source: https://pub.dev/documentation/dartchess/latest/dartchess/PgnGame/startingPosition.html

Use this static method to create a chess position from PGN headers. It supports 'Variant' and 'Fen' keys. Throws `PositionSetupException` if the setup is invalid. Ensure the 'Variant' header is present.

```dart
static Position startingPosition(PgnHeaders headers,
    {bool? ignoreImpossibleCheck}) {
  final rule = Rule.fromPgn(headers['Variant']);
  if (rule == null) throw PositionSetupException.variant;
  if (!headers.containsKey('FEN')) {
    return Position.initialPosition(rule);
  }
  final fen = headers['FEN']!;
  try {
    return Position.setupPosition(rule, Setup.parseFen(fen),
        ignoreImpossibleCheck: ignoreImpossibleCheck);
  } catch (err) {
    rethrow;
  }
}
```

--------------------------------

### GET bySide

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Board/bySide.html

Retrieves all squares occupied by the specified side.

```APIDOC
## GET bySide

### Description
Gets all squares occupied by the specified Side (white or black).

### Method
GET

### Parameters
#### Path Parameters
- **side** (Side) - Required - The side to query (Side.white or Side.black).

### Request Example
bySide(Side.white)

### Response
#### Success Response (200)
- **SquareSet** - A set of squares occupied by the requested side.
```

--------------------------------

### GET squaresReversed

Source: https://pub.dev/documentation/dartchess/latest/dartchess/SquareSet/squaresReversed.html

Retrieves the squares in the set as an iterable in reverse order.

```APIDOC
## GET squaresReversed

### Description
Returns the squares in the set as an iterable in reverse order.

### Method
GET

### Endpoint
squaresReversed

### Response
- **Iterable<Square>** - An iterable containing the squares in reverse order.
```

--------------------------------

### GET size property

Source: https://pub.dev/documentation/dartchess/latest/dartchess/SquareSet/size.html

Retrieves the number of squares currently in the set.

```APIDOC
## GET size

### Description
Returns the total number of squares in the set.

### Method
GET

### Endpoint
/size

### Response
#### Success Response (200)
- **size** (int) - The number of squares in the set.
```

--------------------------------

### GET /isNotEmpty

Source: https://pub.dev/documentation/dartchess/latest/dartchess/SquareSet/isNotEmpty.html

Retrieves the boolean status indicating if the set is not empty.

```APIDOC
## GET /isNotEmpty

### Description
Returns a boolean value indicating whether the set is not empty.

### Method
GET

### Endpoint
/isNotEmpty

### Response
#### Success Response (200)
- **isNotEmpty** (bool) - Returns true if the set is not empty, false otherwise.
```

--------------------------------

### Create a Position using setupPosition

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Position/setupPosition.html

Initializes a game position by mapping a Rule to its corresponding variant implementation.

```dart
static Position setupPosition(Rule rule, Setup setup,
    {bool? ignoreImpossibleCheck}) {
  switch (rule) {
    case Rule.chess:
      return Chess.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.antichess:
      return Antichess.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.atomic:
      return Atomic.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.kingofthehill:
      return KingOfTheHill.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.crazyhouse:
      return Crazyhouse.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.threecheck:
      return ThreeCheck.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.horde:
      return Horde.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
    case Rule.racingKings:
      return RacingKings.fromSetup(setup,
          ignoreImpossibleCheck: ignoreImpossibleCheck);
  }
}
```

--------------------------------

### KingOfTheHill.fromSetup Factory Constructor

Source: https://pub.dev/documentation/dartchess/latest/dartchess/KingOfTheHill/KingOfTheHill.fromSetup.html

Creates a playable KingOfTheHill position from a given setup. It includes an optional parameter to ignore impossible check validations.

```APIDOC
## KingOfTheHill.fromSetup Factory Constructor

### Description
Sets up a playable KingOfTheHill position. Throws a PositionSetupException if the Setup does not meet basic validity requirements. Optionally pass `ignoreImpossibleCheck` if you want to skip that requirement.

### Method
Factory Constructor

### Endpoint
N/A (Class Method)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (200)
- **KingOfTheHill** (object) - An instance of the KingOfTheHill class representing the setup position.

#### Response Example
```dart
// Example usage (assuming Setup class is defined elsewhere)
// final setup = Setup(...);
// final kingOfTheHillGame = KingOfTheHill.fromSetup(setup, ignoreImpossibleCheck: true);
```
```

--------------------------------

### Initialize File with index

Source: https://pub.dev/documentation/dartchess/latest/dartchess/File/File.html

Creates a File object using an integer index. The index must be between 0 and 7 inclusive.

```dart
const File(this.value) : assert(value >= 0 && value < 8);
```

--------------------------------

### GET turnLetter property

Source: https://pub.dev/documentation/dartchess/latest/dartchess/Setup/turnLetter.html

Retrieves the FEN character for the side to move.

```APIDOC
## GET turnLetter

### Description
Returns the FEN character representing the side currently to move.

### Method
GET

### Response
- **turnLetter** (String) - The FEN character for the side to move (e.g., 'w' or 'b').
```
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