// McCooey Chess
// Copyright 2020, Jay M. Coskey, except functions drawn from Chess.lud, as noted

//----------------------------------------
// General functions
//----------------------------------------

// Source: Chess.lud - CaptureToPieceAndResetCounter
(define "CaptureToPieceAndResetCounter"
    (apply
        (if ("IsEnemyAt" (to))
            (remove (to)
                (then (set Counter))
            )
        )
    )
)

// Usage: ("Directions" <p1_directions> <p2_directions>)
(define "Directions"
    ("P12" (directions #1) (directions #2))
)

(define "IsFromInStartCell"
    (is In (from) (sites Start (piece (what at:(from)))))
)

(define "IsToEmpty"
    (is In (to) (sites Empty))
)

(define "IsToEmptyOrEnemy"
    (or "IsToEmpty"
        ("IsEnemyAt" (to))
    )
)

// Usage: ("P12" <player1_arg> <player2_arg>)
(define "P12"
    (if (is Mover P1) #1 #2)
)

// Usage: ("SlideCaptureMove" <direction> <then>)
(define "SlideCaptureMove"
    (move Slide
        #1
        (to if:("IsEnemyAt" (to))
            "CaptureToPieceAndResetCounter"
        )
        #2
    )
)

//----------------------------------------
// King movement
//----------------------------------------

// Usage: ("KingCaptureStep" <direction> <then>)
(define "KingCaptureStep"
    (move Step
        #1
        (to if:"IsToEmptyOrEnemy"
            "CaptureToPieceAndResetCounter"
        )
        #2
    )
)

//----------------------------------------
// Pawn movement
// Note: Counter is reset in (piece "Pawn" ...).
//----------------------------------------

// Source: Derived from Chess.lud - DoubleStep
// Usage: ("PawnHop" <fwd_dir> <back_dir>)
(define "PawnHop"
    (move Hop
        #1
        (between if:(is In (between) (sites Empty)))
        (to if:"IsToEmpty")
        (then (and
                {
                (set Pending (ahead (last To) #2))
                (set Var (last To))
                }
        ))
    )
)

// Source: Chess.lud - CaptureForwardDiagonal
(define "PawnCapture_Diag"
    (move Step
        ("Directions" {NNW NNE} {SSW SSE})
        (to if:("IsEnemyAt" (to))
            (apply (remove (to)))
        )
    )
)

(define "PawnStep_Double"
    ("PawnHop" Forward Backward)
)

//----------------------------------------
// Pawn movement: En passant
// - Save skipped-over spaces in Pending
// - Save location of last-moved Pawn in Var.
// Note: Counter is reset in (piece "Pawn" ...).
//----------------------------------------

// Usage: ("EnPassant_Base" <directions>)
(define "EnPassant_Base"
    (move Step
        #1
        (to if:"IsEnPassantCapture")
        (then (remove (var)))
    )
)

(define "EnPassant_Diag"
    ("EnPassant_Base" ("Directions" {NNW NNE} {SSW SSE}))
)

(define "IsEnPassantCapture"
    (and
        (is Pending)
        (= (to) (value Pending))
    )
)

//----------------------------------------
// Pawn promotion
//----------------------------------------

// Usage: ("PromoteTo" <piece_types>)
(define "PromoteTo"
    (move Promote (last To) #1 Mover)
)

//------------------------------------------------------------------------------

(game "McCooey Chess"
    ("TwoPlayersNorthSouth")
    (equipment {
        (board (rotate 90 (hex 6)))
        
        (piece "King" Each ("KingCaptureStep" All ~))
        (piece "Queen" Each ("SlideCaptureMove" All ~))
        (piece "Rook" Each ("SlideCaptureMove" Orthogonal ~))
        (piece "Bishop" Each ("SlideCaptureMove" Diagonal ~))
        (piece "Knight" Each (move Leap
                "KnightWalk"
                (to if:"IsToEmptyOrEnemy"
                    "CaptureToPieceAndResetCounter"
                )
            )
        )
        
        (piece "Pawn" Each
            (or {
                "StepForwardToEmpty"
                (if (and
                        "IsFromInStartCell"
                        (not (is In (from) (sites Mover "CentrePawnStartCell")))
                    )
                    "PawnStep_Double"
                )
                "PawnCapture_Diag"
                "EnPassant_Diag"
                }
                (then
                    (and
                        (if (is In (last To) (sites Mover "PromotionZone"))
                            (moveAgain)
                        )
                        (set Counter)
                    )
                )
            )
        )
        
        (regions "CentrePawnStartCell" P1 (sites {"D4"}))
        (regions "CentrePawnStartCell" P2 (sites {"H8"}))
        
        (regions "PromotionZone" P1 (union (sites Side NW) (sites Side NE)))
        (regions "PromotionZone" P2 (union (sites Side SW) (sites Side SE)))
        
        (regions "Region-Dark" (sites Phase 0))
        (regions "Region-Light" (sites Phase 2))
        (regions "Region-Medium" (sites Phase 1))
    })
    
    (rules
        (start {
            (place "King1" coord:"B1")
            (place "Queen1" coord:"A2")
            (place "Rook1" {"A3" "C1"})
            (place "Bishop1" {"A1" "B2" "C3"})
            (place "Knight1" {"B3" "C2"})
            
            (place "King2" coord:"K10")
            (place "Queen2" coord:"J11")
            (place "Rook2" {"I11" "K9"})
            (place "Bishop2" {"K11" "J10" "I9"})
            (place "Knight2" {"I10" "J9"})
            
            (place "Pawn1" {"A4" "B4" "C4" "D4" "D3" "D2" "D1"})
            (place "Pawn2" {"H11" "H10" "H9" "H8" "I8" "J8" "K8"})
        })
        phases:{
        (phase "Movement"
            (play
                (if ("SameTurn")
                    ("PromoteTo" (piece {"Queen" "Rook" "Bishop" "Knight"}))
                    (do (forEach Piece)
                        ifAfterwards:(not ("IsInCheck" "King" Mover))
                    )
                )
            )
            (end {
                ("Checkmate" "King")
                (if (or
                        (no Moves Mover)
                        (= (counter) 100)
                    )
                    (result Mover Draw)
                )
            })
        )
        }
    )
)

//------------------------------------------------------------------------------

(metadata
    
    (info
        {
        (description "A chess variant played on boards made of hexagons invented by Dave McCooey and Richard Honeycutt in 1978-1979.")
        (aliases {"McCooey's Chess" "Hexagonal Chess"})
        (rules "McCooey Chess is played on a hexagonal board with each side having length 6, and each space oriented horizontally. The board has has 91 spaces.
            
            Piece Movement:
            * All pieces other than Pawns move as in Glinski Chess.
            - Kings step one space in any of the 12 directions. They do not castle.
            - Queens slide in any of the 12 directions.
            - Rooks slide in any of the 6 adjacent direction.
            - Bishops slide in any of the 6 'diagonal' directions.
            - Knights move two spaces in any adjacent direction, then one space in another direction.
            * Pawns can advance one space forward without capturing. A Pawn on a Pawn start space but not in the innermost column can advance two spaces forward without capturing. Pawns capture 'diagonally forward' (i.e., to a space ahead connected by an edge, and having the same colour). En Passant capture and Pawn promotion take place as in Glinski Chess.
            
        The game ends on a checkmate or stalemate.")
        (id "857")
        (source "For a comparison of popular versions of hexagonal chess, see <a href=\"https://en.wikipedia.org/wiki/Hexagonal_chess\" target=\"_blank\" class=\"style1\" style=\"color: #0000EE\" />Wikipedia</a>. For more details on other chess variants, see The Classified Encyclopedia of Chess Variants, by D. B. Pritchard (2nd edition, completed and edited by John Beasley, 2007).")
        (version "1.3.12")
        (classification "board/war/replacement/checkmate/chess")
        (author "Dave McCooey and Richard Honeycutt")
        (credit "Jay Coskey, with some small functions drawn from Chess.lud, by Eric Piette")
        (date "1978")
        }
    )
    
    (graphics {
        (piece Scale "Pawn" 0.7)
        (piece Scale "King" 0.8)
        (piece Scale "Knight" 0.8)
        (piece Scale "Queen" 0.8)
        (piece Scale "Bishop" 0.8)
        (piece Scale "Rook" 0.8)
        (board Style Chess)
        
        (region Colour "Region-Dark" (colour "#b5651d"))
        (region Colour "Region-Light" (colour "#fff8dc"))
        (region Colour "Region-Medium" (colour "#daae7c"))
    })
    
    (ai
        "McCooey Chess_ai"
    )
)