Implement 'isAttackedBy' logic in Ultima; but is that required?

diff --git a/public/javascripts/variants/Ultima.js b/public/javascripts/variants/Ultima.js
index d667643..b3679f7 100644 (file)
--- a/public/javascripts/variants/Ultima.js
+++ b/public/javascripts/variants/Ultima.js
@@ -370,35 +370,130 @@ class UltimaRules extends ChessRules
        isAttackedByPawn([x,y], colors)
        {
                // Square (x,y) must be surrounded by two enemy pieces,
-               // and one of them at least should be a pawn
+               // and one of them at least should be a pawn.
+               const dirs = [ [1,0],[0,1],[1,1],[-1,1] ];
+               const [sizeX,sizeY] = VariantRules.size;
+               for (let dir of dirs)
+               {
+                       const [i1,j1] = [x-dir[0],y-dir[1]]; //"before"
+                       const [i2,j2] = [x+dir[0],y+dir[1]]; //"after"
+                       if (i1>=0 && i1<sizeX && i2>=0 && i2<sizeX
+                               && j1>=0 && j1<sizeY && j2>=0 && j2<sizeY
+                               && this.board[i1][j1]!=VariantRules.EMPTY
+                               && this.board[i2][j2]!=VariantRules.EMPTY
+                               && colors.includes(this.getColor(i1,j1))
+                               && colors.includes(this.getColor(i2,j2))
+                               && [this.getPiece(i1,j1),this.getPiece(i2,j2)].includes(VariantRules.PAWN))
+                       {
+                               return true;
+                       }
+               }
                return false;
        }
 
-       isAttackedByRook(sq, colors)
+       isAttackedByRook([x,y], colors)
        {
-               // Enemy king must be on same file and a rook on same row (or reverse)
+               const [sizeX,sizeY] = VariantRules.size;
+               // King must be on same column and a rook on same row (or reverse)
+               if (x == this.kingPos[colors[0]][0]) //using colors[0], only element in this case
+               {
+                       // Look for enemy rook on this column
+                       for (let i=0; i<sizeY; i++)
+                       {
+                               if (this.board[x][i] != VariantRules.EMPTY
+                                       && colors.includes(this.getColor(x,i))
+                                       && this.getPiece(x,i) == VariantRules.ROOK)
+                               {
+                                       return true;
+                               }
+                       }
+               }
+               else if (y == this.kingPos[colors[0]][1])
+               {
+                       // Look for enemy rook on this row
+                       for (let i=0; i<sizeX; i++)
+                       {
+                               if (this.board[i][y] != VariantRules.EMPTY
+                                       && colors.includes(this.getColor(i,y))
+                                       && this.getPiece(i,y) == VariantRules.ROOK)
+                               {
+                                       return true;
+                               }
+                       }
+               }
                return false;
        }
 
-       isAttackedByKnight(sq, colors)
+       isAttackedByKnight([x,y], colors)
        {
                // Square (x,y) must be on same line as a knight,
                // and there must be empty square(s) behind.
+               const V = VariantRules;
+               const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+               const [sizeX,sizeY] = V.size;
+               for (let step of steps)
+               {
+                       const [i0,j0] = [x+step[0],y+step[1]];
+                       if (i0>=0 && i0<sizeX && j0>=0 && j0<sizeY && this.board[i0][j0] == V.EMPTY)
+                       {
+                               // Try in opposite direction:
+                               let [i,j] = [x-step[0],y-step[1]];
+                               while (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j] == V.EMPTY)
+                               {
+                                       i -= step[0];
+                                       j -= step[1];
+                               }
+                               if (i>=0 && i<sizeX && j>=0 && j<sizeY && colors.includes(this.getColor(i,j))
+                                       && this.getPiece(i,j) == V.KNIGHT)
+                               {
+                                       return true;
+                               }
+                       }
+               }
                return false;
        }
 
-       isAttackedByBishop(sq, colors)
+       isAttackedByBishop([x,y], colors)
        {
-               // switch on piece nature on square sq: a chameleon attack as this piece
-               // ==> call the appropriate isAttackedBy... (exception of immobilizers)
-               // Other exception: a chameleon cannot attack a chameleon (seemingly...)
+               // We cheat a little here: since this function is used exclusively for king,
+               // it's enough to check the immediate surrounding of the square.
+               const V = VariantRules;
+               const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+               const [sizeX,sizeY] = V.size;
+               for (let step of adjacentSteps)
+               {
+                       const [i,j] = [x+step[0],y+step[1]];
+                       if (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j]!=V.EMPTY
+                               && colors.includes(this.getColor(i,j)) && this.getPiece(i,j) == V.BISHOP)
+                       {
+                               return true;
+                       }
+               }
                return false;
        }
 
-       isAttackedByQueen(sq, colors)
+       isAttackedByQueen([x,y], colors)
        {
                // Square (x,y) must be adjacent to a queen, and the queen must have
                // some free space in the opposite direction from (x,y)
+               const V = VariantRules;
+               const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
+               const [sizeX,sizeY] = V.size;
+               for (let step of adjacentSteps)
+               {
+                       const sq2 = [x+2*step[0],y+2*step[1]];
+                       if (sq2[0]>=0 && sq2[0]<sizeX && sq2[1]>=0 && sq2[1]<sizeY
+                               && this.board[sq2[0]][sq2[1]] == V.EMPTY)
+                       {
+                               const sq1 = [x+step[0],y+step[1]];
+                               if (this.board[sq1[0]][sq1[1]] != V.EMPTY
+                                       && colors.includes(this.getColor(sq1[0],sq1[1]))
+                                       && this.getPiece(sq1[0],sq1[1]) == V.QUEEN)
+                               {
+                                       return true;
+                               }
+                       }
+               }
                return false;
        }