commit f8fad902471361958668d7f16dc4e535b6d54e17
Author: nihilazo <nico@itwont.work>
Date:   Wed Mar 30 20:08:45 2022 +0100

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4e0e3a0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+compiled/*
+*~
diff --git a/main.rkt b/main.rkt
new file mode 100644
index 0000000..efd4105
--- /dev/null
+++ b/main.rkt
@@ -0,0 +1,95 @@
+#lang racket
+
+(require rackunit)
+
+; a Board is a list of lines.
+
+; represents a point in 2d space.
+(struct point (x y) #:transparent)
+
+; represents a line drawn from one point to another and which player drew it.
+(struct line (from to player) #:transparent)
+
+; width and height of the playing grid.
+(define GRID-WIDTH 6)
+(define GRID-HEIGHT 6)
+
+; Board -> Image
+; renders the game board.
+(define (draw board) board)
+
+; Line Line -> Bool
+; tests if two lines are in the same position
+(define (same-position? l1 l2)
+  (or
+   (and
+    (equal? (line-from l1) (line-from l2))
+    (equal? (line-to l1) (line-to l2)))
+   (and
+    (equal? (line-to l1) (line-from l2))
+    (equal? (line-from l1) (line-to l2)))))
+
+(test-case
+ "same-position?"
+ (check-true (same-position? (line (point 0 0) (point 0 1) 1)
+                             (line (point 0 0) (point 0 1) 0)))
+ (check-true (same-position? (line (point 0 0) (point 0 1) 1)
+                             (line (point 0 1) (point 0 0) 0)))
+ (check-true (same-position? (line (point 0 2) (point 0 1) 0)
+                             (line (point 0 2) (point 0 1) 0)))
+ (check-false (same-position? (line (point 0 0) (point 0 1) 1)
+                              (line (point 2 4) (point 0 3) 0))))
+ 
+               
+
+; Line -> Bool
+; returns #t if a line is valid in terms of length (only moving one point in one direction)
+(define (valid-length? line)
+  (= 1
+     (+ (abs (- (point-x (line-from line)) (point-x (line-to line))))
+        (abs (- (point-y (line-from line)) (point-y (line-to line)))))))
+
+(test-case
+ "valid-length?"
+ (check-true (valid-length? (line (point 0 0) (point 0 1) 1)))
+ (check-true (valid-length? (line (point 0 1) (point 0 0) 1)))
+ (check-false (valid-length? (line (point 0 0) (point 1 1) 0)))
+ (check-false (valid-length? (line (point 0 0) (point 0 2) 1)))
+ (check-false (valid-length? (line (point 0 0) (point 0 2) 1))))
+
+; Point -> Bool
+; returns #t if a point is out of bounds (off the edge of the grid)
+(define (out-of-bounds? p)
+  (or
+   (> 0 (point-x p))
+   (> 0 (point-y p))
+   (< (- GRID-WIDTH 1) (point-x p))
+   (< (- GRID-WIDTH 1) (point-y p))))
+
+(test-case
+ "out-of-bounds?"
+ (check-false (out-of-bounds? (point 0 0)))
+ (check-false (out-of-bounds? (point 0 (- GRID-WIDTH 1))))
+ (check-true (out-of-bounds? (point GRID-WIDTH 0)))
+ (check-true (out-of-bounds? (point -2 0)))
+ (check-true (out-of-bounds? (point 0 -2))))
+
+; Line Board -> Bool
+; returns #t if adding the given move to the board is valid.
+(define (valid-move? line board)
+  (and
+   (empty? (filter (lambda (l) (same-position? l line)) board)) ; line doesn't already exist on board
+   (valid-length? line)
+   (and
+    (not (out-of-bounds? (line-from line)))
+    (not (out-of-bounds? (line-to line))))))
+
+(test-case
+ "valid-move?"
+ (define board (list (line (point 0 0) (point 0 1) 1) (line (point 0 1) (point 0 2) 0) (line (point 3 2) (point 3 3) 0)))
+ (check-false (valid-move? (line (point 0 0) (point 0 1) 1) board))
+ (check-true (valid-move? (line (point 0 2) (point 0 3) 0) board))  ; not overwriting existing moves
+ (check-false (valid-move? (line (point 0 0) (point 0 2) 1) board)) ; valid length check
+ (check-false (valid-move? (line (point (+ GRID-WIDTH 1) 0) (point 0 2) 1) board))
+ (check-false (valid-move? (line (point (+ GRID-WIDTH 1) 0) (point 0 2) 1) board)) ; out of bounds
+ )
\ No newline at end of file