From e238c3df5ead21be7868e649dc405b54793ad4eb Mon Sep 17 00:00:00 2001
From: Joop Kiefte <ikojba@gmail.com>
Date: Sun, 20 Sep 2020 08:02:33 +0200
Subject: Fix wall kicks

---
 go.mod       |  5 ++++-
 go.sum       |  2 ++
 tris/move.go | 37 ++++++++++++++++---------------------
 3 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/go.mod b/go.mod
index ac56704..22c3b57 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module git.kiefte.eu/lapingvino/clitris
 
 go 1.15
 
-require github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03
+require (
+	github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03
+	golang.org/x/sys v0.0.0-20200918174421-af09f7315aff // indirect
+)
diff --git a/go.sum b/go.sum
index ea41137..91fa815 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,4 @@
 github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03 h1:pd4YKIqCB0U7O2I4gWHgEUA2mCEOENmco0l/bM957bU=
 github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03/go.mod h1:Z9+Ul5bCbBKnbCvdOWbLqTHhJiYV414CURZJba6L8qA=
+golang.org/x/sys v0.0.0-20200918174421-af09f7315aff h1:1CPUrky56AcgSpxz/KfgzQWzfG09u5YOL8MvPYBlrL8=
+golang.org/x/sys v0.0.0-20200918174421-af09f7315aff/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
diff --git a/tris/move.go b/tris/move.go
index c5ba1ef..927645f 100644
--- a/tris/move.go
+++ b/tris/move.go
@@ -20,24 +20,24 @@ var LCW = Kicks{
 }
 
 // Try all possible kicks
-func (ks Kicks) Try(rot Rotation, reverse bool, p Placement, f Field) (np Placement) {
-	orot := (rot + 3)%4
-	if reverse { // for going backwards, you start from one more
-		rot--
-		orot = (rot + 1)%4
+func (ks Kicks) Try(p, np Placement, f Field) Placement {
+	direction := (np.Rot - p.Rot + 4) % 4
+	rot := np.Rot
+	factor := 1
+	if direction == Spawn {
+		factor = 0
 	}
+	if direction == CounterClockwise {
+		rot = (rot + 1) % 4
+		factor = -1
+	}
+	x, y := np.X, np.Y
 	for _, k := range ks[rot] {
-		np = p
-		x, y := k.X, k.Y
-		if reverse {
-			x, y = -x, -y
-		}
-		np.X, np.Y = p.X+x, p.Y+y
+		np.X, np.Y = x + k.X * factor, y + k.Y * factor
 		if !np.Collide(f) {
 			return np
 		}
 	}
-	p.Rot = orot
 	return p
 }
 
@@ -48,12 +48,6 @@ func (p Placement) Floor(f Field) bool {
 	return fp.Collide(f)
 }
 
-// CW checks if the rotation from r to nr is a Clockwise rotation
-func (r Rotation) CW(nr Rotation) bool {
-	r += 4
-	return (r - nr)%4 == 1 // if nr is 1 modulo 4 higher than r, it is a CW rotation
-}
-
 // Move tries the move indicated by the parameters, applies kicks to fix when it doesn't work,
 // and returns if the piece is on the floor or topping out
 func (p Placement) Move(f Field, rot Rotation, x, y int) (np Placement, floor, topout bool) {
@@ -67,12 +61,13 @@ func (p Placement) Move(f Field, rot Rotation, x, y int) (np Placement, floor, t
 	// start handling kicks
 	switch p.piece {
 	case IPiece:
-		np = LCW.Try(rot, np.Rot.CW(rot), np, f)
+		np = LCW.Try(p, np, f)
 	case JPiece, SPiece, ZPiece, TPiece, LPiece:
-		np = K3CW.Try(rot, np.Rot.CW(rot), np, f)
+		np = K3CW.Try(p, np, f)
+	default:
+		np = p
 	}
 
-	np = p // last resort reset p
 	if np.Floor(f) && np.Y < 0 {
 		return np, true, true
 	}
-- 
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