From e495b361e0e9ac5f723928c9e626320ae5e26716 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sun, 15 May 2016 20:37:18 -0400
Subject: Factor out all game model code into the relevant modules.

---
 lisparuga/stats.scm | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

(limited to 'lisparuga/stats.scm')

diff --git a/lisparuga/stats.scm b/lisparuga/stats.scm
index 3abcdef..8d159ec 100644
--- a/lisparuga/stats.scm
+++ b/lisparuga/stats.scm
@@ -16,6 +16,8 @@
 
 (define-module (lisparuga stats)
   #:use-module (sly records)
+  #:use-module (lisparuga enemies)
+  #:use-module (lisparuga player)
   #:use-module (lisparuga utils)
   #:export (make-stats
             stats?
@@ -23,7 +25,10 @@
             stats-lives
             stats-chain
             stats-chain-type
-            stats-chain-progress))
+            stats-chain-progress
+            decrement-life
+            add-to-score
+            add-to-chain))
 
 (define-record-type* <stats>
   %make-stats make-stats
@@ -33,3 +38,41 @@
   (chain stats-chain 0)
   (chain-type stats-chain-type #f)
   (chain-progress stats-chain-progress 0))
+
+(define (decrement-life stats)
+  (make-stats #:inherit stats
+              #:lives (max 0 (1- (stats-lives stats)))))
+
+(define max-chain-multiplier 10)
+
+(define (add-to-score enemy stats)
+  ;; TODO: Award different points for different types of enemies.
+  (make-stats #:inherit stats
+              #:score (+ (stats-score stats)
+                         1000          ; base kill points
+                         ;; Chain multiplier.
+                         (* 255
+                            (min (stats-chain stats)
+                                 max-chain-multiplier)))))
+
+(define (add-to-chain enemy stats)
+  (let* ((enemy-polarity (enemy-polarity enemy))
+         (chain-polarity (stats-chain-type stats))
+         (progress (stats-chain-progress stats)))
+    (cond
+     ((or (zero? progress) (= progress 3))
+      (make-stats #:inherit stats
+                  #:chain-type enemy-polarity
+                  #:chain-progress 1))
+     ((not (eq? enemy-polarity chain-polarity))
+      (make-stats #:inherit stats
+                  #:chain-type #f
+                  #:chain-progress 0
+                  #:chain 0))
+     ((= progress 1)
+      (make-stats #:inherit stats
+                  #:chain-progress 2))
+     ((= progress 2)
+      (make-stats #:inherit stats
+                  #:chain-progress 3
+                  #:chain (1+ (stats-chain stats)))))))
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