From 1677d7a1b901f9bf86b566de64339cefddf3c2bd Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Fri, 8 Mar 2024 13:00:29 -0500
Subject: Fix negative index issue and add array:random()

---
 builtins/array.c | 14 +++++++++++---
 builtins/array.h |  1 +
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/builtins/array.c b/builtins/array.c
index ee583b5b..93c20bab 100644
--- a/builtins/array.c
+++ b/builtins/array.c
@@ -44,7 +44,7 @@ public void Array__compact(array_t *arr, const TypeInfo *type)
 
 public void Array__insert(array_t *arr, const void *item, int64_t index, const TypeInfo *type)
 {
-    if (index < 1) index = arr->length - index + 1;
+    if (index < 1) index = arr->length + index;
 
     if (index < 1) index = 1;
     else if (index > (int64_t)arr->length + 1) index = (int64_t)arr->length + 1;
@@ -79,7 +79,7 @@ public void Array__insert(array_t *arr, const void *item, int64_t index, const T
 
 public void Array__insert_all(array_t *arr, array_t to_insert, int64_t index, const TypeInfo *type)
 {
-    if (index < 1) index = arr->length - index + 1;
+    if (index < 1) index = arr->length + index;
 
     if (index < 1) index = 1;
     else if (index > (int64_t)arr->length + 1) index = (int64_t)arr->length + 1;
@@ -112,7 +112,7 @@ public void Array__insert_all(array_t *arr, array_t to_insert, int64_t index, co
 
 public void Array__remove(array_t *arr, int64_t index, int64_t count, const TypeInfo *type)
 {
-    if (index < 1) index = arr->length - index + 1;
+    if (index < 1) index = arr->length + index;
 
     if (index < 1 || index > (int64_t)arr->length || count < 1) return;
 
@@ -171,6 +171,14 @@ public void Array__shuffle(array_t *arr, const TypeInfo *type)
     }
 }
 
+public void *Array_random(array_t arr)
+{
+    if (arr.length == 0)
+        return NULL; // fail("Cannot get a random item from an empty array!");
+    uint32_t index = arc4random_uniform(arr.length);
+    return arr.data + arr.stride*index;
+}
+
 public array_t Array__slice(array_t *array, int64_t first, int64_t stride, int64_t length, const TypeInfo *type)
 {
     if (stride > MAX_STRIDE || stride < MIN_STRIDE)
diff --git a/builtins/array.h b/builtins/array.h
index 8b7b3b40..c61b03a2 100644
--- a/builtins/array.h
+++ b/builtins/array.h
@@ -51,6 +51,7 @@ void Array__insert_all(array_t *arr, array_t to_insert, int64_t index, const Typ
 void Array__remove(array_t *arr, int64_t index, int64_t count, const TypeInfo *type);
 void Array__sort(array_t *arr, const TypeInfo *type);
 void Array__shuffle(array_t *arr, const TypeInfo *type);
+void *Array_random(array_t arr);
 void Array__clear(array_t *array, const TypeInfo *type);
 void Array__compact(array_t *arr, const TypeInfo *type);
 bool Array__contains(array_t array, void *item, const TypeInfo *type);
-- 
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