From d852805aea5553eac59e7ad2ea36cb929b6b1130 Mon Sep 17 00:00:00 2001
From: Richard Klees <richard.klees@concepts-and-training.de>
Date: Tue, 24 Oct 2023 15:34:31 +0200
Subject: [PATCH] Data: add Range::croppedTo

---
 src/Data/Range.php       | 20 ++++++++++++++++++--
 tests/Data/RangeTest.php | 36 ++++++++++++++++++++++++------------
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/src/Data/Range.php b/src/Data/Range.php
index 0b24eebeebbd..ae2a00ea376b 100644
--- a/src/Data/Range.php
+++ b/src/Data/Range.php
@@ -31,8 +31,8 @@ protected function checkStart(int $start): void
 
     protected function checkLength(int $length): void
     {
-        if ($length < 1) {
-            throw new \InvalidArgumentException("Length must be larger than 0", 1);
+        if ($length < 0) {
+            throw new \InvalidArgumentException("Length must be larger or equal then 0", 1);
         }
     }
 
@@ -71,4 +71,20 @@ public function withLength(int $length): Range
         $clone->length = $length;
         return $clone;
     }
+
+    /**
+     * This will create a range that is guaranteed to not exceed $max.
+     */
+    public function croppedTo(int $max): Range
+    {
+        if ($max > $this->getEnd()) {
+            return $this;
+        }
+
+        if ($this->getStart() > $max) {
+            return new self($max, 0);
+        }
+
+        return $this->withLength($this->getLength() - $this->getEnd() + $max);
+    }
 }
diff --git a/tests/Data/RangeTest.php b/tests/Data/RangeTest.php
index 1f970d81f6c2..fc2eb6bf0726 100644
--- a/tests/Data/RangeTest.php
+++ b/tests/Data/RangeTest.php
@@ -88,15 +88,6 @@ public function testNegativeLength(Range $range): void
         $range = $range->withLength(-1);
     }
 
-    /**
-     * @depends testFactory
-     */
-    public function testNullLength(Range $range): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $range = $range->withLength(0);
-    }
-
     public function testConstructionWrongStart(): void
     {
         $this->expectException(InvalidArgumentException::class);
@@ -111,10 +102,31 @@ public function testConstructionWrongLength(): void
         $range = $f->range(1, -2);
     }
 
-    public function testConstructionNullLength(): void
+    /**
+     * @dataProvider cropCases
+     */
+    public function testCroppedTo($start, $length, $max, $has_changed): void
     {
-        $this->expectException(InvalidArgumentException::class);
         $f = new ILIAS\Data\Factory();
-        $range = $f->range(1, 0);
+        $range = $f->range($start, $length);
+        $cropped = $range->croppedTo($max);
+
+        if (!$has_changed) {
+            $this->assertEquals($range, $cropped);
+        } else {
+            $this->assertEquals(min($max, $start), $cropped->getStart());
+            $this->assertEquals($max, $cropped->getEnd());
+        }
+    }
+
+    public function cropCases(): array
+    {
+        return [
+            [0, 100, 1000, false],
+            [0, 1000, 100, true],
+            [50, 100, 75, true],
+            [50, 100, 200, false],
+            [100, 100, 50, true]
+        ];
     }
 }