Feat/Add getStatistics method to Diff class (#55)

Author: mansoorkhan96

src/Diff.php

@@ -3,6 +3,8 @@
 namespace Overtrue\LaravelVersionable;
 
 use Illuminate\Support\Arr;
+use Illuminate\Support\Collection;
+use Jfcherng\Diff\Differ;
 use Jfcherng\Diff\DiffHelper;
 
 /**
@@ -92,4 +94,34 @@ public function render(?string $renderer = null, array $differOptions = [], arra
 
         return $diff;
     }
+
+    public function getStatistics(array $differOptions = []): array
+    {
+        if (empty($differOptions)) {
+            $differOptions = $this->differOptions;
+        }
+
+        $oldContents = $this->fromVersion->contents;
+        $newContents = $this->toVersion->contents;
+
+        $diffStats = new Collection;
+
+        foreach ($oldContents as $key => $value) {
+            if ($newContents[$key] !== $oldContents[$key]) {
+                $diffStats->push(
+                    (new Differ(
+                        explode("\n", $newContents[$key]),
+                        explode("\n", $oldContents[$key]),
+                    ))->getStatistics()
+                );
+            }
+        }
+
+        return [
+            'inserted' => $diffStats->sum('inserted'),
+            'deleted' => $diffStats->sum('deleted'),
+            'unmodified' => $diffStats->sum('unmodified'),
+            'changedRatio' => $diffStats->sum('changedRatio'),
+        ];
+    }
 }

tests/DiffTest.php

@@ -140,6 +140,79 @@ public function test_diff_to_side_by_side_html()
         );
     }
 
+    /**
+     * @test
+     */
+    public function it_can_return_the_diff_statistics()
+    {
+        $old = new Version(['contents' => ['title' => 'example title', 'content' => 'example content']]);
+
+        // we are modifying everything
+        $new = new Version(['contents' => ['title' => 'changing the title', 'content' => 'changing the content']]);
+
+        $stats = (new Diff($new, $old))->getStatistics();
+
+        $this->assertIsArray($stats);
+        $this->assertArrayHasKey('inserted', $stats);
+        $this->assertArrayHasKey('deleted', $stats);
+        $this->assertArrayHasKey('unmodified', $stats);
+
+        $this->assertEquals(2, $stats['inserted']); // two new lines inserted
+        $this->assertEquals(2, $stats['deleted']); // two lines deleted
+        $this->assertEquals(0, $stats['unmodified']); // modified everything
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_return_correct_statistics_for_new_line_insertions()
+    {
+        $old = new Version(['contents' => ['title' => 'example title', 'content' => 'example content']]);
+
+        // we are adding two new lines
+        $new = new Version(['contents' => ['content' => "example content\n adding new line \n another new line"]]);
+
+        $stats = (new Diff($new, $old))->getStatistics();
+
+        $this->assertEquals(2, $stats['inserted']); // two new lines inserted
+        $this->assertEquals(0, $stats['deleted']); // no deletions
+        $this->assertEquals(1, $stats['unmodified']); // one line unmodified
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_return_correct_statistics_for_deleted_lines()
+    {
+        $old = new Version(['contents' => ['title' => 'example title', 'content' => "example content\n adding new line \n another new line"]]);
+
+        // we are removing last two lines
+        $new = new Version(['contents' => ['content' => 'example content']]);
+
+        $stats = (new Diff($new, $old))->getStatistics();
+
+        $this->assertEquals(0, $stats['inserted']); // no insertions
+        $this->assertEquals(2, $stats['deleted']); // two lines deleted
+        $this->assertEquals(1, $stats['unmodified']); // one line unmodified
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_return_correct_statistics_for_unmodified_lines()
+    {
+        $old = new Version(['contents' => ['title' => 'example title', 'content' => "example content\n adding new line \n another new line"]]);
+
+        // we are just removing the last line
+        $new = new Version(['contents' => ['content' => "example content\n adding new line "]]);
+
+        $stats = (new Diff($new, $old))->getStatistics();
+
+        $this->assertEquals(0, $stats['inserted']); // no insertions
+        $this->assertEquals(1, $stats['deleted']); // one line deleted
+        $this->assertEquals(2, $stats['unmodified']); // two lines unmodified
+    }
+
     public function test_diff_nested_array_to_array()
     {
         $oldContent = [