From 0c05215b9466ae0218a53d25dca6fdd3c169db12 Mon Sep 17 00:00:00 2001
From: "Valeriano A.R" <valen.alfonso@protonmail.com>
Date: Mon, 21 Aug 2023 03:20:24 +0200
Subject: [PATCH] Add ByteArraySearcher to CsvLib.

---
 CsvLib.Tests/ByteArraySearcherTests.cs | 66 ++++++++++++++++++++++++++
 CsvLib/ByteArraySearcher.cs            | 41 ++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 CsvLib.Tests/ByteArraySearcherTests.cs
 create mode 100644 CsvLib/ByteArraySearcher.cs

diff --git a/CsvLib.Tests/ByteArraySearcherTests.cs b/CsvLib.Tests/ByteArraySearcherTests.cs
new file mode 100644
index 0000000..b7c5c5d
--- /dev/null
+++ b/CsvLib.Tests/ByteArraySearcherTests.cs
@@ -0,0 +1,66 @@
+using CsvLib;
+
+namespace CvsLib;
+
+public class ByteArraySearcherTests
+{
+    [Fact]
+    public void Contains__EmptyNeedle_ReturnsTrue()
+    {
+        byte[] haystack = { 1, 2, 3, 4, 5 };
+        byte[] needle = Array.Empty<byte>();
+        ByteArraySearcher searcher = new(needle);
+
+        bool result = searcher.Contains(haystack);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void Contains__NeedleAtBeginning_ReturnsTrue()
+    {
+        byte[] haystack = { 1, 2, 3, 4, 5 };
+        byte[] needle = { 1, 2, 3 };
+        ByteArraySearcher searcher = new(needle);
+
+        bool result = searcher.Contains(haystack);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void Contains__NeedleInMiddle_ReturnsTrue()
+    {
+        byte[] haystack = { 1, 2, 3, 4, 5 };
+        byte[] needle = { 3, 4 };
+        ByteArraySearcher searcher = new(needle);
+
+        bool result = searcher.Contains(haystack);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void Contains__NeedleAtEnd_ReturnsTrue()
+    {
+        byte[] haystack = { 1, 2, 3, 4, 5 };
+        byte[] needle = { 4, 5 };
+        ByteArraySearcher searcher = new(needle);
+
+        bool result = searcher.Contains(haystack);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void Contains__NeedleNotPresent_ReturnsFalse()
+    {
+        byte[] haystack = { 1, 2, 3, 4, 5 };
+        byte[] needle = { 5, 6, 7 };
+        ByteArraySearcher searcher = new(needle);
+
+        bool result = searcher.Contains(haystack);
+
+        Assert.False(result);
+    }
+}
diff --git a/CsvLib/ByteArraySearcher.cs b/CsvLib/ByteArraySearcher.cs
new file mode 100644
index 0000000..f6ac65c
--- /dev/null
+++ b/CsvLib/ByteArraySearcher.cs
@@ -0,0 +1,41 @@
+#nullable enable
+
+namespace CsvLib;
+
+public class ByteArraySearcher
+{
+    private readonly byte[] _needle;
+
+    public ByteArraySearcher(byte[] needle)
+    {
+        _needle = needle;
+    }
+
+    public bool Contains(byte[] haystack)
+    {
+        return Contains(haystack, haystack.Length);
+    }
+
+    public bool Contains(byte[] haystack, int length)
+    {
+        // TODO: Implement the Boyer-Moore algorithm
+        for (int i = 0; i <= length - _needle.Length; i++)
+        {
+            bool found = true;
+
+            for (int j = 0; j < _needle.Length; j++)
+            {
+                if (haystack[i + j] != _needle[j])
+                {
+                    found = false;
+                    break;
+                }
+            }
+
+            if (found)
+                return true;
+        }
+
+        return false;
+    }
+}