From cb2cc6f79e69136df585befa34c6c0cf0fe84e3e Mon Sep 17 00:00:00 2001
From: xutao <1506085843@qq.com>
Date: Mon, 13 Mar 2023 15:01:55 +0800
Subject: [PATCH 1/6] Add generateOriginalAndDiff method and test class

---
 .../com/github/difflib/UnifiedDiffUtils.java  | 143 +++++++++++++++++-
 .../difflib/examples/OriginalAndDiffTest.java |  39 +++++
 2 files changed, 179 insertions(+), 3 deletions(-)
 create mode 100644 java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java

diff --git a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
index 06a61073..b65550b9 100644
--- a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
+++ b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
@@ -19,11 +19,11 @@
 import com.github.difflib.patch.Chunk;
 import com.github.difflib.patch.AbstractDelta;
 import com.github.difflib.patch.Patch;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
+
+import java.util.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 /**
  *
@@ -313,4 +313,141 @@ private static List<String> getDeltaText(AbstractDelta<String> delta) {
 
     private UnifiedDiffUtils() {
     }
+
+    /**
+     * Compare the differences between two files and return to the original file and diff format
+     *
+     * (This method compares the original file with the comparison file to obtain a diff, and inserts the diff into the corresponding position of the original file.
+     * You can see all the differences and unmodified places from the original file.
+     * Also, this will be very easy and useful for making side-by-side comparison display applications,
+     * for example, if you use diff2html (https://github.com/rtfpessoa/diff2html#usage)
+     * Wait for tools to display your differences on html pages, you only need to insert the return value into your js code)
+     *
+     * @param original Original file content
+     * @param revised  revised file content
+     *
+     */
+    public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised) {
+        return generateOriginalAndDiff(original, revised, null, null);
+    }
+
+
+    /**
+     * Compare the differences between two files and return to the original file and diff format
+     *
+     * (This method compares the original file with the comparison file to obtain a diff, and inserts the diff into the corresponding position of the original file.
+     * You can see all the differences and unmodified places from the original file.
+     * Also, this will be very easy and useful for making side-by-side comparison display applications,
+     * for example, if you use diff2html (https://github.com/rtfpessoa/diff2html#usage)
+     * Wait for tools to display your differences on html pages, you only need to insert the return value into your js code)
+     *
+     * @param original         Original file content
+     * @param revised          revised file content
+     * @param originalFileName Original file name
+     * @param revisedFileName  revised file name
+     */
+    public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised, String originalFileName, String revisedFileName) {
+        originalFileName = originalFileName == null ? "original" : originalFileName;
+        revisedFileName = revisedFileName == null ? "revised" : revisedFileName;
+        Patch<String> patch = com.github.difflib.DiffUtils.diff(original, revised);
+        List<String> unifiedDiff = generateUnifiedDiff(originalFileName, revisedFileName, original, patch, 0);
+        if (unifiedDiff.size() == 0) {
+            unifiedDiff.add("--- " + originalFileName);
+            unifiedDiff.add("+++ " + revisedFileName);
+            unifiedDiff.add("@@ -0,0 +0,0 @@");
+        } else if (unifiedDiff.size() >= 3 && !unifiedDiff.get(2).contains("@@ -1,")) {
+            unifiedDiff.set(1, unifiedDiff.get(1));
+            unifiedDiff.add(2, "@@ -0,0 +0,0 @@");
+        }
+        List<String> original1 = original.stream().map(v -> " " + v).collect(Collectors.toList());
+        return insertOrig(original1, unifiedDiff);
+    }
+
+
+    //Insert the diff format to the original file
+    private static List<String> insertOrig(List<String> original, List<String> unifiedDiff) {
+        List<String> result = new ArrayList<>();
+        List<List<String>> diffList = new ArrayList<>();
+        List<String> d = new ArrayList<>();
+        for (int i = 0; i < unifiedDiff.size(); i++) {
+            String u = unifiedDiff.get(i);
+            if (u.startsWith("@@") && !"@@ -0,0 +0,0 @@".equals(u) && !u.contains("@@ -1,")) {
+                List<String> twoList = new ArrayList<>();
+                twoList.addAll(d);
+                diffList.add(twoList);
+                d.clear();
+                d.add(u);
+                continue;
+            }
+            if (i == unifiedDiff.size() - 1) {
+                d.add(u);
+                List<String> twoList = new ArrayList<>();
+                twoList.addAll(d);
+                diffList.add(twoList);
+                d.clear();
+                break;
+            }
+            d.add(u);
+        }
+        for (int i = 0; i < diffList.size(); i++) {
+            List<String> diff = diffList.get(i);
+            List<String> nexDiff = i == diffList.size() - 1 ? null : diffList.get(i + 1);
+            String simb = i == 0 ? diff.get(2) : diff.get(0);
+            String nexSimb = nexDiff == null ? null : nexDiff.get(0);
+            insert(result, diff);
+            Map<String, Integer> map = getRowMap(simb);
+            if (null != nexSimb) {
+                Map<String, Integer> nexMap = getRowMap(nexSimb);
+                int start = 0;
+                if (map.get("orgRow") != 0) {
+                    start = map.get("orgRow") + map.get("orgDel") - 1;
+                }
+                int end = nexMap.get("revRow") - 2;
+                insert(result, getOrigList(original, start, end));
+            }
+
+            if (simb.contains("@@ -1,") && null == nexSimb && map.get("orgDel") != original.size()) {
+                insert(result, getOrigList(original, 0, original.size() - 1));
+            } else if (null == nexSimb && (map.get("orgRow") + map.get("orgDel") - 1) < original.size()) {
+                int start = (map.get("orgRow") + map.get("orgDel") - 1);
+                start = start == -1 ? 0 : start;
+                insert(result, getOrigList(original, start, original.size() - 1));
+            }
+        }
+        return result;
+    }
+
+    //Insert the unchanged content in the source file into result
+    private static void insert(List<String> result, List<String> noChangeContent) {
+        for (String ins : noChangeContent) {
+            result.add(ins);
+        }
+    }
+
+    //Parse the line containing @@ to get the modified line number to delete or add a few lines
+    private static Map<String, Integer> getRowMap(String str) {
+        Map<String, Integer> map = new HashMap<>();
+        if (str.startsWith("@@")) {
+            String[] sp = str.split(" ");
+            String org = sp[1];
+            String[] orgSp = org.split(",");
+            map.put("orgRow", Integer.valueOf(orgSp[0].substring(1)));
+            map.put("orgDel", Integer.valueOf(orgSp[1]));
+            String[] revSp = org.split(",");
+            map.put("revRow", Integer.valueOf(revSp[0].substring(1)));
+            map.put("revAdd", Integer.valueOf(revSp[1]));
+        }
+        return map;
+    }
+
+    //Get the specified part of the line from the original file
+    private static List<String> getOrigList(List<String> original1, int start, int end) {
+        List<String> list = new ArrayList<>();
+        if (original1.size() >= 1 && start <= end && end < original1.size()) {
+            for (; start <= end; start++) {
+                list.add(original1.get(start));
+            }
+        }
+        return list;
+    }
 }
diff --git a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
new file mode 100644
index 00000000..060fb47f
--- /dev/null
+++ b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
@@ -0,0 +1,39 @@
+package com.github.difflib.examples;
+
+import com.github.difflib.TestConstants;
+import com.github.difflib.UnifiedDiffUtils;
+import org.junit.jupiter.api.Test;
+
+import java.io.BufferedReader;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.util.stream.Collectors.joining;
+
+public class OriginalAndDiffTest {
+
+    @Test
+    public void testGenerateOriginalAndDiff() throws  IOException {
+        List<String> origLines = fileToLines(TestConstants.MOCK_FOLDER + "original.txt");
+        List<String> revLines = fileToLines(TestConstants.MOCK_FOLDER + "revised.txt");
+
+        List<String> originalAndDiff = UnifiedDiffUtils.generateOriginalAndDiff(origLines,revLines);
+        System.out.println(originalAndDiff.stream().collect(joining("\n")));
+    }
+
+    public static List<String> fileToLines(String filename) throws FileNotFoundException, IOException {
+        List<String> lines = new ArrayList<>();
+        String line = "";
+        try (BufferedReader in = new BufferedReader(new FileReader(filename))) {
+            while ((line = in.readLine()) != null) {
+                lines.add(line);
+            }
+        }
+        return lines;
+    }
+
+
+}

From e7910910693d60eb82c0f08a7ae0429993c155c0 Mon Sep 17 00:00:00 2001
From: xutao <1506085843@qq.com>
Date: Tue, 14 Mar 2023 10:27:32 +0800
Subject: [PATCH 2/6] Add generateOriginalAndDiff method and test class.I split
 long code into short methods, changed ambiguous variable names to explicit
 variable names

---
 .../com/github/difflib/UnifiedDiffUtils.java  | 42 +++++++++++--------
 .../difflib/examples/OriginalAndDiffTest.java |  2 -
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
index b65550b9..575a30e5 100644
--- a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
+++ b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
@@ -20,7 +20,11 @@
 import com.github.difflib.patch.AbstractDelta;
 import com.github.difflib.patch.Patch;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -351,7 +355,7 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
         revisedFileName = revisedFileName == null ? "revised" : revisedFileName;
         Patch<String> patch = com.github.difflib.DiffUtils.diff(original, revised);
         List<String> unifiedDiff = generateUnifiedDiff(originalFileName, revisedFileName, original, patch, 0);
-        if (unifiedDiff.size() == 0) {
+        if (unifiedDiff.isEmpty()) {
             unifiedDiff.add("--- " + originalFileName);
             unifiedDiff.add("+++ " + revisedFileName);
             unifiedDiff.add("@@ -0,0 +0,0 @@");
@@ -359,8 +363,8 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
             unifiedDiff.set(1, unifiedDiff.get(1));
             unifiedDiff.add(2, "@@ -0,0 +0,0 @@");
         }
-        List<String> original1 = original.stream().map(v -> " " + v).collect(Collectors.toList());
-        return insertOrig(original1, unifiedDiff);
+        List<String> originalWithPrefix = original.stream().map(v -> " " + v).collect(Collectors.toList());
+        return insertOrig(originalWithPrefix, unifiedDiff);
     }
 
 
@@ -368,27 +372,33 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
     private static List<String> insertOrig(List<String> original, List<String> unifiedDiff) {
         List<String> result = new ArrayList<>();
         List<List<String>> diffList = new ArrayList<>();
-        List<String> d = new ArrayList<>();
+        List<String> diff = new ArrayList<>();
         for (int i = 0; i < unifiedDiff.size(); i++) {
             String u = unifiedDiff.get(i);
             if (u.startsWith("@@") && !"@@ -0,0 +0,0 @@".equals(u) && !u.contains("@@ -1,")) {
                 List<String> twoList = new ArrayList<>();
-                twoList.addAll(d);
+                twoList.addAll(diff);
                 diffList.add(twoList);
-                d.clear();
-                d.add(u);
+                diff.clear();
+                diff.add(u);
                 continue;
             }
             if (i == unifiedDiff.size() - 1) {
-                d.add(u);
+                diff.add(u);
                 List<String> twoList = new ArrayList<>();
-                twoList.addAll(d);
+                twoList.addAll(diff);
                 diffList.add(twoList);
-                d.clear();
+                diff.clear();
                 break;
             }
-            d.add(u);
+            diff.add(u);
         }
+        insertOrig(diffList,result,original);
+        return result;
+    }
+
+    //Insert the diff format to the original file
+    private static void insertOrig(List<List<String>> diffList, List<String> result,List<String> original) {
         for (int i = 0; i < diffList.size(); i++) {
             List<String> diff = diffList.get(i);
             List<String> nexDiff = i == diffList.size() - 1 ? null : diffList.get(i + 1);
@@ -405,7 +415,6 @@ private static List<String> insertOrig(List<String> original, List<String> unifi
                 int end = nexMap.get("revRow") - 2;
                 insert(result, getOrigList(original, start, end));
             }
-
             if (simb.contains("@@ -1,") && null == nexSimb && map.get("orgDel") != original.size()) {
                 insert(result, getOrigList(original, 0, original.size() - 1));
             } else if (null == nexSimb && (map.get("orgRow") + map.get("orgDel") - 1) < original.size()) {
@@ -414,7 +423,6 @@ private static List<String> insertOrig(List<String> original, List<String> unifi
                 insert(result, getOrigList(original, start, original.size() - 1));
             }
         }
-        return result;
     }
 
     //Insert the unchanged content in the source file into result
@@ -441,11 +449,11 @@ private static Map<String, Integer> getRowMap(String str) {
     }
 
     //Get the specified part of the line from the original file
-    private static List<String> getOrigList(List<String> original1, int start, int end) {
+    private static List<String> getOrigList(List<String> originalWithPrefix, int start, int end) {
         List<String> list = new ArrayList<>();
-        if (original1.size() >= 1 && start <= end && end < original1.size()) {
+        if (originalWithPrefix.size() >= 1 && start <= end && end < originalWithPrefix.size()) {
             for (; start <= end; start++) {
-                list.add(original1.get(start));
+                list.add(originalWithPrefix.get(start));
             }
         }
         return list;
diff --git a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
index 060fb47f..62057cc7 100644
--- a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
+++ b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
@@ -34,6 +34,4 @@ public static List<String> fileToLines(String filename) throws FileNotFoundExcep
         }
         return lines;
     }
-
-
 }

From 61407b49c39ae6aa2442f917ae038c78dd7d32a1 Mon Sep 17 00:00:00 2001
From: xutao <1506085843@qq.com>
Date: Tue, 14 Mar 2023 11:02:32 +0800
Subject: [PATCH 3/6] fixes #164

---
 .../java/com/github/difflib/UnifiedDiffUtils.java     | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
index 575a30e5..c5e1d103 100644
--- a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
+++ b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
@@ -351,9 +351,13 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
      * @param revisedFileName  revised file name
      */
     public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised, String originalFileName, String revisedFileName) {
-        originalFileName = originalFileName == null ? "original" : originalFileName;
-        revisedFileName = revisedFileName == null ? "revised" : revisedFileName;
-        Patch<String> patch = com.github.difflib.DiffUtils.diff(original, revised);
+        if (originalFileName == null) {
+            originalFileName = "original";
+        }
+        if (revisedFileName == null) {
+            revisedFileName = "revised";
+        }
+        Patch<String> patch = DiffUtils.diff(original, revised);
         List<String> unifiedDiff = generateUnifiedDiff(originalFileName, revisedFileName, original, patch, 0);
         if (unifiedDiff.isEmpty()) {
             unifiedDiff.add("--- " + originalFileName);
@@ -367,7 +371,6 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
         return insertOrig(originalWithPrefix, unifiedDiff);
     }
 
-
     //Insert the diff format to the original file
     private static List<String> insertOrig(List<String> original, List<String> unifiedDiff) {
         List<String> result = new ArrayList<>();

From 7d9d1ca2f6b059ebfb1faacd0c5e2933f34f9b35 Mon Sep 17 00:00:00 2001
From: xutao <1506085843@qq.com>
Date: Wed, 22 Mar 2023 10:07:37 +0800
Subject: [PATCH 4/6] fix build issues

---
 .../com/github/difflib/UnifiedDiffUtils.java  | 27 ++++++++++---------
 .../difflib/examples/OriginalAndDiffTest.java | 15 ++++++++---
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
index c5e1d103..e926560d 100644
--- a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
+++ b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
@@ -351,17 +351,19 @@ public static List<String> generateOriginalAndDiff(List<String> original, List<S
      * @param revisedFileName  revised file name
      */
     public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised, String originalFileName, String revisedFileName) {
-        if (originalFileName == null) {
-            originalFileName = "original";
+        String originalFileNameTemp = originalFileName;
+        String revisedFileNameTemp = originalFileName;
+        if (originalFileNameTemp == null) {
+            originalFileNameTemp = "original";
         }
-        if (revisedFileName == null) {
-            revisedFileName = "revised";
+        if (revisedFileNameTemp == null) {
+            revisedFileNameTemp = "revised";
         }
         Patch<String> patch = DiffUtils.diff(original, revised);
-        List<String> unifiedDiff = generateUnifiedDiff(originalFileName, revisedFileName, original, patch, 0);
+        List<String> unifiedDiff = generateUnifiedDiff(originalFileNameTemp, revisedFileNameTemp, original, patch, 0);
         if (unifiedDiff.isEmpty()) {
-            unifiedDiff.add("--- " + originalFileName);
-            unifiedDiff.add("+++ " + revisedFileName);
+            unifiedDiff.add("--- " + originalFileNameTemp);
+            unifiedDiff.add("+++ " + revisedFileNameTemp);
             unifiedDiff.add("@@ -0,0 +0,0 @@");
         } else if (unifiedDiff.size() >= 3 && !unifiedDiff.get(2).contains("@@ -1,")) {
             unifiedDiff.set(1, unifiedDiff.get(1));
@@ -396,12 +398,12 @@ private static List<String> insertOrig(List<String> original, List<String> unifi
             }
             diff.add(u);
         }
-        insertOrig(diffList,result,original);
+        insertOrig(diffList, result, original);
         return result;
     }
 
     //Insert the diff format to the original file
-    private static void insertOrig(List<List<String>> diffList, List<String> result,List<String> original) {
+    private static void insertOrig(List<List<String>> diffList, List<String> result, List<String> original) {
         for (int i = 0; i < diffList.size(); i++) {
             List<String> diff = diffList.get(i);
             List<String> nexDiff = i == diffList.size() - 1 ? null : diffList.get(i + 1);
@@ -421,7 +423,7 @@ private static void insertOrig(List<List<String>> diffList, List<String> result,
             if (simb.contains("@@ -1,") && null == nexSimb && map.get("orgDel") != original.size()) {
                 insert(result, getOrigList(original, 0, original.size() - 1));
             } else if (null == nexSimb && (map.get("orgRow") + map.get("orgDel") - 1) < original.size()) {
-                int start = (map.get("orgRow") + map.get("orgDel") - 1);
+                int start = map.get("orgRow") + map.get("orgDel") - 1;
                 start = start == -1 ? 0 : start;
                 insert(result, getOrigList(original, start, original.size() - 1));
             }
@@ -455,8 +457,9 @@ private static Map<String, Integer> getRowMap(String str) {
     private static List<String> getOrigList(List<String> originalWithPrefix, int start, int end) {
         List<String> list = new ArrayList<>();
         if (originalWithPrefix.size() >= 1 && start <= end && end < originalWithPrefix.size()) {
-            for (; start <= end; start++) {
-                list.add(originalWithPrefix.get(start));
+            int startTemp = start;
+            for (; startTemp <= end; startTemp++) {
+                list.add(originalWithPrefix.get(startTemp));
             }
         }
         return list;
diff --git a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
index 62057cc7..7f2d3b29 100644
--- a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
+++ b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
@@ -12,15 +12,22 @@
 import java.util.List;
 
 import static java.util.stream.Collectors.joining;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class OriginalAndDiffTest {
 
     @Test
-    public void testGenerateOriginalAndDiff() throws  IOException {
-        List<String> origLines = fileToLines(TestConstants.MOCK_FOLDER + "original.txt");
-        List<String> revLines = fileToLines(TestConstants.MOCK_FOLDER + "revised.txt");
+    public void testGenerateOriginalAndDiff()  {
+        List<String> origLines = null;
+        List<String> revLines = null;
+        try {
+            origLines = fileToLines(TestConstants.MOCK_FOLDER + "original.txt");
+            revLines = fileToLines(TestConstants.MOCK_FOLDER + "revised.txt");
+        } catch (IOException e) {
+            fail(e.getMessage());
+        }
 
-        List<String> originalAndDiff = UnifiedDiffUtils.generateOriginalAndDiff(origLines,revLines);
+        List<String> originalAndDiff = UnifiedDiffUtils.generateOriginalAndDiff(origLines, revLines);
         System.out.println(originalAndDiff.stream().collect(joining("\n")));
     }
 

From 9da4012b478e06d722e43306d4fdb550ec2e85a1 Mon Sep 17 00:00:00 2001
From: xutao <1506085843@qq.com>
Date: Fri, 16 Jun 2023 15:00:25 +0800
Subject: [PATCH 5/6] fix issues about (#164),detail: When deleting the first
 line of comparison text and adding several lines of text, the first diff of
 the result returned by the generateOriginalAndDiff method is inserted
 incorrectly

---
 .../src/main/java/com/github/difflib/UnifiedDiffUtils.java  | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
index e926560d..727008db 100644
--- a/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
+++ b/java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java
@@ -420,11 +420,11 @@ private static void insertOrig(List<List<String>> diffList, List<String> result,
                 int end = nexMap.get("revRow") - 2;
                 insert(result, getOrigList(original, start, end));
             }
+            int start = map.get("orgRow") + map.get("orgDel") - 1;
+            start = start == -1 ? 0 : start;
             if (simb.contains("@@ -1,") && null == nexSimb && map.get("orgDel") != original.size()) {
-                insert(result, getOrigList(original, 0, original.size() - 1));
+                insert(result, getOrigList(original, start, original.size() - 1));
             } else if (null == nexSimb && (map.get("orgRow") + map.get("orgDel") - 1) < original.size()) {
-                int start = map.get("orgRow") + map.get("orgDel") - 1;
-                start = start == -1 ? 0 : start;
                 insert(result, getOrigList(original, start, original.size() - 1));
             }
         }

From d0b42504f35d797b45c1a6b8b0904ad9088b8a8d Mon Sep 17 00:00:00 2001
From: xutao <xutao@apexsoft.com.cn>
Date: Sun, 18 Jun 2023 16:49:28 +0800
Subject: [PATCH 6/6] add a test for #170

---
 .../difflib/examples/OriginalAndDiffTest.java |  15 +++
 .../resources/mocks/issue_170_original.txt    |  95 +++++++++++++++
 .../resources/mocks/issue_170_revised.txt     | 114 ++++++++++++++++++
 3 files changed, 224 insertions(+)
 create mode 100644 java-diff-utils/src/test/resources/mocks/issue_170_original.txt
 create mode 100644 java-diff-utils/src/test/resources/mocks/issue_170_revised.txt

diff --git a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
index 7f2d3b29..17283b4d 100644
--- a/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
+++ b/java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java
@@ -31,6 +31,21 @@ public void testGenerateOriginalAndDiff()  {
         System.out.println(originalAndDiff.stream().collect(joining("\n")));
     }
 
+    @Test
+    public void testGenerateOriginalAndDiffFirstLineChange()  {
+        List<String> origLines = null;
+        List<String> revLines = null;
+        try {
+            origLines = fileToLines(TestConstants.MOCK_FOLDER + "issue_170_original.txt");
+            revLines = fileToLines(TestConstants.MOCK_FOLDER + "issue_170_revised.txt");
+        } catch (IOException e) {
+            fail(e.getMessage());
+        }
+
+        List<String> originalAndDiff = UnifiedDiffUtils.generateOriginalAndDiff(origLines, revLines);
+        System.out.println(originalAndDiff.stream().collect(joining("\n")));
+    }
+
     public static List<String> fileToLines(String filename) throws FileNotFoundException, IOException {
         List<String> lines = new ArrayList<>();
         String line = "";
diff --git a/java-diff-utils/src/test/resources/mocks/issue_170_original.txt b/java-diff-utils/src/test/resources/mocks/issue_170_original.txt
new file mode 100644
index 00000000..8aa703f0
--- /dev/null
+++ b/java-diff-utils/src/test/resources/mocks/issue_170_original.txt
@@ -0,0 +1,95 @@
+//According to the original text, an html will be generated by comparing the text
+public class generateDiffHtmlTest {
+    /**
+     * Here's a simple example of getting a nice html page based on the original text and the contrasted text,Read n1.txt and n2.txt of D disk, and finally generate an html file
+     *
+     */
+    @Test
+    public static void generateOriginalAndDiffDemo(){
+        List<String> origLines = getFileContent("D:\\n1.txt");
+        List<String> revLines =getFileContent("D:\\n2.txt");
+        List<String> originalAndDiff =UnifiedDiffUtils.generateOriginalAndDiff(origLines, revLines);
+        //System.out.println(originalAndDiff.size());
+        generateDiffHtml(originalAndDiff,"D:\\diff.html");
+    }
+
+    /**
+     * get file content
+     * @param filePath file path
+     */
+    public static List<String> getFileContent(String filePath) {
+        //origin
+        List<String> fileContent =null;
+        File file = new File(filePath);
+        try {
+            fileContent = Files.readAllLines(file.toPath());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return fileContent;
+    }
+
+    /**
+     * The html file is generated by the difference diff between the two files, and the detailed content of the file comparison can be seen by opening the html file
+     *
+     */
+    public static void generateDiffHtml(List<String> diffString, String htmlPath) {
+        StringBuilder builder = new StringBuilder();
+        for (String line : diffString) {
+            builder.append(line);
+            builder.append("\n");
+        }
+        String githubCss = "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.1/styles/github.min.css";
+        String diff2htmlCss = "https://cdn.jsdelivr.net/npm/diff2html/bundles/css/diff2html.min.css";
+        String diff2htmlJs = "https://cdn.jsdelivr.net/npm/diff2html/bundles/js/diff2html-ui.min.js";
+
+        String template = "<!DOCTYPE html>\n" +
+                "<html lang=\"en-us\">\n" +
+                "  <head>\n" +
+                "    <meta charset=\"utf-8\" />\n" +
+                "    <link rel=\"stylesheet\" href=\"" + githubCss + "\" />\n" +
+                "     <link rel=\"stylesheet\" type=\"text/css\" href=\"" + diff2htmlCss + "\" />\n" +
+                "    <script type=\"text/javascript\" src=\"" + diff2htmlJs + "\"></script>\n" +
+                "  </head>\n" +
+                "  <script>\n" +
+                "    const diffString = `\n" +
+                "temp\n" +
+                "`;\n" +
+                "\n" +
+                "\n" +
+                "     document.addEventListener('DOMContentLoaded', function () {\n" +
+                "      var targetElement = document.getElementById('myDiffElement');\n" +
+                "      var configuration = {\n" +
+                "        drawFileList: true,\n" +
+                "        fileListToggle: true,\n" +
+                "        fileListStartVisible: true,\n" +
+                "        fileContentToggle: true,\n" +
+                "        matching: 'lines',\n" +
+                "        outputFormat: 'side-by-side',\n" +
+                "        synchronisedScroll: true,\n" +
+                "        highlight: true,\n" +
+                "        renderNothingWhenEmpty: true,\n" +
+                "      };\n" +
+                "      var diff2htmlUi = new Diff2HtmlUI(targetElement, diffString, configuration);\n" +
+                "      diff2htmlUi.draw();\n" +
+                "      diff2htmlUi.highlightCode();\n" +
+                "    });\n" +
+                "  </script>\n" +
+                "  <body>\n" +
+                "    <div id=\"myDiffElement\"></div>\n" +
+                "  </body>\n" +
+                "</html>";
+        template = template.replace("temp", builder.toString());
+        FileWriter fileWriter = null;
+        try {
+            fileWriter = new FileWriter(htmlPath);
+            BufferedWriter buf = new BufferedWriter(fileWriter);
+            buf.write(template);
+            buf.close();
+            fileWriter.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}
diff --git a/java-diff-utils/src/test/resources/mocks/issue_170_revised.txt b/java-diff-utils/src/test/resources/mocks/issue_170_revised.txt
new file mode 100644
index 00000000..7aa91dc2
--- /dev/null
+++ b/java-diff-utils/src/test/resources/mocks/issue_170_revised.txt
@@ -0,0 +1,114 @@
+package com.github.difflib.examples;
+
+import com.github.difflib.UnifiedDiffUtils;
+import org.junit.jupiter.api.Test;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.List;
+
+// According to the original text, an html will be generated by comparing the text.
+public class generateDiffHtmlTest {
+
+    /**
+     * Here's a simple example of getting a nice html page based on the original text and the contrasted text,
+     * Read n1.txt and n2.txt of D disk, and finally generate an html file
+     *
+     */
+    @Test
+    public static void generateOriginalAndDiffDemo(){
+        List<String> origLines = getFileContent("D:\\n1.txt");
+        List<String> revLines = getFileContent("D:\\n2.txt");
+        List<String> originalAndDiff =  UnifiedDiffUtils.generateOriginalAndDiff(origLines, revLines);
+
+        //generateDiffHtml
+        generateDiffHtml(originalAndDiff,"D:\\diff.html");
+    }
+
+    /**
+     * get file content
+     *
+     * @param filePath file path
+     */
+    public static List<String> getFileContent(String filePath) {
+        //原始文件
+        List<String> fileContent = null;
+        File file = new File(filePath);
+        try {
+            fileContent = Files.readAllLines(file.toPath());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return fileContent;
+    }
+
+    /**
+     * The html file is generated by the difference diff between the two files,
+     * and the detailed content of the file comparison can be seen by opening the html file
+     *
+     * @param diffString The comparison result obtained by calling the above diffString method
+     * @param htmlPath   Generated html path，e.g:/user/var/mbos/ent/21231/diff.html
+     */
+    public static void generateDiffHtml(List<String> diffString, String htmlPath) {
+        StringBuilder builder = new StringBuilder();
+        for (String line : diffString) {
+            builder.append(line);
+            builder.append("\n");
+        }
+        String githubCss = "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.1/styles/github.min.css";
+        String diff2htmlCss = "https://cdn.jsdelivr.net/npm/diff2html/bundles/css/diff2html.min.css";
+        String diff2htmlJs = "https://cdn.jsdelivr.net/npm/diff2html/bundles/js/diff2html-ui.min.js";
+
+        String template = "<!DOCTYPE html>\n" +
+                "<html lang=\"en-us\">\n" +
+                "  <head>\n" +
+                "    <meta charset=\"utf-8\" />\n" +
+                "    <link rel=\"stylesheet\" href=\"" + githubCss + "\" />\n" +
+                "     <link rel=\"stylesheet\" type=\"text/css\" href=\"" + diff2htmlCss + "\" />\n" +
+                "    <script type=\"text/javascript\" src=\"" + diff2htmlJs + "\"></script>\n" +
+                "  </head>\n" +
+                "  <script>\n" +
+                "    const diffString = `\n" +
+                "temp\n" +
+                "`;\n" +
+                "\n" +
+                "\n" +
+                "     document.addEventListener('DOMContentLoaded', function () {\n" +
+                "      var targetElement = document.getElementById('myDiffElement');\n" +
+                "      var configuration = {\n" +
+                "        drawFileList: true,\n" +
+                "        fileListToggle: true,\n" +
+                "        fileListStartVisible: true,\n" +
+                "        fileContentToggle: true,\n" +
+                "        matching: 'lines',\n" +
+                "        outputFormat: 'side-by-side',\n" +
+                "        synchronisedScroll: true,\n" +
+                "        highlight: true,\n" +
+                "        renderNothingWhenEmpty: true,\n" +
+                "      };\n" +
+                "      var diff2htmlUi = new Diff2HtmlUI(targetElement, diffString, configuration);\n" +
+                "      diff2htmlUi.draw();\n" +
+                "      diff2htmlUi.highlightCode();\n" +
+                "    });\n" +
+                "  </script>\n" +
+                "  <body>\n" +
+                "    <div id=\"myDiffElement\"></div>\n" +
+                "  </body>\n" +
+                "</html>";
+        template = template.replace("temp", builder.toString());
+        FileWriter fileWriter = null;
+        try {
+            fileWriter = new FileWriter(htmlPath);
+            BufferedWriter buf = new BufferedWriter(fileWriter);
+            buf.write(template);
+            buf.close();
+            fileWriter.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}
+