From 044e30e0b1a6c9aadbd973374e5ec2a3368b5c3e Mon Sep 17 00:00:00 2001
From: Edmundo Carmona Antoranz <eantoranz@gmail.com>
Date: Fri, 18 Apr 2025 04:13:05 +0200
Subject: [PATCH] repository - diff blobs: consider the values of context_lines
 and interhunk_lines

---
 pygit2/repository.py |  4 ++-
 src/blob.c           | 17 +++++++---
 test/test_diff.py    | 76 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+), 5 deletions(-)

diff --git a/pygit2/repository.py b/pygit2/repository.py
index 9a6594d0..61ecd9ec 100644
--- a/pygit2/repository.py
+++ b/pygit2/repository.py
@@ -541,7 +541,9 @@ def diff(
 
         # Case 4: Diff blob to blob
         if isinstance(a, Blob) and isinstance(b, Blob):
-            return a.diff(b)
+            opt_values.insert(1, 'file')
+            opt_values.insert(1, 'file')
+            return a.diff(b, *opt_values)
 
         raise ValueError('Only blobs and treeish can be diffed')
 
diff --git a/src/blob.c b/src/blob.c
index 0561660f..6fd6e734 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -60,7 +60,15 @@ PyDoc_STRVAR(Blob_diff__doc__,
   "    Treat old blob as if it had this filename.\n"
   "\n"
   "new_as_path : str\n"
-  "    Treat new blob as if it had this filename.\n");
+  "    Treat new blob as if it had this filename.\n"
+  "\n"
+  "context_lines: int\n"
+  "    Number of unchanged lines that define the boundary of a hunk\n"
+  "    (and to display before and after).\n"
+  "\n"
+  "interhunk_lines: int\n"
+  "    Maximum number of unchanged lines between hunk boundaries\n"
+  "    before the hunks will be merged into one.\n");
 
 PyObject *
 Blob_diff(Blob *self, PyObject *args, PyObject *kwds)
@@ -70,11 +78,12 @@ Blob_diff(Blob *self, PyObject *args, PyObject *kwds)
     char *old_as_path = NULL, *new_as_path = NULL;
     Blob *other = NULL;
     int err;
-    char *keywords[] = {"blob", "flag", "old_as_path", "new_as_path", NULL};
+    char *keywords[] = {"blob", "flag", "old_as_path", "new_as_path", "context_lines", "interhunk_lines", NULL};
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O!Iss", keywords,
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O!IssHH", keywords,
                                      &BlobType, &other, &opts.flags,
-                                     &old_as_path, &new_as_path))
+                                     &old_as_path, &new_as_path,
+                                     &opts.context_lines, &opts.interhunk_lines))
         return NULL;
 
     if (Object__load((Object*)self) == NULL) { return NULL; } // Lazy load
diff --git a/test/test_diff.py b/test/test_diff.py
index 28e1b0c3..f73a4c64 100644
--- a/test/test_diff.py
+++ b/test/test_diff.py
@@ -107,6 +107,68 @@
  delete mode 100644 c/d
 """
 
+TEXT_BLOB1 = """Common header of the file
+Blob 1 line 1
+Common middle line 1
+Common middle line 2
+Common middle line 3
+Blob 1 line 2
+Common footer of the file
+"""
+
+TEXT_BLOB2 = """Common header of the file
+Blob 2 line 1
+Common middle line 1
+Common middle line 2
+Common middle line 3
+Blob 2 line 2
+Common footer of the file
+"""
+
+PATCH_BLOBS_DEFAULT = """diff --git a/file b/file
+index 0b5ac93..ddfdbcc 100644
+--- a/file
++++ b/file
+@@ -1,7 +1,7 @@
+ Common header of the file
+-Blob 1 line 1
++Blob 2 line 1
+ Common middle line 1
+ Common middle line 2
+ Common middle line 3
+-Blob 1 line 2
++Blob 2 line 2
+ Common footer of the file
+"""
+
+PATCH_BLOBS_NO_LEEWAY = """diff --git a/file b/file
+index 0b5ac93..ddfdbcc 100644
+--- a/file
++++ b/file
+@@ -2 +2 @@ Common header of the file
+-Blob 1 line 1
++Blob 2 line 1
+@@ -6 +6 @@ Common middle line 3
+-Blob 1 line 2
++Blob 2 line 2
+"""
+
+PATCH_BLOBS_ONE_CONTEXT_LINE = """diff --git a/file b/file
+index 0b5ac93..ddfdbcc 100644
+--- a/file
++++ b/file
+@@ -1,3 +1,3 @@
+ Common header of the file
+-Blob 1 line 1
++Blob 2 line 1
+ Common middle line 1
+@@ -5,3 +5,3 @@ Common middle line 2
+ Common middle line 3
+-Blob 1 line 2
++Blob 2 line 2
+ Common footer of the file
+"""
+
 
 def test_diff_empty_index(dirtyrepo):
     repo = dirtyrepo
@@ -382,3 +444,17 @@ def test_parse_diff_bad():
     )
     with pytest.raises(pygit2.GitError):
         pygit2.Diff.parse_diff(diff)
+
+
+def test_diff_blobs(emptyrepo):
+    repo = emptyrepo
+    blob1 = repo.create_blob(TEXT_BLOB1.encode())
+    blob2 = repo.create_blob(TEXT_BLOB2.encode())
+    diff_default = repo.diff(blob1, blob2)
+    assert diff_default.text == PATCH_BLOBS_DEFAULT
+    diff_no_leeway = repo.diff(blob1, blob2, context_lines=0)
+    assert diff_no_leeway.text == PATCH_BLOBS_NO_LEEWAY
+    diff_one_context_line = repo.diff(blob1, blob2, context_lines=1)
+    assert diff_one_context_line.text == PATCH_BLOBS_ONE_CONTEXT_LINE
+    diff_all_together = repo.diff(blob1, blob2, context_lines=1, interhunk_lines=1)
+    assert diff_all_together.text == PATCH_BLOBS_DEFAULT