add -c context option

6 files changed, 49 insertions, 22 deletions

diff --git a/.editorconfig b/.editorconfig
index a5ddde0..22da3f7 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -2,7 +2,7 @@ root = true
 
 [*]
 end_of_line = lf
-insert_final_newline = false
+insert_final_newline = true
 max_line_length = 80
 
 [*.py]
diff --git a/patchtree/cli.py b/patchtree/cli.py
index 7b1a108..2535256 100644
--- a/patchtree/cli.py
+++ b/patchtree/cli.py
@@ -33,11 +33,20 @@ def parse_arguments(config: Config) -> Context:
         help="patch target in-place",
         action="store_true",
     )
+    parser.add_argument(
+        "-c",
+        "--context",
+        help="lines of context in output diff",
+        type=int,
+    )
     parser.add_argument("target", help="target directory or archive")
     parser.add_argument("patch", help="patch input glob(s)", nargs="+")
 
     options = parser.parse_args()
 
+    if options.context is not None:
+        config.diff_context = options.context
+
     try:
         return config.context(options)
     except Exception as e:
diff --git a/patchtree/config.py b/patchtree/config.py
index 555494e..743307b 100644
--- a/patchtree/config.py
+++ b/patchtree/config.py
@@ -58,6 +58,7 @@ class Config:
         default_factory=lambda: DEFAULT_DIFFS
     )
     header: type[Header] = Header
+    diff_context: int = 3
 
     def __post_init__(self):
         self.processors = {**DEFAULT_PROCESSORS, **self.processors}
diff --git a/patchtree/context.py b/patchtree/context.py
index c864307..554d09e 100644
--- a/patchtree/context.py
+++ b/patchtree/context.py
@@ -109,21 +109,13 @@ class Context:
     output: IO
     options: Namespace
 
-    cache: Path
-
     def __init__(self, options: Namespace):
         self.options = options
         self.fs = self.get_fs()
         self.output = self.get_output()
 
         if self.options.in_place:
-            location = cast(DiskFS, self.fs).path
-            self.cache = location.joinpath(".patchtree.diff")
-            if self.cache.exists():
-                run(
-                    ("git", "apply", "--reverse", str(self.cache.absolute())),
-                    cwd=str(location.absolute()),
-                )
+            self.apply(True)
 
     def __del__(self):
         # patch must have a trailing newline
@@ -131,15 +123,7 @@ class Context:
         self.output.flush()
 
         if self.options.in_place:
-            self.output.seek(0)
-            patch = self.output.read()
-            location = cast(DiskFS, self.fs).path
-            if len(patch) > 0:
-                self.cache.write_text(patch)
-                run(
-                    ("git", "apply", str(self.cache.absolute())),
-                    cwd=str(location.absolute()),
-                )
+            self.apply(False)
 
         self.output.close()
 
@@ -181,3 +165,26 @@ class Context:
                 return open(self.options.out, "w+")
 
         return stdout
+
+    def apply(self, reverse: bool) -> None:
+        location = cast(DiskFS, self.fs).path
+        cache = location.joinpath(".patchtree.diff")
+
+        cmd = [
+            "git",
+            "apply",
+            "--unidiff-zero",
+            "--allow-empty",
+        ]
+
+        if reverse:
+            if not cache.exists():
+                return
+            cmd.append("--reverse")
+        else:
+            self.output.seek(0)
+            patch = self.output.read()
+            cache.write_text(patch)
+
+        cmd.append(str(cache.absolute()))
+        run(cmd, cwd=str(location.absolute()))
diff --git a/patchtree/diff.py b/patchtree/diff.py
index 9712f77..3982296 100644
--- a/patchtree/diff.py
+++ b/patchtree/diff.py
@@ -1,6 +1,12 @@
+from __future__ import annotations
+from typing import TYPE_CHECKING
+
 from dataclasses import dataclass
 from difflib import unified_diff
 
+if TYPE_CHECKING:
+    from .config import Config
+
 
 @dataclass
 class DiffFile:
@@ -18,12 +24,14 @@ class Diff:
     with the file in the patch directory.
     """
 
+    config: Config
     file: str
 
     a: DiffFile
     b: DiffFile
 
-    def __init__(self, file: str):
+    def __init__(self, config: Config, file: str):
+        self.config = config
         self.file = file
 
     def compare(self) -> str:
@@ -58,7 +66,9 @@ class Diff:
 
         lines_a = a.lines()
         lines_b = b.lines()
-        diff = unified_diff(lines_a, lines_b, fromfile, tofile, lineterm="")
+        diff = unified_diff(
+            lines_a, lines_b, fromfile, tofile, lineterm="", n=self.config.diff_context
+        )
         delta += "".join(f"{line}\n" for line in diff)
 
         return delta
diff --git a/patchtree/patch.py b/patchtree/patch.py
index 0b1f69c..d2d0ae8 100644
--- a/patchtree/patch.py
+++ b/patchtree/patch.py
@@ -61,7 +61,7 @@ class Patch:
         diff_class = self.get_diff()
         processor_classes = self.get_processors()
 
-        diff = diff_class(self.file)
+        diff = diff_class(self.config, self.file)
 
         diff.a = DiffFile(
             content=context.get_content(self.file),