feat: add git_creation_date method

jwebsite/git.py

@@ -0,0 +1,26 @@
+from datetime import datetime
+from subprocess import check_output
+
+from jwebsite.content import Content
+
+
+def git_creation_date(content: Content) -> datetime:
+    git_dir = check_output(["git", "rev-parse", "--show-toplevel"], encoding="utf-8")
+    git_dir = git_dir.strip()
+    log = check_output(
+        [
+            "git",
+            "log",
+            "--pretty=format:%ad",
+            "--date=iso-strict",
+            "--diff-filter=A",
+            "--",
+            str(content.path.relative_to(git_dir)),
+        ],
+        encoding="utf-8",
+    )
+    log_lines = log.splitlines()
+    if len(log_lines) == 0:
+        return datetime.now()
+
+    return datetime.fromisoformat(log_lines[0])

jwebsite/site.py

@@ -6,6 +6,7 @@ from jinja2.environment import Environment
 from jinja2.loaders import FileSystemLoader
 
 from jwebsite.content import ContentDirectory
+from jwebsite.git import git_creation_date
 
 
 class Site:
@@ -13,7 +14,7 @@ class Site:
         self.__root_directory = root_directory
         self.__output_directory = root_directory / "build"
         self.__environment = Environment(loader=FileSystemLoader(searchpath=root_directory / "src"))
-        self.__environment.filters.update({"output": self.__output})
+        self.__environment.filters.update({"output": self.__output, "git_creation_date": git_creation_date})
         self.__content = ContentDirectory(root_directory / "content")
 
     @property