added globals to template environment, including a path function

src/dragonglass/template.py

@@ -4,7 +4,7 @@
 import sys
 
 from jinja2 import Environment, BaseLoader, ChoiceLoader, FunctionLoader, FileSystemLoader
-from typing import Any
+from typing import Any, Callable
 from urllib.parse import quote as urlquote
 
 from .config import Context, DEFAULT_TEMPLATE_NAME
@@ -73,6 +73,28 @@ def _create_loader(ctxt: Context) -> BaseLoader:
     return ChoiceLoader(choices)
 
 
+def makepath(ctxt: Context, node: SourceNode | None, s: str) -> str:
+    """
+    Turn a string into a proper path reference, based on relative link settings and prefix.
+
+    Args:
+        ctxt (Context): The context to use for the operation.
+        node (SourceNode): The current node being processed; if this is ``None``, it's taken from the context.
+        s (str): The string to interpret.
+
+    Returns:
+        str: The resolved link.
+    """
+    if not node:
+        node = ctxt.current_node
+    if ctxt.relative_links:
+        in_path = ctxt.source_dir / s
+        rel_path = ctxt.source_dir / node.path
+        return urlquote(in_path.relative_to(rel_path.parent, walk_up=True).as_posix())
+    else:
+        return urlquote(ctxt.url_prefix + s)
+
+
 def create_template_environment(ctxt: Context) -> Environment:
     """
     Create the template environment used to render the data to the destination.
@@ -83,7 +105,23 @@ def create_template_environment(ctxt: Context) -> Environment:
     Returns:
         Environment: The new template environment.
     """
-    return Environment(loader=_create_loader(ctxt))
+    tenv = Environment(loader=_create_loader(ctxt))
+
+    # Add global variables easily calculated.
+    tenv.globals['dragonglass_version'] = __version__
+    tenv.globals["python_version"] = f"{sys.version_info[0]}.{sys.version_info[1]}.{sys.version_info[2]}"
+
+    # Add values derived from configuration.
+    t = ctxt.site_base
+    if t:
+        tenv.globals["site_base"] = t
+    t = ctxt.site_title
+    if t:
+        tenv.globals["site_title"] = t
+
+    # Add global functions.
+    tenv.globals['makepath'] = lambda s: makepath(ctxt, None, s)
+    return tenv
 
 
 def template_vars(node: SourceNode, ctxt: Context) -> dict[str, Any]:
@@ -103,18 +141,6 @@ def template_vars(node: SourceNode, ctxt: Context) -> dict[str, Any]:
     if not tvars["description"] and ctxt.description_title:
         tvars["description"] = node.page_title
 
-    # Add easily-calculated "global" variables.
-    tvars["dragonglass_version"] =  __version__
-    tvars["python_version"] = f"{sys.version_info[0]}.{sys.version_info[1]}.{sys.version_info[2]}"
-
-    # Add values derived from configuration.
-    t = ctxt.site_base
-    if t:
-        tvars["site_base"] = t
-    t = ctxt.site_title
-    if t:
-        tvars["site_title"] = t
-
     # Compute backlinks for this node.  Don't include nodes that aren't published.
     backlinks = sorted([n for n in node.backlinks if n.publish], key=lambda n: n.page_title)
     tvars['backlinks'] = [{'title': n.page_title,
@@ -122,12 +148,7 @@ def template_vars(node: SourceNode, ctxt: Context) -> dict[str, Any]:
                           for n in backlinks]
 
     # Add reference to the default stylesheet.
-    if ctxt.relative_links:
+    tvars['default_stylesheet'] = makepath(ctxt, node, ctxt.default_stylesheet)
-        stylesheet_path = ctxt.source_dir / ctxt.default_stylesheet
-        rel_path = ctxt.source_dir / node.path
-        tvars['default_stylesheet'] = urlquote(stylesheet_path.relative_to(rel_path.parent, walk_up=True).as_posix())
-    else:
-        tvars['default_stylesheet'] = urlquote(ctxt.url_prefix + ctxt.default_stylesheet)
 
     return tvars