introduce breadcrumbs in the web config

owrx/breadcrumb.py

@@ -0,0 +1,42 @@
+from typing import List
+from abc import ABC, abstractmethod
+
+
+class BreadcrumbItem(object):
+    def __init__(self, title, href):
+        self.title = title
+        self.href = href
+
+    def render(self, documentRoot):
+        return '<li class="breadcrumb-item"><a href="{documentRoot}{href}">{title}</a></li>'.format(
+            documentRoot=documentRoot, href=self.href, title=self.title
+        )
+
+
+class Breadcrumb(object):
+    def __init__(self, breadcrumbs: List[BreadcrumbItem]):
+        self.items = breadcrumbs
+
+    def render(self, documentRoot):
+        return """
+            <ol class="breadcrumb">
+                {crumbs}
+            </ol>
+        """.format(
+            crumbs="".join(item.render(documentRoot) for item in self.items)
+        )
+
+    def append(self, crumb: BreadcrumbItem):
+        self.items.append(crumb)
+        return self
+
+
+class BreadcrumbMixin(ABC):
+    def template_variables(self):
+        variables = super().template_variables()
+        variables["breadcrumb"] = self.get_breadcrumb().render(self.get_document_root())
+        return variables
+
+    @abstractmethod
+    def get_breadcrumb(self) -> Breadcrumb:
+        pass