inital commit

server/app/mailer/domain/template.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass
+
+_FIELD_PATTERN = re.compile(r"(?<!\\)\$\{(.*?)(?<!\\)\}")
+
+
+@dataclass
+class MailTemplate:
+    template_string: str = ""
+
+    def set_template_string(self, template: str) -> "MailTemplate":
+        self.template_string = template
+        return self
+
+    def get_used_fields(self) -> set[str]:
+        return set(_FIELD_PATTERN.findall(self.template_string))
+
+    def apply_values(self, values: dict[str, str], *, keep_missing: bool = True) -> str:
+        def replace(match: re.Match[str]) -> str:
+            key = match.group(1)
+            if key in values:
+                return values[key]
+            return match.group(0) if keep_missing else ""
+
+        rendered = _FIELD_PATTERN.sub(replace, self.template_string)
+        return rendered.replace(r"\${", "${").replace(r"\}", "}")