Deduplicate campaign template rendering

src/govoplan_campaign/backend/messages/builder.py

@@ -36,6 +36,10 @@ from govoplan_campaign.backend.campaign.models import (
 )
 from govoplan_campaign.backend.campaign.template_values import build_template_values
 from govoplan_campaign.backend.services.zip_service import create_zip_archive
+from govoplan_campaign.backend.template_rendering import (
+    find_unresolved_placeholders as _find_unresolved_placeholders,
+    render_template as _render_template,
+)
 
 from .models import (
     CampaignBuildReport,
@@ -47,28 +51,6 @@ from .models import (
     MessageValidationStatus,
 )
 
-_DOLLAR_FIELD_PATTERN = re.compile(r"(?<!\\)\$\{(.*?)(?<!\\)\}")
-_BRACE_FIELD_PATTERN = re.compile(r"(?<!\\)\{\{\s*(.*?)\s*\}\}")
-
-
-def _normalize_template_key(raw: str) -> str:
-    key = raw.strip()
-    if key.startswith("fields."):
-        key = key.removeprefix("fields.")
-    elif key.startswith("local."):
-        key = "local::" + key.removeprefix("local.")
-    elif key.startswith("global."):
-        key = "global::" + key.removeprefix("global.")
-
-    if key.startswith("local::") or key.startswith("global::"):
-        return key
-    if key.startswith("local:"):
-        return "local::" + key.removeprefix("local:")
-    if key.startswith("global:"):
-        return "global::" + key.removeprefix("global:")
-    return key
-
-
 @dataclass(slots=True)
 class BuiltMessage:
     draft: MessageDraft
@@ -123,29 +105,6 @@ def _read_text(campaign_file: str | Path, raw_path: str | None, encoding: str =
     return path.read_text(encoding=encoding)
 
 
-def _render_template(template: str, values: dict[str, Any], *, keep_missing: bool = True) -> str:
-    def replace(match: re.Match[str]) -> str:
-        key = _normalize_template_key(match.group(1))
-        if key in values:
-            value = values[key]
-            return "" if value is None else str(value)
-        return match.group(0) if keep_missing else ""
-
-    rendered = _DOLLAR_FIELD_PATTERN.sub(replace, template)
-    rendered = _BRACE_FIELD_PATTERN.sub(replace, rendered)
-    return rendered.replace(r"\${", "${").replace(r"\}", "}")
-
-
-def _find_unresolved_placeholders(text: str | None) -> set[str]:
-    if not text:
-        return set()
-    return {
-        _normalize_template_key(match.group(1))
-        for pattern in (_DOLLAR_FIELD_PATTERN, _BRACE_FIELD_PATTERN)
-        for match in pattern.finditer(text)
-    }
-
-
 def _message_address(recipient: RecipientConfig | None) -> MessageAddress | None:
     if recipient is None:
         return None