Add bulk calendar invitation delivery

src/govoplan_campaign/backend/campaign/validation.py

@@ -2,9 +2,11 @@ from __future__ import annotations
 
 import csv
 from dataclasses import dataclass
+from datetime import datetime
 from enum import StrEnum
 from pathlib import Path
 from typing import Iterable
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
 from pydantic import BaseModel, ConfigDict, Field
 
@@ -483,6 +485,7 @@ def _delivery_issues(
     *,
     postbox_available: bool,
     templates_available: bool,
+    calendar_available: bool,
 ) -> list[SemanticIssue]:
     issues: list[SemanticIssue] = []
     policies = _delivery_policies(config)
@@ -574,9 +577,110 @@ def _delivery_issues(
                         f"/entries/inline/{entry_index}/print_target",
                     )
                 )
+    invitation = config.delivery.calendar_invitation
+    if invitation.enabled:
+        if not calendar_available:
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_unavailable",
+                    "Calendar invitations require the optional Calendar module.",
+                    "/delivery/calendar_invitation/enabled",
+                )
+            )
+        if not policies or any(not policy.uses_mail for policy in policies):
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_requires_mail",
+                    "Calendar invitations require Mail delivery for every active recipient.",
+                    "/delivery/channel_policy",
+                )
+            )
+        if not invitation.calendar_id:
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_calendar_missing",
+                    "Select a writable calendar for campaign invitation tracking.",
+                    "/delivery/calendar_invitation/calendar_id",
+                )
+            )
+        if not invitation.start_at_template:
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_start_missing",
+                    "Calendar invitations require a start date and time or a field template.",
+                    "/delivery/calendar_invitation/start_at_template",
+                )
+            )
+        if invitation.timezone:
+            try:
+                ZoneInfo(invitation.timezone)
+            except ZoneInfoNotFoundError:
+                issues.append(
+                    _issue(
+                        Severity.ERROR,
+                        "calendar_invitation_timezone_invalid",
+                        f"Unknown calendar invitation timezone: {invitation.timezone}",
+                        "/delivery/calendar_invitation/timezone",
+                    )
+                )
+        valid_start, fixed_start = _fixed_invitation_datetime(
+            invitation.start_at_template
+        )
+        valid_end, fixed_end = _fixed_invitation_datetime(invitation.end_at_template)
+        if invitation.start_at_template and not valid_start:
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_start_invalid",
+                    "The fixed invitation start must be ISO 8601; recipient field templates are also supported.",
+                    "/delivery/calendar_invitation/start_at_template",
+                )
+            )
+        if invitation.end_at_template and not valid_end:
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_end_invalid",
+                    "The fixed invitation end must be ISO 8601; recipient field templates are also supported.",
+                    "/delivery/calendar_invitation/end_at_template",
+                )
+            )
+        if fixed_start and fixed_end and _invitation_range_invalid(
+            fixed_start,
+            fixed_end,
+        ):
+            issues.append(
+                _issue(
+                    Severity.ERROR,
+                    "calendar_invitation_range_invalid",
+                    "Calendar invitation end must be after its start.",
+                    "/delivery/calendar_invitation/end_at_template",
+                )
+            )
     return issues
 
 
+def _fixed_invitation_datetime(value: str | None) -> tuple[bool, datetime | None]:
+    if not value:
+        return True, None
+    if "${" in value or "{{" in value:
+        return True, None
+    try:
+        return True, datetime.fromisoformat(value.replace("Z", "+00:00"))
+    except ValueError:
+        return False, None
+
+
+def _invitation_range_invalid(start_at: datetime, end_at: datetime) -> bool:
+    if (start_at.tzinfo is None) != (end_at.tzinfo is None):
+        return True
+    return end_at <= start_at
+
+
 def _sender_issues(config: CampaignConfig) -> list[SemanticIssue]:
     """Require Campaign-owned sender data before a send-mode build."""
 
@@ -826,6 +930,7 @@ def validate_campaign_config(
     check_files: bool = False,
     postbox_available: bool = False,
     templates_available: bool = False,
+    calendar_available: bool = False,
 ) -> SemanticReport:
     campaign_path = Path(campaign_file).resolve() if campaign_file else Path.cwd() / "campaign.json"
     issues: list[SemanticIssue] = []
@@ -842,6 +947,7 @@ def validate_campaign_config(
             config,
             postbox_available=postbox_available,
             templates_available=templates_available,
+            calendar_available=calendar_available,
         )
     )
     issues.extend(_sender_issues(config))