from pydantic import BaseModel, ConfigDict
from datetime import datetime
from typing import Literal, Optional


class RecurrenceRule(BaseModel):
    """Structured recurrence rule — serialized to/from JSON string in the DB column."""
    type: Literal["every_n_days", "weekly", "monthly_nth_weekday", "monthly_date"]
    # every_n_days
    interval: Optional[int] = None
    # weekly / monthly_nth_weekday
    weekday: Optional[int] = None  # 0=Mon … 6=Sun
    # monthly_nth_weekday
    week: Optional[int] = None     # 1-4
    # monthly_date
    day: Optional[int] = None      # 1-31


class CalendarEventCreate(BaseModel):
    title: str
    description: Optional[str] = None
    start_datetime: datetime
    end_datetime: datetime
    all_day: bool = False
    color: Optional[str] = None
    location_id: Optional[int] = None
    recurrence_rule: Optional[RecurrenceRule] = None  # structured; router serializes to JSON string
    is_starred: bool = False
    calendar_id: Optional[int] = None  # If None, server assigns default calendar


class CalendarEventUpdate(BaseModel):
    title: Optional[str] = None
    description: Optional[str] = None
    start_datetime: Optional[datetime] = None
    end_datetime: Optional[datetime] = None
    all_day: Optional[bool] = None
    color: Optional[str] = None
    location_id: Optional[int] = None
    recurrence_rule: Optional[RecurrenceRule] = None  # structured; router serializes to JSON string
    is_starred: Optional[bool] = None
    calendar_id: Optional[int] = None
    # Controls which occurrences an edit applies to; absent = non-recurring or whole-series
    edit_scope: Optional[Literal["this", "this_and_future"]] = None


class CalendarEventResponse(BaseModel):
    id: int
    title: str
    description: Optional[str]
    start_datetime: datetime
    end_datetime: datetime
    all_day: bool
    color: Optional[str]
    location_id: Optional[int]
    recurrence_rule: Optional[str]  # raw JSON string from DB; frontend parses
    is_starred: bool
    calendar_id: int
    calendar_name: str
    calendar_color: str
    is_virtual: bool = False
    # Recurrence fields
    parent_event_id: Optional[int] = None
    is_recurring: bool = False
    original_start: Optional[datetime] = None
    created_at: datetime
    updated_at: datetime

    model_config = ConfigDict(from_attributes=True)