"""Calendar and event tools."""

from __future__ import annotations

from datetime import datetime, timezone

from fabledassistant.services.events import (
    create_event as events_create_event,
    delete_event as events_delete_event,
    find_events_by_query,
    list_events as events_list_events,
    search_events as events_search_events,
    update_event as events_update_event,
)
from fabledassistant.services.tools._helpers import resolve_project
from fabledassistant.services.tools._registry import tool
from fabledassistant.services.tz import get_user_tz


async def _parse_datetime_in_user_tz(
    user_id: int, value: str
) -> tuple[datetime, bool]:
    """Parse a date/datetime string from the model into a UTC-aware datetime.

    Naive inputs are interpreted in the **user's local timezone** and then
    converted to UTC for storage. Never default to UTC for naive inputs —
    that's how all-day events landed on the wrong day for non-UTC users.

    Returns ``(utc_datetime, was_date_only)``.
    """
    was_date_only = "T" not in value and " " not in value
    if was_date_only:
        value = f"{value}T00:00:00"
    dt = datetime.fromisoformat(value.replace("Z", "+00:00"))
    if dt.tzinfo is None:
        user_tz = await get_user_tz(user_id)
        dt = dt.replace(tzinfo=user_tz)
    return dt.astimezone(timezone.utc), was_date_only


@tool(
    name="create_event",
    description="Create a calendar event for the user. Use this when the user asks to schedule, add, or create a meeting, appointment, or event. Pass dates and datetimes in the user's local time — a bare date like '2026-09-30' is interpreted as that day in the user's configured timezone.",
    parameters={
        "title": {"type": "string", "description": "A descriptive event title"},
        "start": {"type": "string", "description": "Start date (YYYY-MM-DD) or datetime (YYYY-MM-DDTHH:MM) in the user's local time. Include a timezone offset only if the user explicitly mentions one."},
        "end": {"type": "string", "description": "Optional end date or datetime in the user's local time"},
        "duration": {"type": "integer", "description": "Optional duration in minutes (default 60, ignored if end is set or all_day is true)"},
        "description": {"type": "string", "description": "Optional event description"},
        "location": {"type": "string", "description": "Optional event location"},
        "color": {"type": "string", "description": "Optional hex color for the event (e.g. '#6366f1')"},
        "all_day": {"type": "boolean", "description": "True for all-day events (birthdays, holidays, deadlines)"},
        "recurrence": {"type": "string", "description": "Optional iCalendar RRULE (e.g. 'FREQ=YEARLY' for annual, 'FREQ=WEEKLY' for weekly, 'FREQ=MONTHLY' for monthly)"},
        "reminder_minutes": {"type": "integer", "description": "Optional reminder N minutes before the event (e.g. 30 for 30 minutes before)"},
        "attendees": {"type": "array", "items": {"type": "string"}, "description": "Optional list of attendee email addresses"},
        "calendar_name": {"type": "string", "description": "Optional calendar name to create the event in. Falls back to default calendar."},
        "project": {"type": "string", "description": "Optional project name to associate this event with"},
    },
    required=["title", "start"],
)
async def create_event_tool(*, user_id, arguments, **_ctx):
    start_str = arguments["start"]
    end_str = arguments.get("end")
    all_day = arguments.get("all_day", False)
    try:
        # Naive dates/datetimes are interpreted in the user's local
        # timezone, not UTC. Storing UTC for naive inputs caused all-day
        # events to land on the previous day for negative-offset users.
        start_dt, start_was_date_only = await _parse_datetime_in_user_tz(
            user_id, start_str
        )
    except (ValueError, TypeError):
        return {"success": False, "error": f"Invalid start datetime: {start_str!r}"}
    if start_was_date_only:
        all_day = True
    end_dt = None
    if end_str:
        try:
            end_dt, _ = await _parse_datetime_in_user_tz(user_id, end_str)
        except (ValueError, TypeError):
            return {"success": False, "error": f"Invalid end datetime: {end_str!r}"}
    project_id = None
    project_name = arguments.get("project")
    if project_name:
        proj = await resolve_project(user_id, project_name)
        if proj:
            project_id = proj.id
    event = await events_create_event(
        user_id=user_id,
        title=arguments.get("title", "Untitled Event"),
        start_dt=start_dt,
        end_dt=end_dt,
        all_day=all_day,
        description=arguments.get("description") or "",
        location=arguments.get("location") or "",
        color=arguments.get("color") or "",
        recurrence=arguments.get("recurrence"),
        project_id=project_id,
        duration=arguments.get("duration"),
        reminder_minutes=arguments.get("reminder_minutes"),
        attendees=arguments.get("attendees"),
        calendar_name=arguments.get("calendar_name"),
    )
    return {"success": True, "type": "event", "data": event.to_dict()}


@tool(
    name="list_events",
    description="List calendar events in a date range. Use this when the user asks what events or meetings they have. Pass plain local dates (YYYY-MM-DD) — the server interprets them in the user's timezone and expands to a full local day.",
    parameters={
        "date_from": {"type": "string", "description": "Start of range as a local date (YYYY-MM-DD) or local datetime. Interpreted in the user's timezone."},
        "date_to": {"type": "string", "description": "End of range as a local date (YYYY-MM-DD) or local datetime. A bare date is expanded to 23:59:59 local."},
    },
    required=["date_from", "date_to"],
    read_only=True,
    briefing=True,
)
async def list_events_tool(*, user_id, arguments, **_ctx):
    # Bare local dates are expanded to a full local day in the user's TZ:
    # date_from → 00:00 local, date_to → 23:59:59 local, both converted to
    # UTC before the DB query. Previously the tool description told the
    # model to pass UTC ranges, which missed events for non-UTC users.
    try:
        date_from, _ = await _parse_datetime_in_user_tz(
            user_id, arguments["date_from"]
        )
        date_to_str = arguments["date_to"]
        if "T" not in date_to_str and " " not in date_to_str:
            date_to_str = f"{date_to_str}T23:59:59"
        date_to, _ = await _parse_datetime_in_user_tz(user_id, date_to_str)
    except (ValueError, TypeError, KeyError) as exc:
        return {"success": False, "error": f"Invalid date range: {exc}"}
    events = await events_list_events(user_id=user_id, date_from=date_from, date_to=date_to)
    return {
        "success": True,
        "type": "events",
        "data": {"count": len(events), "events": events},
    }


@tool(
    name="search_events",
    description="Search calendar events by keyword. Use this when the user asks to find a specific event or meeting.",
    parameters={
        "query": {"type": "string", "description": "Search keyword to match against event titles, locations, and descriptions"},
        "include_past": {"type": "boolean", "description": "Set to true to include past events in results (default: future events only)"},
    },
    required=["query"],
    read_only=True,
    briefing=True,
)
async def search_events_tool(*, user_id, arguments, **_ctx):
    events = await events_search_events(
        user_id=user_id,
        query=arguments.get("query", ""),
        include_past=arguments.get("include_past", False),
    )
    return {
        "success": True,
        "type": "events",
        "data": {
            "query": arguments.get("query", ""),
            "count": len(events),
            "events": [e.to_dict() for e in events],
        },
    }


@tool(
    name="update_event",
    description="Update an existing calendar event. Use this when the user asks to change, move, reschedule, or modify an event.",
    parameters={
        "query": {"type": "string", "description": "Search term to find the event to update (matches against title)"},
        "title": {"type": "string", "description": "New title for the event"},
        "start": {"type": "string", "description": "New start datetime in ISO 8601 format"},
        "end": {"type": "string", "description": "New end datetime in ISO 8601 format"},
        "all_day": {"type": "boolean", "description": "Whether the event is all-day"},
        "description": {"type": "string", "description": "New event description"},
        "location": {"type": "string", "description": "New event location"},
        "color": {"type": "string", "description": "New hex color for the event (e.g. '#6366f1')"},
        "recurrence": {"type": "string", "description": "New iCalendar RRULE"},
        "reminder_minutes": {"type": "integer", "description": "Reminder N minutes before the event. Pass 0 to remove an existing reminder."},
    },
    required=["query"],
)
async def update_event_tool(*, user_id, arguments, **_ctx):
    query = arguments.get("query", "")
    matches = await find_events_by_query(user_id=user_id, query=query)
    if not matches:
        return {"success": False, "error": f"No event found matching '{query}'."}
    event_to_update = matches[0]
    fields: dict = {}
    for str_field in ("title", "description", "location", "color", "recurrence"):
        if arguments.get(str_field) is not None:
            fields[str_field] = arguments[str_field]
    if arguments.get("all_day") is not None:
        fields["all_day"] = arguments["all_day"]
    if "reminder_minutes" in arguments:
        rm = arguments["reminder_minutes"]
        fields["reminder_minutes"] = None if rm == 0 else rm
    for dt_field, key in (("start_dt", "start"), ("end_dt", "end")):
        val = arguments.get(key)
        if val:
            try:
                # Naive datetimes are user-local, not UTC — see
                # ``_parse_datetime_in_user_tz`` docstring.
                dt, _ = await _parse_datetime_in_user_tz(user_id, val)
                fields[dt_field] = dt
            except (ValueError, TypeError):
                return {"success": False, "error": f"Invalid datetime for {key}: {val!r}"}
    updated = await events_update_event(user_id=user_id, event_id=event_to_update.id, **fields)
    if updated is None:
        return {"success": False, "error": "Event not found or update failed."}
    return {"success": True, "type": "event_updated", "data": updated.to_dict()}


@tool(
    name="delete_event",
    description="Delete a calendar event. Use this when the user asks to cancel, remove, or delete an event.",
    parameters={
        "query": {"type": "string", "description": "Search term to find the event to delete (matches against title)"},
    },
    required=["query"],
)
async def delete_event_tool(*, user_id, arguments, **_ctx):
    query = arguments.get("query", "")
    matches = await find_events_by_query(user_id=user_id, query=query)
    if not matches:
        return {"success": False, "error": f"No event found matching '{query}'."}
    event_to_delete = matches[0]
    await events_delete_event(user_id=user_id, event_id=event_to_delete.id)
    return {"success": True, "type": "event_deleted", "data": {"id": event_to_delete.id, "title": event_to_delete.title}}


@tool(
    name="list_calendars",
    description="List all available calendars. Use this when the user asks which calendars they have.",
    parameters={},
    read_only=True,
    requires="caldav",
)
async def list_calendars_tool(*, user_id, arguments, **_ctx):
    from fabledassistant.services.caldav import list_calendars

    calendars = await list_calendars(user_id=user_id)
    return {
        "success": True,
        "type": "calendars",
        "data": {"count": len(calendars), "calendars": calendars},
    }