import uuid
from datetime import datetime, timezone
from typing import Optional
from fastapi import APIRouter, HTTPException
from app.models import TripCreate, TripEventCreate, AttendeeAction
from app.internal import firestore as fstore

router = APIRouter(prefix="/trips", tags=["trips"])


@router.get("")
async def list_trips():
    return await fstore.collection_list("trips")


@router.post("")
async def create_trip(body: TripCreate):
    if body.end_date < body.start_date:
        raise HTTPException(400, "end_date must be on or after start_date.")
    trip_id = str(uuid.uuid4())
    now = datetime.now(timezone.utc).isoformat()
    doc = {
        "trip_id": trip_id,
        "name": body.name,
        "location": body.location,
        "maps_link": body.maps_link,
        "start_date": body.start_date,
        "end_date": body.end_date,
        "attendees": {},  # {discord_user_id: discord_username}
        "created_at": now,
    }
    await fstore.doc_set("trips", trip_id, doc, merge=False)
    return doc


@router.get("/{trip_id}")
async def get_trip(trip_id: str):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    events = await fstore.collection_list("trip_events", trip_id=trip_id)
    events.sort(key=lambda e: (e["date"], e.get("time") or ""))
    return {**trip, "events": events}


@router.delete("/{trip_id}")
async def delete_trip(trip_id: str):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    events = await fstore.collection_list("trip_events", trip_id=trip_id)
    for e in events:
        await fstore.doc_delete("trip_events", e["event_id"])
    await fstore.doc_delete("trips", trip_id)
    return {"ok": True}


@router.post("/{trip_id}/join")
async def join_trip(trip_id: str, body: AttendeeAction):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    attendees = trip.get("attendees", {})
    attendees[body.discord_user_id] = body.discord_username or body.discord_user_id
    await fstore.doc_update("trips", trip_id, {"attendees": attendees})
    return {"ok": True, "attendees": attendees}


@router.post("/{trip_id}/leave")
async def leave_trip(trip_id: str, body: AttendeeAction):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    attendees = trip.get("attendees", {})
    attendees.pop(body.discord_user_id, None)
    await fstore.doc_update("trips", trip_id, {"attendees": attendees})
    # cascade: remove from all events in this trip
    events = await fstore.collection_list("trip_events", trip_id=trip_id)
    for e in events:
        event_attendees = e.get("attendees", {})
        if body.discord_user_id in event_attendees:
            event_attendees.pop(body.discord_user_id)
            await fstore.doc_update("trip_events", e["event_id"], {"attendees": event_attendees})
    return {"ok": True}


@router.post("/{trip_id}/events")
async def create_event(trip_id: str, body: TripEventCreate):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    if not (trip["start_date"] <= body.date <= trip["end_date"]):
        raise HTTPException(
            400,
            f"Event date {body.date} is outside the trip range "
            f"{trip['start_date']} – {trip['end_date']}.",
        )
    event_id = str(uuid.uuid4())
    now = datetime.now(timezone.utc).isoformat()
    doc = {
        "event_id": event_id,
        "trip_id": trip_id,
        "title": body.title,
        "date": body.date,
        "time": body.time,
        "location": body.location if body.location is not None else trip["location"],
        "location_inherited": body.location is None,
        "maps_link": body.maps_link,
        "notes": body.notes,
        "attendees": {},
        "created_at": now,
    }
    await fstore.doc_set("trip_events", event_id, doc, merge=False)
    return doc


@router.delete("/{trip_id}/events/{event_id}")
async def delete_event(trip_id: str, event_id: str):
    event = await fstore.doc_get("trip_events", event_id)
    if not event or event.get("trip_id") != trip_id:
        raise HTTPException(404, f"Event '{event_id}' not found in trip '{trip_id}'.")
    await fstore.doc_delete("trip_events", event_id)
    return {"ok": True}


@router.post("/{trip_id}/events/{event_id}/join")
async def join_event(trip_id: str, event_id: str, body: AttendeeAction):
    trip = await fstore.doc_get("trips", trip_id)
    if not trip:
        raise HTTPException(404, f"Trip '{trip_id}' not found.")
    if body.discord_user_id not in trip.get("attendees", {}):
        raise HTTPException(403, "You must join the trip before joining an event.")
    event = await fstore.doc_get("trip_events", event_id)
    if not event or event.get("trip_id") != trip_id:
        raise HTTPException(404, f"Event '{event_id}' not found in trip '{trip_id}'.")
    attendees = event.get("attendees", {})
    attendees[body.discord_user_id] = body.discord_username or body.discord_user_id
    await fstore.doc_update("trip_events", event_id, {"attendees": attendees})
    return {"ok": True, "attendees": attendees}


@router.post("/{trip_id}/events/{event_id}/leave")
async def leave_event(trip_id: str, event_id: str, body: AttendeeAction):
    event = await fstore.doc_get("trip_events", event_id)
    if not event or event.get("trip_id") != trip_id:
        raise HTTPException(404, f"Event '{event_id}' not found in trip '{trip_id}'.")
    attendees = event.get("attendees", {})
    attendees.pop(body.discord_user_id, None)
    await fstore.doc_update("trip_events", event_id, {"attendees": attendees})
    return {"ok": True}