from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import joinedload, selectinload

from app.core.database import get_session
from app.models.pokemon import Pokemon
from app.models.route import Route
from app.models.route_encounter import RouteEncounter
from app.schemas.pokemon import (
    BulkImportItem,
    BulkImportResult,
    PokemonCreate,
    PokemonResponse,
    PokemonUpdate,
    RouteEncounterCreate,
    RouteEncounterDetailResponse,
    RouteEncounterUpdate,
)

router = APIRouter()


@router.get("/pokemon", response_model=list[PokemonResponse])
async def list_pokemon(
    search: str | None = Query(None),
    limit: int = Query(50, ge=1, le=500),
    offset: int = Query(0, ge=0),
    session: AsyncSession = Depends(get_session),
):
    query = select(Pokemon)
    if search:
        query = query.where(
            func.lower(Pokemon.name).contains(search.lower())
        )
    query = query.order_by(Pokemon.national_dex).offset(offset).limit(limit)
    result = await session.execute(query)
    return result.scalars().all()


@router.post("/pokemon/bulk-import", response_model=BulkImportResult)
async def bulk_import_pokemon(
    items: list[BulkImportItem],
    session: AsyncSession = Depends(get_session),
):
    created = 0
    updated = 0
    errors: list[str] = []

    for item in items:
        try:
            existing = await session.execute(
                select(Pokemon).where(Pokemon.national_dex == item.national_dex)
            )
            pokemon = existing.scalar_one_or_none()

            if pokemon is not None:
                pokemon.name = item.name
                pokemon.types = item.types
                if item.sprite_url is not None:
                    pokemon.sprite_url = item.sprite_url
                updated += 1
            else:
                pokemon = Pokemon(**item.model_dump())
                session.add(pokemon)
                created += 1
        except Exception as e:
            errors.append(f"Dex #{item.national_dex} ({item.name}): {e}")

    await session.commit()
    return BulkImportResult(created=created, updated=updated, errors=errors)


@router.post("/pokemon", response_model=PokemonResponse, status_code=201)
async def create_pokemon(
    data: PokemonCreate, session: AsyncSession = Depends(get_session)
):
    existing = await session.execute(
        select(Pokemon).where(Pokemon.national_dex == data.national_dex)
    )
    if existing.scalar_one_or_none() is not None:
        raise HTTPException(
            status_code=409,
            detail=f"Pokemon with national dex #{data.national_dex} already exists",
        )

    pokemon = Pokemon(**data.model_dump())
    session.add(pokemon)
    await session.commit()
    await session.refresh(pokemon)
    return pokemon


@router.get("/pokemon/{pokemon_id}", response_model=PokemonResponse)
async def get_pokemon(
    pokemon_id: int, session: AsyncSession = Depends(get_session)
):
    pokemon = await session.get(Pokemon, pokemon_id)
    if pokemon is None:
        raise HTTPException(status_code=404, detail="Pokemon not found")
    return pokemon


@router.put("/pokemon/{pokemon_id}", response_model=PokemonResponse)
async def update_pokemon(
    pokemon_id: int,
    data: PokemonUpdate,
    session: AsyncSession = Depends(get_session),
):
    pokemon = await session.get(Pokemon, pokemon_id)
    if pokemon is None:
        raise HTTPException(status_code=404, detail="Pokemon not found")

    update_data = data.model_dump(exclude_unset=True)
    if "national_dex" in update_data:
        existing = await session.execute(
            select(Pokemon).where(
                Pokemon.national_dex == update_data["national_dex"],
                Pokemon.id != pokemon_id,
            )
        )
        if existing.scalar_one_or_none() is not None:
            raise HTTPException(
                status_code=409,
                detail=f"Pokemon with national dex #{update_data['national_dex']} already exists",
            )

    for field, value in update_data.items():
        setattr(pokemon, field, value)

    await session.commit()
    await session.refresh(pokemon)
    return pokemon


@router.delete("/pokemon/{pokemon_id}", status_code=204)
async def delete_pokemon(
    pokemon_id: int, session: AsyncSession = Depends(get_session)
):
    result = await session.execute(
        select(Pokemon)
        .where(Pokemon.id == pokemon_id)
        .options(selectinload(Pokemon.encounters))
    )
    pokemon = result.scalar_one_or_none()
    if pokemon is None:
        raise HTTPException(status_code=404, detail="Pokemon not found")

    if pokemon.encounters:
        raise HTTPException(
            status_code=409,
            detail="Cannot delete pokemon with existing encounters.",
        )

    await session.delete(pokemon)
    await session.commit()


@router.get(
    "/routes/{route_id}/pokemon",
    response_model=list[RouteEncounterDetailResponse],
)
async def list_route_encounters(
    route_id: int, session: AsyncSession = Depends(get_session)
):
    # Verify route exists
    route = await session.get(Route, route_id)
    if route is None:
        raise HTTPException(status_code=404, detail="Route not found")

    result = await session.execute(
        select(RouteEncounter)
        .where(RouteEncounter.route_id == route_id)
        .options(joinedload(RouteEncounter.pokemon))
        .order_by(RouteEncounter.encounter_rate.desc())
    )
    return result.scalars().unique().all()


@router.post(
    "/routes/{route_id}/pokemon",
    response_model=RouteEncounterDetailResponse,
    status_code=201,
)
async def add_route_encounter(
    route_id: int,
    data: RouteEncounterCreate,
    session: AsyncSession = Depends(get_session),
):
    route = await session.get(Route, route_id)
    if route is None:
        raise HTTPException(status_code=404, detail="Route not found")

    pokemon = await session.get(Pokemon, data.pokemon_id)
    if pokemon is None:
        raise HTTPException(status_code=404, detail="Pokemon not found")

    encounter = RouteEncounter(route_id=route_id, **data.model_dump())
    session.add(encounter)
    await session.commit()

    # Reload with pokemon relationship
    result = await session.execute(
        select(RouteEncounter)
        .where(RouteEncounter.id == encounter.id)
        .options(joinedload(RouteEncounter.pokemon))
    )
    return result.scalar_one()


@router.put(
    "/routes/{route_id}/pokemon/{encounter_id}",
    response_model=RouteEncounterDetailResponse,
)
async def update_route_encounter(
    route_id: int,
    encounter_id: int,
    data: RouteEncounterUpdate,
    session: AsyncSession = Depends(get_session),
):
    result = await session.execute(
        select(RouteEncounter)
        .where(RouteEncounter.id == encounter_id, RouteEncounter.route_id == route_id)
        .options(joinedload(RouteEncounter.pokemon))
    )
    encounter = result.scalar_one_or_none()
    if encounter is None:
        raise HTTPException(status_code=404, detail="Route encounter not found")

    for field, value in data.model_dump(exclude_unset=True).items():
        setattr(encounter, field, value)

    await session.commit()
    await session.refresh(encounter)

    # Reload with pokemon relationship
    result = await session.execute(
        select(RouteEncounter)
        .where(RouteEncounter.id == encounter.id)
        .options(joinedload(RouteEncounter.pokemon))
    )
    return result.scalar_one()


@router.delete("/routes/{route_id}/pokemon/{encounter_id}", status_code=204)
async def remove_route_encounter(
    route_id: int,
    encounter_id: int,
    session: AsyncSession = Depends(get_session),
):
    encounter = await session.execute(
        select(RouteEncounter).where(
            RouteEncounter.id == encounter_id,
            RouteEncounter.route_id == route_id,
        )
    )
    encounter = encounter.scalar_one_or_none()
    if encounter is None:
        raise HTTPException(status_code=404, detail="Route encounter not found")

    await session.delete(encounter)
    await session.commit()