import random
from datetime import datetime, timezone
from zoneinfo import ZoneInfo, ZoneInfoNotFoundError

from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, Field
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from app.dependencies import get_db, get_current_user
from app.models.child import Child
from app.models.strike import StrikeEvent
from app.models.user import User
from app.schemas.child import ChildCreate, ChildOut, ChildUpdate
from app.websocket.manager import manager

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


def _today_in_tz(tz_name: str):
    """Return today's date in the given IANA timezone, falling back to UTC."""
    try:
        tz = ZoneInfo(tz_name)
    except (ZoneInfoNotFoundError, Exception):
        tz = timezone.utc
    return datetime.now(tz).date()


@router.get("", response_model=list[ChildOut])
async def list_children(
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Child).where(Child.user_id == current_user.id).order_by(Child.name)
    )
    children = result.scalars().all()

    today = _today_in_tz(current_user.timezone)
    needs_commit = False
    for child in children:
        if child.strikes != 0 and child.strikes_last_reset != today:
            child.strikes = 0
            child.strikes_last_reset = today
            needs_commit = True
            await manager.broadcast(child.id, {"event": "strikes_update", "strikes": 0})
    if needs_commit:
        await db.commit()

    return children


async def _generate_tv_token(db: AsyncSession) -> int:
    while True:
        token = random.randint(1000, 9999)
        result = await db.execute(select(Child).where(Child.tv_token == token))
        if not result.scalar_one_or_none():
            return token


@router.post("", response_model=ChildOut, status_code=status.HTTP_201_CREATED)
async def create_child(
    body: ChildCreate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    tv_token = await _generate_tv_token(db)
    child = Child(**body.model_dump(), user_id=current_user.id, tv_token=tv_token)
    db.add(child)
    await db.commit()
    await db.refresh(child)
    return child


@router.get("/{child_id}", response_model=ChildOut)
async def get_child(
    child_id: int,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Child).where(Child.id == child_id, Child.user_id == current_user.id)
    )
    child = result.scalar_one_or_none()
    if not child:
        raise HTTPException(status_code=404, detail="Child not found")
    return child


@router.patch("/{child_id}", response_model=ChildOut)
async def update_child(
    child_id: int,
    body: ChildUpdate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Child).where(Child.id == child_id, Child.user_id == current_user.id)
    )
    child = result.scalar_one_or_none()
    if not child:
        raise HTTPException(status_code=404, detail="Child not found")

    for field, value in body.model_dump(exclude_none=True).items():
        setattr(child, field, value)
    await db.commit()
    await db.refresh(child)
    return child


class StrikesBody(BaseModel):
    strikes: int = Field(..., ge=0, le=3)


@router.patch("/{child_id}/strikes", response_model=ChildOut)
async def update_strikes(
    child_id: int,
    body: StrikesBody,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Child).where(Child.id == child_id, Child.user_id == current_user.id)
    )
    child = result.scalar_one_or_none()
    if not child:
        raise HTTPException(status_code=404, detail="Child not found")
    prev = child.strikes
    child.strikes = body.strikes
    db.add(StrikeEvent(child_id=child.id, prev_strikes=prev, new_strikes=body.strikes))
    await db.commit()
    await db.refresh(child)
    await manager.broadcast(child_id, {"event": "strikes_update", "strikes": child.strikes})
    return child


@router.delete("/{child_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_child(
    child_id: int,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Child).where(Child.id == child_id, Child.user_id == current_user.id)
    )
    child = result.scalar_one_or_none()
    if not child:
        raise HTTPException(status_code=404, detail="Child not found")
    await db.delete(child)
    await db.commit()