from typing import Annotated

from fastapi import Depends, HTTPException, status, Header
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.config import settings
from app.core.database import get_db
from app.core.security import decode_access_token
from app.models import User, Participant, Marathon, UserRole, ParticipantRole

security = HTTPBearer()


async def get_current_user(
    credentials: Annotated[HTTPAuthorizationCredentials, Depends(security)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> User:
    token = credentials.credentials
    payload = decode_access_token(token)

    if payload is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
            headers={"WWW-Authenticate": "Bearer"},
        )

    user_id = payload.get("sub")
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token payload",
        )

    result = await db.execute(select(User).where(User.id == int(user_id)))
    user = result.scalar_one_or_none()

    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
        )

    return user


def require_admin(user: User) -> User:
    """Check if user is admin"""
    if not user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin access required",
        )
    return user


async def get_participant(
    db: AsyncSession,
    user_id: int,
    marathon_id: int,
) -> Participant | None:
    """Get participant record for user in marathon"""
    result = await db.execute(
        select(Participant).where(
            Participant.user_id == user_id,
            Participant.marathon_id == marathon_id,
        )
    )
    return result.scalar_one_or_none()


async def require_participant(
    db: AsyncSession,
    user_id: int,
    marathon_id: int,
) -> Participant:
    """Require user to be participant of marathon"""
    participant = await get_participant(db, user_id, marathon_id)
    if not participant:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You are not a participant of this marathon",
        )
    return participant


async def require_organizer(
    db: AsyncSession,
    user: User,
    marathon_id: int,
) -> Participant:
    """Require user to be organizer of marathon (or admin)"""
    if user.is_admin:
        # Admins can act as organizers
        participant = await get_participant(db, user.id, marathon_id)
        if participant:
            return participant
        # Create virtual participant for admin
        result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
        marathon = result.scalar_one_or_none()
        if not marathon:
            raise HTTPException(status_code=404, detail="Marathon not found")
        # Return a temporary object for admin
        return Participant(
            user_id=user.id,
            marathon_id=marathon_id,
            role=ParticipantRole.ORGANIZER.value
        )

    participant = await get_participant(db, user.id, marathon_id)
    if not participant:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You are not a participant of this marathon",
        )
    if not participant.is_organizer:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only organizers can perform this action",
        )
    return participant


async def require_creator(
    db: AsyncSession,
    user: User,
    marathon_id: int,
) -> Marathon:
    """Require user to be creator of marathon (or admin)"""
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()

    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    if not user.is_admin and marathon.creator_id != user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only the creator can perform this action",
        )
    return marathon


# Type aliases for cleaner dependency injection
CurrentUser = Annotated[User, Depends(get_current_user)]
DbSession = Annotated[AsyncSession, Depends(get_db)]


async def verify_bot_secret(
    x_bot_secret: str | None = Header(None, alias="X-Bot-Secret")
) -> None:
    """Verify that request comes from trusted bot using secret key."""
    if not settings.BOT_API_SECRET:
        # If secret is not configured, skip check (for development)
        return

    if x_bot_secret != settings.BOT_API_SECRET:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Invalid or missing bot secret"
        )


BotSecretDep = Annotated[None, Depends(verify_bot_secret)]