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

from app.auth.dependencies import get_current_user
from app.auth.security import hash_password, verify_password
from app.db.models import User
from app.db.session import get_session

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

_MIN_PASSWORD_LENGTH = 8


class MeResponse(BaseModel):
    id: int
    username: str
    address: str
    balance_sats: int
    created_at: str


@router.get("/me", response_model=MeResponse)
async def me(user: User = Depends(get_current_user)) -> MeResponse:
    return MeResponse(
        id=user.id,
        username=user.username,
        address=user.address,
        balance_sats=user.cached_balance_sats,
        created_at=user.created_at.isoformat(),
    )


class ChangePasswordRequest(BaseModel):
    current_password: str
    new_password: str


@router.post("/me/change-password", status_code=status.HTTP_204_NO_CONTENT)
async def change_password(
    body: ChangePasswordRequest,
    user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> None:
    """Self-service password change — requires the current password, unlike the
    admin-only /admin/users/{id}/reset-password (which is for a user who's
    actually locked out and can't provide it)."""
    if not verify_password(body.current_password, user.password_hash):
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "current password is incorrect")
    if len(body.new_password) < _MIN_PASSWORD_LENGTH:
        raise HTTPException(status.HTTP_400_BAD_REQUEST, f"new password must be at least {_MIN_PASSWORD_LENGTH} characters")

    user.password_hash = hash_password(body.new_password)
    await session.commit()