"""Device management — a logical view spanning three tables.

A "device" is a client identified by its MAC address, which is used verbatim as
the RADIUS ``username``. One device touches three tables:

    radcheck      username = MAC, Cleartext-Password := MAC   (auth)
    radusergroup  username = MAC, groupname = <group>         (VLAN/group membership)
    customers     username = MAC, mac_address = MAC, status   (billing/metadata)

This router hides that fan-out behind mac_address + group + status.
"""
from fastapi import APIRouter, Depends
from sqlalchemy import delete, func, select, update
from sqlalchemy.orm import Session

from ..database import get_db
from ..errors import APIError
from ..models import Customer, RadCheck, RadGroupReply, RadUserGroup
from ..pagination import Page, PageParams
from ..schemas import DeviceCreate, DeviceEdit, DeviceOut

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


def _group_exists(db: Session, group: str) -> bool:
    stmt = select(RadGroupReply.id).where(RadGroupReply.groupname == group).limit(1)
    return db.execute(stmt).first() is not None


def _device_exists(db: Session, mac: str) -> bool:
    stmt = select(Customer.id).where(Customer.username == mac).limit(1)
    return db.execute(stmt).first() is not None


@router.get("/", response_model=Page[DeviceOut])
def list_devices(page: PageParams = Depends(), db: Session = Depends(get_db)):
    """List devices — MAC, group and status, joined from customers + radusergroup."""
    base = select(
        Customer.mac_address, RadUserGroup.groupname, Customer.status,
        Customer.name, Customer.phone, Customer.device_alias,
    ).outerjoin(RadUserGroup, RadUserGroup.username == Customer.username)
    total = db.execute(select(func.count()).select_from(Customer)).scalar_one()
    rows = db.execute(base.order_by(Customer.id.desc()).limit(page.limit).offset(page.offset)).all()
    items = [
        DeviceOut(mac_address=mac, group=gn, status=st, name=nm, phone=ph, alias=al)
        for mac, gn, st, nm, ph, al in rows
    ]
    return Page(total=int(total), limit=page.limit, offset=page.offset, items=items)


@router.get("/{mac_address}", response_model=DeviceOut)
def get_device(mac_address: str, db: Session = Depends(get_db)):
    mac = mac_address.strip().upper().replace(":", "-")
    stmt = (
        select(
            Customer.mac_address, RadUserGroup.groupname, Customer.status,
            Customer.name, Customer.phone, Customer.device_alias,
        )
        .outerjoin(RadUserGroup, RadUserGroup.username == Customer.username)
        .where(Customer.username == mac)
    )
    row = db.execute(stmt).first()
    if row is None:
        raise APIError(status_code=404, detail=f"Device '{mac}' not found")
    return DeviceOut(
        mac_address=row[0], group=row[1], status=row[2],
        name=row[3], phone=row[4], alias=row[5],
    )


@router.post("/add", response_model=DeviceOut, status_code=201)
def add_device(payload: DeviceCreate, db: Session = Depends(get_db)):
    """Register a device: create its radcheck, radusergroup and customer rows."""
    mac = payload.mac_address

    if not _group_exists(db, payload.group):
        raise APIError(status_code=400, detail=f"Group '{payload.group}' not found — create it first")
    if _device_exists(db, mac):
        raise APIError(status_code=409, detail=f"Device '{mac}' already exists")

    db.add(RadCheck(username=mac, attribute="Cleartext-Password", op=":=", value=mac))
    db.add(RadUserGroup(username=mac, groupname=payload.group, priority=1))
    db.add(Customer(
        username=mac, mac_address=mac, status="paid",
        name=payload.name, phone=payload.phone, device_alias=payload.alias,
    ))
    db.commit()
    return DeviceOut(
        mac_address=mac, group=payload.group, status="paid",
        name=payload.name, phone=payload.phone, alias=payload.alias,
    )


@router.post("/edit", response_model=DeviceOut)
def edit_device(payload: DeviceEdit, db: Session = Depends(get_db)):
    """Edit a device — any subset of group, status, name, phone, alias."""
    mac = payload.mac_address
    customer = db.execute(select(Customer).where(Customer.username == mac)).scalar_one_or_none()
    if customer is None:
        raise APIError(status_code=404, detail=f"Device '{mac}' not found")

    if payload.group is not None:
        if not _group_exists(db, payload.group):
            raise APIError(status_code=400, detail=f"Group '{payload.group}' not found")
        db.execute(
            update(RadUserGroup).where(RadUserGroup.username == mac).values(groupname=payload.group)
        )

    if payload.status is not None:
        customer.status = payload.status
    if payload.name is not None:
        customer.name = payload.name
    if payload.phone is not None:
        customer.phone = payload.phone
    if payload.alias is not None:
        customer.device_alias = payload.alias

    db.commit()

    group = db.execute(
        select(RadUserGroup.groupname).where(RadUserGroup.username == mac).limit(1)
    ).scalar_one_or_none()
    return DeviceOut(
        mac_address=mac, group=group, status=customer.status,
        name=customer.name, phone=customer.phone, alias=customer.device_alias,
    )


@router.delete("/{mac_address}", status_code=204)
def delete_device(mac_address: str, db: Session = Depends(get_db)):
    """Remove a device from radcheck, radusergroup and customers."""
    mac = mac_address.strip().upper().replace(":", "-")
    if not _device_exists(db, mac):
        raise APIError(status_code=404, detail=f"Device '{mac}' not found")

    db.execute(delete(RadCheck).where(RadCheck.username == mac))
    db.execute(delete(RadUserGroup).where(RadUserGroup.username == mac))
    db.execute(delete(Customer).where(Customer.username == mac))
    db.commit()