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

from app.core.database import get_db
from app.crud import attachment_point as attachment_point_crud
from app.crud import audit as audit_crud
from app.deps import require_permission
from app.models.user import User
from app.schemas.attachment_point import (
    AttachmentPointCreate,
    AttachmentPointRead,
    AttachmentPointUpdate,
)

router = APIRouter()


def _connection_label(ap) -> str:
    if ap.iso_thread:
        return f"M{ap.iso_thread.diameter_mm}×{ap.iso_thread.pitch_mm}"
    if ap.unc_thread:
        return f"{ap.unc_thread.diameter_fraction}-{ap.unc_thread.tpi} {ap.unc_thread.series}"
    if ap.clamp_connection:
        cc = ap.clamp_connection
        if cc.min_mm is not None:
            return f"{cc.min_mm}–{cc.max_mm} mm"
        return f"{cc.min_in}–{cc.max_in} in"
    if ap.static_connection:
        return f"{ap.static_connection.od_mm} mm OD"
    return "—"


@router.get("", response_model=list[AttachmentPointRead])
async def list_attachment_points(
    skip: int = 0,
    limit: int = 100,
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_permission("attachment_points:read")),
):
    return await attachment_point_crud.list_all(db, skip=skip, limit=limit)


@router.post("", response_model=AttachmentPointRead, status_code=status.HTTP_201_CREATED)
async def create_attachment_point(
    payload: AttachmentPointCreate,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("attachment_points:write")),
):
    conn_ids = [
        payload.iso_thread_id,
        payload.unc_thread_id,
        payload.clamp_connection_id,
        payload.static_connection_id,
    ]
    if sum(v is not None for v in conn_ids) != 1:
        raise HTTPException(
            status_code=400,
            detail="Exactly one connection (iso_thread, unc_thread, clamp_connection, or static_connection) must be provided.",
        )
    ap = await attachment_point_crud.create(db, **payload.model_dump())
    await audit_crud.log(
        db, actor=actor, action="create", resource_type="AttachmentPoint",
        resource_id=ap.id,
        description=audit_crud.describe_create(
            "AttachmentPoint", ap.id, _connection_label(ap)
        ),
    )
    return ap


@router.get("/{attachment_point_id}", response_model=AttachmentPointRead)
async def get_attachment_point(
    attachment_point_id: int,
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_permission("attachment_points:read")),
):
    ap = await attachment_point_crud.get(db, attachment_point_id)
    if ap is None:
        raise HTTPException(status_code=404, detail="Attachment point not found")
    return ap


@router.patch("/{attachment_point_id}", response_model=AttachmentPointRead)
async def update_attachment_point(
    attachment_point_id: int,
    payload: AttachmentPointUpdate,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("attachment_points:write")),
):
    ap = await attachment_point_crud.get(db, attachment_point_id)
    if ap is None:
        raise HTTPException(status_code=404, detail="Attachment point not found")
    changes = payload.model_dump(exclude_unset=True)
    ap = await attachment_point_crud.update(db, ap, changes)
    await audit_crud.log(
        db, actor=actor, action="update", resource_type="AttachmentPoint",
        resource_id=ap.id,
        description=audit_crud.describe_update("AttachmentPoint", ap.id, changes),
    )
    return ap


@router.delete("/{attachment_point_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_attachment_point(
    attachment_point_id: int,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("attachment_points:delete")),
):
    ap = await attachment_point_crud.get(db, attachment_point_id)
    if ap is None:
        raise HTTPException(status_code=404, detail="Attachment point not found")
    label = _connection_label(ap)
    await attachment_point_crud.delete(db, ap)
    await audit_crud.log(
        db, actor=actor, action="delete", resource_type="AttachmentPoint",
        resource_id=attachment_point_id,
        description=audit_crud.describe_delete("AttachmentPoint", attachment_point_id, label),
    )