from __future__ import annotations

from fastapi import APIRouter, Depends, HTTPException, Query, status
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import Session

from govoplan_core.auth import ApiPrincipal, get_api_principal, has_scope
from govoplan_core.db.session import get_session
from govoplan_dashboard.backend.db.models import DashboardLayout
from govoplan_dashboard.backend.permissions import READ_SCOPE
from govoplan_dashboard.backend.schemas import (
    DashboardLayoutResponse,
    DashboardLayoutUpdateRequest,
)
from govoplan_dashboard.backend.service import (
    DashboardLayoutConflict,
    DashboardLayoutLimitExceeded,
    delete_dashboard_layout,
    get_dashboard_layout,
    normalize_view_id,
    save_dashboard_layout,
)


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


def _require_read(principal: ApiPrincipal) -> None:
    if not has_scope(principal, READ_SCOPE):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=f"Missing required scope: {READ_SCOPE}",
        )


def _response(
    layout: DashboardLayout | None,
    *,
    view_id: str | None,
) -> DashboardLayoutResponse:
    if layout is None:
        return DashboardLayoutResponse(
            exists=False,
            view_id=normalize_view_id(view_id),
        )
    return DashboardLayoutResponse(
        exists=True,
        view_id=layout.view_id,
        layout_version=layout.layout_version,
        revision=layout.revision,
        placements=layout.placements,
        known_widget_ids=layout.known_widget_ids,
        updated_at=layout.updated_at,
    )


@router.get("/layout", response_model=DashboardLayoutResponse)
def api_get_dashboard_layout(
    view_id: str | None = Query(default=None, max_length=255),
    session: Session = Depends(get_session),
    principal: ApiPrincipal = Depends(get_api_principal),
) -> DashboardLayoutResponse:
    _require_read(principal)
    return _response(
        get_dashboard_layout(
            session,
            tenant_id=principal.tenant_id,
            account_id=principal.account_id,
            view_id=view_id,
        ),
        view_id=view_id,
    )


@router.put("/layout", response_model=DashboardLayoutResponse)
def api_save_dashboard_layout(
    payload: DashboardLayoutUpdateRequest,
    view_id: str | None = Query(default=None, max_length=255),
    session: Session = Depends(get_session),
    principal: ApiPrincipal = Depends(get_api_principal),
) -> DashboardLayoutResponse:
    _require_read(principal)
    try:
        layout = save_dashboard_layout(
            session,
            tenant_id=principal.tenant_id,
            account_id=principal.account_id,
            view_id=view_id,
            expected_revision=payload.expected_revision,
            layout_version=payload.layout_version,
            placements=payload.placements,
            known_widget_ids=payload.known_widget_ids,
        )
        session.commit()
    except DashboardLayoutConflict as exc:
        session.rollback()
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail=str(exc),
        ) from exc
    except DashboardLayoutLimitExceeded as exc:
        session.rollback()
        raise HTTPException(
            status_code=status.HTTP_422_UNPROCESSABLE_CONTENT,
            detail=str(exc),
        ) from exc
    except IntegrityError as exc:
        session.rollback()
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail=(
                "The dashboard layout changed in another session. "
                "Reload it before saving."
            ),
        ) from exc
    return _response(layout, view_id=view_id)


@router.delete("/layout", status_code=status.HTTP_204_NO_CONTENT)
def api_delete_dashboard_layout(
    view_id: str | None = Query(default=None, max_length=255),
    session: Session = Depends(get_session),
    principal: ApiPrincipal = Depends(get_api_principal),
) -> None:
    _require_read(principal)
    delete_dashboard_layout(
        session,
        tenant_id=principal.tenant_id,
        account_id=principal.account_id,
        view_id=view_id,
    )
    session.commit()


__all__ = ["router"]