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.crud import fit as fit_crud
from app.crud import fit_note as fit_note_crud
from app.deps import require_permission
from app.models.fit import FitLabel
from app.models.user import User
from app.schemas.fit import (
    FitCreate,
    FitNoteCreate,
    FitNoteRead,
    FitRead,
    FitRecomputeResult,
    FitUpdate,
)
from app.services import fit_matching

router = APIRouter()


@router.get("", response_model=list[FitRead])
async def list_fits(
    augmented_part_id: int | None = None,
    label: FitLabel | None = None,
    skip: int = 0,
    limit: int = 100,
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_permission("fits:read")),
):
    if augmented_part_id is not None:
        fits = await fit_crud.list_for_part(db, augmented_part_id)
        if label is not None:
            fits = [f for f in fits if f.label == label]
        return fits[skip : skip + limit]
    return await fit_crud.list_all(db, skip=skip, limit=limit, label=label)


@router.get("/{fit_id}", response_model=FitRead)
async def get_fit(
    fit_id: int,
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_permission("fits:read")),
):
    fit = await fit_crud.get(db, fit_id)
    if fit is None:
        raise HTTPException(status_code=404, detail="Fit not found")
    return fit


@router.post("", response_model=FitRead, status_code=status.HTTP_201_CREATED)
async def create_fit(
    payload: FitCreate,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("fits:write")),
):
    """Manually declare a fit between two attachment points; recorded as Exact."""
    if payload.attachment_point_a_id == payload.attachment_point_b_id:
        raise HTTPException(
            status_code=422, detail="attachment points must be different"
        )
    ap_a = await attachment_point_crud.get(db, payload.attachment_point_a_id)
    ap_b = await attachment_point_crud.get(db, payload.attachment_point_b_id)
    if ap_a is None or ap_b is None:
        raise HTTPException(status_code=404, detail="Attachment point not found")
    if ap_a.augmented_part_id == ap_b.augmented_part_id:
        raise HTTPException(
            status_code=422, detail="a part cannot fit itself"
        )
    existing = await fit_crud.get_by_attachment_points(db, ap_a, ap_b)
    if existing is not None:
        raise HTTPException(status_code=409, detail="Fit already exists")

    fit = await fit_crud.create(db, ap_a=ap_a, ap_b=ap_b, label=FitLabel.EXACT)
    await audit_crud.log(
        db,
        actor=actor,
        action="create",
        resource_type="Fit",
        resource_id=fit.id,
        description=audit_crud.describe_create(
            "Fit", fit.id, f"attachment points {ap_a.id}↔{ap_b.id}"
        ),
    )
    return fit


@router.patch("/{fit_id}", response_model=FitRead)
async def update_fit_label(
    fit_id: int,
    payload: FitUpdate,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("fits:write")),
):
    """Promote a Possible fit to Exact, or mark a pairing as None (impossible)."""
    fit = await fit_crud.get(db, fit_id)
    if fit is None:
        raise HTTPException(status_code=404, detail="Fit not found")
    fit = await fit_crud.set_label(db, fit, payload.label)
    await audit_crud.log(
        db,
        actor=actor,
        action="update",
        resource_type="Fit",
        resource_id=fit.id,
        description=audit_crud.describe_update(
            "Fit", fit.id, {"label": payload.label.value}
        ),
    )
    return fit


@router.delete("/{fit_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_fit(
    fit_id: int,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("fits:delete")),
):
    fit = await fit_crud.get(db, fit_id)
    if fit is None:
        raise HTTPException(status_code=404, detail="Fit not found")
    label = f"attachment points {fit.attachment_point_a_id}↔{fit.attachment_point_b_id}"
    await fit_crud.delete(db, fit)
    await audit_crud.log(
        db,
        actor=actor,
        action="delete",
        resource_type="Fit",
        resource_id=fit_id,
        description=audit_crud.describe_delete("Fit", fit_id, label),
    )


@router.post("/recompute", response_model=FitRecomputeResult)
async def recompute_fits(
    augmented_part_id: int | None = None,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("fits:write")),
):
    """Re-run the matching algorithm, scoped to one part or across all parts."""
    if augmented_part_id is not None:
        result = await fit_matching.recompute_for_part(db, augmented_part_id)
    else:
        result = await fit_matching.recompute_all(db)
    await audit_crud.log(
        db,
        actor=actor,
        action="update",
        resource_type="Fit",
        resource_id=augmented_part_id,
        description=f"Recomputed fits: {result.created} created, {result.removed} removed",
    )
    return FitRecomputeResult(created=result.created, removed=result.removed)


@router.post(
    "/{fit_id}/notes", response_model=FitNoteRead, status_code=status.HTTP_201_CREATED
)
async def create_fit_note(
    fit_id: int,
    payload: FitNoteCreate,
    db: AsyncSession = Depends(get_db),
    actor: User = Depends(require_permission("fits:write")),
):
    fit = await fit_crud.get(db, fit_id)
    if fit is None:
        raise HTTPException(status_code=404, detail="Fit not found")
    return await fit_note_crud.create(db, fit=fit, author=actor, body=payload.body)