import { Quaternion, Vector3 } from "three";

export function sourceNavigationAnchors(recipe, placement) {
  const policy = recipe.navigation?.sourceAnchorComponents;
  if (!policy) return [];
  if (policy.kind !== "native-source-anchor-components-v1"
    || recipe.navigation.includeDetourTopology !== true) {
    throw new Error("Source anchor components require the supported policy and Detour topology.");
  }
  const finiteVector = (values, length) => Array.isArray(values)
    && values.length === length && values.every(Number.isFinite);
  if (!finiteVector(placement.translation, 3) || !finiteVector(placement.rotation, 4)
    || !finiteVector(placement.scale, 3) || placement.scale.some(value => value === 0)
    || !Number.isFinite(recipe.coordinateSystem.metersPerSourceUnit)
    || recipe.coordinateSystem.metersPerSourceUnit <= 0) {
    throw new Error("Source navigation anchors require a finite invertible primary WDB placement.");
  }
  const transform = sourcePosition => {
    if (!finiteVector(sourcePosition, 3)) throw new Error("Source navigation anchor requires finite XYZ coordinates.");
    const point = new Vector3(...sourcePosition).sub(new Vector3(...placement.translation))
      .applyQuaternion(new Quaternion(...placement.rotation).invert())
      .divide(new Vector3(...placement.scale));
    const meters = recipe.coordinateSystem.metersPerSourceUnit;
    return [point.x * meters, point.y * meters, -point.z * meters];
  };
  if (!Array.isArray(recipe.source.sourceAnchorSupport?.points)
    || !Number.isFinite(policy.maximumProjectionDistance)
    || policy.maximumProjectionDistance <= 0
    || !Array.isArray(policy.requiredSourcePoints) || !policy.requiredSourcePoints.length) {
    throw new Error("Source navigation selection needs native anchor points, a projection limit and required source guards.");
  }
  const anchors = recipe.source.sourceAnchorSupport.points.map((sourcePosition, index) => ({
    id: `native-source-anchor-${index}`, kind: "native-source-anchor",
    sourcePosition: [...sourcePosition], position: transform(sourcePosition),
    maximumDistance: policy.maximumProjectionDistance,
  }));
  for (const guard of policy.requiredSourcePoints) {
    if (typeof guard.id !== "string" || !guard.id.trim() || !guard.evidence
      || !Number.isFinite(guard.maximumDistance) || guard.maximumDistance <= 0) {
      throw new Error("Required source navigation guards need an ID, evidence and a projection limit.");
    }
    if (guard.kind === "source-entry"
      && JSON.stringify(guard.sourcePosition) !== JSON.stringify(recipe.source.entryCoordinates?.position)) {
      throw new Error("The navigation entry guard must match the authoritative source entry.");
    }
    anchors.push({
      ...guard, sourcePosition: [...guard.sourcePosition],
      position: transform(guard.sourcePosition), required: true,
    });
  }
  if (new Set(anchors.map(anchor => anchor.id)).size !== anchors.length) {
    throw new Error("Source navigation anchor IDs must be unique.");
  }
  return anchors;
}