import type RAPIER from "@dimforge/rapier3d-compat";
import type { World } from "@dimforge/rapier3d-compat";
import type { PartyWorldPosition } from "../game/partyRuntimeRegistry";
import { ACTOR_TERRAIN_QUERY_GROUPS } from "./actorCollision";

const COLLISION_RADIUS = 0.34;
const COLLISION_HALF_HEIGHT = 0.48;
const COLLISION_CENTER_HEIGHT = COLLISION_RADIUS + COLLISION_HALF_HEIGHT + 0.04;
const WALKABLE_STEP_HEIGHT = 0.32;
export const PARTY_FLOOR_RAY_HEIGHT = 1.25;
export const PARTY_FLOOR_RAY_DEPTH = 2;
const FLOOR_SAMPLE_SPACING = 0.6;
const MAX_FLOOR_DELTA = 0.55;

/** Shared by live party routing and collision-backed traversal regressions. */
export function createPartyDirectSegmentValidator(rapier: typeof RAPIER, world: World) {
  const capsule = new rapier.Capsule(
    COLLISION_HALF_HEIGHT - WALKABLE_STEP_HEIGHT * 0.5,
    COLLISION_RADIUS,
  );
  const rotation = { x: 0, y: 0, z: 0, w: 1 };
  const flags = rapier.QueryFilterFlags.EXCLUDE_SENSORS;
  return (start: PartyWorldPosition, end: PartyWorldPosition): boolean => {
    const dx = end[0] - start[0];
    const dy = end[1] - start[1];
    const dz = end[2] - start[2];
    const distance = Math.hypot(dx, dy, dz);
    if (!Number.isFinite(distance)) return false;
    if (Math.hypot(dx, dz) <= 0.04) return Math.abs(dy) <= WALKABLE_STEP_HEIGHT;
    const obstacle = world.castShape(
      { x: start[0], y: start[1] + COLLISION_CENTER_HEIGHT + WALKABLE_STEP_HEIGHT * 0.5, z: start[2] },
      rotation,
      { x: dx / distance, y: dy / distance, z: dz / distance },
      capsule,
      0.025,
      distance,
      false,
      flags,
      ACTOR_TERRAIN_QUERY_GROUPS,
    );
    if (obstacle && obstacle.time_of_impact < distance - 0.04) return false;
    const sampleCount = Math.max(1, Math.ceil(distance / FLOOR_SAMPLE_SPACING));
    for (let sample = 0; sample <= sampleCount; sample += 1) {
      const progress = sample / sampleCount;
      const expectedY = start[1] + dy * progress;
      const ray = new rapier.Ray({
        x: start[0] + dx * progress,
        y: expectedY + PARTY_FLOOR_RAY_HEIGHT,
        z: start[2] + dz * progress,
      }, { x: 0, y: -1, z: 0 });
      const floor = world.castRay(ray, PARTY_FLOOR_RAY_DEPTH, true, flags, ACTOR_TERRAIN_QUERY_GROUPS);
      if (!floor || Math.abs(ray.origin.y - floor.timeOfImpact - expectedY) > MAX_FLOOR_DELTA) return false;
    }
    return true;
  };
}

/** Triangle corridors need wall/overhang validation, not a second radius erosion. */
export function createPartyRouteSegmentValidator(rapier: typeof RAPIER, world: World) {
  const flags = rapier.QueryFilterFlags.EXCLUDE_SENSORS;
  return (start: PartyWorldPosition, end: PartyWorldPosition): boolean => {
    const dx = end[0] - start[0];
    const dy = end[1] - start[1];
    const dz = end[2] - start[2];
    const distance = Math.hypot(dx, dy, dz);
    if (!Number.isFinite(distance)) return false;
    if (distance <= 0.04) return true;
    const ray = new rapier.Ray({
      x: start[0], y: start[1] + 0.9, z: start[2],
    }, { x: dx / distance, y: dy / distance, z: dz / distance });
    const hit = world.castRay(ray, distance, true, flags, ACTOR_TERRAIN_QUERY_GROUPS);
    return !hit || hit.timeOfImpact >= distance - 0.04;
  };
}