import { findNearestPartyNavigationSurface, findPartyNavigationPath, type PartyNavigationGraph } from "./partyNavigation";
import { derivePartySpawnSlots } from "./partySpawnSlots";
import type { BiteSizedLayoutBlocker, BiteSizedSpot, LayoutVector } from "../../shared/bite-sized-layouts.mjs";

export function biteSizedRouteSegmentClear(blockers: readonly BiteSizedLayoutBlocker[], from: LayoutVector, to: LayoutVector): boolean {
  return blockers.every((blocker) => {
    const sin = Math.sin(blocker.yaw), cos = Math.cos(blocker.yaw);
    const local = (point: LayoutVector) => {
      const x = point[0] - blocker.position[0], z = point[2] - blocker.position[2];
      return [x * cos - z * sin, point[1] - blocker.position[1], x * sin + z * cos];
    };
    const start = local(from), end = local(to);
    let enter = 0, leave = 1;
    for (let axis = 0; axis < 3; axis++) {
      const extent = blocker.halfExtents[axis] + (axis === 1 ? 1 : 0.34);
      const delta = end[axis] - start[axis];
      if (Math.abs(delta) < 1e-9) { if (Math.abs(start[axis]) > extent) return true; continue; }
      const first = (-extent - start[axis]) / delta, second = (extent - start[axis]) / delta;
      enter = Math.max(enter, Math.min(first, second));
      leave = Math.min(leave, Math.max(first, second));
      if (enter > leave) return true;
    }
    return false;
  });
}

export function validateBiteSizedSpotNavigation(spot: BiteSizedSpot, graph: PartyNavigationGraph, regions?: readonly number[], blockers: readonly BiteSizedLayoutBlocker[] = []): void {
  const start = findNearestPartyNavigationSurface(graph, spot.partySpawn.footPosition, 0.75);
  if (!start) throw new Error(`${spot.name}: Party anchor is off the walkable floor. Move its spawn point.`);
  const points: { label: string; position: readonly [number, number, number]; snapDistance?: number }[] = [
    ...derivePartySpawnSlots(spot.partySpawn).map((s, i) => ({ label: `Party member ${i + 1}`, position: s.footPosition, snapDistance: i === 0 ? 0.75 : 6 })),
    ...spot.mobs.map((m, i) => ({ label: `Mob ${i + 1}`, position: m.position })),
    { label: "Boss", position: spot.bossSpawn.footPosition },
  ];
  for (const point of points) {
    // Companions project their formation seats onto the floor within six metres,
    // exactly as PartyPopulation does. Authored mob/boss points never auto-snap.
    const match = findNearestPartyNavigationSurface(graph, point.position, point.snapDistance ?? 0.75);
    if (!match) throw new Error(`${spot.name}: ${point.label} is off the walkable floor. Move its spawn point.`);
    if (!biteSizedRouteSegmentClear(blockers, match.position, match.position)) throw new Error(`${spot.name}: ${point.label} is inside a route blocker.`);
    const reachable = regions ? regions[start.triangleId] === regions[match.triangleId]
      : findPartyNavigationPath(graph, start.position, match.position, { maxSnapDistance: 0.75,
        routeSegmentAllowed: (from, to) => biteSizedRouteSegmentClear(blockers, from, to) });
    if (!reachable) throw new Error(`${spot.name}: ${point.label} cannot be reached from the party start.`);
  }
}