import type { MobVector3 } from "./mobPopulation";

export type DungeonWorldObjectKind =
  | "door"
  | "gate"
  | "bridge"
  | "switch"
  | "key"
  | "chest"
  | "npc"
  | "quest-object"
  | "trigger";

export type DungeonWorldObjectFidelity =
  | "source-exact"
  | "source-backed-adapted"
  | "healer-man-authored";

export interface DungeonWorldObjectSource {
  readonly fidelity: DungeonWorldObjectFidelity;
  readonly files: readonly string[];
  readonly templateId?: number;
  readonly spawnId?: number;
  readonly note?: string;
}

export interface DungeonWorldObjectStateDefinition {
  readonly id: string;
  readonly label: string;
  readonly visible: boolean;
  readonly blocksMovement: boolean;
  readonly blocksSight?: boolean;
  readonly interactionEnabled?: boolean;
}

export interface DungeonWorldObjectInteraction {
  readonly prompt: string;
  readonly range: number;
  readonly signalId: string;
  readonly allowedStates?: readonly string[];
  readonly oneShot?: boolean;
  readonly instructions?: string;
}

export interface DungeonWorldObjectVisual {
  /** Optional independently packaged GLB. Procedural geometry remains the safe fallback. */
  readonly assetUrl?: string;
  readonly color?: string;
  readonly emissive?: string;
  readonly scale?: MobVector3;
}

export interface DungeonWorldObjectDefinition {
  readonly id: string;
  readonly name: string;
  readonly kind: DungeonWorldObjectKind;
  readonly position: MobVector3;
  readonly yaw?: number;
  /** Half-extents of the interaction/collision box in metres. */
  readonly halfExtents: MobVector3;
  readonly initialState: string;
  readonly states: readonly DungeonWorldObjectStateDefinition[];
  readonly interaction?: DungeonWorldObjectInteraction;
  readonly visual?: DungeonWorldObjectVisual;
  readonly source?: DungeonWorldObjectSource;
}

export interface DungeonWorldInteractionCandidate {
  readonly object: DungeonWorldObjectDefinition;
  readonly state: DungeonWorldObjectStateDefinition;
  readonly distance: number;
}

function finiteDistance(left: MobVector3, right: MobVector3): number {
  if (!left.every(Number.isFinite) || !right.every(Number.isFinite)) return Number.POSITIVE_INFINITY;
  return Math.hypot(left[0] - right[0], left[1] - right[1], left[2] - right[2]);
}

export function dungeonWorldObjectState(
  object: DungeonWorldObjectDefinition,
  stateId: string | undefined,
): DungeonWorldObjectStateDefinition {
  const requested = stateId ?? object.initialState;
  return object.states.find((state) => state.id === requested)
    ?? object.states.find((state) => state.id === object.initialState)
    ?? {
      id: object.initialState,
      label: object.initialState,
      visible: true,
      blocksMovement: false,
      interactionEnabled: false,
    };
}

export function validateDungeonWorldObject(object: DungeonWorldObjectDefinition): void {
  if (!object.id.trim()) throw new Error("Dungeon world objects require a stable id.");
  if (!object.name.trim()) throw new Error(`Dungeon world object ${object.id} requires a name.`);
  if (!object.position.every(Number.isFinite) || !object.halfExtents.every((value) => Number.isFinite(value) && value > 0)) {
    throw new Error(`Dungeon world object ${object.id} has invalid geometry.`);
  }
  const stateIds = new Set<string>();
  for (const state of object.states) {
    if (!state.id.trim() || stateIds.has(state.id)) {
      throw new Error(`Dungeon world object ${object.id} has an invalid or duplicate state id.`);
    }
    stateIds.add(state.id);
  }
  if (!stateIds.has(object.initialState)) {
    throw new Error(`Dungeon world object ${object.id} does not define initial state ${object.initialState}.`);
  }
  if (object.interaction && (!object.interaction.signalId.trim() || object.interaction.range <= 0)) {
    throw new Error(`Dungeon world object ${object.id} has an invalid interaction.`);
  }
}

export function nearestDungeonWorldInteraction(
  objects: readonly DungeonWorldObjectDefinition[],
  states: Readonly<Record<string, string>>,
  origin: MobVector3,
  hasLineOfSight: (from: MobVector3, to: MobVector3) => boolean = () => true,
): DungeonWorldInteractionCandidate | null {
  let nearest: DungeonWorldInteractionCandidate | null = null;
  for (const object of objects) {
    const interaction = object.interaction;
    if (!interaction) continue;
    const state = dungeonWorldObjectState(object, states[object.id]);
    if (!state.visible) continue;
    if (state.interactionEnabled === false) continue;
    if (interaction.allowedStates?.length && !interaction.allowedStates.includes(state.id)) continue;
    const distance = finiteDistance(origin, object.position);
    if (distance > interaction.range || !hasLineOfSight(origin, object.position)) continue;
    if (!nearest || distance < nearest.distance || (distance === nearest.distance && object.id < nearest.object.id)) {
      nearest = { object, state, distance };
    }
  }
  return nearest;
}