import type { DialogNode, StepCallback } from './types.js';

/**
 * Cross-module step hook registry.
 *
 * Create one shared instance and import it wherever you need to react to
 * Planty steps — no reference to the <Planty> component required.
 *
 * @example
 * // tutorial-steps.ts
 * export const steps = createPlantySteps();
 *
 * // graph-editor.ts
 * steps.before('highlight_graph', () => graphEditor.setHighlight(true));
 * steps.after ('highlight_graph', () => graphEditor.setHighlight(false));
 *
 * // +page.svelte
 * <Planty {config} {steps} />
 */
export class PlantySteps {
  private _before = new Map<string, StepCallback[]>();
  private _after = new Map<string, StepCallback[]>();

  /** Register a handler to run before `nodeId` becomes active. Chainable. */
  before(nodeId: string, fn: StepCallback): this {
    const list = this._before.get(nodeId) ?? [];
    this._before.set(nodeId, [...list, fn]);
    return this;
  }

  /** Register a handler to run after the user leaves `nodeId`. Chainable. */
  after(nodeId: string, fn: StepCallback): this {
    const list = this._after.get(nodeId) ?? [];
    this._after.set(nodeId, [...list, fn]);
    return this;
  }

  /** Remove all handlers for a node (or all nodes if omitted). */
  clear(nodeId?: string) {
    if (nodeId) {
      this._before.delete(nodeId);
      this._after.delete(nodeId);
    } else {
      this._before.clear();
      this._after.clear();
    }
  }

  /** @internal — called by Planty */
  async runBefore(nodeId: string, node: DialogNode): Promise<void> {
    for (const fn of this._before.get(nodeId) ?? []) {
      await fn(nodeId, node);
    }
  }

  /** @internal — called by Planty */
  async runAfter(nodeId: string, node: DialogNode): Promise<void> {
    for (const fn of this._after.get(nodeId) ?? []) {
      await fn(nodeId, node);
    }
  }
}

export function createPlantySteps(): PlantySteps {
  return new PlantySteps();
}