"use strict";

/** Coordinate CMap routes, parent contexts and browser-history state. */
export class CmapNavigationController {
  constructor({ navigateToHash, cmapRoute, getEditor, getCurrentMap,
    getParentMap, storage, historyObject = window.history, locationObject = window.location }) {
    this.navigateToHash = navigateToHash;
    this.cmapRoute = cmapRoute;
    this.getEditor = getEditor;
    this.getCurrentMap = getCurrentMap;
    this.getParentMap = getParentMap;
    this.storage = storage;
    this.history = historyObject;
    this.location = locationObject;
  }

  /** Open a stored CMap through the central hash-navigation contract. */
  open(slug) {
    return this.navigateToHash(this.cmapRoute(slug));
  }

  /** Remember the active separate-submap root before following a linked CMap. */
  openLinked(record) {
    if (!record?.cmapSlug) return false;
    this.rememberContext();
    this.open(record.cmapSlug).catch((error) => console.error(error));
    return true;
  }

  /** Return to a source CMap when present, otherwise leave one inline submap level. */
  openParent() {
    const source = this.getParentMap();
    if (source?.slug) {
      this.open(source.slug).catch((error) => console.error(error));
      return true;
    }
    const editor = this.getEditor();
    return Boolean(editor?.openParentMap());
  }

  requestTransition(action) {
    return this.storage.requestTransition(action);
  }

  /** Store the active separate-submap context in the current browser history entry. */
  rememberContext() {
    const editor = this.getEditor();
    const current = this.getCurrentMap();
    const root = editor?.activeMapRoot;
    if (!current?.slug || !root) return;
    this.history.replaceState({ ...this.history.state, cmapContext: {
      mapSlug: current.slug,
      rootItemId: Number(root.id)
    } }, "", this.location.href);
  }

  /**
   * Restore a remembered separate-submap root after browser navigation.
   * post   : A consumed context is removed from history state to prevent repeated restoration.
   */
  async restoreContext(slug) {
    const context = this.history.state?.cmapContext;
    if (!context || context.mapSlug !== slug) return false;
    const editor = this.getEditor();
    const root = editor?.itemRecord(context.rootItemId);
    if (root?.kind === "submap" && root.separateMap) editor.openSubmapMap(root);
    this.history.replaceState({ ...this.history.state, cmapContext: null }, "", this.location.href);
    return true;
  }
}