import { createContext, useContext } from 'react';

/** A page in the current pond, as the wikilink UI needs it (issue #46). */
export interface WikilinkTarget {
  slug: string;
  title: string;
}

/** How a wikilink node resolves its target for display and navigation. */
export interface WikilinkResolution {
  /** Current title of the target page, or null when it does not exist (phantom). */
  title: string | null;
  exists: boolean;
}

export interface WikilinkContextValue {
  /** Pages of the current pond, for the `[[` autocomplete. */
  targets: WikilinkTarget[];
  /** Resolve a slug to its live title and existence. */
  resolve: (slug: string) => WikilinkResolution;
  /** Pond slug, so a wikilink can build its navigation URL. */
  pondSlug: string;
  /** Whether the editor is in edit mode (click behaviour differs from read mode). */
  editable: boolean;
}

/**
 * Live pond context for wikilinks (issue #46). Provided by the page editor,
 * consumed by the wikilink NodeView (title resolution, phantom styling) and the
 * autocomplete popup. Defaults are inert so a wikilink still renders (as its
 * slug) if it is ever mounted without a provider.
 */
export const WikilinkContext = createContext<WikilinkContextValue>({
  targets: [],
  resolve: () => ({ title: null, exists: false }),
  pondSlug: '',
  editable: false,
});

export function useWikilinks(): WikilinkContextValue {
  return useContext(WikilinkContext);
}

/** Builds a slug→title lookup and a resolver from a pond's page list. */
export function makeWikilinkResolver(
  targets: WikilinkTarget[],
): (slug: string) => WikilinkResolution {
  const bySlug = new Map(targets.map((t) => [t.slug, t.title]));
  return (slug) => {
    const title = bySlug.get(slug);
    return title !== undefined ? { title, exists: true } : { title: null, exists: false };
  };
}