import {
    useActiveDocContext,
    useVersions,
} from "@docusaurus/plugin-content-docs/client";
import { useLocation } from "@docusaurus/router";

type VersionLink = {
    to: string;
    label: string;
};

/**
 * Returns a list of links. Each link points to the same doc, but in a different version.
 * If the doc is not available in a version, it will fallback to the "main doc" of the version.
 * The list is ordered by version, from the newest to the oldest.
 * @returns {VersionLink[]} A list of links
 */
const useVersionLinks = () => {
    const { search, hash } = useLocation();
    const docContext = useActiveDocContext();
    const versions = useVersions();

    const getVersionMainDoc = (version) =>
        version.docs.find((doc) => doc.id === version.mainDocId);

    const links = versions.map((version) => {
        // We try to link to the same doc, in another version
        // When not possible, fallback to the "main doc" of the version
        const versionDoc =
            docContext.alternateDocVersions[version.name] ??
            getVersionMainDoc(version);
        return {
            to: `${versionDoc.path}${search}${hash}`,
            label: version.label,
        };
    }) as VersionLink[];

    return {
        links,
    };
};

export default useVersionLinks;