static SV path_to_name(SV path) {
    while (true) {
        SV component = noh_sv_chop_by_delim(&path, '/');
        if (path.count == 0) return component;
    }
}

static void append_entry(Noh_String *response, SV url, Library_Entry entry) {
    noh_string_append_cstr(response, "<entry>");
    noh_string_append_cstr(response, noh_arena_sprintf(&temp, "<id>"Nsv_Fmt"</id>", Nsv_Arg(get_id(entry.full_path))));
    noh_string_append_cstr(response, noh_arena_sprintf(&temp, "<title>"Nsv_Fmt"</title>", entry.name));
    noh_string_append_cstr(response, noh_arena_sprintf(&temp, "<updated>%s</updated>", format_time(entry)));
    if (entry.is_dir) {
        SV opds = sv("opds");
        Noh_String entry_url = build_path(true, &opds, &url, &entry.name);
        noh_string_append_cstr(response,  noh_arena_sprintf(&temp, "<link rel=\"subsection\" href=\""Nsv_Fmt"\" type=\"application/atom+xml;profile=opds-catalog;kind=navigation\"/>", Nsv_Arg(entry_url)));
        noh_string_free(&entry_url);
    } else {
        SV get = sv("get");
        Noh_String entry_url = build_path(true, &get, &url, &entry.name);
        noh_string_append_cstr(response,  noh_arena_sprintf(&temp, "<link rel=\"http://opds-spec.org/acquisition\" href=\""Nsv_Fmt"\" type=\"application/epub+zip\"/>", Nsv_Arg(entry_url)));
        noh_string_free(&entry_url);
    }
    noh_string_append_cstr(response, "</entry>");
}

static Noh_String create_feed_response(Library_Entry self_path, SV url, Library_Entries list) {
    (void)self_path;
    Noh_String response = {0};

    noh_string_append_cstr(&response, "<feed>");
    noh_string_append_cstr(&response, noh_arena_sprintf(&temp, "<id>"Nsv_Fmt"</id>", Nsv_Arg(get_id(self_path.full_path))));
    noh_string_append_cstr(&response, noh_arena_sprintf(&temp, "<title>"Nsv_Fmt"</title>", self_path.name));
    noh_string_append_cstr(&response, noh_arena_sprintf(&temp, "<updated>%s</updated>", format_time(self_path)));

    SV opds = sv("opds");
    Noh_String self_url = build_path(true, &opds, &url);
    noh_string_append_cstr(&response, noh_arena_sprintf(&temp, "<link rel=\"self\" href=\""Nsv_Fmt"\" type=\"application/atom+xml;profile=opds-catalog;kind=navigation\"/>", Nsv_Arg(self_url)));
    noh_string_free(&self_url);

    noh_string_append_cstr(&response, "<link rel=\"root\" href=\"/opds\" type=\"application/atom+xml;profile=opds-catalog;kind=navigation\"/>");

    for (size_t i = 0; i < list.count; i++) append_entry(&response, url, list.elems[i]);
    noh_string_append_cstr(&response, "</feed>");

    return response;
}

static enum MHD_Result handle_opds(struct MHD_Connection *connection, SV url, Settings settings, SV username) {
    noh_arena_save(&temp);
    Noh_String fs_path = build_path(false, &settings.base_path, &username, &url);
    Noh_String fs_path_cstr = fs_path;
    noh_string_append_null(&fs_path_cstr);

    Library_Entry self_entry = {
        .is_dir = true,
        .full_path = noh_sv_from_string(fs_path),
        .name = (url.count == 0) ? settings.library_name : path_to_name(noh_sv_from_string(fs_path)),
        .modified_at = {0},
    };
    set_modified_time(&self_entry);
    noh_log(NOH_INFO, "Physical path: "Nsv_Fmt, Nsv_Arg(self_entry.full_path));

    DIR *dir = opendir(fs_path_cstr.elems);
    if (dir) {
        Library_Entries list = {0};

        // Build up list of entries.
        struct dirent *entry = noh_arena_alloc(&temp, sizeof(struct dirent));
        while ((entry = readdir(dir)) != NULL) {
            Library_Entry result = {0};
            if (create_entry(entry, fs_path_cstr.elems, &result)) noh_da_append(&list, result);
        }

        // Sort entries, folders first, then by name.
        if (list.count > 1) qsort(list.elems, list.count, sizeof(list.elems[0]), compare_library_entries);

        // Create and send response.
        Noh_String response = create_feed_response(self_entry, url, list);
        bool result = send_response(connection, 200, noh_sv_from_string(response), true);

        // Cleanup.
        noh_da_free(&list);
        noh_string_free(&response);
        noh_arena_reset(&temp);
        closedir(dir);

        return result;

    } else if (errno == ENOENT) {
        closedir(dir);
        noh_arena_reset(&temp);
        return send_response(connection, 404, sv(""), false);

    } else {
        noh_log(NOH_ERROR, "Opening directory failed.");
        noh_arena_reset(&temp);
        return send_response(connection, 500, sv(""), false);
    }
}