thi-ng/umbrella

import type { Nullable } from "@thi.ng/api";
import type { Attribs } from "./api.js";

/**
 * Variadic element factory function. Takes an element specific attrib
 * object (or `null` if no user attribs are needed) and any number of
 * arbitrary body elements (unless children are explicitly disallowed as
 * is the case for some HTML elements).
 *
 * Optionally, an Emmet-style string in the form `#id.class1.class2` or
 * `.class1.class2` can be given as first argument.
 *
 * Returns element as hiccup tuple, e.g. `["tag", attribs|null,
 * ...body]`
 */
export interface ElementFactory<T, B> {
    (attribs?: Nullable<T>, ...body: B[]): [string, Nullable<T>, ...B[]];
    (emmet: string, attribs?: Nullable<T>, ...body: B[]): [
        string,
        Nullable<T>,
        ...B[]
    ];
}

/**
 * HOF element. Returns new optimized element factory for given tag
 * name, optional `baseAttribs` defaults and generics for defining
 * supported attributes and children. See {@link ElementFactory} for
 * supported call formats of the resulting function..
 *
 * @param tag -
 * @param baseAttribs -
 */
export const defElement =
    <T = Partial<Attribs>, B = any>(
        tag: string,
        baseAttribs?: Partial<T>
    ): ElementFactory<T, B> =>
    (...args: any[]): any => {
        const $tag = typeof args[0] === "string" ? tag + args.shift() : tag;
        const n = args.length;
        const attribs =
            n > 0
                ? baseAttribs
                    ? { ...baseAttribs, ...args[0] }
                    : args[0]
                : baseAttribs || null;
        return n > 1 ? [$tag, attribs, ...args.slice(1)] : [$tag, attribs];
    };

/**
 * @internal
 */
export const defElements = <T = Partial<Attribs>, B = any>(tags: string[]) =>
    tags.map((t) => defElement<T, B>(t));