thi-ng/umbrella

import type { SomeRequired } from "@thi.ng/api";
import { readText } from "@thi.ng/file-io/text";
import { ConsoleLogger } from "@thi.ng/logger";
import { resolve } from "node:path";
import type { TranscludeCtx } from "./api.js";

export type Mandatory = "src" | "templates" | "user";

const DEFAULT_LOGGER = new ConsoleLogger("transclude");

export const transclude = <T>(
    ctx: SomeRequired<TranscludeCtx<T>, Mandatory>,
    path: string
) => {
    const $ctx: TranscludeCtx<T> = {
        logger: DEFAULT_LOGGER,
        match: /\{\{([a-z0-9.]+)([^}]*)\}\}/gi,
        pre: [],
        post: [],
        eol: "\n",
        ...ctx,
    };
    $ctx.pre.reduce((acc, fn) => ($ctx.src = fn($ctx, [acc], path)), $ctx.src);
    $ctx.src = $ctx.src.replace($ctx.match, (...args) => {
        const [orig, id] = args;
        const tpl = $ctx.templates[id];
        if (tpl !== undefined) {
            return typeof tpl === "function" ? tpl($ctx, args, path) : tpl;
        } else {
            $ctx.logger.warn(`skipping unknown tpl ID: "${id}"`);
            return orig;
        }
    });
    $ctx.post.reduce((acc, fn) => ($ctx.src = fn($ctx, [acc], path)), $ctx.src);
    return $ctx;
};

export const transcludeFile = <T>(
    path: string,
    ctx: SomeRequired<TranscludeCtx<T>, Exclude<Mandatory, "src">>
) => {
    const $ctx = {
        logger: DEFAULT_LOGGER,
        src: "",
        ...ctx,
    };
    path = resolve(path);
    $ctx.src = readText(path, $ctx.logger);
    return transclude($ctx, path);
};