thi-ng/umbrella

// thing:no-export
import type { FnAny } from "@thi.ng/api";
import { isArray } from "@thi.ng/checks/is-array";
import { isFunction } from "@thi.ng/checks/is-function";
import { isIterable } from "@thi.ng/checks/is-iterable";
import { isPlainObject } from "@thi.ng/checks/is-plain-object";
import { isString } from "@thi.ng/checks/is-string";
import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
import type { Transducer } from "@thi.ng/transducers";
import { comp } from "@thi.ng/transducers/comp";
import { flatten } from "@thi.ng/transducers/flatten";
import { map } from "@thi.ng/transducers/map";
import { permutations } from "@thi.ng/transducers/permutations";
import { repeat } from "@thi.ng/transducers/repeat";
import { str } from "@thi.ng/transducers/str";
import { transduce } from "@thi.ng/transducers/transduce";
import type { CSSOpts, RuleFn } from "./api.js";

const EMPTY = new Set<string>();

const NO_SPACES = ":[";

const xfSel = comp<any, string, string>(
    flatten(),
    map((x) =>
        x[0] === "&" ? x.substring(1) : NO_SPACES.includes(x[0]) ? x : " " + x
    )
);

const withScope = (xf: Transducer<any, any>, scope: string) =>
    comp(
        xf,
        map((x) => (isString(x) && x.startsWith(" .") ? x + scope : x))
    );

/** @internal */
export const expand = (
    acc: string[],
    parent: any[],
    rules: any[],
    opts: CSSOpts
) => {
    const n = rules.length;
    const sel: string[] = [];
    let curr: any, isFn;

    const process = (i: number, r: any) => {
        let rfn: FnAny<RuleFn> | null = null;
        if (isArray(r)) {
            expand(acc, makeSelector(parent, sel), r, opts);
        } else if (isIterable(r) && !isString(r)) {
            expand(acc, makeSelector(parent, sel), [...r], opts);
        } else if ((isFn = isFunction(r)) || (rfn = opts.fns[r])) {
            if (!parent.length) {
                if (rfn) {
                    rfn.apply(null, <any>rules.slice(i + 1))(acc, opts);
                    return true;
                }
                r(acc, opts);
            } else if (isFn) {
                process(i, r());
            } else {
                illegalArgs(`quoted fn ('${r}') only allowed at head position`);
            }
        } else if (isPlainObject(r)) {
            curr = Object.assign(curr || {}, r);
        } else if (r != null) {
            sel.push(r);
        }
    };

    for (let i = 0; i < n; i++) {
        if (process(i, rules[i])) {
            return acc;
        }
    }
    curr && acc.push(formatRule(parent, sel, curr, opts));
    return acc;
};

const makeSelector = (parent: any[], curr: any[]) =>
    parent.length ? [...permutations(parent, curr)] : curr;

const formatRule = (parent: any[], sel: any[], curr: any, opts: CSSOpts) => {
    const f = opts.format;
    const space = indent(opts);
    const xf = opts.scope ? withScope(xfSel, opts.scope) : xfSel;
    return [
        space,
        transduce(
            map((sel: any[]) =>
                transduce(xf, str(), isArray(sel) ? sel : [sel]).trim()
            ),
            str(f.ruleSep),
            makeSelector(parent, sel)
        ),
        f.declStart,
        formatDecls(curr, opts),
        space,
        f.declEnd,
    ].join("");
};

/** @internal */
export const formatDecls = (rules: any, opts: CSSOpts) => {
    const f = opts.format;
    const prefixes = <Set<string>>(opts.autoprefix || EMPTY);
    const space = indent(opts, opts.depth + 1);
    const acc = [];
    for (let r in rules) {
        if (rules.hasOwnProperty(r)) {
            let val = rules[r];
            if (isFunction(val)) {
                val = val(rules);
            }
            if (isArray(val)) {
                val = val
                    .map((v) => (isArray(v) ? v.join(" ") : v))
                    .join(f.ruleSep);
            }
            if (prefixes.has(r)) {
                for (let v of opts.vendors) {
                    acc.push(`${space}${v}${r}:${f.valSep}${val};`);
                }
            }
            acc.push(`${space}${r}:${f.valSep}${val};`);
        }
    }
    return acc.join(f.decls) + f.decls;
};

/** @internal */
export const indent = (opts: CSSOpts, d = opts.depth) =>
    d > 1
        ? [...repeat(opts.format.indent, d)].join("")
        : d > 0
        ? opts.format.indent
        : "";