thi-ng/umbrella

import type { TypedArray } from "@thi.ng/api";
import { isFunction } from "@thi.ng/checks";
import {
    FMT_HH,
    FMT_HHmmss_ALT,
    FMT_MM,
    FMT_dd,
    FMT_mm,
    FMT_ss,
    FMT_ww,
    FMT_yyyy,
    FMT_yyyyMMdd_ALT,
} from "@thi.ng/date";
import { illegalArgs as unsupported } from "@thi.ng/errors";
import { createHash } from "node:crypto";
import { basename } from "node:path";
import type { ImgProcCtx, OutputSpec } from "./api.js";

/** @internal */
const _ = undefined;

/**
 * Expands/replaces all `{xyz}`-templated identifiers in given file path.
 *
 * @remarks
 * The following built-in IDs are supported and custom IDs will be looked up via
 * the {@link ImgProcOpts.pathParts} options provided to {@link processImage}.
 * Any others will remain as is. Custom IDs take precedence over built-in ones.
 *
 * - name: original base filename (w/o ext)
 * - sha1/224/256/384/512: truncated hash of output
 * - w: current width
 * - h: current height
 * - aspect: "p" (portrait), "l" (landscape) or "sq" (square)
 * - date: yyyyMMdd
 * - time: HHmmss
 * - year: 4-digit year
 * - month: 2-digit month
 * - week: 2-digit week
 * - day: 2-digit day in month
 * - hour: 2-digit hour (24h system)
 * - minute: 2-digit minute
 * - second: 2-digit second
 *
 * All date/time related values will be in UTC.
 *
 * @param path
 * @param ctx
 * @param spec
 * @param buf
 */
export const formatPath = (
    path: string,
    ctx: ImgProcCtx,
    spec: OutputSpec,
    buf: Buffer | TypedArray
) =>
    path.replace(/\{(\w+)\}/g, (match, id) => {
        const custom = ctx.opts.pathParts?.[id];
        if (custom != null) {
            return isFunction(custom) ? custom(ctx, spec, buf) : custom;
        }
        switch (id) {
            case "name": {
                !path &&
                    unsupported(
                        "cannot format `{name}`, image has no file source"
                    );
                const name = basename(ctx.path!);
                const idx = name.lastIndexOf(".");
                return idx > 0 ? name.substring(0, idx) : name;
            }
            case "sha1":
            case "sha224":
            case "sha256":
            case "sha384":
            case "sha512":
                return createHash(id).update(buf).digest("hex").substring(0, 8);
            case "w":
                return String(ctx.size[0]);
            case "h":
                return String(ctx.size[1]);
            case "aspect": {
                const [w, h] = ctx.size;
                return w > h ? "l" : w < h ? "p" : "sq";
            }
            case "date":
                return FMT_yyyyMMdd_ALT(_, true);
            case "time":
                return FMT_HHmmss_ALT(_, true);
            case "year":
                return FMT_yyyy(_, true);
            case "month":
                return FMT_MM(_, true);
            case "week":
                return FMT_ww(_, true);
            case "day":
                return FMT_dd(_, true);
            case "hour":
                return FMT_HH(_, true);
            case "minute":
                return FMT_mm(_, true);
            case "second":
                return FMT_ss(_, true);
        }
        return match;
    });