/**
 * Every colour comes from `design/tokens.json`. This refuses a raw one —
 * `#hex`, `rgb(`, `hsl(` — anywhere else the app draws from: `static/`
 * and `src/`, tests aside. A colour spelled out in a stylesheet is a colour
 * the dark theme never hears about. It refuses a `var(--…)` in a stylesheet
 * that names no token, too: a typo there is a page quietly unstyled.
 *
 *   bun run lint:design    exit 1 and one line per raw colour, or silence
 */

import { readdirSync, readFileSync } from "node:fs";
import { join } from "node:path";
import { tokens } from "../src/tokens.ts";

const RAW =
  /(?<![\w&])#(?:[0-9a-f]{8}|[0-9a-f]{6}|[0-9a-f]{3,4})(?![\w-])|\b(?:rgba?|hsla?)\(/gi;

/** The raw colours in one file's text: `path:line: …`, one per find. */
export function rawColours(path: string, text: string): string[] {
  return text
    .split("\n")
    .flatMap((line, i) =>
      [...line.matchAll(RAW)].map(
        (m) =>
          `${path}:${i + 1}: raw colour ${m[0]} — name it in design/tokens.json and use var(--…)`,
      ),
    );
}

/** The custom properties a stylesheet uses that no token defines. */
export function unknownTokens(
  path: string,
  text: string,
  known = new Set(tokens.map((t) => t.name)),
): string[] {
  return text
    .split("\n")
    .flatMap((line, i) =>
      [...line.matchAll(/var\((--[\w-]+)/g)]
        .filter((m) => !known.has(m[1]!))
        .map(
          (m) =>
            `${path}:${i + 1}: ${m[1]} is not a token in design/tokens.json`,
        ),
    );
}

/** The files the lint reads: what the page is drawn from, never the tokens themselves or the tests. */
export function drawnFrom(root: string): string[] {
  const walk = (dir: string): string[] =>
    readdirSync(join(root, dir), { withFileTypes: true }).flatMap((entry) => {
      const path = join(dir, entry.name);
      if (entry.isDirectory()) return walk(path);
      return /\.(css|js|ts|html)$/.test(entry.name) &&
        !/\.test\.ts$/.test(entry.name)
        ? [path]
        : [];
    });
  return ["static", "src"].flatMap(walk);
}

export function lint(root: string): string[] {
  return drawnFrom(root).flatMap((path) => {
    const text = readFileSync(join(root, path), "utf8");
    return [
      ...rawColours(path, text),
      ...(path.endsWith(".css") ? unknownTokens(path, text) : []),
    ];
  });
}

if (import.meta.main) {
  const problems = lint(join(import.meta.dir, ".."));
  for (const problem of problems) console.error(problem);
  process.exit(problems.length === 0 ? 0 : 1);
}