import { describe, expect, test } from "bun:test";
import { readFileSync } from "node:fs";

const css = (name: string) => readFileSync(new URL(name, import.meta.url), "utf8");

describe("shared typography contract", () => {
  test("all component and page styles use the fixed shared type utilities", () => {
    for (const file of ["design-system.css"]) {
      const source = css(file);
      expect(source).not.toMatch(/font-size\s*:/);
      expect(source).not.toMatch(/font:\s*\d/);
      expect(source).toContain("@apply type-");
    }
    const typography = css("typography.css");
    expect(typography).not.toMatch(/clamp\(|\d(?:vw|vh|px)\b/);
    expect(typography).toContain("--text-copy: 1rem");
    expect(typography).toContain("--text-caption: 0.875rem");
    for (const role of ["body", "small", "label", "lead", "title", "section", "display", "control"]) {
      expect(typography).toContain(`@utility type-${role}`);
    }
  });

  test("text colors meet WCAG AA normal-text contrast on paper", () => {
    const source = css("design-system.css");
    const luminance = (token: string) => {
      let hex = source.match(new RegExp(`--ds-${token}: #([\\da-f]+);`))![1]!;
      if (hex.length === 3) hex = [...hex].map((c) => c + c).join("");
      const channels = [0, 2, 4].map((start) => {
        const value = parseInt(hex.slice(start, start + 2), 16) / 255;
        return value <= 0.04045 ? value / 12.92 : ((value + 0.055) / 1.055) ** 2.4;
      });
      return channels[0]! * 0.2126 + channels[1]! * 0.7152 + channels[2]! * 0.0722;
    };
    for (const color of ["ink", "secondary"]) {
      expect((luminance("paper") + 0.05) / (luminance(color) + 0.05)).toBeGreaterThanOrEqual(4.5);
    }
  });
});