import { assert, assertEquals } from "@std/assert";
import { COLORS, contrast, readable } from "./palette.ts";

const [black, red, , yellow] = COLORS.palette;

Deno.test("text that would not read on its background moves just far enough that it does", () => {
  // black on the terminal's own background, as a prompt's dimmest segment might be, becomes a dark gray
  const gray = readable(black, COLORS.background);
  assertEquals(gray[0], gray[1]);
  assertEquals(gray[1], gray[2]);
  assert(gray[0] < 128, `${gray} is dark`);
  // the default foreground on a bright background, as a status bar's might be, darkens
  const darker = readable(COLORS.foreground, yellow);
  assert(darker.every((c, i) => c < COLORS.foreground[i]), `${darker} is darker`);
  for (const [color, background] of [[gray, COLORS.background], [darker, yellow]]) {
    const ratio = contrast(color, background);
    assert(ratio >= 3 && ratio < 3.2, `${color} on ${background} reads, and only just: ${ratio}`);
  }
  // and anything that reads already stays as it is
  assertEquals(readable(red, COLORS.background), red);
  assertEquals(readable(black, yellow), black);
});