import { test, expect, type Page } from '@playwright/test';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import fs from 'node:fs';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const ARTIFACTS = path.resolve(__dirname, 'artifacts');

const shot = async (page: Page, name: string) => {
  fs.mkdirSync(ARTIFACTS, { recursive: true });
  await page.screenshot({
    path: path.join(ARTIFACTS, name),
    fullPage: true,
  });
};

/**
 * WCAG contrast helpers (in-page evaluate). Binary observable: ratio < 4.5:1 fails.
 * Matches visual-qa color check patterns for luminance/contrast.
 */
async function assertReadableContrast(
  page: Page,
  selectors: string[],
  label: string
): Promise<void> {
  const minRatio = await page.evaluate((sels: string[]) => {
    function luminance(r: number, g: number, b: number): number {
      const a = [r, g, b].map((v) => {
        v /= 255;
        return v <= 0.03928 ? v / 12.92 : Math.pow((v + 0.055) / 1.055, 2.4);
      });
      return a[0] * 0.2126 + a[1] * 0.7152 + a[2] * 0.0722;
    }
    function contrastRatio(c1: number[], c2: number[]): number {
      const l1 = luminance(c1[0], c1[1], c1[2]);
      const l2 = luminance(c2[0], c2[1], c2[2]);
      const hi = Math.max(l1, l2);
      const lo = Math.min(l1, l2);
      return (hi + 0.05) / (lo + 0.05);
    }
    function parse(c: string): [number, number, number] {
      const m = c.match(/rgba?\((\d+),\s*(\d+),\s*(\d+)/i);
      return m ? [parseInt(m[1], 10), parseInt(m[2], 10), parseInt(m[3], 10)] : [255, 255, 255];
    }

    let minR = 21;
    for (const sel of sels) {
      const els = document.querySelectorAll(sel);
      for (const el of Array.from(els)) {
        if (!(el instanceof HTMLElement)) continue;
        const fg = parse(window.getComputedStyle(el).color);
        // collect ALL non-transparent bgs in ancestor chain; pick darkest (min lum) as the surface
        const bgs: [number, number, number][] = [];
        let p: HTMLElement | null = el;
        while (p) {
          const pst = window.getComputedStyle(p);
          const bstr = pst.backgroundColor;
          if (!bstr.includes('0)')) {
            const b = parse(bstr);
            // avoid pure black default if transparent resolved
            if (!(b[0] === 0 && b[1] === 0 && b[2] === 0)) {
              bgs.push(b);
            }
          }
          p = p.parentElement;
        }
        // also include body/html
        const bodyB = parse(window.getComputedStyle(document.body).backgroundColor);
        if (!(bodyB[0] === 0 && bodyB[1] === 0 && bodyB[2] === 0)) bgs.push(bodyB);
        const htmlB = parse(window.getComputedStyle(document.documentElement).backgroundColor);
        if (!(htmlB[0] === 0 && htmlB[1] === 0 && htmlB[2] === 0)) bgs.push(htmlB);

        let surface = [255, 255, 255] as [number, number, number];
        let minLum = 1;
        for (const b of bgs) {
          const l = luminance(b[0], b[1], b[2]);
          if (l < minLum) {
            minLum = l;
            surface = b;
          }
        }
        const r = contrastRatio(fg, surface);
        if (r < minR) minR = r;
      }
    }
    return minR;
  }, selectors);

  expect(minRatio, `contrast < 4.5:1 (${label})`).toBeGreaterThanOrEqual(4.5);
}

test.describe('Settings contrast (Gitea bug #75 black-on-black)', () => {
  test('Happy: Settings form labels/inputs/selects readable (contrast ≥4.5:1)', async ({ page }) => {
    await page.goto('/');
    await page.getByRole('button', { name: 'Settings (dev)' }).click();
    await shot(page, 'settings-happy.png');
    // labels, inputs, selects on the form
    await assertReadableContrast(page, ['label', 'input', 'select'], 'happy-settings-form');
  });

  test('Edge: <select> dropdown options visible and readable on dark surface', async ({ page }) => {
    await page.goto('/');
    await page.getByRole('button', { name: 'Settings (dev)' }).click();
    await shot(page, 'settings-edge.png');
    // options may render on dark surface when select is dark-themed
    await assertReadableContrast(page, ['select', 'option', 'label'], 'edge-select-dropdown');
  });

  test('Regression: SlabList.svelte / Review.svelte / Publish.svelte / GenerateText.svelte remain unchanged (still pass their existing contrast)', async ({ page }) => {
    const regressionScreens = [
      { name: 'Slabs (dev)', heading: /slabs/i },
      { name: 'Review (dev)', heading: 'Review to Ready' },
      { name: 'Publish (dev)', heading: 'Publish to WooCommerce' },
      { name: 'Generate (dev)', heading: 'Generate text' },
    ];

    for (const scr of regressionScreens) {
      await page.goto('/');
      await page.getByRole('button', { name: scr.name }).click();
      if (scr.heading) {
        await expect(page.getByRole('heading', { name: scr.heading })).toBeVisible({ timeout: 10_000 });
      }
      // these already set color:#eee on root → must still pass ≥4.5
      await assertReadableContrast(page, ['body', 'main', 'label', 'input', 'select'], `regression-${scr.name}`);
      await shot(page, `regression-${scr.name.replace(/\s|\(|\)/g, '')}.png`);
    }

    // regression also confirms settings still exhibits the low-contrast bug (until T2 fix)
    await page.goto('/');
    await page.getByRole('button', { name: 'Settings (dev)' }).click();
    await assertReadableContrast(page, ['label', 'input', 'select', 'option'], 'regression-settings-still-bad');
  });
});