import AxeBuilder from "@axe-core/playwright";
import { expect, test } from "@playwright/test";
import { spawn } from "node:child_process";
import { createInterface } from "node:readline";

const AXE_TAGS = [
  "wcag2a",
  "wcag2aa",
  "wcag21a",
  "wcag21aa",
  "wcag22a",
  "wcag22aa",
];
const MANUAL_AXE_TAGS = AXE_TAGS.filter((tag) => !tag.startsWith("wcag22"));

let fixtureProcess;
let surfaces;

function startFixture() {
  const python = process.env.DOCFORGE_PYTHON || ".venv/bin/python";
  const child = spawn(python, ["tools/accessibility_fixture.py"], {
    cwd: process.cwd(),
    stdio: ["pipe", "pipe", "pipe"],
  });
  let stderr = "";
  child.stderr.setEncoding("utf8");
  child.stderr.on("data", (chunk) => {
    stderr += chunk;
  });
  const lines = createInterface({ input: child.stdout });
  const ready = new Promise((resolve, reject) => {
    let settled = false;
    lines.once("line", (line) => {
      settled = true;
      try {
        const payload = JSON.parse(line);
        if (
          payload.schema_version !== 1
          || typeof payload.manual_html !== "string"
          || typeof payload.portable_html !== "string"
          || typeof payload.live_url !== "string"
        ) {
          throw new Error("Accessibility fixture returned an invalid payload");
        }
        resolve(payload);
      } catch (error) {
        reject(error);
      } finally {
        lines.close();
      }
    });
    child.once("exit", (code, signal) => {
      if (!settled) {
        reject(
          new Error(
            `Accessibility fixture exited before readiness `
            + `(code=${code}, signal=${signal}):\n${stderr}`,
          ),
        );
      }
    });
  });
  return { child, ready };
}

async function stopFixture(child) {
  if (child.exitCode !== null || child.signalCode !== null) {
    return;
  }
  const exited = new Promise((resolve) => child.once("exit", resolve));
  child.stdin.end();
  await Promise.race([
    exited,
    new Promise((_, reject) => {
      setTimeout(() => reject(new Error("Accessibility fixture did not stop")), 5_000);
    }),
  ]);
}

function violationReport(violations) {
  return violations.map((violation) => {
    const targets = violation.nodes
      .flatMap((node) => node.target)
      .join(", ");
    return `${violation.id} (${violation.impact}): ${violation.help}\n  ${targets}`;
  }).join("\n");
}

async function expectNoAxeViolations(page, tags = AXE_TAGS) {
  const results = await new AxeBuilder({ page }).withTags(tags).analyze();
  expect(results.violations, violationReport(results.violations)).toEqual([]);
}

async function tabTo(page, selector, maximumTabs = 40) {
  for (let count = 0; count < maximumTabs; count += 1) {
    await page.keyboard.press("Tab");
    if (await page.evaluate((target) => document.activeElement?.matches(target), selector)) {
      return page.locator(selector).filter({ visible: true }).first();
    }
  }
  throw new Error(`Keyboard focus did not reach ${selector}`);
}

test.beforeAll(async () => {
  const fixture = startFixture();
  fixtureProcess = fixture.child;
  surfaces = await fixture.ready;
});

test.afterAll(async () => {
  await stopFixture(fixtureProcess);
});

test("generated manual has no axe violations and its navigation works by keyboard", async ({
  page,
}) => {
  await page.setContent(surfaces.manual_html, { waitUntil: "load" });
  await expect(page.locator("main section")).not.toHaveCount(0);
  // The generic renderer owns structure, while this frozen project template owns target sizing.
  await expectNoAxeViolations(page, MANUAL_AXE_TAGS);

  await page.keyboard.press("Tab");
  const firstNavigationLink = page.locator("nav[aria-label='Documentation'] a").first();
  await expect(firstNavigationLink).toBeFocused();
  const target = await firstNavigationLink.getAttribute("href");
  expect(target).toMatch(/^#[A-Za-z0-9_.-]+$/);
  await page.keyboard.press("Enter");
  await expect.poll(() => page.evaluate(() => window.location.hash)).toBe(target);
});

test("portable graph supports skip, filter, view, and dialog keyboard flows", async ({ page }) => {
  await page.goto("about:blank");
  await page.setContent(surfaces.portable_html, { waitUntil: "load" });
  await expect(page.locator("#status")).toContainText("nodes and");
  await expectNoAxeViolations(page);

  await page.keyboard.press("Tab");
  await expect(page.locator("a.skip")).toBeFocused();
  await page.keyboard.press("Enter");
  await expect(page.locator("main#main")).toBeFocused();

  await page.goto("about:blank");
  await page.setContent(surfaces.portable_html, { waitUntil: "load" });
  await page.keyboard.press("Tab");
  await page.keyboard.press("Tab");
  await expect(page.locator("#filter")).toBeFocused();
  await page.keyboard.type("guide.workflow");
  await expect(page.locator("#status")).toContainText("1 nodes and");

  await page.keyboard.press("Tab");
  await expect(page.locator("#mode")).toBeFocused();
  await page.keyboard.press("ArrowDown");
  await expect(page.locator("main#main")).toHaveAttribute("data-mode", "flow");
  await page.keyboard.press("ArrowUp");
  await expect(page.locator("main#main")).toHaveAttribute("data-mode", "nodes");

  await page.keyboard.press("Tab");
  const nodeButton = page.locator("#node-list button").first();
  await expect(nodeButton).toBeFocused();
  await page.keyboard.press("Enter");
  await expect(page.locator("#node-dialog")).toHaveAttribute("open", "");
  await expect(page.locator("#close-dialog")).toBeFocused();
  await expectNoAxeViolations(page);
  await page.keyboard.press("Escape");
  await expect(page.locator("#node-dialog")).not.toHaveAttribute("open", "");
  await expect(nodeButton).toBeFocused();
});

test("live viewer passes axe and exposes keyboard graph and resize controls", async ({ page }) => {
  await page.goto(surfaces.live_url);
  await expect(page.locator("#status")).toContainText("nodes ·");
  await expect(page.locator("#graph g.node[role='button']").first()).toBeVisible();
  await expectNoAxeViolations(page);

  const resizer = await tabTo(page, "#left-resizer");
  const originalWidth = Number(await resizer.getAttribute("aria-valuenow"));
  await page.keyboard.press("ArrowRight");
  await expect(resizer).toHaveAttribute("aria-valuenow", String(originalWidth + 16));

  await tabTo(page, "#graph g.node[role='button']");
  await page.keyboard.press("Shift+Enter");
  await expect(page.locator("#node-dialog")).toHaveAttribute("open", "");
  await expect(page.locator("#close-node-dialog")).toBeFocused();
  await expectNoAxeViolations(page);
  await page.keyboard.press("Escape");
  await expect(page.locator("#node-dialog")).not.toHaveAttribute("open", "");
});