import test from "node:test";
import assert from "node:assert/strict";
import { readFileSync } from "node:fs";
import { fileURLToPath } from "node:url";
import { dirname, join } from "node:path";
import { READING_LIST } from "../data/reading-list.js";
import {
  escapeHtml,
  groupByCategory,
  isValidEntry,
  isValidUrl,
  renderReadingList,
} from "../js/reading-list.js";

const root = join(dirname(fileURLToPath(import.meta.url)), "..");
const readingHtml = readFileSync(join(root, "reading.html"), "utf8");
const indexHtml = readFileSync(join(root, "index.html"), "utf8");
const contactHtml = readFileSync(join(root, "contact.html"), "utf8");
const rendererSource = readFileSync(join(root, "js/reading-list.js"), "utf8");

const ANCHOR_RE = /<a class="reading-link" href="([^"]*)"[^>]*>([^<]*)<\/a>/g;
const ENTRY_LI_RE = /<li class="reading-entry">/g;
const SECTION_RE = /<section class="reading-category"/g;

/** Build a deterministic fixture with `count` entries across `categories`. */
function makeFixture(count, categories) {
  const entries = [];
  for (let i = 1; i <= count; i++) {
    entries.push({
      category: categories[i % categories.length],
      title: `Entry ${String(i).padStart(3, "0")}`,
      url: `https://example.com/articles/${i}`,
      ...(i % 3 === 0 ? { note: `Note ${i}` } : {}),
    });
  }
  return entries;
}

// ---------------------------------------------------------------------------
// Component tests: the reading list page is wired up and reachable
// ---------------------------------------------------------------------------

test("reading page renders a reading list container and loads the renderer module", () => {
  assert.match(readingHtml, /<div[^>]*id="reading-list"/);
  assert.match(
    readingHtml,
    /<script[^>]*type="module"[^>]*src="js\/reading-list\.js"/
  );
});

test("home and contact pages link to the reading list page from the nav", () => {
  assert.match(indexHtml, /<a href="reading\.html">Reading<\/a>/);
  assert.match(contactHtml, /<a href="reading\.html">Reading<\/a>/);
});

test("reading page nav marks the reading link as the current page", () => {
  assert.match(
    readingHtml,
    /<a href="reading\.html"[^>]*aria-current="page"[^>]*>Reading<\/a>/
  );
});

test("renderer module loads the reading list data file", () => {
  assert.match(
    rendererSource,
    /import\s*\{\s*READING_LIST\s*\}\s*from\s*"\.\.\/data\/reading-list\.js"/
  );
});

// ---------------------------------------------------------------------------
// Data file tests: every entry is renderable, note stays optional
// ---------------------------------------------------------------------------

test("every entry in the data file has a title, a category, and a valid http(s) url", () => {
  assert.ok(Array.isArray(READING_LIST), "data file exports an array");
  assert.ok(READING_LIST.length > 0, "data file has at least one entry");
  for (const entry of READING_LIST) {
    assert.ok(
      typeof entry.title === "string" && entry.title.trim().length > 0,
      `entry needs a title: ${JSON.stringify(entry)}`
    );
    assert.ok(
      typeof entry.category === "string" && entry.category.trim().length > 0,
      `entry needs a category: ${JSON.stringify(entry)}`
    );
    assert.ok(
      isValidUrl(entry.url),
      `entry url must be an absolute http(s) url: ${entry.url}`
    );
    assert.ok(
      entry.note === undefined ||
        (typeof entry.note === "string" && entry.note.length > 0),
      `note must be a non-empty string or absent: ${JSON.stringify(entry)}`
    );
  }
});

test("seed data includes an entry without a note so the optional path is exercised", () => {
  assert.ok(
    READING_LIST.some((entry) => !entry.note),
    "expected at least one entry with no note"
  );
});

// ---------------------------------------------------------------------------
// Renderer tests: grouping, links, notes, and robustness
// ---------------------------------------------------------------------------

test("renders links grouped by category from the data file", () => {
  const html = renderReadingList(READING_LIST);
  const categories = [...new Set(READING_LIST.map((entry) => entry.category))];

  assert.equal((html.match(SECTION_RE) || []).length, categories.length);
  for (const category of categories) {
    assert.ok(
      html.includes(`>${escapeHtml(category)}</h2>`),
      `expected a heading for category ${category}`
    );
  }
  for (const entry of READING_LIST) {
    assert.ok(
      html.includes(escapeHtml(entry.title)),
      `expected title ${entry.title}`
    );
    assert.ok(html.includes(entry.url), `expected url ${entry.url}`);
  }
});

test("each rendered link has a valid href and shows its title, with the note shown only when present", () => {
  const fixture = [
    {
      category: "Testing",
      title: "With a note",
      url: "https://example.com/with-note",
      note: "One line of context.",
    },
    {
      category: "Testing",
      title: "Without a note",
      url: "https://example.com/without-note",
    },
  ];
  const html = renderReadingList(fixture);

  const anchors = [...html.matchAll(ANCHOR_RE)];
  assert.equal(anchors.length, 2);
  for (const [, href, title] of anchors) {
    assert.ok(isValidUrl(href), `href must be a valid http(s) url: ${href}`);
    assert.ok(
      fixture.some((entry) => entry.title === title && entry.url === href),
      `rendered link ${title} -> ${href} must match a data entry`
    );
  }

  // All reading links point at external sites, so each carries the
  // rel="noopener noreferrer" hardening attribute.
  assert.equal(
    (html.match(/rel="noopener noreferrer"/g) || []).length,
    anchors.length,
    "every rendered link carries rel=\"noopener noreferrer\""
  );

  assert.ok(html.includes("One line of context."), "note is rendered when present");
  assert.equal(
    (html.match(/<p class="reading-note">/g) || []).length,
    1,
    "no note paragraph for the entry without a note"
  );
});

test("renders correctly against a 500+ entry fixture", () => {
  const fixture = makeFixture(500, ["A", "B", "C", "D", "E"]);

  const start = performance.now();
  const html = renderReadingList(fixture);
  const elapsed = performance.now() - start;

  assert.ok(
    elapsed < 5000,
    `rendering 500 entries should stay fast, took ${elapsed.toFixed(1)}ms`
  );

  // Every entry rendered exactly once.
  assert.equal((html.match(ENTRY_LI_RE) || []).length, fixture.length);
  assert.equal((html.match(ANCHOR_RE) || []).length, fixture.length);
  assert.ok(html.includes("https://example.com/articles/1"));
  assert.ok(html.includes("https://example.com/articles/500"));

  // Notes rendered only for entries that have them.
  assert.equal(
    (html.match(/<p class="reading-note">/g) || []).length,
    fixture.filter((entry) => entry.note).length
  );

  // Grouped by category: one section per category, containing exactly that
  // category's entries, in the first-seen category order.
  const expectedOrder = [...new Set(fixture.map((entry) => entry.category))];
  const expectedCounts = new Map();
  for (const entry of fixture) {
    expectedCounts.set(entry.category, (expectedCounts.get(entry.category) || 0) + 1);
  }

  const sections = html.split(/<section class="reading-category"[^>]*>/).slice(1);
  assert.equal(sections.length, expectedOrder.length);
  sections.forEach((section, index) => {
    const category = expectedOrder[index];
    const heading = section.match(/<h2[^>]*>([^<]*)<\/h2>/);
    assert.ok(heading, `section ${index} should have a heading`);
    assert.equal(heading[1], category);
    assert.equal(
      (section.match(ENTRY_LI_RE) || []).length,
      expectedCounts.get(category),
      `section for ${category} should contain exactly its own entries`
    );
  });
});

test("escapes HTML in titles, notes, and categories", () => {
  const nasty = [
    {
      category: 'Design <img src=x onerror=alert(1)>',
      title: '<script>alert("x")</script>',
      url: "https://example.com/?a=1&b=2",
      note: 'note "quoted" & <b>bold</b>',
    },
  ];
  const html = renderReadingList(nasty);

  assert.ok(!html.includes("<script>"), "raw script tag must not appear");
  assert.ok(html.includes("&lt;script&gt;"), "title is escaped");
  assert.ok(!html.includes("<img"), "raw img tag must not appear");
  assert.ok(html.includes("&lt;img"), "category is escaped");
  assert.ok(html.includes('&quot;quoted&quot; &amp; &lt;b&gt;bold&lt;/b&gt;'));
});

test("skips invalid entries and shows an empty-state message when nothing renders", () => {
  const mixed = [
    { category: "Good", title: "Fine", url: "https://example.com/fine" },
    { category: "Good", title: "Bad protocol", url: "javascript:alert(1)" },
    { category: "Good", title: "Empty url", url: "" },
    { category: "Good", title: "", url: "https://example.com/empty-title" },
    { category: "Good", title: "Ftp url", url: "ftp://example.com/x" },
    null,
  ];
  const html = renderReadingList(mixed);
  assert.ok(html.includes("Fine"));
  assert.ok(!html.includes("Bad protocol"));
  assert.ok(!html.includes("Empty url"));
  assert.ok(!html.includes("Ftp url"));
  assert.ok(!html.includes("javascript:"));
  assert.equal((html.match(ENTRY_LI_RE) || []).length, 1);

  assert.equal(
    renderReadingList([]),
    '<p class="reading-empty">The reading list is empty.</p>'
  );
  assert.equal(
    renderReadingList([{ title: "No url" }]),
    '<p class="reading-empty">The reading list is empty.</p>'
  );
});

test("a new link can be added by editing only the data file", () => {
  const original = renderReadingList(READING_LIST);
  assert.ok(!original.includes("https://example.com/brand-new"));

  // Simulate an author adding a link to the data file — nothing else changes.
  const extended = [
    ...READING_LIST,
    {
      category: "Engineering",
      title: "A brand new link",
      url: "https://example.com/brand-new",
      note: "added later, no code changes",
    },
  ];
  const html = renderReadingList(extended);
  assert.ok(html.includes("https://example.com/brand-new"));
  assert.ok(html.includes("A brand new link"));
  assert.ok(html.includes("added later, no code changes"));
});

// ---------------------------------------------------------------------------
// Unit tests: helpers
// ---------------------------------------------------------------------------

test("escapeHtml escapes the five HTML-sensitive characters", () => {
  assert.equal(escapeHtml(`&<>"'`), "&amp;&lt;&gt;&quot;&#39;");
  assert.equal(escapeHtml("plain text"), "plain text");
});

test("isValidUrl accepts http(s) and rejects everything else", () => {
  assert.ok(isValidUrl("https://example.com"));
  assert.ok(isValidUrl("http://example.com/path?q=1"));
  assert.ok(!isValidUrl("javascript:alert(1)"));
  assert.ok(!isValidUrl("ftp://example.com"));
  assert.ok(!isValidUrl("/relative/path"));
  assert.ok(!isValidUrl(""));
});

test("isValidEntry requires a non-empty title and a valid url", () => {
  assert.ok(isValidEntry({ title: "T", url: "https://example.com" }));
  assert.ok(!isValidEntry(null));
  assert.ok(!isValidEntry({}));
  assert.ok(!isValidEntry({ title: "T" }));
  assert.ok(!isValidEntry({ url: "https://example.com" }));
  assert.ok(!isValidEntry({ title: "", url: "https://example.com" }));
  assert.ok(!isValidEntry({ title: "T", url: "javascript:alert(1)" }));
});

test("groupByCategory preserves first-seen order and falls back to Uncategorized", () => {
  const groups = groupByCategory([
    { title: "A", url: "https://example.com/a", category: "Zebra" },
    { title: "B", url: "https://example.com/b", category: "Alpha" },
    { title: "C", url: "https://example.com/c" },
    { title: "D", url: "https://example.com/d", category: "Zebra" },
    { title: "Broken", url: "javascript:alert(1)", category: "Zebra" },
  ]);
  assert.deepEqual([...groups.keys()], ["Zebra", "Alpha", "Uncategorized"]);
  assert.deepEqual(
    groups.get("Zebra").map((entry) => entry.title),
    ["A", "D"]
  );
  assert.deepEqual(
    groups.get("Uncategorized").map((entry) => entry.title),
    ["C"]
  );
});