import assert from "node:assert/strict";
import { readFileSync, readdirSync } from "node:fs";
import test from "node:test";

// Guards the defect class behind BUG-434 / BUG-435: a className the CSS never
// defines renders as an unstyled element and silently breaks the layout, with
// nothing in the build or the type checker to catch it.
//
// Scope: only the project's own class families. A token counts as ours when its
// first segment already names a family in our CSS (`paywall-`, `message-`,
// `dialog-`, `danger-`, ...), which keeps Tailwind utilities out without having
// to enumerate them.

const projectRoot = new URL("../", import.meta.url);
const sourceRoot = new URL("src/", projectRoot);

const walk = (dir: URL, ext: readonly string[]): string[] =>
  readdirSync(dir, { recursive: true, encoding: "utf8" })
    .filter((entry) => ext.some((suffix) => entry.endsWith(suffix)))
    .map((entry) => `src/${entry.split("\\").join("/")}`);

const read = (path: string) => readFileSync(new URL(path, projectRoot), "utf8");

const styleSheets = walk(sourceRoot, [".css"]).map(read);
const componentFiles = walk(sourceRoot, [".tsx", ".ts"]);
// Boundary pages under the root layout carry their rules in an inline <style>.
const inlineStyles = componentFiles.flatMap((path) =>
  [...read(path).matchAll(/<style>\{`([\s\S]*?)`\}<\/style>/g)].map((hit) => hit[1]));

// Comments are stripped first: a class name that only survives in a `/* ... */`
// note is not a definition, and counting it would hide exactly the bug we want.
const styleSource = [...styleSheets, ...inlineStyles].join("\n").replace(/\/\*[\s\S]*?\*\//g, " ");
const definedClasses = new Set(
  [...styleSource.matchAll(/\.(-?[A-Za-z_][A-Za-z0-9_-]*)/g)].map((hit) => hit[1]),
);

const projectFamilies = new Set([...definedClasses].map((name) => name.split("-")[0]));

// Tailwind utilities whose first segment collides with one of our families.
const tailwindCollisions = new Set([
  "inline-flex", "inline-block", "inline-grid", "inline-table",
  "select-none", "select-all", "select-text", "select-auto",
]);

// Classes that carry no styling on purpose: dead modifiers on already-styled
// elements, or hooks handed to a component that styles itself. Each one is a
// no-op today; the point of listing them is that a NEW undefined class fails.
//
// The `is-*` entries are state hooks whose visual is carried by a sibling
// element instead — the thinking step's marker icon, the board minute's
// "当前时间" / "已更新" note. `sidebar-header` and `chart-nav` land on shadcn
// components that style themselves. The rest are modifiers sitting beside an
// already-styled class on the same element.
const knownUnstyled = new Set([
  "birth-time-evidence-receipt",
  "chart-nav",
  "consultation-run-timeline__summary",
  "consultation-step-tree",
  "is-changed",
  "is-done",
  "is-live",
  "is-working",
  "membership-orders",
  "membership-segment",
  "onboarding-step-card",
  "personal-report-additional-charts",
  "rectification-pending-note",
  "rectification-terminal-actions",
  "rectification-terminal-note",
  "sidebar-header",
  "starter-workbench",
]);

/** Static class tokens; `${...}` holes split the string and their ragged edges are dropped. */
function staticClassTokens(source: string): string[] {
  const segments = [...source.matchAll(/className\s*=\s*"([^"]*)"/g)].map((hit) => hit[1]);
  for (const opener of source.matchAll(/className\s*=\s*\{/g)) {
    let depth = 1;
    let cursor = opener.index + opener[0].length;
    const start = cursor;
    while (cursor < source.length && depth > 0) {
      if (source[cursor] === "{") depth += 1;
      else if (source[cursor] === "}") depth -= 1;
      cursor += 1;
    }
    const expression = source.slice(start, cursor - 1);
    for (const literal of expression.matchAll(/`([^`]*)`|"([^"]*)"|'([^']*)'/g)) {
      segments.push(literal[1] ?? literal[2] ?? literal[3] ?? "");
    }
  }
  return segments.flatMap((segment) => (
    ` ${segment} `.split(/\$\{[^}]*\}/).flatMap((piece) => {
      const tokens = piece.split(/\s+/).filter(Boolean);
      if (!/^\s/.test(piece)) tokens.shift();
      if (!/\s$/.test(piece)) tokens.pop();
      return tokens;
    })
  ));
}

const ownershipSuspects = new Map<string, Set<string>>();
for (const path of componentFiles) {
  for (const token of staticClassTokens(read(path))) {
    if (definedClasses.has(token)) continue;
    if (tailwindCollisions.has(token)) continue;
    if (!token.includes("-") || /[:[\]()/@!$.{}]/.test(token)) continue;
    if (!projectFamilies.has(token.split("-")[0])) continue;
    const seen = ownershipSuspects.get(token) ?? new Set<string>();
    seen.add(path);
    ownershipSuspects.set(token, seen);
  }
}

test("every project class a component renders has a rule in our CSS", () => {
  const undefinedClasses = [...ownershipSuspects.entries()]
    .filter(([name]) => !knownUnstyled.has(name))
    .map(([name, files]) => `${name} (${[...files].sort().join(", ")})`)
    .sort();
  assert.deepEqual(
    undefinedClasses,
    [],
    "These class names style nothing. Define them in CSS, drop them, or add them "
      + "to knownUnstyled with a reason:\n  " + undefinedClasses.join("\n  "),
  );
});

test("the knownUnstyled allowlist has no stale entries", () => {
  // An entry that got a rule, or stopped being rendered, must leave the list —
  // otherwise the allowlist grows into a blindfold.
  const stale = [...knownUnstyled].filter((name) => (
    definedClasses.has(name) || !ownershipSuspects.has(name)
  ));
  assert.deepEqual(stale, [], `no longer undefined-and-used: ${stale.join(", ")}`);
});

test("the guard actually sees the codebase", () => {
  assert.ok(componentFiles.length > 100, `only walked ${componentFiles.length} components`);
  assert.ok(definedClasses.size > 500, `only parsed ${definedClasses.size} classes`);
  assert.ok(projectFamilies.has("paywall") && projectFamilies.has("message"));
});