import { readdirSync, readFileSync, statSync } from "node:fs";
import path from "node:path";
import { describe, expect, it } from "vitest";

const ROOT = process.cwd();
const TEMPLATES_DIR = path.join(ROOT, "src/pdf/templates");

/**
 * Model fields that carry regulated data. Templates must not read them: the data may leave the model
 * only through the Slot components, so the contract test can see every place it is printed.
 */
const REGULATED = [
  /\.gstin\b/,
  /\.showGstin\b/,
  /\.posLabel\b/,
  /\.hsnSac\b/,
  /\.taxRows\b/,
  /\.amountInWords\b/,
  /\.reverseCharge\b/,
  /\.signature\b/,
  /\.slots\b/,
];

function sources(dir: string): string[] {
  return readdirSync(dir).flatMap((name) => {
    const full = path.join(dir, name);
    if (statSync(full).isDirectory()) return sources(full);
    return /\.(ts|tsx)$/.test(name) && !/\.test\.|harness(\.check)?\.ts$/.test(name) ? [full] : [];
  });
}

describe("templates read regulated data only through Slot.*", () => {
  it("scans the classic template", () => {
    expect(sources(TEMPLATES_DIR).some((f) => f.endsWith("classic/Layout.tsx"))).toBe(true);
  });

  it("finds no direct access to the regulated model fields", () => {
    const hits: string[] = [];
    for (const file of sources(TEMPLATES_DIR)) {
      readFileSync(file, "utf8")
        .split("\n")
        .forEach((line, i) => {
          if (/^\s*(\/\/|\*|\/\*)/.test(line)) return;
          // The slot API itself is the sanctioned way in: Slot.TaxRows, slotHeights.amountInWords, ...
          const code = line.replace(/\b(Slot|slotHeights)\.\w+/g, "");
          for (const re of REGULATED) if (re.test(code)) hits.push(`${path.relative(ROOT, file)}:${i + 1} ${line.trim()}`);
        });
    }
    expect(hits).toEqual([]);
  });
});