/**
 * earth-now.co
 * Author:  Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 * File:    scripts/check-headers.ts
 * Purpose: CI lint — fail any source file missing or with a malformed mandatory author header
 */

import { readFileSync, readdirSync, statSync } from "node:fs";
import { join, relative, extname } from "node:path";

const ROOT = join(import.meta.dirname, "..");

// Extensions where comments are allowed and the header is mandatory.
const CHECKED_EXTENSIONS = new Set([
  ".ts",
  ".tsx",
  ".js",
  ".mjs",
  ".cjs",
  ".py",
  ".sql",
  ".sh",
  ".yaml",
  ".yml",
]);

const ALWAYS_SKIPPED_DIRS = new Set([
  "node_modules",
  "dist",
  ".next",
  ".turbo",
  ".git",
  "coverage",
]);

function loadIgnorePatterns(): string[] {
  const raw = readFileSync(join(ROOT, "scripts", "check-headers.ignore"), "utf8");
  return raw
    .split("\n")
    .map((l) => l.trim())
    .filter((l) => l.length > 0 && !l.startsWith("#"));
}

function isIgnored(relPath: string, patterns: string[]): boolean {
  return patterns.some((p) => {
    if (p.endsWith("/")) return relPath.startsWith(p);
    if (p.includes("*")) {
      const rx = new RegExp(
        "^" + p.split("*").map((s) => s.replace(/[.+?^${}()|[\]\\]/g, "\\$&")).join(".*") + "$",
      );
      return rx.test(relPath);
    }
    return relPath === p;
  });
}

function* walk(dir: string): Generator<string> {
  for (const entry of readdirSync(dir)) {
    const full = join(dir, entry);
    const st = statSync(full);
    if (st.isDirectory()) {
      if (ALWAYS_SKIPPED_DIRS.has(entry)) continue;
      yield* walk(full);
    } else {
      yield full;
    }
  }
}

interface HeaderProblem {
  file: string;
  reason: string;
}

// The header must contain these lines (comment syntax varies by language).
function checkHeader(relPath: string, content: string): string | null {
  const head = content.slice(0, 600);
  if (!head.includes("earth-now.co")) return "missing 'earth-now.co' banner line";
  if (!head.includes("Author:") || !head.includes("Simon-Pierre Boucher"))
    return "missing 'Author: Simon-Pierre Boucher' line";
  if (!head.includes("Contact:") || !head.includes("contact@spboucher.ai"))
    return "missing 'Contact: contact@spboucher.ai' line";
  const fileLine = head.match(/File:\s+(\S+)/);
  if (!fileLine) return "missing 'File:' line";
  if (fileLine[1] !== relPath)
    return `'File:' line says '${fileLine[1]}' but actual path is '${relPath}'`;
  if (!/Purpose:\s+\S/.test(head)) return "missing or empty 'Purpose:' line";
  // Shebang scripts may put the header right after the shebang; otherwise it must open the file.
  const firstMeaningful = content.startsWith("#!")
    ? content.slice(content.indexOf("\n") + 1)
    : content;
  if (!/^\s*(\/\*\*|#|--)/.test(firstMeaningful))
    return "header must be the first thing in the file (after an optional shebang)";
  return null;
}

const patterns = loadIgnorePatterns();
const problems: HeaderProblem[] = [];
let checked = 0;

for (const file of walk(ROOT)) {
  const rel = relative(ROOT, file);
  if (!CHECKED_EXTENSIONS.has(extname(file))) continue;
  if (isIgnored(rel, patterns)) continue;
  checked++;
  const reason = checkHeader(rel, readFileSync(file, "utf8"));
  if (reason) problems.push({ file: rel, reason });
}

if (problems.length > 0) {
  console.error(`✗ ${problems.length} file(s) with missing/malformed author header:\n`);
  for (const p of problems) console.error(`  ${p.file} — ${p.reason}`);
  process.exit(1);
}
console.log(`✓ Author header OK on ${checked} source files.`);