#!/usr/bin/env node
/**
 * ObsiGate — Frontend import/export validator.
 * Runs in CI to catch missing exports, broken imports, and syntax errors.
 * Usage: node tests/frontend/validate-imports.mjs
 */

import { readFileSync, readdirSync } from 'fs';
import { join, dirname } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const JS_DIR = join(__dirname, '../../frontend/js');

// ── Step 1: Collect all exports from every module ──────────────────────────
const allExports = {};

function collectExports(filePath, modName) {
  const content = readFileSync(filePath, 'utf-8');
  const lines = content.split('\n');
  const exports = new Set();

  // Handle multi-line export { ... } blocks
  let inExportBlock = false;
  let exportBlockText = '';

  for (const line of lines) {
    // Start of multi-line export block
    if (/^export\s*\{/.test(line) && !/\}/.test(line)) {
      inExportBlock = true;
      exportBlockText = line;
      continue;
    }
    if (inExportBlock) {
      exportBlockText += ' ' + line.trim();
      if (/\}/.test(line)) {
        inExportBlock = false;
        const m = exportBlockText.match(/^export\s*\{([^}]+)\}/);
        if (m) {
          for (const name of m[1].split(',')) {
            const n = name.trim().replace(/\s+as\s+\w+.*/, '').trim();
            if (n && n !== '') exports.add(n);
          }
        }
        exportBlockText = '';
      }
      continue;
    }

    // export const/let/function/async function X
    let m = line.match(/^export\s+(?:const|let|function|async\s+function|class)\s+(\w+)/);
    if (m) exports.add(m[1]);

    // Single-line export { a, b }
    m = line.match(/^export\s*\{([^}]+)\}/);
    if (m) {
      for (const name of m[1].split(',')) {
        const n = name.trim().replace(/\s+as\s+.*/, '');
        if (n) exports.add(n);
      }
    }

    // export { a } from './x.js'
    m = line.match(/^export\s*\{([^}]+)\}\s*from\s*['"]\.\/(\w+\.js)['"]/);
    if (m) {
      const source = m[2];
      for (const name of m[1].split(',')) {
        const n = name.trim().replace(/\s+as\s+.*/, '').trim();
        if (n) exports.add(n);
      }
      // Re-exports: verify source actually exports these
      if (allExports[source]) {
        for (const name of m[1].split(',')) {
          const n = name.trim().replace(/\s+as\s+.*/, '').trim();
          if (n && !allExports[source].has(n)) {
            errors.push(`${modName}: re-exports '${n}' but ${source} doesn't export it`);
          }
        }
      }
    }
  }

  allExports[modName] = exports;
}

// ── Step 2: Check all imports resolve to actual exports ────────────────────
const errors = [];

function checkImports(filePath, modName) {
  const content = readFileSync(filePath, 'utf-8');
  const lines = content.split('\n');

  for (const line of lines) {
    // import { a, b } from './source.js'
    let m = line.match(/^import\s*\{([^}]+)\}\s*from\s*['"]\.\/(\w+\.js)['"]/);
    if (m) {
      const source = m[2];
      const names = m[1].split(',').map(n => n.trim().split(/\s+as\s+/)[0].trim());

      if (!allExports[source]) {
        errors.push(`${modName}: imports from ${source} but couldn't read that file`);
        continue;
      }

      for (const name of names) {
        if (!allExports[source].has(name)) {
          errors.push(`${modName}: imports '${name}' from ${source} but it's NOT exported`);
        }
      }
    }

    // import * as NS from './source.js'
    m = line.match(/^import\s+\*\s+as\s+(\w+)\s+from\s*['"]\.\/(\w+\.js)['"]/);
    if (m) {
      const ns = m[1];
      const source = m[2];

      if (!allExports[source]) {
        errors.push(`${modName}: namespace imports from ${source} but couldn't read that file`);
        continue;
      }

      // Check all NS.xxx usages in this file
      const nsUsage = new RegExp(`\\b${ns}\\.(\\w+)`, 'g');
      let usageMatch;
      while ((usageMatch = nsUsage.exec(content)) !== null) {
        const accessed = usageMatch[1];
        if (!allExports[source].has(accessed)) {
          errors.push(`${modName}: uses ${ns}.${accessed} but ${source} doesn't export '${accessed}'`);
        }
      }
    }
  }
}

// ── Main ───────────────────────────────────────────────────────────────────
const files = readdirSync(JS_DIR).filter(f => f.endsWith('.js') && f !== 'sidebar_raw.js');

// Phase 1: collect all exports
for (const file of files) {
  collectExports(join(JS_DIR, file), file);
}

// Phase 2: verify all imports
for (const file of files) {
  checkImports(join(JS_DIR, file), file);
}

// ── Step 3: Check for const reassignment patterns ──────────────────────────
for (const file of files) {
  const content = readFileSync(join(JS_DIR, file), 'utf-8');
  const lines = content.split('\n');

  // Find all imported names
  const importedNames = new Set();
  for (const line of lines) {
    const m = line.match(/^import\s*\{([^}]+)\}\s*from/);
    if (m) {
      for (const name of m[1].split(',')) {
        importedNames.add(name.trim().split(/\s+as\s+/)[0].trim());
      }
    }
  }

  // Check if any imported name is reassigned
  for (const line of lines) {
    for (const name of importedNames) {
      // Check for: name = (not ===, !==, ==, !=)
      if (new RegExp(`^\\s*${name}\\s*=[^=]`).test(line) ||
          new RegExp(`^\\s*${name}\\s*=\\s*function`).test(line) ||
          new RegExp(`^\\s*${name}\\s*=\\s*async`).test(line) ||
          new RegExp(`^\\s*${name}\\s*=\\s*\\{`).test(line) ||
          new RegExp(`^\\s*${name}\\s*=\\s*\\[`).test(line)) {
        errors.push(`${file}:${lines.indexOf(line) + 1} — imported '${name}' is reassigned (const violation)`);
      }
    }
  }
}

// ── Report ─────────────────────────────────────────────────────────────────
if (errors.length > 0) {
  console.error(`\n❌ ${errors.length} frontend validation error(s):\n`);
  for (const err of errors) {
    console.error(`  • ${err}`);
  }
  console.error('');
  process.exit(1);
} else {
  console.log(`✅ All ${files.length} modules validated — ${Object.values(allExports).reduce((s, e) => s + e.size, 0)} exports, 0 errors`);
  process.exit(0);
}