import path from "path";

export function generateMarkdownLog({
  fromVersion,
  toVersion,
  deprecatedItems,
  autoFixes
}) {
  const required: string[] = [];
  const optional: string[] = [];
  const fileMap: Record<string, Set<string>> = {};
  let ignoredCacheMatches = 0;

  deprecatedItems.forEach(item => {
    const isOptional = item.trim().startsWith("ℹ");
    if (isOptional) optional.push(item);
    else required.push(item);

    // Extract file reference
    const match = item.match(/→ (.*)$/);
    if (match) {
      const file = match[1].trim();
      if (file.includes(".angular/cache")) {
        ignoredCacheMatches++;
        return;
      }
      const cleaned = path.normalize(file);
      if (!fileMap[cleaned]) fileMap[cleaned] = new Set();
      fileMap[cleaned].add(item.split("→")[0].trim());
    }
  });

  const affectedFiles = Object.keys(fileMap);
  const autofixesList = autoFixes ?? [];

  return `# Migration ${fromVersion} → ${toVersion}

---

## 🚨 Required Changes (may break project if ignored)
${required.length ? required.map(r => `- ${r}`).join("\n") : "✓ None — no blockers"}

---

## ⚙️ Autofixes Applied Automatically
${autofixesList.length ? autofixesList.map(a => `- ${a}`).join("\n") : "No autofixes applied"}

---

## 🔍 Optional Improvements (not required but recommended)
${optional.length ? optional.map(o => `- ${o}`).join("\n") : "✓ No suggestions — this project is aligned with modern Angular"}

---

## 📌 Files Needing Manual Attention
${affectedFiles.length ? affectedFiles.map(f => `- ${f}`).join("\n") : "✓ None"}

${ignoredCacheMatches > 0
  ? `\n> 🔹 ${ignoredCacheMatches} internal/cache files matched but were ignored intentionally — they do not require developer action.\n`
  : ""}

---

## 📊 Migration Summary
| Category | Count |
|----------|-------|
| Required changes | ${required.length} |
| Optional suggestions | ${optional.length} |
| Autofixes applied | ${autofixesList.length} |
| Files needing attention | ${affectedFiles.length} |
| Cache matches ignored | ${ignoredCacheMatches} |

---

📄 Generated by **MigratorX — Quantum Migration Core**
`;
}