"""Stage 2: Filter — Deterministic noise removal before LLM."""

def filter_repos(repos, config):
    """
    Apply deterministic rules to filter out irrelevant repos.
    Goal: eliminate obvious noise, not perfect classification.
    """
    filter_config = config.get("filter", {})
    reject_categories = set(filter_config.get("reject", []))
    keep_categories = set(filter_config.get("keep", []))
    min_stars = filter_config.get("min_stars", 50)
    max_age_days = filter_config.get("max_age_days", 365)

    from datetime import datetime, timedelta

    kept = []
    rejected = []
    now = datetime.now()

    for repo in repos:
        if repo.get("status") == "ERROR":
            continue

        reasons = []

        # Archived
        if repo.get("archived", False):
            reasons.append("archived")

        # Stars too low
        if repo.get("stars", 0) < min_stars:
            reasons.append(f"stars {repo.get('stars', 0)} < {min_stars}")

        # Too old
        updated = repo.get("updated_at", "")
        if updated:
            try:
                updated_dt = datetime.fromisoformat(updated.replace("Z", "+00:00"))
                if (now - updated_dt).days > max_age_days:
                    reasons.append(f"too old ({(now - updated_dt).days} days)")
            except:
                pass

        # Wrong category
        lang = repo.get("language", "")
        if lang in reject_categories:
            reasons.append(f"rejected language: {lang}")

        # Size check — too small to have meaningful workflow
        size_kb = repo.get("size_kb", 0)
        if size_kb < 20:
            reasons.append(f"too small ({size_kb}KB)")

        # Check description for obvious non-AI content
        desc_lower = (repo.get("description") or "").lower()
        skip_keywords = ["css", "animation library", "color picker", "bootstrap theme",
                         "game", "minecraft", "pygame", "flappy bird", "snake game",
                         "dataset", "kaggle", "csv only", "data dump"]
        for kw in skip_keywords:
            if kw in desc_lower:
                reasons.append(f"description contains: {kw}")
                break

        if reasons:
            rejected.append({
                "repo": repo,
                "decision": "REJECT",
                "reasons": reasons,
            })
        else:
            repo["status"] = "FILTERED"
            kept.append(repo)

    return {
        "status": "OK",
        "kept": kept,
        "rejected": rejected,
        "kept_count": len(kept),
        "rejected_count": len(rejected),
    }