#!/usr/bin/env python3
import argparse
import json
from pathlib import Path

from rank_bm25 import BM25Okapi


def load_cases(path: Path):
    cases = []
    with path.open() as f:
        for line in f:
            line = line.strip()
            if line:
                cases.append(json.loads(line))
    return cases


def tokenize(text: str):
    return [token.lower() for token in text.replace("?", " ").replace(",", " ").replace(".", " ").split() if token]


def run_case(case: dict):
    corpus = [entry["text"] for entry in case["entries"]]
    tokenized = [tokenize(doc) for doc in corpus]
    bm25 = BM25Okapi(tokenized)
    scores = bm25.get_scores(tokenize(case["query"]))
    ranked = sorted(zip(scores, case["entries"]), key=lambda item: (-item[0], item[1]["id"]))
    ranked_ids = [entry["id"] for _, entry in ranked]
    relevant = set(case["relevant_ids"])
    hit_at_1 = bool(ranked_ids[:1] and ranked_ids[0] in relevant)
    hit_at_5 = any(item in relevant for item in ranked_ids[:5])
    mrr = 0.0
    for i, item in enumerate(ranked_ids):
        if item in relevant:
            mrr = 1.0 / float(i + 1)
            break
    return {
        "id": case["id"],
        "adversary_type": case["adversary_type"],
        "query": case["query"],
        "relevant_ids": case["relevant_ids"],
        "ranked_ids": ranked_ids,
        "hit_at_1": hit_at_1,
        "hit_at_5": hit_at_5,
        "mrr": mrr,
    }


def summarize(results):
    hits1 = hits5 = 0
    total_mrr = 0.0
    per_category = {}
    for item in results:
        hits1 += 1 if item["hit_at_1"] else 0
        hits5 += 1 if item["hit_at_5"] else 0
        total_mrr += item["mrr"]
        bucket = per_category.setdefault(item["adversary_type"], {"hit": 0, "total": 0})
        bucket["total"] += 1
        bucket["hit"] += 1 if item["hit_at_5"] else 0
    return {
        "cases": len(results),
        "recall_at_1": hits1 / len(results) if results else 0,
        "recall_at_5": hits5 / len(results) if results else 0,
        "mrr": total_mrr / len(results) if results else 0,
        "per_category": {key: value["hit"] / value["total"] for key, value in per_category.items()},
        "results": results,
    }


def main() -> int:
    parser = argparse.ArgumentParser(description="Run a BM25 baseline on FalseMemBench")
    parser.add_argument("--data", default=str(Path(__file__).resolve().parents[1] / "data" / "cases.jsonl"))
    parser.add_argument("--out", default="")
    args = parser.parse_args()
    cases = load_cases(Path(args.data))
    results = [run_case(case) for case in cases]
    report = summarize(results)
    print(json.dumps({key: report[key] for key in ["cases", "recall_at_1", "recall_at_5", "mrr"]}, indent=2))
    if args.out:
        out = Path(args.out)
        out.parent.mkdir(parents=True, exist_ok=True)
        out.write_text(json.dumps(report, indent=2))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())