from __future__ import annotations

import json
import re
import time
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Dict, List, Optional


def _normalize(text: str) -> str:
    return re.sub(r"\s+", " ", (text or "")).strip()


def _tokens(text: str) -> List[str]:
    return re.findall(r"[a-z0-9_]+", (text or "").lower())


@dataclass
class MemoryItem:
    timestamp: float
    query: str
    text: str
    source: str
    reward: float
    tags: List[str]
    metadata: Dict[str, Any]


class PersistentMemoryPool:
    def __init__(self, path: str | Path):
        self.path = Path(path)
        self.path.parent.mkdir(parents=True, exist_ok=True)
        self.items: List[MemoryItem] = []
        self._load()

    def _load(self) -> None:
        self.items = []
        if not self.path.exists():
            return
        for line in self.path.read_text(encoding="utf-8").splitlines():
            line = line.strip()
            if not line:
                continue
            try:
                payload = json.loads(line)
            except json.JSONDecodeError:
                continue
            self.items.append(
                MemoryItem(
                    timestamp=float(payload.get("timestamp", 0.0) or 0.0),
                    query=str(payload.get("query", "")),
                    text=str(payload.get("text", "")),
                    source=str(payload.get("source", "")),
                    reward=float(payload.get("reward", 0.0) or 0.0),
                    tags=[str(tag) for tag in payload.get("tags", [])],
                    metadata=dict(payload.get("metadata", {}) or {}),
                )
            )

    def add(
        self,
        *,
        query: str,
        text: str,
        source: str,
        reward: float = 0.0,
        tags: Optional[List[str]] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> None:
        item = MemoryItem(
            timestamp=time.time(),
            query=_normalize(query),
            text=_normalize(text),
            source=_normalize(source),
            reward=float(reward),
            tags=[str(tag) for tag in (tags or [])],
            metadata=dict(metadata or {}),
        )
        self.items.append(item)
        with self.path.open("a", encoding="utf-8") as handle:
            handle.write(
                json.dumps(
                    {
                        "timestamp": item.timestamp,
                        "query": item.query,
                        "text": item.text,
                        "source": item.source,
                        "reward": item.reward,
                        "tags": item.tags,
                        "metadata": item.metadata,
                    },
                    ensure_ascii=False,
                )
                + "\n"
            )

    def search(self, query: str, max_results: int = 5) -> List[Dict[str, Any]]:
        query_terms = set(_tokens(query))
        ranked: List[tuple[float, MemoryItem]] = []
        for item in self.items:
            haystack_terms = set(_tokens(item.query + " " + item.text + " " + " ".join(item.tags)))
            overlap = len(query_terms.intersection(haystack_terms))
            if overlap == 0 and query_terms:
                continue
            score = float(overlap) + (item.reward * 0.25)
            ranked.append((score, item))
        ranked.sort(key=lambda pair: (pair[0], pair[1].timestamp), reverse=True)
        results: List[Dict[str, Any]] = []
        for score, item in ranked[:max_results]:
            results.append(
                {
                    "score": round(score, 4),
                    "query": item.query,
                    "text": item.text[:400],
                    "source": item.source,
                    "reward": item.reward,
                    "tags": item.tags,
                }
            )
        return results

    def build_context(self, query: str, max_results: int = 5, max_chars: int = 1200) -> str:
        entries = self.search(query, max_results=max_results)
        lines: List[str] = []
        total = 0
        for item in entries:
            line = f"- [{item['source']}] {item['text']}"
            total += len(line)
            if total > max_chars:
                break
            lines.append(line)
        return "\n".join(lines).strip()