from __future__ import annotations

import os
from datetime import datetime
from typing import List, Optional, Tuple


class LogsService:
    def __init__(self, log_dir: str) -> None:
        self.log_dir = log_dir

    def _parse_time(self, line: str) -> Optional[datetime]:
        try:
            prefix = line.split("|", 1)[0].strip()
            return datetime.strptime(prefix, "%Y-%m-%d %H:%M:%S")
        except Exception:
            return None

    def _list_log_files(self) -> List[str]:
        if not os.path.isdir(self.log_dir):
            return []
        files = [
            os.path.join(self.log_dir, name)
            for name in os.listdir(self.log_dir)
            if name.startswith(("app.log", "access.log", "error.log"))
        ]
        return sorted(files)

    def query(
        self,
        keyword: str = "",
        start: Optional[str] = None,
        end: Optional[str] = None,
        page: int = 1,
        size: int = 50,
    ) -> Tuple[int, List[str]]:
        start_dt = datetime.fromisoformat(start) if start else None
        end_dt = datetime.fromisoformat(end) if end else None

        matched: List[Tuple[datetime, str]] = []
        for path in self._list_log_files():
            try:
                with open(path, "r", encoding="utf-8") as f:
                    for line in f:
                        line = line.rstrip("\n")
                        if "path=/logs/query" in line or "path=/logs/" in line:
                            continue
                        if keyword and keyword not in line:
                            continue
                        ts = self._parse_time(line)
                        if start_dt and ts and ts < start_dt:
                            continue
                        if end_dt and ts and ts > end_dt:
                            continue
                        matched.append((ts or datetime.min, line))
            except Exception:
                continue

        matched.sort(key=lambda item: item[0], reverse=True)
        total = len(matched)
        if size <= 0:
            size = 50
        if page <= 0:
            page = 1
        start_idx = (page - 1) * size
        end_idx = start_idx + size
        return total, [line for _, line in matched[start_idx:end_idx]]