"""Log parser abstraction (Chapter 07)."""
from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime
from typing import Protocol, TYPE_CHECKING

if TYPE_CHECKING:
    from app.models.log_file import LogFile


@dataclass
class ParsedEntry:
    timestamp: datetime
    ip: str
    method: str
    path: str
    status_code: int
    bytes_sent: int
    referrer: str | None
    user_agent: str | None


class LogParser(Protocol):
    def parse_line(self, line: str) -> ParsedEntry | None: ...


def get_parser_for(log_file: "LogFile") -> LogParser:
    """Build the right LogParser for a given upload's format_string.

    ASSUMPTION (flagged): a blank format_string — which the upload form
    allows — falls back to Combined, since Chapter 07 states no default
    for that case. Anything else is compiled as-is; a real custom
    LiteSpeed format is never silently replaced by a preset.
    """
    # Imported lazily to avoid a circular import (apache.py imports
    # ParsedEntry from this module).
    from app.services.log_parser.apache import FormatCompiledParser, combined_parser, common_parser
    from app.services.log_parser.format_compiler import compile_format

    fmt = (log_file.format_string or "").strip()
    key = fmt.lower()
    if key in ("", "combined"):
        return combined_parser()
    if key == "common":
        return common_parser()
    return FormatCompiledParser(compile_format(fmt))