"""Apache Common/Combined presets + the generic parser built from
format_compiler (Chapter 07)."""
from __future__ import annotations

from app.services.log_parser import ParsedEntry
from app.services.log_parser.format_compiler import (
    CompiledFormat, compile_format, parse_apache_timestamp, parse_request_line, validate_ip,
)

COMMON_LOG_FORMAT = '%h %l %u %t "%r" %>s %b'
COMBINED_LOG_FORMAT = '%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i"'


class FormatCompiledParser:
    """LogParser implementation driven by any CompiledFormat (Ch04/07 protocol)."""

    def __init__(self, compiled: CompiledFormat):
        self._compiled = compiled

    def parse_line(self, line: str) -> ParsedEntry | None:
        match = self._compiled.pattern.match(line.rstrip("\n"))
        if match is None:
            return None  # malformed line — skip, never raise (Ch07)
        fields = match.groupdict()

        ip = validate_ip(fields["ip"])
        if ip is None:
            return None

        req = parse_request_line(fields["request"])
        if req is None:
            return None
        method, path = req

        try:
            timestamp = parse_apache_timestamp(fields["timestamp"])
            status_code = int(fields["status"])
            bytes_sent = 0 if fields["bytes"] == "-" else int(fields["bytes"])
        except (ValueError, KeyError):
            return None

        referrer = fields.get("referrer")
        user_agent = fields.get("user_agent")
        return ParsedEntry(
            timestamp=timestamp, ip=ip, method=method, path=path,
            status_code=status_code, bytes_sent=bytes_sent,
            referrer=None if referrer in (None, "-") else referrer,
            user_agent=None if user_agent in (None, "-") else user_agent,
        )


def common_parser() -> FormatCompiledParser:
    return FormatCompiledParser(compile_format(COMMON_LOG_FORMAT))


def combined_parser() -> FormatCompiledParser:
    return FormatCompiledParser(compile_format(COMBINED_LOG_FORMAT))