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app/services/log_parser/__init__.py

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+"""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))