"""Logging utilities — PII redaction filter for GDPR/compliance safety."""

import logging
import re
from typing import ClassVar


class PiiRedactionFilter(logging.Filter):
    """Logging filter that redacts personally identifiable information.

    Automatically scrubs email addresses, JWT tokens, API keys, bearer tokens,
    and password-like values from log messages to prevent PII leaks to
    log aggregators (Datadog, CloudWatch, Logfire, etc.).

    Usage:
        logging.getLogger().addFilter(PiiRedactionFilter())
    """

    PATTERNS: ClassVar[list[tuple[re.Pattern[str], str]]] = [
        (re.compile(r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}"), "[EMAIL_REDACTED]"),
        # JWT tokens (header.payload.signature)
        (re.compile(r"eyJ[A-Za-z0-9_-]{10,}\.eyJ[A-Za-z0-9_-]{10,}\.[A-Za-z0-9_-]+"), "[JWT_REDACTED]"),
        (re.compile(r"sk-[a-zA-Z0-9]{20,}"), "[API_KEY_REDACTED]"),
        (re.compile(r"sk-ant-[a-zA-Z0-9_-]{20,}"), "[API_KEY_REDACTED]"),
        # Generic long hex/base64 secrets (40+ chars, likely tokens)
        (re.compile(r"(?:token|key|secret|password|authorization)[=: ]+['\"]?([A-Za-z0-9_/+=.-]{40,})", re.IGNORECASE), "[SECRET_REDACTED]"),
        (re.compile(r"Bearer\s+[A-Za-z0-9._~+/=-]{10,}"), "Bearer [TOKEN_REDACTED]"),
        # Password/secret in key=value or key: value patterns
        (
            re.compile(
                r"(password|passwd|pwd|secret_key|api_key|apikey|auth_token|access_token|refresh_token)"
                r"[\s]*[=:]\s*['\"]?\S+['\"]?",
                re.IGNORECASE,
            ),
            r"\1=[REDACTED]",
        ),
    ]

    def filter(self, record: logging.LogRecord) -> bool:
        """Redact PII from log record message and args."""
        if isinstance(record.msg, str):
            record.msg = self._redact(record.msg)
        if record.args:
            if isinstance(record.args, dict):
                record.args = {k: self._redact(v) if isinstance(v, str) else v for k, v in record.args.items()}
            elif isinstance(record.args, tuple):
                record.args = tuple(self._redact(a) if isinstance(a, str) else a for a in record.args)
        return True

    def _redact(self, value: str) -> str:
        for pattern, replacement in self.PATTERNS:
            value = pattern.sub(replacement, value)
        return value


def setup_logging() -> None:
    """Configure root logger with PII redaction filter."""
    root_logger = logging.getLogger()
    # Avoid adding duplicate filters
    if not any(isinstance(f, PiiRedactionFilter) for f in root_logger.filters):
        root_logger.addFilter(PiiRedactionFilter())
