"""JSON logs on stdout with a request id (AD-18)."""

from __future__ import annotations

import json
import logging
import re
from contextvars import ContextVar
from datetime import UTC, datetime

request_id_var: ContextVar[str] = ContextVar("request_id", default="-")

# Attributes set by logging itself; everything else passed via `extra` is emitted.
_STANDARD = set(logging.LogRecord("", 0, "", 0, "", (), None).__dict__) | {"message", "asctime"}


# One-time links carry their token in the path (AD-9); a log line must never hold it.
_LINK_TOKEN = re.compile(r"(/email/(?:confirm|undo)/)[^/\s\"']+")


def redact(text: str) -> str:
    return _LINK_TOKEN.sub(r"\1<redacted>", text)


class RedactLinkTokens(logging.Filter):
    """Blank the token of a one-time link in a record's message."""

    def filter(self, record: logging.LogRecord) -> bool:
        message = record.getMessage()
        redacted = redact(message)
        if redacted != message:
            record.msg, record.args = redacted, ()
        return True


class JsonFormatter(logging.Formatter):
    def format(self, record: logging.LogRecord) -> str:
        payload: dict[str, object] = {
            "ts": datetime.fromtimestamp(record.created, UTC).isoformat(timespec="milliseconds"),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
            "request_id": getattr(record, "request_id", None) or request_id_var.get(),
        }
        for key, value in record.__dict__.items():
            if key in _STANDARD or key in ("request_id", "request"):
                continue
            if value is None or isinstance(value, str | int | float | bool):
                payload[key] = value
        if record.exc_info:
            payload["exception"] = self.formatException(record.exc_info)
        return json.dumps(payload, default=str)


def build_logging(level: str) -> dict:
    return {
        "version": 1,
        "disable_existing_loggers": False,
        "formatters": {"json": {"()": "portal.config.logging.JsonFormatter"}},
        "filters": {"redact_link_tokens": {"()": "portal.config.logging.RedactLinkTokens"}},
        "handlers": {
            "stdout": {
                "class": "logging.StreamHandler",
                "stream": "ext://sys.stdout",
                "formatter": "json",
                "filters": ["redact_link_tokens"],
            }
        },
        "loggers": {"django.request": {"level": "ERROR"}},
        "root": {"handlers": ["stdout"], "level": level},
    }