"""Central logging configuration for the Seed project.

Usage anywhere in the codebase:
    from logger import get_logger
    log = get_logger(__name__)
    log.info("message")
    log.warning("watch out")
    log.error("something broke")

Environment variables:
    LOG_LEVEL   — DEBUG | INFO | WARNING | ERROR | CRITICAL  (default: INFO)
    LOG_FILE    — path to write a rotating log file (optional)
"""
from __future__ import annotations

import logging
import logging.handlers
import os
import sys
from typing import Final

_LEVEL_MAP: Final = {
    "DEBUG": logging.DEBUG,
    "INFO": logging.INFO,
    "WARNING": logging.WARNING,
    "ERROR": logging.ERROR,
    "CRITICAL": logging.CRITICAL,
}

_LOG_LEVEL: int = _LEVEL_MAP.get(os.getenv("LOG_LEVEL", "INFO").upper(), logging.INFO)
_LOG_FILE: str | None = os.getenv("LOG_FILE")

# ── ANSI colour codes (console only) ─────────────────────────────────────────
_RESET  = "\033[0m"
_BOLD   = "\033[1m"
_GREY   = "\033[90m"
_CYAN   = "\033[96m"
_YELLOW = "\033[93m"
_RED    = "\033[91m"
_BRED   = "\033[1;91m"

_LEVEL_COLOURS: Final[dict[int, str]] = {
    logging.DEBUG:    _GREY,
    logging.INFO:     _CYAN,
    logging.WARNING:  _YELLOW,
    logging.ERROR:    _RED,
    logging.CRITICAL: _BRED,
}


class _ColourFormatter(logging.Formatter):
    _FMT = "{colour}{level:<8}{reset} {grey}{asctime}  {name}{reset}  {msg}"

    def format(self, record: logging.LogRecord) -> str:
        colour = _LEVEL_COLOURS.get(record.levelno, "")
        level  = record.levelname
        grey   = _GREY if sys.stderr.isatty() else ""
        reset  = _RESET if sys.stderr.isatty() else ""
        col    = colour if sys.stderr.isatty() else ""

        self.datefmt = "%H:%M:%S"
        base = super().format(record)
        return self._FMT.format(
            colour=col, level=level, reset=reset,
            grey=grey, asctime=self.formatTime(record, self.datefmt),
            name=record.name, msg=record.getMessage(),
        ) + (f"\n{record.exc_text}" if record.exc_info and self.formatException(record.exc_info) else "")


_FILE_FMT = logging.Formatter(
    fmt="%(asctime)s  %(levelname)-8s  %(name)s  %(message)s",
    datefmt="%Y-%m-%dT%H:%M:%S",
)


def _build_root_logger() -> logging.Logger:
    root = logging.getLogger("seed")
    root.setLevel(_LOG_LEVEL)

    if root.handlers:
        return root  # already configured (e.g. imported twice)

    # Console handler
    console = logging.StreamHandler(sys.stderr)
    console.setLevel(_LOG_LEVEL)
    console.setFormatter(_ColourFormatter())
    root.addHandler(console)

    # Optional rotating file handler
    if _LOG_FILE:
        fh = logging.handlers.RotatingFileHandler(
            _LOG_FILE, maxBytes=10 * 1024 * 1024, backupCount=5, encoding="utf-8"
        )
        fh.setLevel(_LOG_LEVEL)
        fh.setFormatter(_FILE_FMT)
        root.addHandler(fh)

    root.propagate = False
    return root


_root = _build_root_logger()


def get_logger(name: str) -> logging.Logger:
    """Return a child logger namespaced under 'seed'."""
    if name.startswith("seed.") or name == "seed":
        return logging.getLogger(name)
    return logging.getLogger(f"seed.{name}")