import logging
import re
import contextvars
import os
import sys
import time
from contextlib import contextmanager
from logging.handlers import TimedRotatingFileHandler
from pathlib import Path

LOG_DIR = Path(__file__).parent / "logs"
LOG_FILE = LOG_DIR / "sunat.log"
_LOG_CONFIGURED = False

_ANSI_RE = re.compile(r"\033\[[0-9;]*m")

_stack: contextvars.ContextVar[list] = contextvars.ContextVar("log_stack", default=[])
# ============================================================================

class TreeFormatter(logging.Formatter):
    def format(self, record):
        return f"{self.formatTime(record)} ─── {record.getMessage()}"

    def formatTime(self, record, datefmt=None):
        import datetime
        return datetime.datetime.fromtimestamp(record.created).strftime("%Y-%m-%d %H:%M:%S")

# ============================================================================
class PlainFileFormatter(TreeFormatter):
    """Igual que TreeFormatter pero sin códigos ANSI de color, para el archivo."""
    def format(self, record):
        return _ANSI_RE.sub("", super().format(record))

# ============================================================================
def _build_prefix(stack, is_last):
    if not stack:
        return ""
    parts = []
    for sib_is_last in stack[:-1]:
        parts.append("    " if sib_is_last else "│   ")
    parts.append("└── " if is_last else "├── ")
    return "".join(parts)

# ============================================================================
class _TaskContext:
    def __init__(self, logger, msg, emoji, is_last):
        self._logger = logger
        self._msg = msg
        self._emoji = emoji
        self._is_last = is_last

    def __enter__(self):
        stack = _stack.get()
        prefix = _build_prefix(stack, self._is_last)
        emoji_str = f"{self._emoji} " if self._emoji else ""
        self._logger._logger.info(f"{prefix}{emoji_str}{self._msg}")
        _stack.set(stack + [self._is_last])
        return TaskLogger(self._logger._logger)

    def __exit__(self, exc_type, exc_val, exc_tb):
        _stack.set(_stack.get()[:-1])

# ============================================================================
class TaskLogger:
    def __init__(self, logger):
        self._logger = logger

    @contextmanager
    def task(self, msg, emoji=""):
        with _TaskContext(self, msg, emoji, is_last=False) as sub_logger:
            yield sub_logger

    @contextmanager
    def last_task(self, msg, emoji=""):
        with _TaskContext(self, msg, emoji, is_last=True) as sub_logger:
            yield sub_logger

    def info(self, msg, *args, _last=False, **kwargs):
        self._log(logging.INFO, msg, args, kwargs, _last)

    def warning(self, msg, *args, _last=False, **kwargs):
        self._log(logging.WARNING, msg, args, kwargs, _last)

    def error(self, msg, *args, _last=False, **kwargs):
        self._log(logging.ERROR, msg, args, kwargs, _last)

    def _log(self, level, msg, args, kwargs, is_last):
        stack = _stack.get()
        prefix = _build_prefix(stack, is_last)
        self._logger.log(level, f"{prefix}{msg}", *args, **kwargs)

def _rotated_name(default_name):
    """TimedRotatingFileHandler entrega 'sunat.log.2026-08-30'; lo convertimos
    a 'sunat_2026-08-30.log' para que sea más legible como nombre de archivo."""
    date_part = default_name.rsplit(".", 1)[-1]
    return str(LOG_FILE.with_name(f"{LOG_FILE.stem}_{date_part}{LOG_FILE.suffix}"))

# ============================================================================
def limpiar_logs_antiguos(dias=7):
    """Borra los logs rotados (sunat_YYYY-MM-DD.log) con más de 'dias' de antigüedad."""
    limite = time.time() - dias * 86400
    count = 0
    for p in LOG_DIR.glob(f"{LOG_FILE.stem}_*{LOG_FILE.suffix}"):
        try:
            if p.stat().st_mtime < limite:
                p.unlink()
                count += 1
        except OSError:
            pass
    return count

# ============================================================================
def setup_logging(level=None, console=True):
    global _LOG_CONFIGURED
    if _LOG_CONFIGURED:
        return

    if level is None:
        level_name = os.getenv("LOG_LEVEL", "INFO").upper()
        level = getattr(logging, level_name, logging.INFO)

    LOG_DIR.mkdir(exist_ok=True)

    file_handler = TimedRotatingFileHandler(
        LOG_FILE,
        when="midnight",
        interval=1,
        backupCount=0,  # la retención la maneja limpiar_logs_antiguos() con el namer de abajo
        encoding="utf-8",
    )
    file_handler.namer = _rotated_name
    file_handler.setFormatter(PlainFileFormatter())

    handlers = [file_handler]
    if console:
        console_handler = logging.StreamHandler(sys.stdout)
        console_handler.setFormatter(TreeFormatter())
        handlers.append(console_handler)

    logging.basicConfig(level=level, handlers=handlers, force=True)
    _LOG_CONFIGURED = True

# ============================================================================
def get_logger(name="sunat"):
    setup_logging()
    return TaskLogger(logging.getLogger(name))