# tractor: structured concurrent "actors".
# Copyright 2018-eternity Tyler Goodlet.

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

"""
Log like a forester!

"""
from collections.abc import Mapping
import sys
import logging
import colorlog  # type: ignore

import trio

from ._state import current_actor


_proj_name: str = 'tractor'
_default_loglevel: str = 'ERROR'

# Super sexy formatting thanks to ``colorlog``.
# (NOTE: we use the '{' format style)
# Here, `thin_white` is just the layperson's gray.
LOG_FORMAT = (
    # "{bold_white}{log_color}{asctime}{reset}"
    "{log_color}{asctime}{reset}"
    " {bold_white}{thin_white}({reset}"
    "{thin_white}{actor_name}[{actor_uid}], "
    "{process}, {task}){reset}{bold_white}{thin_white})"
    " {reset}{log_color}[{reset}{bold_log_color}{levelname}{reset}{log_color}]"
    " {log_color}{name}"
    " {thin_white}{filename}{log_color}:{reset}{thin_white}{lineno}{log_color}"
    " {reset}{bold_white}{thin_white}{message}"
)

DATE_FORMAT = '%b %d %H:%M:%S'

LEVELS = {
    'TRANSPORT': 5,
    'RUNTIME': 15,
    'CANCEL': 16,
    'PDB': 500,
}

STD_PALETTE = {
    'CRITICAL': 'red',
    'ERROR': 'red',
    'PDB': 'white',
    'WARNING': 'yellow',
    'INFO': 'green',
    'CANCEL': 'yellow',
    'RUNTIME': 'white',
    'DEBUG': 'white',
    'TRANSPORT': 'cyan',
}

BOLD_PALETTE = {
    'bold': {
        level: f"bold_{color}" for level, color in STD_PALETTE.items()}
}


# TODO: this isn't showing the correct '{filename}'
# as it did before..
class StackLevelAdapter(logging.LoggerAdapter):

    def transport(
        self,
        msg: str,

    ) -> None:
        '''
        IPC level msg-ing.

        '''
        return self.log(5, msg)

    def runtime(
        self,
        msg: str,
    ) -> None:
        return self.log(15, msg)

    def cancel(
        self,
        msg: str,
    ) -> None:
        '''
        Cancellation logging, mostly for runtime reporting.

        '''
        return self.log(16, msg)

    def pdb(
        self,
        msg: str,
    ) -> None:
        '''
        Debugger logging.

        '''
        return self.log(500, msg)

    def log(self, level, msg, *args, **kwargs):
        """
        Delegate a log call to the underlying logger, after adding
        contextual information from this adapter instance.
        """
        if self.isEnabledFor(level):
            # msg, kwargs = self.process(msg, kwargs)
            self._log(level, msg, args, **kwargs)

    # LOL, the stdlib doesn't allow passing through ``stacklevel``..
    def _log(
        self,
        level,
        msg,
        args,
        exc_info=None,
        extra=None,
        stack_info=False,

        # XXX: bit we added to show fileinfo from actual caller.
        # this level then ``.log()`` then finally the caller's level..
        stacklevel=3,
    ):
        """
        Low-level log implementation, proxied to allow nested logger adapters.
        """
        return self.logger._log(
            level,
            msg,
            args,
            exc_info=exc_info,
            extra=self.extra,
            stack_info=stack_info,
            stacklevel=stacklevel,
        )


_conc_name_getters = {
    'task': lambda: trio.lowlevel.current_task().name,
    'actor': lambda: current_actor(),
    'actor_name': lambda: current_actor().name,
    'actor_uid': lambda: current_actor().uid[1][:6],
}


class ActorContextInfo(Mapping):
    "Dyanmic lookup for local actor and task names"
    _context_keys = (
        'task',
        'actor',
        'actor_name',
        'actor_uid',
    )

    def __len__(self):
        return len(self._context_keys)

    def __iter__(self):
        return iter(self._context_keys)

    def __getitem__(self, key: str) -> str:
        try:
            return _conc_name_getters[key]()
        except RuntimeError:
            # no local actor/task context initialized yet
            return f'no {key} context'


def get_logger(

    name: str | None = None,
    _root_name: str = _proj_name,

) -> StackLevelAdapter:
    '''Return the package log or a sub-logger for ``name`` if provided.

    '''
    log = rlog = logging.getLogger(_root_name)

    if name and name != _proj_name:

        # handling for modules that use ``get_logger(__name__)`` to
        # avoid duplicate project-package token in msg output
        rname, _, tail = name.partition('.')
        if rname == _root_name:
            name = tail

        log = rlog.getChild(name)
        log.level = rlog.level

    # add our actor-task aware adapter which will dynamically look up
    # the actor and task names at each log emit
    logger = StackLevelAdapter(log, ActorContextInfo())

    # additional levels
    for name, val in LEVELS.items():
        logging.addLevelName(val, name)

        # ensure customs levels exist as methods
        assert getattr(logger, name.lower()), f'Logger does not define {name}'

    return logger


def get_console_log(
    level: str | None = None,
    **kwargs,
) -> logging.LoggerAdapter:
    '''Get the package logger and enable a handler which writes to stderr.

    Yeah yeah, i know we can use ``DictConfig``. You do it.
    '''
    log = get_logger(**kwargs)  # our root logger
    logger = log.logger

    if not level:
        return log

    log.setLevel(level.upper() if not isinstance(level, int) else level)

    if not any(
        handler.stream == sys.stderr  # type: ignore
        for handler in logger.handlers if getattr(handler, 'stream', None)
    ):
        handler = logging.StreamHandler()
        formatter = colorlog.ColoredFormatter(
            LOG_FORMAT,
            datefmt=DATE_FORMAT,
            log_colors=STD_PALETTE,
            secondary_log_colors=BOLD_PALETTE,
            style='{',
        )
        handler.setFormatter(formatter)
        logger.addHandler(handler)

    return log


def get_loglevel() -> str:
    return _default_loglevel