# -*- coding: utf-8 -*-
"""This module provides functions used by the UFL implementation to
output messages. These may be redirected by the user of UFL."""

# Copyright (C) 2005-2016 Anders Logg and Martin Sandve Alnaes
#
# This file is part of UFL (https://www.fenicsproject.org)
#
# SPDX-License-Identifier:    LGPL-3.0-or-later
#
# Modified by Johan Hake, 2009.
# Modified by Massimiliano Leoni, 2016

import sys
import types
import logging
from logging import DEBUG, INFO, WARNING, ERROR, CRITICAL  # noqa: F401

log_functions = ["log", "debug", "info", "deprecate", "warning", "error",
                 "begin", "end",
                 "set_level", "push_level", "pop_level", "set_indent",
                 "add_indent",
                 "set_handler", "get_handler", "get_logger", "add_logfile",
                 "set_prefix",
                 "info_red", "info_green", "info_blue",
                 "warning_red", "warning_green", "warning_blue"]

__all__ = log_functions + ["Logger", "log_functions"] +\
    ["DEBUG", "INFO", "DEPRECATE", "WARNING", "ERROR", "CRITICAL"]


DEPRECATE = (INFO + WARNING) // 2


# This is used to override emit() in StreamHandler for printing
# without newline
def emit(self, record):
    message = self.format(record)
    format_string = "%s" if getattr(record, "continued", False) else "%s\n"
    self.stream.write(format_string % message)
    self.flush()


# Colors if the terminal supports it (disabled e.g. when piped to
# file)
if sys.stdout.isatty() and sys.stderr.isatty():
    RED = "\033[1;37;31m%s\033[0m"
    BLUE = "\033[1;37;34m%s\033[0m"
    GREEN = "\033[1;37;32m%s\033[0m"
else:
    RED = "%s"
    BLUE = "%s"
    GREEN = "%s"


# Logger class
class Logger:

    def __init__(self, name, exception_type=Exception):
        "Create logger instance."
        self._name = name
        self._exception_type = exception_type

        # Set up handler
        h = logging.StreamHandler(sys.stdout)
        h.setLevel(WARNING)
        # Override emit() in handler for indentation
        h.emit = types.MethodType(emit, h)
        self._handler = h

        # Set up logger
        self._log = logging.getLogger(name)
        assert len(self._log.handlers) == 0
        self._log.addHandler(h)
        self._log.setLevel(DEBUG)

        self._logfiles = {}

        # Set initial indentation level
        self._indent_level = 0

        # Setup stack with default logging level
        self._level_stack = [DEBUG]

        # Set prefix
        self._prefix = ""

    def add_logfile(self, filename=None, mode="a", level=DEBUG):
        "Add a log file."
        if filename is None:
            filename = "%s.log" % self._name
        if filename in self._logfiles:
            self.warning("Adding logfile %s multiple times." % filename)
            return
        h = logging.FileHandler(filename, mode)
        h.emit = types.MethodType(emit, h)
        h.setLevel(level)
        self._log.addHandler(h)
        self._logfiles[filename] = h
        return h

    def get_logfile_handler(self, filename):
        "Gets the handler to the file identified by the given file name."
        return self._logfiles[filename]

    def log(self, level, *message):
        "Write a log message on given log level."
        text = self._format_raw(*message)
        if len(text) >= 3 and text[-3:] == "...":
            self._log.log(level, self._format(*message),
                          extra={"continued": True})
        else:
            self._log.log(level, self._format(*message))

    def debug(self, *message):
        "Write debug message."
        self.log(DEBUG, *message)

    def info(self, *message):
        "Write info message."
        self.log(INFO, *message)

    def info_red(self, *message):
        "Write info message in red."
        self.log(INFO, RED % self._format_raw(*message))

    def info_green(self, *message):
        "Write info message in green."
        self.log(INFO, GREEN % self._format_raw(*message))

    def info_blue(self, *message):
        "Write info message in blue."
        self.log(INFO, BLUE % self._format_raw(*message))

    def deprecate(self, *message):
        "Write deprecation message."
        self.log(DEPRECATE, RED % self._format_raw(*message))

    def warning(self, *message):
        "Write warning message."
        self._log.warning(self._format(*message))

    def warning_red(self, *message):
        "Write warning message in red."
        self._log.warning(RED % self._format(*message))

    def warning_green(self, *message):
        "Write warning message in green."
        self._log.warning(GREEN % self._format(*message))

    def warning_blue(self, *message):
        "Write warning message in blue."
        self._log.warning(BLUE % self._format(*message))

    def error(self, *message):
        "Write error message and raise an exception."
        self._log.error(*message)
        raise self._exception_type(self._format_raw(*message))

    def begin(self, *message):
        "Begin task: write message and increase indentation level."
        self.info(*message)
        self.info("-" * len(self._format_raw(*message)))
        self.add_indent()

    def end(self):
        "End task: write a newline and decrease indentation level."
        self.info("")
        self.add_indent(-1)

    def push_level(self, level):
        "Push a log level on the level stack."
        self._level_stack.append(level)
        self.set_level(level)

    def pop_level(self):
        "Pop log level from the level stack, reverting to before the last push_level."
        self._level_stack.pop()
        level = self._level_stack[-1]
        self.set_level(level)

    def set_level(self, level):
        "Set log level."
        self._level_stack[-1] = level
        self._handler.setLevel(level)

    def set_indent(self, level):
        "Set indentation level."
        self._indent_level = level

    def add_indent(self, increment=1):
        "Add to indentation level."
        self._indent_level += increment

    def get_handler(self):
        "Get handler for logging."
        return self._handler

    def set_handler(self, handler):
        """Replace handler for logging.
        To add additional handlers instead of replacing the existing one, use
        `log.get_logger().addHandler(myhandler)`.
        See the logging module for more details.
        """
        self._log.removeHandler(self._handler)
        self._log.addHandler(handler)
        self._handler = handler
        handler.emit = types.MethodType(emit, self._handler)

    def get_logger(self):
        "Return message logger."
        return self._log

    def set_prefix(self, prefix):
        "Set prefix for log messages."
        self._prefix = prefix

    def _format(self, *message):
        "Format message including indentation."
        indent = self._prefix + 2 * self._indent_level * " "
        return "\n".join([indent + line for line in (message[0] % message[1:]).split("\n")])

    def _format_raw(self, *message):
        "Format message without indentation."
        return message[0] % message[1:]


# --- Set up global log functions ---

class UFLException(Exception):
    "Base class for UFL exceptions."
    pass


class UFLValueError(UFLException):
    "Value type error."
    pass


ufl_logger = Logger("UFL_LEGACY", UFLException)

for foo in log_functions:
    exec("%s = ufl_logger.%s" % (foo, foo))

set_level(DEPRECATE)  # noqa
