Add logging handler with history and signal emision

1 files changed, 99 insertions, 0 deletions

diff --git a/src/leap/util/leap_log_handler.py b/src/leap/util/leap_log_handler.py
new file mode 100644
index 00000000..0e598032
--- /dev/null
+++ b/src/leap/util/leap_log_handler.py
@@ -0,0 +1,99 @@
+# -*- coding: utf-8 -*-
+# leap_log_handler.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Custom handler for the logger window.
+"""
+import logging
+
+from PySide import QtCore
+
+
+class LeapLogHandler(logging.Handler, QtCore.QObject):
+    """
+    Custom logging handler. It emits Qt signals so it can be plugged to a gui.
+    Also stores an history of logs that can be fetched after connect to a gui.
+    """
+    # All dicts returned are of the form
+    # {'record': LogRecord, 'message': str}
+    new_log = QtCore.Signal(dict)
+
+    MESSAGE_KEY = 'message'
+    RECORD_KEY = 'record'
+
+    def __init__(self):
+        logging.Handler.__init__(self)
+        QtCore.QObject.__init__(self)
+
+        self._log_history = []
+
+    def _set_format(self, logging_level):
+        """
+        Sets the log format depending on the parameter.
+        It uses html and css to set the colors for the logs.
+
+        :param logging_level: the debug level to define the color.
+        :type logging_level: str.
+        """
+        html_style = {
+            'DEBUG': "color: blue",
+            'INFO': "color: black",
+            'WARNING': "color: black; background: yellow;",
+            'ERROR': "color: red",
+            'CRITICAL': "color: red; font-weight: bold;"
+        }
+
+        style_open = "<span style='" + html_style[logging_level] + "'>"
+        style_close = "</span>"
+        time = "%(asctime)s"
+        name = style_open + "%(name)s"
+        level = "%(levelname)s"
+        message = "%(message)s" + style_close
+        format_attrs = [time, name, level, message]
+        log_format = ' - '.join(format_attrs)
+        formatter = logging.Formatter(log_format)
+        self.setFormatter(formatter)
+
+    def emit(self, logRecord):
+        """
+        This method is fired every time that a record is logged by the
+        logging module.
+        This method reimplements logging.Handler.emit that is fired
+        in every logged message.
+        QObject.emit gets in the way on the PySide signal model but we
+        workarouded that issue.
+
+        :param logRecord: the record emitted by the logging module.
+        :type logRecord: logging.LogRecord.
+        """
+        self._set_format(logRecord.levelname)
+        log = self.format(logRecord)
+        log_item = {self.RECORD_KEY: logRecord, self.MESSAGE_KEY: log}
+        self._log_history.append(log_item)
+
+        # WARNING: the new-style connection does NOT work because PySide
+        # translates the emit method to self.emit, and that collides with
+        # the emit method for logging.Handler
+        # self.new_log.emit(log_item)
+        QtCore.QObject.emit(self, QtCore.SIGNAL('new_log(PyObject)'), log_item)
+
+    @property
+    def log_history(self):
+        """
+        Returns the history of the logged messages.
+        """
+        return self._log_history