Finished basic reporter

letsencrypt/reporter.py

@@ -0,0 +1,68 @@
+"""Collects and displays information to the user."""
+import collections
+import Queue
+import sys
+import textwrap
+
+import zope.interface
+
+from letsencrypt import interfaces
+
+
+class Reporter(object):
+    """Collects and displays information to the user.
+
+    :ivar `Queue.PriorityQueue` messages: Messages to be displayed to the user.
+
+    """
+
+    zope.interface.implements(interfaces.IReporter)
+
+    HIGH_PRIORITY, MEDIUM_PRIORITY, LOW_PRIORITY = xrange(3)
+    _RESET = '\033[0m'
+    _BOLD = '\033[1m'
+    _msg_type = collections.namedtuple('Msg', 'priority, text, on_crash')
+
+    def __init__(self):
+        self.messages = Queue.PriorityQueue()
+
+    def add_message(self, msg, priority, on_crash=False):
+        """Adds msg to the list of messages to be printed.
+
+        :param str msg: Message to be displayed to the user.
+
+        :param int priority: One of HIGH_PRIORITY, MEDIUM_PRIORITY, or
+            LOW_PRIORITY.
+
+        :param bool on_crash: Whether or not the message should be printed if
+            the program exits abnormally.
+
+        """
+        assert priority >= self.HIGH_PRIORITY and priority <= self.LOW_PRIORITY
+        self.messages.put(self._msg_type(priority, msg, on_crash))
+
+    def print_messages(self):
+        """Prints messages to the user and clears the message queue.
+
+        If there is an unhandled exception, only messages for which on_crash is
+        True are printed.
+
+        """
+        bold_on = False
+        if not self.messages.empty():
+            no_exception = sys.exc_info()[0] is None
+            bold_on = sys.stdout.isatty()
+            if bold_on:
+                sys.stdout.write(self._BOLD)
+            print 'IMPORTANT NOTES:'
+            wrapper = textwrap.TextWrapper(initial_indent=' - ',
+                                           subsequent_indent=' '*3)
+        while not self.messages.empty():
+            msg = self.messages.get()
+            if no_exception or msg.on_crash:
+                if bold_on and msg.priority > self.HIGH_PRIORITY:
+                    sys.stdout.write(self._RESET)
+                    bold_on = False
+                print wrapper.fill(msg.text)
+        if bold_on:
+            sys.stdout.write(self._RESET)