Log the git revision if applicable

During development, the version number does not have much meaning... but
when faced with a reported issue, you would still like to know in more
detail what version of the Manuskript code was at work there.

Knowing the exact git revision will hopefully make it easier to
troubleshoot such issues in the future.

Note: this code takes special care to not rely on external modules
(we have enough dependencies) or even the git executable (invoking a
program can be relatively slow on some operating systems). It might not
handle all the edge cases, but I think it should cover our needs well
enough.

manuskript/functions/__init__.py

@@ -3,6 +3,8 @@
 
 import os
 import re
+import sys
+import pathlib
 from random import *
 
 from PyQt5.QtCore import Qt, QRect, QStandardPaths, QObject, QRegExp, QDir
@@ -13,6 +15,9 @@ from PyQt5.QtWidgets import qApp, QFileDialog
 
 from manuskript.enums import Outline
 
+import logging
+LOGGER = logging.getLogger(__name__)
+
 # Used to detect multiple connections
 AUC = Qt.AutoConnection | Qt.UniqueConnection
 MW = None
@@ -493,5 +498,47 @@ def getSearchResultContext(text, startPos, endPos):
 
     return context
 
+
+# Based on answer by jfs at:
+#  https://stackoverflow.com/questions/3718657/how-to-properly-determine-current-script-directory
+def getManuskriptPath(follow_symlinks=True):
+    """Used to obtain the path Manuskript is located at."""
+    if getattr(sys, 'frozen', False): # py2exe, PyInstaller, cx_Freeze
+        path = os.path.abspath(sys.executable)
+    else:
+        import inspect
+        path = inspect.getabsfile(getManuskriptPath) + "/../.."
+    if follow_symlinks:
+        path = os.path.realpath(path)
+    return os.path.dirname(path)
+
+# Based on answer by kagronik at:
+#   https://stackoverflow.com/questions/14989858/get-the-current-git-hash-in-a-python-script
+def getGitRevision(base_path):
+    """Get git revision without relying on external processes or libraries."""
+    git_dir = pathlib.Path(base_path) / '.git'
+    if not git_dir.exists():
+        return None
+
+    with (git_dir / 'HEAD').open('r') as head:
+        ref = head.readline().split(' ')[-1].strip()
+
+    with (git_dir / ref).open('r') as git_hash:
+        return git_hash.readline().strip()
+
+def getGitRevisionAsString(base_path, short=False):
+    """Catches errors and presents a nice string."""
+    try:
+        rev = getGitRevision(base_path)
+        if rev is not None:
+            if short:
+                rev = rev[:7]
+            return "#" + rev
+        else:
+            return ""  # not a git repository
+    except Exception as e:
+        LOGGER.warning("Failed to obtain Git revision: %s", e)
+        return "#ERROR"
+
 # Spellchecker loads writablePath from this file, so we need to load it after they get defined
 from manuskript.functions.spellchecker import Spellchecker

manuskript/logging.py

@@ -157,6 +157,8 @@ def attributesFromOptionalModule(module, *attributes):
         # The list is consumed as a part of the unpacking syntax.
         return v
 
+import pathlib
+
 def logVersionInformation(logger=None):
     """Logs all important runtime information neatly together.
 
@@ -174,8 +176,11 @@ def logVersionInformation(logger=None):
     logger.info("Hardware: %s / %s", machine(), processor())
 
     # Manuskript and Python info.
+    from manuskript.functions import getGitRevisionAsString, getManuskriptPath
     from manuskript.version import getVersion
-    logger.info("Manuskript %s (Python %s)", getVersion(), python_version())
+    logger.info("Manuskript %s%s (Python %s)", getVersion(),
+                    getGitRevisionAsString(getManuskriptPath(), short=True),
+                    python_version())
 
     # Installed Python packages.