From af410e0b15168c2399822f05008303413e0d8ed5 Mon Sep 17 00:00:00 2001
From: "Veronica K. B. Olsen" <1619840+vkbo@users.noreply.github.com>
Date: Wed, 26 Feb 2020 22:09:37 +0100
Subject: [PATCH] Added functions to read and write project lockfile

---
 nw/config.py              |  6 ++-
 nw/constants/constants.py |  1 +
 nw/project/project.py     | 91 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/nw/config.py b/nw/config.py
index 3149edef..94c30f71 100644
--- a/nw/config.py
+++ b/nw/config.py
@@ -20,7 +20,7 @@ from os import path, mkdir, unlink, rename
 from datetime import datetime
 
 from PyQt5.Qt import PYQT_VERSION_STR
-from PyQt5.QtCore import QT_VERSION_STR, QStandardPaths
+from PyQt5.QtCore import QT_VERSION_STR, QStandardPaths, QSysInfo
 
 from nw.constants import nwFiles, nwUnicode
 from nw.common import splitVersionNumber
@@ -156,6 +156,10 @@ class Config:
         else:
             self.osUnknown = True
 
+        # Other System Info
+        self.hostName  = QSysInfo.machineHostName()
+        self.kernelVer = QSysInfo.kernelVersion()
+
         # Packages
         self.hasEnchant  = False
         self.hasSymSpell = False
diff --git a/nw/constants/constants.py b/nw/constants/constants.py
index 4cc7f040..b39830bc 100644
--- a/nw/constants/constants.py
+++ b/nw/constants/constants.py
@@ -23,6 +23,7 @@ class nwFiles():
     APP_ICON    = "novelWriter.svg"
     PROJ_FILE   = "nwProject.nwx"
     PROJ_DICT   = "wordlist.txt"
+    PROJ_LOCK   = "nwProject.lock"
     SESS_INFO   = "sessionInfo.log"
     INDEX_FILE  = "tagsIndex.json"
     OPTS_FILE   = "guiOptions.json"
diff --git a/nw/project/project.py b/nw/project/project.py
index 887fe38c..afde1e02 100644
--- a/nw/project/project.py
+++ b/nw/project/project.py
@@ -40,6 +40,7 @@ class NWProject():
         self.projOpened  = None # The time stamp of when the project file was opened
         self.projChanged = None # The project has unsaved changes
         self.projAltered = None # The project has been altered this session
+        self.lockedBy    = None # Data on which computer has the project open
 
         # Debug
         self.handleSeed = None
@@ -178,7 +179,7 @@ class NWProject():
 
         return
 
-    def openProject(self, fileName):
+    def openProject(self, fileName, overrideLock=False):
         """Open the project file provided, or if doesn't exist, assume
         it is a folder, and look for the file within it. If successful,
         parse the XML of the file and populate the project variables and
@@ -201,6 +202,21 @@ class NWProject():
         if not self._checkFolder(self.projMeta):
             return
 
+        if overrideLock:
+            self._clearLockFile()
+
+        lockStatus = self._readLockFile()
+        if len(lockStatus) > 0:
+            if lockStatus[0] == "ERROR":
+                logger.warning("Failed to check lock file")
+            else:
+                logger.error("Project is locked, so not opening")
+                self.lockedBy = lockStatus
+                self.clearProject()
+                return False
+        else:
+            logger.verbose("Project is not locked")
+
         try:
             projectMaintenance(self)
         except Exception as E:
@@ -308,6 +324,7 @@ class NWProject():
         self.setProjectChanged(False)
         self.projOpened = time()
         self.projAltered = False
+        self._writeLockFile()
 
         return True
 
@@ -398,14 +415,19 @@ class NWProject():
         self.mainConf.updateRecentCache(self.projPath, self.projName, self.currWCount, saveTime)
         self.mainConf.saveRecentCache()
 
+        self._writeLockFile()
         self.theParent.setStatus("Saved Project: %s" % self.projName)
         self.setProjectChanged(False)
 
         return True
 
     def closeProject(self):
+        """Close the current project and clear all meta data.
+        """
         self._appendSessionStats()
+        self._clearLockFile()
         self.clearProject()
+        self.lockedBy = None
         return True
 
     ##
@@ -645,6 +667,73 @@ class NWProject():
     #  Internal Functions
     ##
 
+    def _readLockFile(self):
+        """Reads the lock file in the project folder.
+        """
+
+        if self.projPath is None:
+            return ["ERROR"]
+
+        lockFile = path.join(self.projPath, nwFiles.PROJ_LOCK)
+        if not path.isfile(lockFile):
+            return []
+
+        try:
+            with open(lockFile, mode="r", encoding="utf8") as inFile:
+                theData = inFile.read()
+                theLines = theData.splitlines()
+                if len(theLines) == 4:
+                    return theLines
+                else:
+                    return ["ERROR"]
+
+        except Exception as e:
+            logger.error("Failed to read project lockfile")
+            logger.error(str(e))
+            return ["ERROR"]
+
+        return ["ERROR"]
+
+    def _writeLockFile(self):
+        """Writes a lock file to the project folder.
+        """
+
+        if self.projPath is None:
+            return False
+
+        lockFile = path.join(self.projPath, nwFiles.PROJ_LOCK)
+        try:
+            with open(lockFile, mode="w+", encoding="utf8") as outFile:
+                outFile.write("%s\n" % self.mainConf.hostName)
+                outFile.write("%s\n" % self.mainConf.osType)
+                outFile.write("%s\n" % self.mainConf.kernelVer)
+                outFile.write("%d\n" % time())
+
+        except Exception as e:
+            logger.error("Failed to write project lockfile")
+            logger.error(str(e))
+            return False
+
+        return True
+
+    def _clearLockFile(self):
+        """Remove the lock file, if it exists.
+        """
+        if self.projPath is None:
+            return False
+
+        lockFile = path.join(self.projPath, nwFiles.PROJ_LOCK)
+        if path.isfile(lockFile):
+            try:
+                unlink(lockFile)
+                return True
+            except Exception as e:
+                logger.error("Failed to remove project lockfile")
+                logger.error(str(e))
+                return False
+
+        return None
+
     def _checkFolder(self, thePath):
         if not path.isdir(thePath):
             try: