WIP: Config suggestion

CMakeLists.txt

@@ -134,9 +134,11 @@ add_executable(flashmq
     globber.cpp
     x509manager.h x509manager.cpp
     backgroundworker.h backgroundworker.cpp
-
+    edlib/src/edlib.cpp
     )
 
+target_include_directories(flashmq PRIVATE edlib/include)
+
 target_link_libraries(flashmq pthread dl ssl crypto resolv anl)
 
 execute_process(COMMAND ../.get-os-codename-and-stamp.sh OUTPUT_VARIABLE OS_CODENAME)

FlashMQTests/CMakeLists.txt

@@ -168,8 +168,11 @@ add_executable(flashmq-tests
     dnstests.cpp
     testinitializer.h testinitializer.cpp
 
+    ../edlib/src/edlib.cpp
     )
 
+target_include_directories(flashmq-tests PRIVATE ../edlib/include)
+
 target_include_directories(flashmq-tests PUBLIC ..)
 
 target_link_libraries(flashmq-tests pthread dl ssl crypto resolv anl)

FlashMQTests/maintests.cpp

@@ -221,6 +221,7 @@ MainTests::MainTests()
     REGISTER_FUNCTION(testOverrideWillDelayOnSessionDestructionByTakeOver);
     REGISTER_FUNCTION(testDisabledWills);
     REGISTER_FUNCTION(testMqtt5DelayedWillsDisabled);
+    REGISTER_FUNCTION(test_config_suggestion);
     REGISTER_FUNCTION(testIncomingTopicAlias);
     REGISTER_FUNCTION(testOutgoingTopicAlias);
     REGISTER_FUNCTION(testOutgoingTopicAliasStoredPublishes);

FlashMQTests/maintests.h

@@ -118,6 +118,7 @@ class MainTests
     void testOverrideWillDelayOnSessionDestructionByTakeOver();
     void testDisabledWills();
     void testMqtt5DelayedWillsDisabled();
+    void test_config_suggestion();
 
 
     void testIncomingTopicAlias();

FlashMQTests/willtests.cpp

@@ -2,6 +2,7 @@
 #include "testhelpers.h"
 #include "flashmqtestclient.h"
 #include "conffiletemp.h"
+#include "exceptions.h"
 
 void MainTests::testMqtt3will()
 {
@@ -323,3 +324,44 @@ void MainTests::testMqtt5DelayedWillsDisabled()
     usleep(250000);
     QVERIFY(receiver.receivedPackets.empty());
 }
+
+
+void MainTests::test_config_suggestion()
+{
+    // User made a small typo
+    {
+        ConfFileTemp config;
+        config.writeLine("expire_session_after_seconds 180");
+        config.closeFile();
+
+        ConfigFileParser parser(config.getFilePath());
+
+        try {
+            parser.loadFile(false);
+            FMQ_FAIL("The parser is too liberal");
+        } catch (ConfigFileException ex)
+        {
+            /* Good! This is where we want to end up in */
+            FMQ_COMPARE(ex.what(), "Config key 'expire_session_after_seconds' is not valid (here). Did you mean: expire_sessions_after_seconds ?");
+        }
+    }
+
+    // User entered gibberish. Let's not suggest gibberish back
+        {
+        ConfFileTemp config;
+        config.writeLine("foobarbaz 180");
+        config.closeFile();
+
+        ConfigFileParser parser(config.getFilePath());
+
+        try {
+            parser.loadFile(false);
+            FMQ_FAIL("The parser is too liberal");
+        } catch (ConfigFileException ex)
+        {
+            FMQ_COMPARE(ex.what(), "Config key 'foobarbaz' is not valid (here).");
+        }
+    }
+
+}
+

configfileparser.cpp

@@ -23,6 +23,7 @@ See LICENSE for license details.
 #include "exceptions.h"
 #include "utils.h"
 #include "globber.h"
+#include "edlib.h"
 
 
 /**
@@ -41,6 +42,29 @@ bool ConfigFileParser::testKeyValidity(const std::string &key, const std::string
     {
         std::ostringstream oss;
         oss << "Config key '" << key << "' is not valid (here).";
+
+        // Maybe the user made a typo
+        EdlibAlignConfig cmpcnf = edlibDefaultAlignConfig();
+        const std::string *alternative = nullptr;
+        int alternative_distance = INT_MAX;
+
+        for (const std::string& possible_key : validKeys)
+        {
+            EdlibAlignResult result = edlibAlign(key.c_str(), key.length(), possible_key.c_str(), key.length(), cmpcnf);
+            if (result.status == EDLIB_STATUS_OK) {
+                // The mathemathical formula "x/y < 0.5"
+                // can be calculated with integers as "x*2/y < 1"
+                if ((result.editDistance * 2) / key.length() < 1 && result.editDistance < alternative_distance) {
+                    alternative = &possible_key;
+                    alternative_distance = result.editDistance;
+                }
+            }
+            edlibFreeAlignResult(result);
+        }
+        if (alternative != nullptr) {
+            oss << " Did you mean: " << alternative->c_str() << " ?";
+        }
+
         throw ConfigFileException(oss.str());
     }
 

edlib/LICENSE

@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Martin Šošić
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

edlib/README

@@ -0,0 +1 @@
+Local copy of https://github.com/Martinsos/edlib