Also merge events in the same location with slightly varying names

This happens when for example details about adult/child tickets end up
being part of the name.

autotests/stringutiltest.cpp

@@ -34,6 +34,16 @@ private Q_SLOTS:
         QFETCH(QString, out);
         QCOMPARE(StringUtil::normalize(in), out);
     }
+
+    void testPrefixSimilarity()
+    {
+        QCOMPARE(StringUtil::prefixSimilarity(QString(), QString()), 0.0f);
+        QCOMPARE(StringUtil::prefixSimilarity(u"aaa", QString()), 0.0f);
+        QCOMPARE(StringUtil::prefixSimilarity(u"aaaa", u"AA"), 0.5f);
+        QCOMPARE(StringUtil::prefixSimilarity(u"aba", u"aBa"), 1.0f);
+        QCOMPARE(StringUtil::prefixSimilarity(u"ab", u"aa"), 0.5f);
+        QCOMPARE(StringUtil::prefixSimilarity(u"ac", u"abbb"), 0.25f);
+    }
 };
 
 QTEST_APPLESS_MAIN(StringUtilTest)

src/lib/mergeutil.cpp

@@ -7,6 +7,7 @@
 #include "mergeutil.h"
 #include "logging.h"
 #include "compare-logging.h"
+#include "locationutil.h"
 #include "stringutil.h"
 #include "sortutil.h"
 
@@ -423,8 +424,14 @@ bool MergeUtil::isSamePerson(const Person& lhs, const Person& rhs)
 
 static bool isSameEvent(const Event &lhs, const Event &rhs)
 {
-    return equalAndPresent(lhs.name(), rhs.name())
-        && equalAndPresent(lhs.startDate(), rhs.startDate());
+    if (!equalAndPresent(lhs.startDate(), rhs.startDate())) {
+        return false;
+    }
+
+    // event names can contain additional qualifiers, like for Adult/Child tickets,
+    // those don't change the event though
+    const auto namePrefix = StringUtil::prefixSimilarity(lhs.name(), rhs.name());
+    return namePrefix == 1.0f || (namePrefix > 0.65f && LocationUtil::isSameLocation(lhs.location(), rhs.location(), LocationUtil::Exact));
 }
 
 static bool isSameRentalCar(const RentalCar &lhs, const RentalCar &rhs)

src/lib/stringutil.cpp

@@ -90,3 +90,23 @@ QStringView StringUtil::betterString(QStringView lhs, QStringView rhs)
     }
     return rhs;
 }
+
+float StringUtil::prefixSimilarity(QStringView s1, QStringView s2)
+{
+    if (s1.empty() || s2.empty()) {
+        return 0.0f;
+    }
+
+    if (s1.size() > s2.size()) {
+        std::swap(s1, s2);
+    }
+
+    for (int i = 0; i < s1.size(); ++i) {
+        if (s1[i].toCaseFolded() == s2[i].toCaseFolded()) {
+            continue;
+        }
+        return (float)i / (float)s2.size();
+    }
+
+    return (float)s1.size() / (float)s2.size();
+}

src/lib/stringutil.h

@@ -29,6 +29,12 @@ namespace StringUtil
      *  That is, prefer the one that didn't lose casing/unicode/etc in previous processing.
      */
     QStringView betterString(QStringView lhs, QStringView rhs);
+
+    /** Returns how much of the prefix of two given strings are equal, in
+     *  relation to the longer of the two input strings.
+     *  @internal only exported for unit tests
+     */
+    KITINERARY_EXPORT float prefixSimilarity(QStringView s1, QStringView s2);
 }
 
 }