Create the Qt File Filter => showOpen/SaveFilePicker options mapper

As a preparatory measure for using showXFilePicker, the Qt file
filter has to be transformed to the format used by the showXFilePicker
(sXFP) options. A class structure reflecting the options was created. Based on
an input in the form of a qt file filter, it will parse the filter to
the sXFP options format. Unit tests were added and the code is not yet
used in non-test env, next change will use it.

Task-number: QTBUG-99611
Change-Id: I277286467a7b5ce6f323c19bdd31740a41b6a6be
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

5 files changed, 520 insertions, 0 deletions

diff --git a/src/gui/CMakeLists.txt b/src/gui/CMakeLists.txt
index 36dae764d7..95579b0c9e 100644
--- a/src/gui/CMakeLists.txt
+++ b/src/gui/CMakeLists.txt
@@ -969,6 +969,7 @@ add_custom_command(
 
 qt_internal_extend_target(Gui CONDITION WASM
     SOURCES
+        platform/wasm/qlocalfileapi.cpp platform/wasm/qlocalfileapi_p.h
         platform/wasm/qwasmlocalfileaccess.cpp platform/wasm/qwasmlocalfileaccess_p.h
 )
 
diff --git a/src/gui/platform/wasm/qlocalfileapi.cpp b/src/gui/platform/wasm/qlocalfileapi.cpp
new file mode 100644
index 0000000000..ec7ae40391
--- /dev/null
+++ b/src/gui/platform/wasm/qlocalfileapi.cpp
@@ -0,0 +1,197 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qlocalfileapi_p.h"
+#include <private/qstdweb_p.h>
+#include <QtCore/QRegularExpression>
+
+QT_BEGIN_NAMESPACE
+namespace LocalFileApi {
+namespace {
+std::optional<emscripten::val> qtFilterListToTypes(const QStringList &filterList)
+{
+    using namespace qstdweb;
+    using namespace emscripten;
+
+    auto types = emscripten::val::array();
+
+    for (const auto &fileFilter : filterList) {
+        auto type = Type::fromQt(fileFilter);
+        if (type)
+            types.call<void>("push", type->asVal());
+    }
+
+    return types["length"].as<int>() == 0 ? std::optional<emscripten::val>() : types;
+}
+}
+
+Type::Type(QStringView description, std::optional<Accept> accept)
+    : m_storage(emscripten::val::object())
+{
+    m_storage.set("description", description.trimmed().toString().toStdString());
+    if (accept)
+        m_storage.set("accept", accept->asVal());
+}
+
+Type::~Type() = default;
+
+std::optional<Type> Type::fromQt(QStringView type)
+{
+    using namespace emscripten;
+
+    // Accepts either a string in format:
+    // GROUP3
+    // or in this format:
+    // GROUP1 (GROUP2)
+    // Group 1 is treated as the description, whereas group 2 or 3 are treated as the filter list.
+    static QRegularExpression regex(
+            QString(QStringLiteral("(?:(?:([^(]*)\\(([^()]+)\\)[^)]*)|([^()]+))")));
+    const auto match = regex.match(type);
+
+    if (!match.hasMatch())
+        return std::nullopt;
+
+    constexpr size_t DescriptionIndex = 1;
+    constexpr size_t FilterListFromParensIndex = 2;
+    constexpr size_t PlainFilterListIndex = 3;
+
+    const auto description = match.hasCaptured(DescriptionIndex)
+            ? match.capturedView(DescriptionIndex)
+            : QStringView();
+    const auto filterList = match.capturedView(match.hasCaptured(FilterListFromParensIndex)
+                                                       ? FilterListFromParensIndex
+                                                       : PlainFilterListIndex);
+
+    auto accept = Type::Accept::fromQt(filterList);
+    if (!accept)
+        return std::nullopt;
+
+    return Type(description, std::move(*accept));
+}
+
+emscripten::val Type::asVal() const
+{
+    return m_storage;
+}
+
+Type::Accept::Accept() : m_storage(emscripten::val::object()) { }
+
+Type::Accept::~Accept() = default;
+
+std::optional<Type::Accept> Type::Accept::fromQt(QStringView qtRepresentation)
+{
+    Accept accept;
+
+    // Used for accepting multiple extension specifications on a filter list.
+    // The next group of non-empty characters.
+    static QRegularExpression internalRegex(QString(QStringLiteral("([^\\s]+)\\s*")));
+    int offset = 0;
+    auto internalMatch = internalRegex.match(qtRepresentation, offset);
+    MimeType mimeType;
+
+    while (internalMatch.hasMatch()) {
+        auto webExtension = MimeType::Extension::fromQt(internalMatch.capturedView(1));
+
+        if (!webExtension)
+            return std::nullopt;
+
+        mimeType.addExtension(*webExtension);
+
+        internalMatch = internalRegex.match(qtRepresentation, internalMatch.capturedEnd());
+    }
+
+    accept.addMimeType(mimeType);
+    return accept;
+}
+
+void Type::Accept::addMimeType(MimeType mimeType)
+{
+    // The mime type provided here does not seem to have any effect at the result at all.
+    m_storage.set("application/octet-stream", mimeType.asVal());
+}
+
+emscripten::val Type::Accept::asVal() const
+{
+    return m_storage;
+}
+
+Type::Accept::MimeType::MimeType() : m_storage(emscripten::val::array()) { }
+
+Type::Accept::MimeType::~MimeType() = default;
+
+void Type::Accept::MimeType::addExtension(Extension extension)
+{
+    m_storage.call<void>("push", extension.asVal());
+}
+
+emscripten::val Type::Accept::MimeType::asVal() const
+{
+    return m_storage;
+}
+
+Type::Accept::MimeType::Extension::Extension(QStringView extension)
+    : m_storage(extension.toString().toStdString())
+{
+}
+
+Type::Accept::MimeType::Extension::~Extension() = default;
+
+std::optional<Type::Accept::MimeType::Extension>
+Type::Accept::MimeType::Extension::fromQt(QStringView qtRepresentation)
+{
+    // Checks for a filter that matches everything:
+    // Any number of asterisks or any number of asterisks with a '.' between them.
+    // The web filter does not support wildcards.
+    static QRegularExpression qtAcceptAllRegex(
+            QRegularExpression::anchoredPattern(QString(QStringLiteral("[*]+|[*]+\\.[*]+"))));
+    if (qtAcceptAllRegex.match(qtRepresentation).hasMatch())
+        return std::nullopt;
+
+    // Checks for correctness. The web filter only allows filename extensions and does not filter
+    // the actual filenames, therefore we check whether the filter provided only filters for the
+    // extension.
+    static QRegularExpression qtFilenameMatcherRegex(
+            QRegularExpression::anchoredPattern(QString(QStringLiteral("(\\*?)(\\.[^*]+)"))));
+
+    auto extensionMatch = qtFilenameMatcherRegex.match(qtRepresentation);
+    if (extensionMatch.hasMatch())
+        return Extension(extensionMatch.capturedView(2));
+
+    // Mapping impossible.
+    return std::nullopt;
+}
+
+emscripten::val Type::Accept::MimeType::Extension::asVal() const
+{
+    return m_storage;
+}
+
+emscripten::val makeOpenFileOptions(const QStringList &filterList, bool acceptMultiple)
+{
+    auto options = emscripten::val::object();
+    if (auto typeList = LocalFileApi::qtFilterListToTypes(filterList)) {
+        options.set("types", std::move(*typeList));
+        options.set("excludeAcceptAllOption", true);
+    }
+
+    options.set("multiple", acceptMultiple);
+
+    return options;
+}
+
+emscripten::val makeSaveFileOptions(const QStringList &filterList, const std::string& suggestedName)
+{
+    auto options = emscripten::val::object();
+
+    if (!suggestedName.empty())
+        options.set("suggestedName", emscripten::val(suggestedName));
+
+    if (auto typeList = LocalFileApi::qtFilterListToTypes(filterList))
+        options.set("types", emscripten::val(std::move(*typeList)));
+
+    return options;
+}
+
+}  // namespace LocalFileApi
+
+QT_END_NAMESPACE
diff --git a/src/gui/platform/wasm/qlocalfileapi_p.h b/src/gui/platform/wasm/qlocalfileapi_p.h
new file mode 100644
index 0000000000..a8e7f666f9
--- /dev/null
+++ b/src/gui/platform/wasm/qlocalfileapi_p.h
@@ -0,0 +1,87 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QLOCALFILEAPI_P_H
+#define QLOCALFILEAPI_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qglobal_p.h>
+#include <qstringview.h>
+#include <emscripten/val.h>
+#include <cstdint>
+#include <functional>
+
+QT_BEGIN_NAMESPACE
+
+namespace LocalFileApi {
+class Q_CORE_EXPORT Type {
+public:
+    class Accept {
+    public:
+        class MimeType {
+        public:
+            class Extension {
+            public:
+                static std::optional<Extension> fromQt(QStringView extension);
+
+                ~Extension();
+
+                emscripten::val asVal() const;
+
+            private:
+                explicit Extension(QStringView extension);
+
+                emscripten::val m_storage;
+            };
+
+            MimeType();
+            ~MimeType();
+
+            void addExtension(Extension type);
+
+            emscripten::val asVal() const;
+
+        private:
+            emscripten::val m_storage;
+        };
+
+        static std::optional<Accept> fromQt(QStringView type);
+
+        ~Accept();
+
+        void addMimeType(MimeType mimeType);
+
+        emscripten::val asVal() const;
+
+    private:
+        Accept();
+        emscripten::val m_storage;
+    };
+
+    Type(QStringView description, std::optional<Accept> accept);
+    ~Type();
+
+    static std::optional<Type> fromQt(QStringView type);
+    emscripten::val asVal() const;
+
+private:
+    emscripten::val m_storage;
+};
+
+Q_CORE_EXPORT emscripten::val makeOpenFileOptions(const QStringList &filterList, bool acceptMultiple);
+Q_CORE_EXPORT emscripten::val makeSaveFileOptions(const QStringList &filterList, const std::string& suggestedName);
+
+}  // namespace LocalFileApi
+QT_END_NAMESPACE
+
+#endif // QLOCALFILEAPI_P_H
diff --git a/tests/auto/wasm/CMakeLists.txt b/tests/auto/wasm/CMakeLists.txt
index 2e6c6976fb..6c10838a92 100644
--- a/tests/auto/wasm/CMakeLists.txt
+++ b/tests/auto/wasm/CMakeLists.txt
@@ -2,6 +2,20 @@
 ## tst_wasm Test:
 #####################################################################
 
+qt_internal_add_test(tst_localfileapi
+    SOURCES
+        tst_localfileapi.cpp
+    DEFINES
+        QT_NO_FOREACH
+        QT_NO_KEYWORDS
+    LIBRARIES
+        Qt::GuiPrivate
+    PUBLIC_LIBRARIES
+        Qt::Core
+        Qt::Gui
+        Qt::Widgets
+)
+
 qt_internal_add_test(tst_qstdweb
     SOURCES
         tst_qstdweb.cpp
diff --git a/tests/auto/wasm/tst_localfileapi.cpp b/tests/auto/wasm/tst_localfileapi.cpp
new file mode 100644
index 0000000000..0d17202d4b
--- /dev/null
+++ b/tests/auto/wasm/tst_localfileapi.cpp
@@ -0,0 +1,221 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// Copyright (C) 2016 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QtGui/private/qlocalfileapi_p.h>
+#include <QTest>
+#include <emscripten/val.h>
+
+class tst_LocalFileApi : public QObject
+{
+    Q_OBJECT
+
+private:
+    emscripten::val makeAccept(std::vector<emscripten::val> types) {
+        auto accept = emscripten::val::object();
+        accept.set("application/octet-stream",
+            emscripten::val::array(std::move(types)));
+        return accept;
+    }
+
+    emscripten::val makeType(QString description, std::vector<emscripten::val> acceptExtensions) {
+        using namespace emscripten;
+
+        auto type = val::object();
+        type.set("description", description.toStdString());
+
+        auto accept = val::object();
+        accept.set("application/octet-stream",
+            val::array(std::move(acceptExtensions)));
+        type.set("accept", makeAccept(std::move(acceptExtensions)));
+
+        return type;
+    }
+
+    emscripten::val makeOpenFileOptions(bool acceptMultiple, std::vector<emscripten::val> types) {
+        using namespace emscripten;
+
+        auto webFilter = val::object();
+        webFilter.set("types", val::array(std::move(types)));
+        if (!types.empty())
+            webFilter.set("excludeAcceptAllOption", val(true));
+        webFilter.set("multiple", val(acceptMultiple));
+
+        return webFilter;
+    }
+
+    emscripten::val makeSaveFileOptions(QString suggestedName, std::vector<emscripten::val> types) {
+        using namespace emscripten;
+
+        auto webFilter = val::object();
+        webFilter.set("suggestedName", val(suggestedName.toStdString()));
+        webFilter.set("types", val::array(std::move(types)));
+
+        return webFilter;
+    }
+
+private Q_SLOTS:
+    void fileExtensionFilterTransformation_data();
+    void fileExtensionFilterTransformation();
+    void acceptTransformation_data();
+    void acceptTransformation();
+    void typeTransformation_data();
+    void typeTransformation();
+    void openFileOptions_data();
+    void openFileOptions();
+    void saveFileOptions_data();
+    void saveFileOptions();
+};
+
+bool valDeepEquals(emscripten::val lhs, emscripten::val rhs)
+{
+    auto json = emscripten::val::global("JSON");
+    auto lhsAsJsonString = json.call<emscripten::val>("stringify", lhs);
+    auto rhsAsJsonString = json.call<emscripten::val>("stringify", rhs);
+
+    return lhsAsJsonString.equals(rhsAsJsonString);
+}
+
+void tst_LocalFileApi::fileExtensionFilterTransformation_data()
+{
+    QTest::addColumn<QString>("qtFileFilter");
+    QTest::addColumn<std::optional<std::string>>("expectedWebExtensionFilter");
+
+    QTest::newRow("PNG extension with an asterisk") << QString("*.png") << std::make_optional<std::string>(".png");
+    QTest::newRow("Long extension with an asterisk") << QString("*.someotherfile") << std::make_optional<std::string>(".someotherfile");
+    QTest::newRow(".dat with no asterisk") << QString(".dat") << std::make_optional<std::string>(".dat");
+    QTest::newRow("Multiple asterisks") << QString("*ot*.abc") << std::optional<std::string>();
+    QTest::newRow("Filename") << QString("abcd.abc") << std::optional<std::string>();
+    QTest::newRow("match all") << QString("*.*") << std::optional<std::string>();
+}
+
+void tst_LocalFileApi::fileExtensionFilterTransformation()
+{
+    QFETCH(QString, qtFileFilter);
+    QFETCH(std::optional<std::string>, expectedWebExtensionFilter);
+
+    auto result = LocalFileApi::Type::Accept::MimeType::Extension::fromQt(qtFileFilter);
+    if (expectedWebExtensionFilter) {
+        QCOMPARE_EQ(expectedWebExtensionFilter, result->asVal().as<std::string>());
+    } else {
+        QVERIFY(!result.has_value());
+    }
+}
+
+void tst_LocalFileApi::acceptTransformation_data()
+{
+    using namespace emscripten;
+
+    QTest::addColumn<QString>("qtFilterList");
+    QTest::addColumn<emscripten::val>("expectedWebType");
+
+    QTest::newRow("Multiple types") << QString("*.png *.other *.txt")
+        << makeAccept(std::vector<val> { val(".png"), val(".other"), val(".txt") });
+
+    QTest::newRow("Single type") << QString("*.png")
+        << makeAccept(std::vector<val> { val(".png") });
+
+    QTest::newRow("No filter when accepts all") << QString("*.*")
+        << val::undefined();
+
+    QTest::newRow("No filter when one filter accepts all") << QString("*.* *.jpg")
+        << val::undefined();
+
+    QTest::newRow("Weird spaces") << QString("    *.jpg     *.png *.icon  ")
+        << makeAccept(std::vector<val> { val(".jpg"), val(".png"), val(".icon") });
+}
+
+void tst_LocalFileApi::acceptTransformation()
+{
+    QFETCH(QString, qtFilterList);
+    QFETCH(emscripten::val, expectedWebType);
+
+    auto result = LocalFileApi::Type::Accept::fromQt(qtFilterList);
+    if (!expectedWebType.isUndefined()) {
+        QVERIFY(valDeepEquals(result->asVal(), expectedWebType));
+    } else {
+        QVERIFY(!result.has_value());
+    }
+}
+
+void tst_LocalFileApi::typeTransformation_data()
+{
+    using namespace emscripten;
+
+    QTest::addColumn<QString>("qtFilterList");
+    QTest::addColumn<emscripten::val>("expectedWebType");
+
+    QTest::newRow("With description") << QString("Text files (*.txt)")
+        << makeType("Text files", std::vector<val> { val(".txt") });
+
+    QTest::newRow("No description") << QString("*.jpg")
+        << makeType("", std::vector<val> { val(".jpg") });
+}
+
+void tst_LocalFileApi::typeTransformation()
+{
+    QFETCH(QString, qtFilterList);
+    QFETCH(emscripten::val, expectedWebType);
+
+    auto result = LocalFileApi::Type::fromQt(qtFilterList);
+    if (!expectedWebType.isUndefined()) {
+        QVERIFY(valDeepEquals(result->asVal(), expectedWebType));
+    } else {
+        QVERIFY(!result.has_value());
+    }
+}
+
+void tst_LocalFileApi::openFileOptions_data()
+{
+    using namespace emscripten;
+
+    QTest::addColumn<QStringList>("qtFilterList");
+    QTest::addColumn<bool>("multiple");
+    QTest::addColumn<emscripten::val>("expectedWebType");
+
+    QTest::newRow("Multiple files") << QStringList({"Text files (*.txt)", "Images (*.jpg *.png)", "*.bat"})
+        << true
+        << makeOpenFileOptions(true, { makeType("Text files", { val(".txt")}), makeType("Images", { val(".jpg"), val(".png")}), makeType("", { val(".bat")})});
+    QTest::newRow("Single file") << QStringList({"Text files (*.txt)", "Images (*.jpg *.png)", "*.bat"})
+        << false
+        << makeOpenFileOptions(false, { makeType("Text files", { val(".txt")}), makeType("Images", { val(".jpg"), val(".png")}), makeType("", { val(".bat")})});
+}
+
+void tst_LocalFileApi::openFileOptions()
+{
+    QFETCH(QStringList, qtFilterList);
+    QFETCH(bool, multiple);
+    QFETCH(emscripten::val, expectedWebType);
+
+    auto result = LocalFileApi::makeOpenFileOptions(qtFilterList, multiple);
+    QVERIFY(valDeepEquals(result, expectedWebType));
+}
+
+void tst_LocalFileApi::saveFileOptions_data()
+{
+    using namespace emscripten;
+
+    QTest::addColumn<QStringList>("qtFilterList");
+    QTest::addColumn<QString>("suggestedName");
+    QTest::addColumn<emscripten::val>("expectedWebType");
+
+    QTest::newRow("Multiple files") << QStringList({"Text files (*.txt)", "Images (*.jpg *.png)", "*.bat"})
+        << "someName1"
+        << makeSaveFileOptions("someName1", { makeType("Text files", { val(".txt")}), makeType("Images", { val(".jpg"), val(".png")}), makeType("", { val(".bat")})});
+    QTest::newRow("Single file") << QStringList({"Text files (*.txt)", "Images (*.jpg *.png)", "*.bat"})
+        << "some name 2"
+        << makeSaveFileOptions("some name 2", { makeType("Text files", { val(".txt")}), makeType("Images", { val(".jpg"), val(".png")}), makeType("", { val(".bat")})});
+}
+
+void tst_LocalFileApi::saveFileOptions()
+{
+    QFETCH(QStringList, qtFilterList);
+    QFETCH(QString, suggestedName);
+    QFETCH(emscripten::val, expectedWebType);
+
+    auto result = LocalFileApi::makeSaveFileOptions(qtFilterList, suggestedName.toStdString());
+    QVERIFY(valDeepEquals(result, expectedWebType));
+}
+
+QTEST_APPLESS_MAIN(tst_LocalFileApi)
+#include "tst_localfileapi.moc"