1 files changed, 162 insertions, 0 deletions
diff --git a/lib/uriresolver.h b/lib/uriresolver.h
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+++ b/lib/uriresolver.h
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+#pragma once
+
+#include "uri.h"
+
+#include <QtCore/QObject>
+
+#include <functional>
+
+namespace Quotient {
+class Connection;
+class Room;
+class User;
+
+/*! \brief Abstract class to resolve the resource and act on it
+ *
+ * This class encapsulates the logic of resolving a Matrix identifier or URI
+ * into a Quotient object (or objects) and calling an appropriate handler on it.
+ * It is a type-safe way of handling a URI with no prior context on its type
+ * in cases like, e.g., when a user clicks on a URI in the application.
+ *
+ * This class provides empty "handlers" for each type of URI to facilitate
+ * gradual implementation. Derived classes are encouraged to override as many
+ * of them as possible.
+ */
+class UriResolverBase {
+public:
+    /*! \brief Resolve the resource and dispatch an action depending on its type
+     *
+     * This method:
+     * 1. Resolves \p uri into an actual object (e.g., Room or User),
+     *    with possible additional data such as event id, in the context of
+     *    \p account.
+     * 2. If the resolving is successful, depending on the type of the object,
+     *    calls the appropriate virtual function (defined in a derived
+     *    concrete class) to perform an action on the resource (open a room,
+     *    mention a user etc.).
+     * 3. Returns the result of resolving the resource.
+     */
+    UriResolveResult visitResource(Connection* account, const Uri& uri);
+
+protected:
+    /// Called by visitResource() when the passed URI identifies a Matrix user
+    virtual void visitUser(User* user, const QString& action) {}
+    /// Called by visitResource() when the passed URI identifies a room or
+    /// an event in a room
+    virtual void visitRoom(Room* room, const QString& eventId) {}
+    /// Called by visitResource() when the passed URI has `action() == "join"`
+    /// and identifies a room that the user defined by the Connection argument
+    /// is not a member of
+    virtual void joinRoom(Connection* account, const QString& roomAliasOrId,
+                          const QStringList& viaServers = {})
+    {}
+    /// Called by visitResource() when the passed URI has `type() == NonMatrix`
+    /*!
+     * Should return true if the URI is considered resolved, false otherwise.
+     * A basic implementation in a graphical client can look like
+     * `return QDesktopServices::openUrl(url);` but it's strongly advised to
+     * ask for a user confirmation beforehand.
+     */
+    virtual bool visitNonMatrix(const QUrl& url) { return false; }
+};
+
+/*! \brief Resolve the resource and invoke an action on it, via function objects
+ *
+ * This function encapsulates the logic of resolving a Matrix identifier or URI
+ * into a Quotient object (or objects) and calling an appropriate handler on it.
+ * Unlike UriResolverBase it accepts the list of handlers from
+ * the caller; internally it's uses a minimal UriResolverBase class
+ *
+ * \param account The connection used as a context to resolve the identifier
+ *
+ * \param uri A URI that can represent a Matrix entity
+ *
+ * \param userHandler Called when the passed URI identifies a Matrix user
+ *
+ * \param roomEventHandler Called when the passed URI identifies a room or
+ *                         an event in a room
+ *
+ * \param joinHandler Called when the passed URI has `action() == "join"` and
+ *                    identifies a room that the user defined by
+ *                    the Connection argument is not a member of
+ *
+ * \param nonMatrixHandler Called when the passed URI has `type() == NonMatrix`;
+ *                         should return true if the URI is considered resolved,
+ *                         false otherwise
+ *
+ * \sa UriResolverBase, UriDispatcher
+ */
+UriResolveResult
+visitResource(Connection* account, const Uri& uri,
+              std::function<void(User*, QString)> userHandler,
+              std::function<void(Room*, QString)> roomEventHandler,
+              std::function<void(Connection*, QString, QStringList)> joinHandler,
+              std::function<bool(const QUrl&)> nonMatrixHandler);
+
+/*! \brief Check that the resource is resolvable with no action on it */
+inline UriResolveResult checkResource(Connection* account,
+                                      const Uri& uri)
+{
+    return visitResource(
+        account, uri, [](auto, auto) {}, [](auto, auto) {},
+        [](auto, auto, auto) {}, [](auto) { return false; });
+}
+
+/*! \brief Resolve the resource and invoke an action on it, via Qt signals
+ *
+ * This is an implementation of UriResolverBase that is based on
+ * QObject and uses Qt signals instead of virtual functions to provide an
+ * open-ended interface for visitors.
+ *
+ * This class is aimed primarily at clients where invoking the resolving/action
+ * and handling the action are happening in decoupled parts of the code; it's
+ * also useful to operate on Matrix identifiers and URIs from QML/JS code
+ * that cannot call resolveResource() due to QML/C++ interface limitations.
+ *
+ * This class does not restrain the client code to a certain type of
+ * connections: both direct and queued (or a mix) will work fine. One limitation
+ * caused by that is there's no way to indicate if a non-Matrix URI has been
+ * successfully resolved - a signal always returns void.
+ *
+ * Note that in case of using (non-blocking) queued connections the code that
+ * calls resolveResource() should not expect the action to be performed
+ * synchronously - the returned value is the result of resolving the URI,
+ * not acting on it.
+ */
+class UriDispatcher : public QObject, public UriResolverBase {
+    Q_OBJECT
+public:
+    explicit UriDispatcher(QObject* parent = nullptr) : QObject(parent) {}
+
+    // It's actually UriResolverBase::visitResource() but with Q_INVOKABLE
+    Q_INVOKABLE UriResolveResult resolveResource(Connection* account,
+                                                 const Uri& uri)
+    {
+        return UriResolverBase::visitResource(account, uri);
+    }
+
+signals:
+    /// An action on a user has been requested
+    void userAction(Quotient::User* user, QString action);
+
+    /// An action on a room has been requested, with optional event id
+    void roomAction(Quotient::Room* room, QString eventId);
+
+    /// A join action has been requested, with optional 'via' servers
+    void joinAction(Quotient::Connection* account, QString roomAliasOrId,
+                    QStringList viaServers);
+
+    /// An action on a non-Matrix URL has been requested
+    void nonMatrixAction(QUrl url);
+
+private:
+    void visitUser(User* user, const QString& action) override;
+    void visitRoom(Room* room, const QString& eventId) override;
+    void joinRoom(Connection* account, const QString& roomAliasOrId,
+                  const QStringList& viaServers = {}) override;
+    bool visitNonMatrix(const QUrl& url) override;
+};
+
+} // namespace Quotient
+
+