/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2017 - ROLI Ltd.

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

namespace ComponentBuilderHelpers
{
    static String getStateId (const ValueTree& state)
    {
        return state [ComponentBuilder::idProperty].toString();
    }

    static Component* removeComponentWithID (OwnedArray<Component>& components, const String& compId)
    {
        jassert (compId.isNotEmpty());

        for (int i = components.size(); --i >= 0;)
        {
            Component* const c = components.getUnchecked (i);

            if (c->getComponentID() == compId)
                return components.removeAndReturn (i);
        }

        return nullptr;
    }

    static Component* findComponentWithID (Component& c, const String& compId)
    {
        jassert (compId.isNotEmpty());
        if (c.getComponentID() == compId)
            return &c;

        for (auto* child : c.getChildren())
            if (auto* found = findComponentWithID (*child, compId))
                return found;

        return nullptr;
    }

    static Component* createNewComponent (ComponentBuilder::TypeHandler& type,
                                          const ValueTree& state, Component* parent)
    {
        Component* const c = type.addNewComponentFromState (state, parent);
        jassert (c != nullptr && c->getParentComponent() == parent);
        c->setComponentID (getStateId (state));
        return c;
    }

    static void updateComponent (ComponentBuilder& builder, const ValueTree& state)
    {
        if (Component* topLevelComp = builder.getManagedComponent())
        {
            ComponentBuilder::TypeHandler* const type = builder.getHandlerForState (state);
            const String uid (getStateId (state));

            if (type == nullptr || uid.isEmpty())
            {
                // ..handle the case where a child of the actual state node has changed.
                if (state.getParent().isValid())
                    updateComponent (builder, state.getParent());
            }
            else
            {
                if (Component* const changedComp = findComponentWithID (*topLevelComp, uid))
                    type->updateComponentFromState (changedComp, state);
            }
        }
    }
}

//==============================================================================
const Identifier ComponentBuilder::idProperty ("id");

ComponentBuilder::ComponentBuilder()
    : imageProvider (nullptr)
{
}

ComponentBuilder::ComponentBuilder (const ValueTree& state_)
    : state (state_), imageProvider (nullptr)
{
    state.addListener (this);
}

ComponentBuilder::~ComponentBuilder()
{
    state.removeListener (this);

   #if JUCE_DEBUG
    // Don't delete the managed component!! The builder owns that component, and will delete
    // it automatically when it gets deleted.
    jassert (componentRef.get() == component.get());
   #endif
}

Component* ComponentBuilder::getManagedComponent()
{
    if (component == nullptr)
    {
        component.reset (createComponent());

       #if JUCE_DEBUG
        componentRef = component.get();
       #endif
    }

    return component.get();
}

Component* ComponentBuilder::createComponent()
{
    jassert (types.size() > 0);  // You need to register all the necessary types before you can load a component!

    if (TypeHandler* const type = getHandlerForState (state))
        return ComponentBuilderHelpers::createNewComponent (*type, state, nullptr);

    jassertfalse; // trying to create a component from an unknown type of ValueTree
    return nullptr;
}

void ComponentBuilder::registerTypeHandler (ComponentBuilder::TypeHandler* const type)
{
    jassert (type != nullptr);

    // Don't try to move your types around! Once a type has been added to a builder, the
    // builder owns it, and you should leave it alone!
    jassert (type->builder == nullptr);

    types.add (type);
    type->builder = this;
}

ComponentBuilder::TypeHandler* ComponentBuilder::getHandlerForState (const ValueTree& s) const
{
    const Identifier targetType (s.getType());

    for (int i = 0; i < types.size(); ++i)
    {
        TypeHandler* const t = types.getUnchecked(i);

        if (t->type == targetType)
            return t;
    }

    return nullptr;
}

int ComponentBuilder::getNumHandlers() const noexcept
{
    return types.size();
}

ComponentBuilder::TypeHandler* ComponentBuilder::getHandler (const int index) const noexcept
{
    return types [index];
}

void ComponentBuilder::registerStandardComponentTypes()
{
}

void ComponentBuilder::setImageProvider (ImageProvider* newImageProvider) noexcept
{
    imageProvider = newImageProvider;
}

ComponentBuilder::ImageProvider* ComponentBuilder::getImageProvider() const noexcept
{
    return imageProvider;
}

void ComponentBuilder::valueTreePropertyChanged (ValueTree& tree, const Identifier&)
{
    ComponentBuilderHelpers::updateComponent (*this, tree);
}

void ComponentBuilder::valueTreeChildAdded (ValueTree& tree, ValueTree&)
{
    ComponentBuilderHelpers::updateComponent (*this, tree);
}

void ComponentBuilder::valueTreeChildRemoved (ValueTree& tree, ValueTree&, int)
{
    ComponentBuilderHelpers::updateComponent (*this, tree);
}

void ComponentBuilder::valueTreeChildOrderChanged (ValueTree& tree, int, int)
{
    ComponentBuilderHelpers::updateComponent (*this, tree);
}

void ComponentBuilder::valueTreeParentChanged (ValueTree& tree)
{
    ComponentBuilderHelpers::updateComponent (*this, tree);
}

//==============================================================================
ComponentBuilder::TypeHandler::TypeHandler (const Identifier& valueTreeType)
   : type (valueTreeType), builder (nullptr)
{
}

ComponentBuilder::TypeHandler::~TypeHandler()
{
}

ComponentBuilder* ComponentBuilder::TypeHandler::getBuilder() const noexcept
{
    // A type handler needs to be registered with a ComponentBuilder before using it!
    jassert (builder != nullptr);
    return builder;
}

void ComponentBuilder::updateChildComponents (Component& parent, const ValueTree& children)
{
    using namespace ComponentBuilderHelpers;

    auto numExistingChildComps = parent.getNumChildComponents();

    Array<Component*> componentsInOrder;
    componentsInOrder.ensureStorageAllocated (numExistingChildComps);

    {
        OwnedArray<Component> existingComponents;
        existingComponents.ensureStorageAllocated (numExistingChildComps);

        for (int i = 0; i < numExistingChildComps; ++i)
            existingComponents.add (parent.getChildComponent (i));

        auto newNumChildren = children.getNumChildren();

        for (int i = 0; i < newNumChildren; ++i)
        {
            auto childState = children.getChild (i);
            auto* c = removeComponentWithID (existingComponents, getStateId (childState));

            if (c == nullptr)
            {
                if (auto* type = getHandlerForState (childState))
                    c = ComponentBuilderHelpers::createNewComponent (*type, childState, &parent);
                else
                    jassertfalse;
            }

            if (c != nullptr)
                componentsInOrder.add (c);
        }

        // (remaining unused items in existingComponents get deleted here as it goes out of scope)
    }

    // Make sure the z-order is correct..
    if (componentsInOrder.size() > 0)
    {
        componentsInOrder.getLast()->toFront (false);

        for (int i = componentsInOrder.size() - 1; --i >= 0;)
            componentsInOrder.getUnchecked(i)->toBehind (componentsInOrder.getUnchecked (i + 1));
    }
}

} // namespace juce