#include <LibGUI/GUndoStack.h>

GUndoStack::GUndoStack()
{
}

GUndoStack::~GUndoStack()
{
}

void GUndoStack::undo()
{
    if (!can_undo())
        return;

    auto& undo_container = m_stack[m_stack_index];
    auto& undo_vector = undo_container.m_undo_vector;

    //If we try to undo a empty vector, delete it and skip over.
    if (undo_vector.is_empty()) {
        m_stack.remove(m_stack_index);
        undo();
        return;
    }

    for (int i = 0; i < undo_vector.size(); i++) {
        auto& undo_command = undo_vector[i];
        undo_command.undo();
    }

    m_stack_index++;
}

void GUndoStack::redo()
{
    if (!can_redo())
        return;

    auto& undo_container = m_stack[m_stack_index - 1];
    auto& redo_vector = undo_container.m_undo_vector;

    for (int i = redo_vector.size() - 1; i >= 0; i--) {
        auto& undo_command = redo_vector[i];
        undo_command.redo();
    }

    m_stack_index--;
}

void GUndoStack::push(NonnullOwnPtr<GCommand>&& command)
{
    if (m_stack.is_empty()) {
        auto undo_commands_container = make<UndoCommandsContainer>();
        m_stack.prepend(move(undo_commands_container));
    }

    // Clear the elements of the stack before the m_undo_stack_index (Excluding our new element)
    for (int i = 1; i < m_stack_index; i++)
        m_stack.remove(1);

    if (m_stack_index > 0 && !m_stack.is_empty())
        m_stack[0].m_undo_vector.clear();

    m_stack_index = 0;

    m_stack[0].m_undo_vector.prepend(move(command));
}


void GUndoStack::finalize_current_combo()
{
    if (m_stack.is_empty())
        return;

    auto& undo_vector = m_stack[0].m_undo_vector;

    if (undo_vector.size() == m_last_updated_undo_vector_size && !undo_vector.is_empty()) {
        auto undo_commands_container = make<UndoCommandsContainer>();
        m_stack.prepend(move(undo_commands_container));
        // Note: Remove dbg() if we're 100% sure there are no bugs left.
        dbg() << "Undo stack increased to " << m_stack.size();

        // Shift the index to the left since we're adding an empty container.
        if (m_stack_index > 0)
            m_stack_index++;
    }

    m_last_updated_undo_vector_size = undo_vector.size();
}