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

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   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
{

//==============================================================================
/** This class is used to invoke a range of text-editor navigation methods on
    an object, based upon a keypress event.

    It's currently used internally by the TextEditor and CodeEditorComponent.

    @tags{GUI}
*/
template <class CallbackClass>
struct TextEditorKeyMapper
{
    /** Checks the keypress and invokes one of a range of navigation functions that
        the target class must implement, based on the key event.
    */
    static bool invokeKeyFunction (CallbackClass& target, const KeyPress& key)
    {
        auto mods = key.getModifiers();

        const bool isShiftDown   = mods.isShiftDown();
        const bool ctrlOrAltDown = mods.isCtrlDown() || mods.isAltDown();

        int numCtrlAltCommandKeys = 0;
        if (mods.isCtrlDown())    ++numCtrlAltCommandKeys;
        if (mods.isAltDown())     ++numCtrlAltCommandKeys;

        if (key == KeyPress (KeyPress::downKey, ModifierKeys::ctrlModifier, 0) && target.scrollUp())   return true;
        if (key == KeyPress (KeyPress::upKey,   ModifierKeys::ctrlModifier, 0) && target.scrollDown()) return true;

       #if JUCE_MAC
        if (mods.isCommandDown() && ! ctrlOrAltDown)
        {
            if (key.isKeyCode (KeyPress::upKey))        return target.moveCaretToTop (isShiftDown);
            if (key.isKeyCode (KeyPress::downKey))      return target.moveCaretToEnd (isShiftDown);
            if (key.isKeyCode (KeyPress::leftKey))      return target.moveCaretToStartOfLine (isShiftDown);
            if (key.isKeyCode (KeyPress::rightKey))     return target.moveCaretToEndOfLine   (isShiftDown);
        }

        if (mods.isCommandDown())
            ++numCtrlAltCommandKeys;
       #endif

        if (numCtrlAltCommandKeys < 2)
        {
            if (key.isKeyCode (KeyPress::leftKey))  return target.moveCaretLeft  (ctrlOrAltDown, isShiftDown);
            if (key.isKeyCode (KeyPress::rightKey)) return target.moveCaretRight (ctrlOrAltDown, isShiftDown);

            if (key.isKeyCode (KeyPress::homeKey))  return ctrlOrAltDown ? target.moveCaretToTop         (isShiftDown)
                                                                         : target.moveCaretToStartOfLine (isShiftDown);
            if (key.isKeyCode (KeyPress::endKey))   return ctrlOrAltDown ? target.moveCaretToEnd         (isShiftDown)
                                                                         : target.moveCaretToEndOfLine   (isShiftDown);
        }

        if (numCtrlAltCommandKeys == 0)
        {
            if (key.isKeyCode (KeyPress::upKey))        return target.moveCaretUp   (isShiftDown);
            if (key.isKeyCode (KeyPress::downKey))      return target.moveCaretDown (isShiftDown);

            if (key.isKeyCode (KeyPress::pageUpKey))    return target.pageUp   (isShiftDown);
            if (key.isKeyCode (KeyPress::pageDownKey))  return target.pageDown (isShiftDown);
        }

        if (key == KeyPress ('c', ModifierKeys::commandModifier, 0)
              || key == KeyPress (KeyPress::insertKey, ModifierKeys::ctrlModifier, 0))
            return target.copyToClipboard();

        if (key == KeyPress ('x', ModifierKeys::commandModifier, 0)
              || key == KeyPress (KeyPress::deleteKey, ModifierKeys::shiftModifier, 0))
            return target.cutToClipboard();

        if (key == KeyPress ('v', ModifierKeys::commandModifier, 0)
              || key == KeyPress (KeyPress::insertKey, ModifierKeys::shiftModifier, 0))
            return target.pasteFromClipboard();

        // NB: checking for delete must happen after the earlier check for shift + delete
        if (numCtrlAltCommandKeys < 2)
        {
            if (key.isKeyCode (KeyPress::backspaceKey)) return target.deleteBackwards (ctrlOrAltDown);
            if (key.isKeyCode (KeyPress::deleteKey))    return target.deleteForwards  (ctrlOrAltDown);
        }

        if (key == KeyPress ('a', ModifierKeys::commandModifier, 0))
            return target.selectAll();

        if (key == KeyPress ('z', ModifierKeys::commandModifier, 0))
            return target.undo();

        if (key == KeyPress ('y', ModifierKeys::commandModifier, 0)
             || key == KeyPress ('z', ModifierKeys::commandModifier | ModifierKeys::shiftModifier, 0))
            return target.redo();

        return false;
    }
};

} // namespace juce