// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * undo.js
 *
 * @package   local_kopere_dashboard
 * @copyright 2026 Eduardo Kraus {@link https://eduardokraus.com}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

/*
Copyright 2017 Ziadin Givan

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

https://github.com/givanz/VvvebJs
*/

/*
https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver

childList                 Set to true if additions and removals of the target node's child elements (including text nodes) are to be observed.
attributes                 Set to true if mutations to target's attributes are to be observed.
characterData             Set to true if mutations to target's data are to be observed.
subtree                 Set to true if mutations to target and target's descendants are to be observed.
attributeOldValue         Set to true if attributes is set to true and target's attribute value before the mutation needs to be recorded.
characterDataOldValue     Set to true if characterData is set to true and target's data before the mutation needs to be recorded.
attributeFilter         Set to an array of attribute local names (without namespace) if not all attribute mutations need to be observed.
*/

/*
MutationRecord.type                     String         Returns "attributes" if the mutation was an attribute mutation,
                                                "characterData" if it was a mutation to a CharacterData node,
                                                and "childList" if it was a mutation to the tree of nodes.

MutationRecord.target                 Node         Returns the node the mutation affected, depending on the MutationRecord.type.
                                                For attributes, it is the element whose attribute changed.
                                                For characterData, it is the CharacterData node.
                                                For childList, it is the node whose children changed.

MutationRecord.addedNodes             NodeList     Return the nodes added. Will be an empty NodeList if no nodes were added.
MutationRecord.removedNodes         NodeList     Return the nodes removed. Will be an empty NodeList if no nodes were removed.
MutationRecord.previousSibling         Node         Return the previous sibling of the added or removed nodes, or null.
MutationRecord.nextSibling             Node         Return the next sibling of the added or removed nodes, or null.
MutationRecord.attributeName         String         Returns the local name of the changed attribute, or null.
MutationRecord.attributeNamespace     String         Returns the namespace of the changed attribute, or null.
MutationRecord.oldValue             String         The return value depends on the MutationRecord.type.
                                                For attributes, it is the value of the changed attribute before the change.
                                                For characterData, it is the data of the changed node before the change.
                                                For childList, it is null.
*/

Vvveb.Undo = {

    mutations   : [],
    undoIndex   : -1,
    enabled     : true,
    /*
    init: function() {
    },
    */
    addMutation : function(mutation) {
        /*
            this.mutations.push(mutation);
            this.undoIndex++;
        */
        this.mutations.splice(++this.undoIndex, this.mutations.length - this.undoIndex, mutation);
        const event = new CustomEvent("vvveb.undo.add", {detail : mutation});
        Vvveb.Builder.frameBody.dispatchEvent(event);
    },

    restore : function(mutation, undo) {

        switch (mutation.type) {
            case 'childList':

                if (undo == true) {
                    addedNodes = mutation.removedNodes;
                    removedNodes = mutation.addedNodes;
                } else { //redo
                    addedNodes = mutation.addedNodes;
                    removedNodes = mutation.removedNodes;
                }

                if (addedNodes) for (i in addedNodes) {
                    node = addedNodes[i];
                    if (mutation.nextSibling) {
                        mutation.nextSibling.parentNode.insertBefore(node, mutation.nextSibling);
                    } else {
                        mutation.target.append(node);
                    }
                }

                if (removedNodes) for (i in removedNodes) {
                    node = removedNodes[i];
                    node.parentNode.removeChild(node);
                }
                break;
            case 'move':
                if (undo == true) {
                    parent = mutation.oldParent;
                    sibling = mutation.oldNextSibling;
                } else { //redo
                    parent = mutation.newParent;
                    sibling = mutation.newNextSibling;
                }

                if (sibling) {
                    sibling.parentNode.insertBefore(mutation.target, sibling);
                } else {
                    parent.append(node);
                }
                break;
            case 'characterData':
                mutation.target.innerHTML = undo ? mutation.oldValue : mutation.newValue;
                break;
            case 'style':
                window.FrameDocument.getElementById("vvvebjs-styles").textContent = (undo ? mutation.oldValue : mutation.newValue);
                break;
            case 'attributes':
                value = undo ? mutation.oldValue : mutation.newValue;

                if (value || value === false || value === 0)
                    mutation.target.setAttribute(mutation.attributeName, value);
                else
                    mutation.target.removeAttribute(mutation.attributeName);

                break;
        }

        const event = new CustomEvent("vvveb.undo.restore", {detail : mutation});
        Vvveb.Builder.frameBody.dispatchEvent(event);
    },

    undo : function() {
        if (this.undoIndex >= 0) {
            this.restore(this.mutations[this.undoIndex--], true);
        }
    },

    redo : function() {
        if (this.undoIndex < this.mutations.length - 1) {
            this.restore(this.mutations[++this.undoIndex], false);
        }
    },

    hasChanges : function() {
        return this.mutations.length;
    },

    reset : function() {
        this.mutations = [];
        this.undoIndex = -1;
    }
};

