/**
* @license Copyright (c) 2003-2026, CKSource Holding sp. z o.o. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
*/
/**
* @module engine/model/differ
*/
import { ModelPosition } from "./position.js";
import { ModelRange } from "./range.js";
import type { MarkerCollection, MarkerData } from "./markercollection.js";
import { type ModelItem } from "./item.js";
import { type ModelNode } from "./node.js";
import { type ModelRootElement } from "./rootelement.js";
import { type Operation } from "./operation/operation.js";
/**
* Calculates the difference between two model states.
*
* Receives operations that are to be applied on the model document. Marks parts of the model document tree which
* are changed and saves the state of these elements before the change. Then, it compares saved elements with the
* changed elements, after all changes are applied on the model document. Calculates the diff between saved
* elements and new ones and returns a change set.
*/
export declare class Differ {
	/**
	* Priority of the {@link ~Differ#_elementState element states}. States on higher indexes of the array can overwrite states on the lower
	* indexes.
	*/
	private static readonly _statesPriority;
	/**
	* Reference to the model's marker collection.
	*/
	private readonly _markerCollection;
	/**
	* A map that stores changes that happened in a given element.
	*
	* The keys of the map are references to the model elements.
	* The values of the map are arrays with changes that were done on this element.
	*/
	private readonly _changesInElement;
	/**
	* Stores a snapshot for these model nodes that might have changed.
	*
	* This complements {@link ~Differ#_elementChildrenSnapshots `_elementChildrenSnapshots`}.
	*
	* See also {@link ~DifferSnapshot}.
	*/
	private readonly _elementsSnapshots;
	/**
	* For each element or document fragment inside which there was a change, it stores a snapshot of the child nodes list (an array
	* of children snapshots that represent the state in the element / fragment before any change has happened).
	*
	* This complements {@link ~Differ#_elementsSnapshots `_elementsSnapshots`}.
	*
	* See also {@link ~DifferSnapshot}.
	*/
	private readonly _elementChildrenSnapshots;
	/**
	* Keeps the state for a given element, describing how the element was changed so far. It is used to evaluate the `action` property
	* of diff items returned by {@link ~Differ#getChanges}.
	*
	* Possible values, in the order from the lowest priority to the highest priority:
	*
	* * `'refresh'` - element was refreshed,
	* * `'rename'` - element was renamed,
	* * `'move'` - element was moved (or, usually, removed, that is moved to the graveyard).
	*
	* Element that was refreshed, may change its state to `'rename'` if it was later renamed, or to `'move'` if it was removed.
	* But the element cannot change its state from `'move'` to `'rename'`, or from `'rename'` to `'refresh'`.
	*
	* Only already existing elements are registered in `_elementState`. If a new element was inserted as a result of a buffered operation,
	* it is not be registered in `_elementState`.
	*/
	private readonly _elementState;
	/**
	* A map that stores all changed markers.
	*
	* The keys of the map are marker names.
	*
	* The values of the map are objects with the following properties:
	*
	* * `oldMarkerData`,
	* * `newMarkerData`.
	*/
	private readonly _changedMarkers;
	/**
	* A map that stores all roots that have been changed.
	*
	* The keys are the names of the roots while value represents the changes.
	*/
	private readonly _changedRoots;
	/**
	* Stores the number of changes that were processed. Used to order the changes chronologically. It is important
	* when changes are sorted.
	*/
	private _changeCount;
	/**
	* For efficiency purposes, `Differ` stores the change set returned by the differ after {@link #getChanges} call.
	* Cache is reset each time a new operation is buffered. If the cache has not been reset, {@link #getChanges} will
	* return the cached value instead of calculating it again.
	*
	* This property stores those changes that did not take place in graveyard root.
	*/
	private _cachedChanges;
	/**
	* For efficiency purposes, `Differ` stores the change set returned by the differ after the {@link #getChanges} call.
	* The cache is reset each time a new operation is buffered. If the cache has not been reset, {@link #getChanges} will
	* return the cached value instead of calculating it again.
	*
	* This property stores all changes evaluated by `Differ`, including those that took place in the graveyard.
	*/
	private _cachedChangesWithGraveyard;
	/**
	* Set of model items that were marked to get refreshed in {@link #_refreshItem}.
	*/
	private _refreshedItems;
	/**
	* Creates a `Differ` instance.
	*
	* @param markerCollection Model's marker collection.
	*/
	constructor(markerCollection: MarkerCollection);
	/**
	* Informs whether there are any changes buffered in `Differ`.
	*/
	get isEmpty(): boolean;
	/**
	* Buffers the given operation. **An operation has to be buffered before it is executed.**
	*
	* @param operationToBuffer An operation to buffer.
	*/
	bufferOperation(operationToBuffer: Operation): void;
	/**
	* Buffers a marker change.
	*
	* @param markerName The name of the marker that changed.
	* @param oldMarkerData Marker data before the change.
	* @param newMarkerData Marker data after the change.
	*/
	bufferMarkerChange(markerName: string, oldMarkerData: MarkerData, newMarkerData: MarkerData): void;
	/**
	* Returns all markers that should be removed as a result of buffered changes.
	*
	* @returns Markers to remove. Each array item is an object containing the `name` and `range` properties.
	*/
	getMarkersToRemove(): Array<{
		name: string;
		range: ModelRange;
	}>;
	/**
	* Returns all markers which should be added as a result of buffered changes.
	*
	* @returns Markers to add. Each array item is an object containing the `name` and `range` properties.
	*/
	getMarkersToAdd(): Array<{
		name: string;
		range: ModelRange;
	}>;
	/**
	* Returns all markers which changed.
	*/
	getChangedMarkers(): Array<{
		name: string;
		data: {
			oldRange: ModelRange | null;
			newRange: ModelRange | null;
		};
	}>;
	/**
	* Checks whether some of the buffered changes affect the editor data.
	*
	* Types of changes which affect the editor data:
	*
	* * model structure changes,
	* * attribute changes,
	* * a root is added or detached,
	* * changes of markers which were defined as `affectsData`,
	* * changes of markers' `affectsData` property.
	*/
	hasDataChanges(): boolean;
	/**
	* Calculates the diff between the old model tree state (the state before the first buffered operations since the last {@link #reset}
	* call) and the new model tree state (actual one). It should be called after all buffered operations are executed.
	*
	* The diff set is returned as an array of {@link module:engine/model/differ~DifferItem diff items}, each describing a change done
	* on the model. The items are sorted by the position on which the change happened. If a position
	* {@link module:engine/model/position~ModelPosition#isBefore is before} another one, it will be on an earlier index in the diff set.
	*
	* **Note**: Elements inside inserted element will not have a separate diff item, only the top most element change will be reported.
	*
	* Because calculating the diff is a costly operation, the result is cached. If no new operation was buffered since the
	* previous {@link #getChanges} call, the next call will return the cached value.
	*
	* @param options Additional options.
	* @param options.includeChangesInGraveyard If set to `true`, also changes that happened
	* in the graveyard root will be returned. By default, changes in the graveyard root are not returned.
	* @returns Diff between the old and the new model tree state.
	*/
	getChanges(options?: {
		includeChangesInGraveyard?: boolean;
	}): Array<DifferItem>;
	/**
	* Returns all roots that have changed (either were attached, or detached, or their attributes changed).
	*
	* @returns Diff between the old and the new roots state.
	*/
	getChangedRoots(): Array<DifferItemRoot>;
	/**
	* Returns a set of model items that were marked to get refreshed.
	*/
	getRefreshedItems(): Set<ModelItem>;
	/**
	* Resets `Differ`. Removes all buffered changes.
	*/
	reset(): void;
	/**
	* Marks the given `item` in differ to be "refreshed". It means that the item will be marked as removed and inserted
	* in the differ changes set, so it will be effectively re-converted when the differ changes are handled by a dispatcher.
	*
	* @internal
	* @param item Item to refresh.
	*/
	_refreshItem(item: ModelItem): void;
	/**
	* Buffers all the data related to given root like it was all just added to the editor.
	*
	* Following changes are buffered:
	*
	* * root is attached,
	* * all root content is inserted,
	* * all root attributes are added,
	* * all markers inside the root are added.
	*
	* @internal
	*/
	_bufferRootLoad(root: ModelRootElement): void;
	/**
	* Buffers the root state change after the root was attached or detached
	*/
	private _bufferRootStateChange;
	/**
	* Buffers a root attribute change.
	*/
	private _bufferRootAttributeChange;
	/**
	* Saves and handles an insert change.
	*/
	private _markInsert;
	/**
	* Saves and handles a remove change.
	*/
	private _markRemove;
	/**
	* Saves and handles an attribute change.
	*/
	private _markAttribute;
	/**
	* Saves and handles a model change.
	*/
	private _markChange;
	/**
	* Tries to set given state for given item.
	*
	* This method does simple validation (it sets the state only for model elements, not for text proxy nodes). It also follows state
	* setting rules, that is, `'refresh'` cannot overwrite `'rename'`, and `'rename'` cannot overwrite `'move'`.
	*/
	private _setElementState;
	/**
	* Returns a value for {@link ~DifferItemAction `action`} property for diff items returned by {@link ~Differ#getChanges}.
	* This method aims to return `'rename'` or `'refresh'` when it should, and `diffItemType` ("default action") in all other cases.
	*
	* It bases on a few factors:
	*
	* * for text nodes, the method always returns `diffItemType`,
	* * for newly inserted element, the method returns `diffItemType`,
	* * if {@link ~Differ#_elementState element state} was not recorded, the method returns `diffItemType`,
	* * if state was recorded, and it was `'move'` (default action), the method returns `diffItemType`,
	* * finally, if state was `'refresh'` or `'rename'`, the method returns the state value.
	*/
	private _getDiffActionForNode;
	/**
	* Gets an array of changes that have already been saved for a given element.
	*/
	private _getChangesForElement;
	/**
	* Creates and saves a snapshot for all children of the given element.
	*/
	private _makeSnapshots;
	/**
	* For a given newly saved change, compares it with a change already done on the element and modifies the incoming
	* change and/or the old change.
	*
	* @param inc Incoming (new) change.
	* @param changes An array containing all the changes done on that element.
	*/
	private _handleChange;
	/**
	* Returns an object with a single insert change description.
	*
	* @param parent The element in which the change happened.
	* @param offset The offset at which change happened.
	* @param action Further specifies what kind of action led to generating this change.
	* @param elementSnapshot Snapshot of the inserted node after changes.
	* @param elementSnapshotBefore Snapshot of the inserted node before changes.
	* @returns The diff item.
	*/
	private _getInsertDiff;
	/**
	* Returns an object with a single remove change description.
	*
	* @param parent The element in which change happened.
	* @param offset The offset at which change happened.
	* @param action Further specifies what kind of action led to generating this change.
	* @param elementSnapshot The snapshot of the removed node before changes.
	* @returns The diff item.
	*/
	private _getRemoveDiff;
	/**
	* Returns an array of objects where each one is a single attribute change description.
	*
	* @param range The range where the change happened.
	* @param oldAttributes A map, map iterator or compatible object that contains attributes before the change.
	* @param newAttributes A map, map iterator or compatible object that contains attributes after the change.
	* @returns An array containing one or more diff items.
	*/
	private _getAttributesDiff;
	/**
	* Checks whether given element or any of its parents is an element that is buffered as an inserted element.
	*/
	private _isInInsertedElement;
	/**
	* Removes deeply all buffered changes that are registered in elements from range specified by `parent`, `offset`
	* and `howMany`.
	*/
	private _removeAllNestedChanges;
}
/**
* Further specifies what kind of action led to generating a change:
*
* * `'insert'` if element was inserted,
* * `'remove'` if element was removed,
* * `'rename'` if element got renamed (e.g. `writer.rename()`),
* * `'refresh'` if element got refreshed (e.g. `model.editing.reconvertItem()`).
*/
export type DifferItemAction = "insert" | "remove" | "rename" | "refresh";
/**
* A snapshot is representing state of a given element before the first change was applied on that element.
*
* @internal
*/
export interface DifferSnapshot {
	/**
	* Node for which was snapshot was made.
	*/
	node: ModelNode;
	/**
	* Name of the element at the time when the snapshot was made. For text node snapshots, it is set to `'$text'`.
	*/
	name: string;
	/**
	* Attributes of the node at the time when the snapshot was made.
	*/
	attributes: Map<string, unknown>;
}
/**
* The single diff item.
*
* Could be one of:
*
* * {@link module:engine/model/differ~DifferItemInsert `DifferItemInsert`},
* * {@link module:engine/model/differ~DifferItemRemove `DifferItemRemove`},
* * {@link module:engine/model/differ~DifferItemAttribute `DifferItemAttribute`}.
*/
export type DifferItem = DifferItemInsert | DifferItemRemove | DifferItemAttribute;
/**
* A single diff item for inserted nodes.
*/
export interface DifferItemInsert {
	/**
	* The type of diff item.
	*/
	type: "insert";
	/**
	* Further specifies what kind of action led to generating this change.
	*
	* The action is set in relation to the document state before any change. It means that, for example, if an element was added and
	* then renamed (during the same {@link module:engine/model/batch~Batch batch}), the action will be set to `'insert'`, because when
	* compared to the document state before changes, a new element was inserted, and the renaming does not matter from this point of view.
	*/
	action: DifferItemAction;
	/**
	* The name of the inserted elements or `'$text'` for a text node.
	*/
	name: string;
	/**
	* Map of attributes of the inserted element.
	*/
	attributes: Map<string, unknown>;
	/**
	* The position where the node was inserted.
	*/
	position: ModelPosition;
	/**
	* The length of an inserted text node. For elements, it is always 1 as each inserted element is counted as a one.
	*/
	length: number;
	/**
	* Holds information about the element state before all changes happened.
	*
	* For example, when `<paragraph textAlign="right">` was changed to `<codeBlock language="plaintext">`,
	* `before.name` will be equal to `'paragraph'` and `before.attributes` map will have one entry: `'textAlign' -> 'right'`.
	*
	* The property is available only if the insertion change was due to element rename or refresh (when `action` property is `'rename'`
	* or `'refresh'`). As such, `before` property is never available for text node changes.
	*/
	before?: {
		/**
		* The name of the inserted element before all changes.
		*/
		name: string;
		/**
		* Map of the attributes of the inserted element before all changes.
		*/
		attributes: Map<string, unknown>;
	};
}
/**
* A single diff item for re-inserted nodes.
*/
export interface DifferItemReinsert {
	/**
	* The type of diff item.
	*/
	type: "reinsert";
	/**
	* The name of the re-inserted elements or `'$text'` for a text node.
	*/
	name: string;
	/**
	* The position where the node was reinserted.
	*/
	position: ModelPosition;
	/**
	* The length of a re-inserted text node. For elements, it is always 1 as each re-inserted element is counted as a one.
	*/
	length: number;
}
/**
* A single diff item for removed nodes.
*/
export interface DifferItemRemove {
	/**
	* The type of diff item.
	*/
	type: "remove";
	/**
	* Further specifies what kind of action led to generating this change.
	*
	* The action is set in relation to the document state before any change. It means that, for example, if an element was renamed and
	* then removed (during the same {@link module:engine/model/batch~Batch batch}), the action will be set to `'remove'`, because when
	* compared to the document state before changes, the element was removed, and it does not matter that it was also renamed at one point.
	*/
	action: DifferItemAction;
	/**
	* The name of the removed element or `'$text'` for a text node.
	*/
	name: string;
	/**
	* Map of attributes that were set on the item while it was removed.
	*/
	attributes: Map<string, unknown>;
	/**
	* The position where the node was removed.
	*/
	position: ModelPosition;
	/**
	* The length of a removed text node. For elements, it is always 1, as each removed element is counted as a one.
	*/
	length: number;
}
/**
* A single diff item for attribute change.
*/
export interface DifferItemAttribute {
	/**
	* The type of diff item.
	*/
	type: "attribute";
	/**
	* The name of the changed attribute.
	*/
	attributeKey: string;
	/**
	* An attribute previous value (before change).
	*/
	attributeOldValue: unknown;
	/**
	* An attribute new value (after change).
	*/
	attributeNewValue: unknown;
	/**
	* The range where the change happened.
	*/
	range: ModelRange;
}
/**
* A single diff item for a changed root.
*/
export interface DifferItemRoot {
	/**
	* Name of the changed root.
	*/
	name: string;
	/**
	* Set accordingly if the root got attached or detached. Otherwise, not set.
	*/
	state?: "attached" | "detached";
	/**
	* Keeps all attribute changes that happened on the root.
	*
	* The keys are keys of the changed attributes. The values are objects containing the attribute value before the change
	* (`oldValue`) and after the change (`newValue`).
	*
	* Note, that if the root state changed (`state` is set), then `attributes` property will not be set. All attributes should be
	* handled together with the root being attached or detached.
	*/
	attributes?: Record<string, {
		oldValue: unknown;
		newValue: unknown;
	}>;
}