All files / roosterjs-content-model-core/lib/corePlugin/undo SnapshotsManagerImpl.ts

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import type { Snapshot, Snapshots, SnapshotsManager } from 'roosterjs-content-model-types';
 
// Max stack size that cannot be exceeded. When exceeded, old undo history will be dropped
// to keep size under limit. This is kept at 10MB
const MAX_SIZE_LIMIT = 1e7;
 
class SnapshotsManagerImpl implements SnapshotsManager {
    private snapshots: Snapshots;
    private hasNewContentValue: boolean = false;
 
    constructor(snapshots?: Snapshots) {
        this.snapshots = snapshots ?? {
            snapshots: [],
            totalSize: 0,
            currentIndex: -1,
            autoCompleteIndex: -1,
            maxSize: MAX_SIZE_LIMIT,
        };
    }
 
    get hasNewContent(): boolean {
        return this.hasNewContentValue;
    }
 
    set hasNewContent(value: boolean) {
        this.hasNewContentValue = value;
    }
 
    canMove(step: number): boolean {
        const newIndex = this.snapshots.currentIndex + step;
        return newIndex >= 0 && newIndex < this.snapshots.snapshots.length;
    }
 
    move(step: number): Snapshot | null {
        let result: Snapshot | null = null;
 
        if (this.canMove(step)) {
            this.snapshots.currentIndex += step;
            this.snapshots.autoCompleteIndex = -1;
            result = this.snapshots.snapshots[this.snapshots.currentIndex];
        }
 
        this.snapshots.onChanged?.('move');
 
        return result;
    }
 
    addSnapshot(snapshot: Snapshot, isAutoCompleteSnapshot: boolean): void {
        const currentSnapshot = this.snapshots.snapshots[this.snapshots.currentIndex];
        const isSameSnapshot =
            currentSnapshot &&
            currentSnapshot.html == snapshot.html &&
            !currentSnapshot.entityStates &&
            !snapshot.entityStates;
        const addSnapshot = !currentSnapshot || shouldAddSnapshot(currentSnapshot, snapshot);
 
        if (this.snapshots.currentIndex < 0 || addSnapshot) {
            this.clearRedo();
            this.snapshots.snapshots.push(snapshot);
            this.snapshots.currentIndex++;
            this.snapshots.totalSize += this.getSnapshotLength(snapshot);
 
            let removeCount = 0;
            while (
                removeCount < this.snapshots.snapshots.length &&
                this.snapshots.totalSize > this.snapshots.maxSize
            ) {
                this.snapshots.totalSize -= this.getSnapshotLength(
                    this.snapshots.snapshots[removeCount]
                );
                removeCount++;
            }
 
            if (removeCount > 0) {
                this.snapshots.snapshots.splice(0, removeCount);
                this.snapshots.currentIndex -= removeCount;
 
                Iif (this.snapshots.autoCompleteIndex >= 0) {
                    this.snapshots.autoCompleteIndex -= removeCount;
                }
            }
 
            if (isAutoCompleteSnapshot) {
                this.snapshots.autoCompleteIndex = this.snapshots.currentIndex;
            }
        } else if (isSameSnapshot) {
            // replace the currentSnapshot's metadata so the selection is updated
            this.snapshots.snapshots.splice(this.snapshots.currentIndex, 1, snapshot);
        }
 
        this.snapshots.onChanged?.('add');
    }
 
    clearRedo(): void {
        if (this.canMove(1)) {
            let removedSize = 0;
            for (
                let i = this.snapshots.currentIndex + 1;
                i < this.snapshots.snapshots.length;
                i++
            ) {
                removedSize += this.getSnapshotLength(this.snapshots.snapshots[i]);
            }
 
            this.snapshots.snapshots.splice(this.snapshots.currentIndex + 1);
            this.snapshots.totalSize -= removedSize;
            this.snapshots.autoCompleteIndex = -1;
 
            this.snapshots.onChanged?.('clear');
        }
    }
 
    canUndoAutoComplete(): boolean {
        return (
            this.snapshots.autoCompleteIndex >= 0 &&
            this.snapshots.currentIndex - this.snapshots.autoCompleteIndex == 1
        );
    }
 
    private getSnapshotLength(snapshot: Snapshot) {
        return snapshot.html?.length ?? 0;
    }
}
 
/**
 * @internal
 * Create a new instance of Undo Snapshots Manager
 * @param snapshots @optional Snapshots object for storing undo snapshots. If not passed, default implementation will be used
 */
export function createSnapshotsManager(snapshots?: Snapshots): SnapshotsManager {
    return new SnapshotsManagerImpl(snapshots);
}
 
function shouldAddSnapshot(currentSnapshot: Snapshot, snapshot: Snapshot) {
    return (
        currentSnapshot.html !== snapshot.html ||
        (currentSnapshot.entityStates &&
            snapshot.entityStates &&
            currentSnapshot.entityStates !== snapshot.entityStates) ||
        (!currentSnapshot.entityStates && snapshot.entityStates)
    );
}