import {CursorPos} from 'app/client/components/Cursor'; import {GristDoc} from 'app/client/components/GristDoc'; import * as dispose from 'app/client/lib/dispose'; import {ActionGroup} from 'app/common/ActionGroup'; import {PromiseChain} from 'app/common/gutil'; import {fromKo, Observable} from 'grainjs'; import * as ko from 'knockout'; export interface ActionGroupWithCursorPos extends ActionGroup { cursorPos?: CursorPos; } // Provides observables indicating disabled state for undo/redo. export interface IUndoState { isUndoDisabled: Observable; isRedoDisabled: Observable; } /** * Maintains the stack of actions which can be undone and redone, and maintains the * position in this stack. Undo and redo actions are generated and sent to the server here. */ export class UndoStack extends dispose.Disposable { public undoDisabledObs: ko.Observable; public redoDisabledObs: ko.Observable; private _gristDoc: GristDoc; private _stack: ActionGroupWithCursorPos[]; private _pointer: number; private _linkMap: {[actionNum: number]: ActionGroup}; // Chain of promises which send undo actions to the server. This delays the execution of the // next action until the current one has been received and moved the pointer index. private _undoChain = new PromiseChain(); public create(log: ActionGroup[], options: {gristDoc: GristDoc}) { this._gristDoc = options.gristDoc; // TODO: _stack and _linkMap grow without bound within a single session. // The top of the stack is stack.length - 1. The pointer points above the most // recently applied (not undone) action. this._stack = []; this._pointer = 0; // Map leading from actionNums to the action groups which link to them. this._linkMap = {}; // Observables for when there is nothing to undo/redo. this.undoDisabledObs = ko.observable(true); this.redoDisabledObs = ko.observable(true); // Set the history nav interface in the DocPageModel to properly enable/disabled undo/redo. if (this._gristDoc.docPageModel) { this._gristDoc.docPageModel.undoState.set({ isUndoDisabled: fromKo(this.undoDisabledObs), isRedoDisabled: fromKo(this.redoDisabledObs) }); } // Initialize the stack from the log of recent actions from the server. log.forEach(ag => { this.pushAction(ag); }); } /** * Should only be given own actions. Pays attention to actionNum, otherId, linkId, and * uses those to adjust undo index. */ public pushAction(ag: ActionGroup): void { if (!ag.fromSelf) { return; } const otherIndex = ag.otherId ? this._stack.findIndex(a => a.actionNum === ag.otherId) : -1; if (ag.linkId) { // Link action. Add the action to the linkMap, but not to any stacks. this._linkMap[ag.linkId] = ag; } else if (otherIndex > -1) { // Undo/redo action from the current session. this._pointer = ag.isUndo ? otherIndex : otherIndex + 1; } else { // Either a normal action from the current session, or an undo/redo which // applies to a non-recent action. Bury all undone actions. if (!this.redoDisabledObs()) { this._stack.splice(this._pointer); } // Reset pointer and add to the stack (if not an undo action). if (!ag.otherId) { this._stack.push(ag); } this._pointer = this._stack.length; } this.undoDisabledObs(this._pointer <= 0); this.redoDisabledObs(this._pointer >= this._stack.length); } // Send an undo action. This should be called when the user presses 'undo'. public sendUndoAction(): Promise { return this._undoChain.add(() => this._sendAction(true)); } // Send a redo action. This should be called when the user presses 'redo'. public sendRedoAction(): Promise { return this._undoChain.add(() => this._sendAction(false)); } private async _sendAction(isUndo: boolean): Promise { // Pick the action group to undo or redo. const ag = this._stack[isUndo ? this._pointer - 1 : this._pointer]; if (!ag) { return; } try { // Get all actions in the bundle that starts at the current index. Typically, an array with a // single action group is returned. const actionGroups = this._findActionBundle(ag); // When we undo/redo, jump to the place where this action occurred, to bring the user to the // context where the change was originally made. We jump first immediately to feel more // responsive, then again when the action is done. The second jump matters more for most // changes, but the first is the important one when Undoing an AddRecord. this._gristDoc.moveToCursorPos(ag.cursorPos, ag); await this._gristDoc.docComm.applyUserActionsById( actionGroups.map(a => a.actionNum), actionGroups.map(a => a.actionHash), isUndo, { otherId: ag.actionNum }); this._gristDoc.moveToCursorPos(ag.cursorPos, ag); } catch (err) { err.message = `Failed to apply ${isUndo ? 'undo' : 'redo'} action: ${err.message}`; throw err; } } /** * Find all actionGroups in the bundle that starts with the given action group. */ private _findActionBundle(ag: ActionGroup) { const prevNums = new Set(); const actionGroups = []; // Follow references through the linkMap adding items to the array bundle. while (ag && !prevNums.has(ag.actionNum)) { // Checking that actions are only accessed once prevents an infinite circular loop. actionGroups.push(ag); prevNums.add(ag.actionNum); ag = this._linkMap[ag.actionNum]; } return actionGroups; } }