61 lines
2.1 KiB
JavaScript
61 lines
2.1 KiB
JavaScript
//@flow
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/*
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Copyright 2017 Aviral Dasgupta
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import _clamp from 'lodash/clamp';
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export default class SendHistoryManager {
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history: Array<HistoryItem> = [];
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prefix: string;
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lastIndex: number = 0; // used for indexing the storage
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currentIndex: number = 0; // used for indexing the loaded validated history Array
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constructor(roomId: string, prefix: string) {
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this.prefix = prefix + roomId;
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// TODO: Performance issues?
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let index = 0;
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let itemJSON;
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while (itemJSON = sessionStorage.getItem(`${this.prefix}[${index}]`)) {
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try {
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const serializedParts = JSON.parse(itemJSON);
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this.history.push(serializedParts);
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} catch (e) {
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console.warn("Throwing away unserialisable history", e);
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break;
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}
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++index;
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}
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this.lastIndex = this.history.length - 1;
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// reset currentIndex to account for any unserialisable history
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this.currentIndex = this.lastIndex + 1;
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}
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save(editorModel: Object) {
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const serializedParts = editorModel.serializeParts();
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this.history.push(serializedParts);
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this.currentIndex = this.history.length;
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this.lastIndex += 1;
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sessionStorage.setItem(`${this.prefix}[${this.lastIndex}]`, JSON.stringify(serializedParts));
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}
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getItem(offset: number): ?HistoryItem {
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this.currentIndex = _clamp(this.currentIndex + offset, 0, this.history.length - 1);
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return this.history[this.currentIndex];
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}
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}
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