app/utils/config-property.ts

0001 import {BehaviorSubject, Observable} from 'rxjs';
0002
0003
0004 /**
0005  * Storage general interface for storing ConfigProperty-ies.
0006  * ConfigProperty uses the storage to save and load values
0007  */
0008 interface ConfigPropertyStorage {
0009   getItem(key: string): string | null;
0010   setItem(key: string, value: string): void;
0011 }
0012
0013 /**
0014  * Use local storage to save load ConfigProperty
0015  */
0016 class ConfigPropertyLocalStorage implements ConfigPropertyStorage {
0017   getItem(key: string): string | null {
0018     return localStorage.getItem(key);
0019   }
0020
0021   setItem(key: string, value: string): void {
0022     localStorage.setItem(key, value);
0023   }
0024 }
0025
0026 /**
0027  * Manages an individual configuration property. Provides reactive updates to subscribers,
0028  * persistence to localStorage, and optional value validation.
0029  *
0030  * @template T The type of the configuration value.
0031  */
0032 export class ConfigProperty<T> {
0033   public subject: BehaviorSubject<T>;
0034
0035   /** Observable for subscribers to react to changes in the property value. */
0036   public changes$: Observable<T>;
0037
0038   /**
0039    * Creates an instance of ConfigProperty.
0040    *
0041    * @param {string} key The localStorage key under which the property value is stored.
0042    * @param {T} defaultValue The default value of the property if not previously stored.
0043    * @param storage
0044    * @param {() => void} saveCallback The callback to execute after setting a new value.
0045    * @param {(value: T) => boolean} [validator] Optional validator function to validate the property value.
0046    */
0047   constructor(
0048     private key: string,
0049     private defaultValue: T,
0050     private saveCallback?: () => void,
0051     private validator?: (value: T) => boolean,
0052     private storage: ConfigPropertyStorage = new ConfigPropertyLocalStorage(),
0053     ) {
0054     const value = this.loadValue();
0055     this.subject = new BehaviorSubject<T>(value);
0056     this.changes$ = this.subject.asObservable();
0057
0058   }
0059
0060
0061   /**
0062    * Loads the property value from localStorage or returns the default value if not found or invalid.
0063    *
0064    * @returns {T} The loaded or default value of the property.
0065    */
0066   private loadValue(): T {
0067     let storedValue: string|null = null;
0068     let parsedValue: any = undefined;
0069     try {
0070       storedValue = this.storage.getItem(this.key);
0071
0072       if (storedValue !== null) {
0073         parsedValue = (typeof this.defaultValue) !== 'string' ? JSON.parse(storedValue) : storedValue;
0074       } else {
0075         parsedValue = this.defaultValue;
0076       }
0077       return this.validator && !this.validator(parsedValue) ? this.defaultValue : parsedValue;
0078     } catch (error) {
0079       console.error(`Error at ConfigProperty.loadValue, key='${this.key}'`);
0080       console.log('   storedValue', storedValue);
0081       console.log('   parsedValue', parsedValue);
0082       console.log('   Default value will be used: ', this.defaultValue);
0083       console.log(error);
0084
0085       return this.defaultValue;
0086     }
0087   }
0088
0089   /**
0090    * Sets the property value after validation. If the value is valid, it updates the property and calls the save callback.
0091    *
0092    * @param {T} value The new value to set for the property.
0093    */
0094   set value(value: T) {
0095     if (this.validator && !this.validator(value)) {
0096       console.error('Validation failed for:', value);
0097       return;
0098     }
0099     this.storage.setItem(this.key, typeof value !== 'string' ? JSON.stringify(value) : value);
0100
0101     if(this.saveCallback) {
0102       this.saveCallback();
0103     }
0104
0105     this.subject.next(value);
0106   }
0107
0108   /**
0109    * Gets the current value of the property.
0110    *
0111    * @returns {T} The current value of the property.
0112    */
0113   get value(): T {
0114     return this.subject.value;
0115   }
0116
0117
0118   /**
0119    * Resets value to its default given at Config construction
0120    */
0121   public setDefault() {
0122     this.subject.next(this.defaultValue);
0123   }
0124 }