### File

`src/ngx-cache-layer.service.ts`

### Index

###### Properties

- Public cachedLayers

###### Methods

- Private createCacheInstance
- Public createLayer
- Public getLayer
- Public getLayersFromLS
- Private instanceHook
- Public isLocalStorageEnabled
- Private onExpire
- Public removeLayer

### Constructor

`constructor(config: CacheServiceConfigInterface)`
Defined in src/ngx-cache-layer.service.ts:35

Parameters :

Name | Type | Optional | Description
config | `CacheServiceConfigInterface` |  |

### Methods

Private createCacheInstance
`createCacheInstance(name: )`
Defined in src/ngx-cache-layer.service.ts:21

Parameters :

Name | Type | Optional | Description
name |  |  |

Returns : `CacheLayer<>`

Public createLayer
`createLayer(settings: CacheLayerInterface)`
Defined in src/ngx-cache-layer.service.ts:61

Parameters :

Name | Type | Optional | Description
settings | `CacheLayerInterface` |  |

Returns : `CacheLayer<>`

Public getLayer
`getLayer(name: string)`
Defined in src/ngx-cache-layer.service.ts:53

Parameters :

Name | Type | Optional | Description
name | `string` |  |

Returns : `CacheLayer<>`

Public getLayersFromLS
`getLayersFromLS()`
Defined in src/ngx-cache-layer.service.ts:91
Returns : `Array<string>`

Private instanceHook
`instanceHook(settings: CacheLayerInterface)`
Defined in src/ngx-cache-layer.service.ts:95

Parameters :

Name | Type | Optional | Description
settings | `CacheLayerInterface` |  |

Returns : `void`

Public isLocalStorageEnabled
`isLocalStorageEnabled()`
Defined in src/ngx-cache-layer.service.ts:25
Returns : `boolean`

Private onExpire
`onExpire(name: string)`
Defined in src/ngx-cache-layer.service.ts:99

Parameters :

Name | Type | Optional | Description
name | `string` |  |

Returns : `void`

Public removeLayer
`removeLayer(name: string)`
Defined in src/ngx-cache-layer.service.ts:83

Parameters :

Name | Type | Optional | Description
name | `string` |  |

Returns : `void`

### Properties

Public cachedLayers
`cachedLayers: `BehaviorSubject<[]>``
Type : `BehaviorSubject<[]>`
Defined in src/ngx-cache-layer.service.ts:19

    import {Injectable, Inject} from '@angular/core';
    import {BehaviorSubject} from 'rxjs/BehaviorSubject';
    import {Observable} from 'rxjs/Observable';

    import {CacheLayer} from './ngx-cache-layer.layer';
    import {CacheLayerInterface, CacheServiceConfigInterface, CacheLayerItem} from './ngx-cache-layer.interfaces';

    import {CACHE_MODULE_CONFIG, CACHE_MODULE_DI_CONFIG} from './index';

    const INTERNAL_PROCEDURE_CACHE_NAME = 'cache_layers';

    const FRIENDLY_ERROR_MESSAGES = {
      LOCAL_STORAGE_DISABLED: 'LocalStorage is disabled switching to regular in-memory storage.Please relate issue if you think it is enabled and there is a problem with the library itself.'
    };

    @Injectable()
    export class CacheService {

      public cachedLayers: BehaviorSubject<CacheLayer<CacheLayerItem<any>>[]> = new BehaviorSubject([]);

      private static createCacheInstance<T>(name): CacheLayer<CacheLayerItem<T>> {
        return new CacheLayer<CacheLayerItem<T>>(name);
      }

      public static isLocalStorageEnabled(): boolean {
        let error = [];
        try {
          localStorage.setItem('test-key', JSON.stringify({key: 'test-object'}));
          localStorage.removeItem('test-key');
        } catch (e) {
          error.push(e);
          console.log(FRIENDLY_ERROR_MESSAGES.LOCAL_STORAGE_DISABLED);
        }
        return error.length ? false : true;
      }

      constructor(@Inject( CACHE_MODULE_CONFIG ) private config: CacheServiceConfigInterface) {
        if (this.config.localStorage && CacheService.isLocalStorageEnabled()) {
          const layers = <Array<string>>JSON.parse(localStorage.getItem(INTERNAL_PROCEDURE_CACHE_NAME));
          if (layers) {
            layers.forEach(layer => {
                const cachedLayer = JSON.parse(localStorage.getItem(layer));
                if (cachedLayer) {
                  this.cachedLayers.next([...this.cachedLayers.getValue(), CacheService.createCacheInstance<any>(cachedLayer)]);
                }
            });
          } else {
            localStorage.setItem(INTERNAL_PROCEDURE_CACHE_NAME, JSON.stringify([]));
          }
        }
      }

      public getLayer<T>(name: string): CacheLayer<CacheLayerItem<T>> {
        let result = this.cachedLayers.getValue().filter(layer => layer.name === name);
        if (!result.length) {
          result = [this.createLayer({name: name})]
        }
        return result[0];
      }

      public createLayer<T>(settings: CacheLayerInterface): CacheLayer<CacheLayerItem<T>> {
        const exists = this.cachedLayers.getValue().filter(result => result.name === settings.name);
        if (exists.length) {
          return exists[0];
        }
        settings.config = settings.config || this.config || CACHE_MODULE_DI_CONFIG;
        settings.items = settings.items || [];
        let cacheLayer = CacheService.createCacheInstance<T>(settings);
        if (settings.config.localStorage && CacheService.isLocalStorageEnabled()) {
            const layer = JSON.parse(localStorage.getItem(settings.name));
            if (layer) {
              cacheLayer = CacheService.createCacheInstance<T>(layer);
            } else {
              localStorage.setItem(INTERNAL_PROCEDURE_CACHE_NAME, JSON.stringify([...CacheService.getLayersFromLS(), settings.name]));
              localStorage.setItem(settings.name, JSON.stringify(settings));
            }
        }
        this.cachedLayers.next([...this.cachedLayers.getValue(), cacheLayer]);
        this.instanceHook(settings);
        return cacheLayer;
      }

      public removeLayer(name: string): void {
        if (this.config.localStorage) {
          localStorage.removeItem(name);
          localStorage.setItem(INTERNAL_PROCEDURE_CACHE_NAME, JSON.stringify(CacheService.getLayersFromLS().filter(layer => layer !== name)));
        }
        this.cachedLayers.next(this.cachedLayers.getValue().filter(result => result.name !== name));
      }

      public static getLayersFromLS(): Array<string> {
        return <Array<string>>JSON.parse(localStorage.getItem(INTERNAL_PROCEDURE_CACHE_NAME));
      }

      private instanceHook(settings: CacheLayerInterface): void {
        this.onExpire(settings.name);
      }

      private onExpire(name: string): void {
        Observable
          .create(observer => observer.next())
          .timeoutWith(this.config.cacheFlushInterval, Observable.of(1))
          .skip(1)
          .subscribe(observer => this.removeLayer(name));
      }

    }

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