commit 2fb6af99ba99525cf9ed62849992b4495381a7b5
Author: TheoryOfNekomata <allan.crisostomo@outlook.com>
Date:   Mon Nov 30 11:57:33 2020 +0800

    Separate project
    
    Extract project from monorepo.

diff --git a/.npmignore b/.npmignore
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index 0000000..bf193c2
--- /dev/null
+++ b/.npmignore
@@ -0,0 +1,2 @@
+*.ts
+tsconfig.json
diff --git a/README.md b/README.md
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index 0000000..621a780
--- /dev/null
+++ b/README.md
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+# Zeichen - Local Storage Plugin
+
+Save and load notes in Zeichen using the browser's local storage.
diff --git a/package.json b/package.json
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--- /dev/null
+++ b/package.json
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+{
+  "name": "zeichen-plugin-local-storage",
+  "author": "TheoryOfNekomata <allan.crisostomo@outlook.com>",
+  "version": "0.1.0",
+  "description": "Save and load notes in Zeichen using the browser's local storage.",
+  "keywords": [
+    "zeichen",
+    "plugin",
+    "storage",
+    "local"
+  ],
+  "devDependencies": {
+    "typescript": "^4.0.3"
+  },
+  "scripts": {
+    "build": "tsc **/*.ts"
+  }
+}
diff --git a/src/Engine.ts b/src/Engine.ts
new file mode 100644
index 0000000..002f81d
--- /dev/null
+++ b/src/Engine.ts
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+export default class LocalStorage<T> {
+  constructor(
+    private readonly source: Storage,
+    private readonly serializer: (t: T) => string = JSON.stringify,
+    private readonly deserializer: (s: string) => T = JSON.parse,
+  ) {}
+
+  getCollection(collectionId: string) {
+    const raw = this.source.getItem(collectionId)
+    if (raw !== null) {
+      return this.deserializer(raw)
+    }
+    return null
+  }
+
+  replaceCollection(collectionId: string, collectionData: T) {
+    this.source.setItem(collectionId, this.serializer(collectionData))
+  }
+
+  removeCollection(collectionId: string) {
+    this.source.removeItem(collectionId)
+  }
+}
diff --git a/src/Storage.ts b/src/Storage.ts
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--- /dev/null
+++ b/src/Storage.ts
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+import Storage, { Collection, OutOfSyncError } from '../../core/src/storage'
+import Engine from './Engine'
+
+export default class LocalStorage<T> implements Storage<T> {
+  private readonly engine: Engine<Collection<T>>
+
+  constructor(
+    private readonly ownerId: string,
+    private readonly storageId: string,
+    private readonly getItemId = item => item['id'],
+  ) {
+    this.engine = new Engine<Collection<T>>(window.localStorage)
+  }
+
+  private getMeta() {
+    const oldMeta = this.engine.getCollection(this.storageId)
+    if (oldMeta === null) {
+      throw new OutOfSyncError()
+    }
+    return oldMeta
+  }
+
+  private existenceCheck(newItem: T) {
+    return oldItem => this.getItemId(oldItem) === this.getItemId(newItem)
+  }
+
+  async queryItems() {
+    return this.getMeta().items
+  }
+
+  async saveItem(newItem: T) {
+    const oldMeta = this.getMeta()
+    const isExistingItem = oldMeta.items.some(this.existenceCheck(newItem))
+    const newMeta: Collection<T> = {
+      items: isExistingItem
+        ? oldMeta.items.map(oldItem => this.existenceCheck(newItem)(oldItem) ? newItem : oldItem)
+        : [...oldMeta.items, newItem],
+      lastModifiedBy: this.ownerId,
+      lastModifiedAt: new Date(),
+    }
+    this.engine.replaceCollection(this.storageId, newMeta)
+  }
+
+  async deleteItem(newItem: T) {
+    const oldMeta = this.getMeta()
+    const newItems = oldMeta.items.filter(oldItem => !this.existenceCheck(newItem)(oldItem))
+    const newMeta: Collection<T> = {
+      items: newItems,
+      lastModifiedBy: this.ownerId,
+      lastModifiedAt: new Date(),
+    }
+    this.engine.replaceCollection(this.storageId, newMeta)
+    return oldMeta.items.length !== newItems.length
+  }
+}
diff --git a/src/index.ts b/src/index.ts
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index 0000000..e25e74d
--- /dev/null
+++ b/src/index.ts
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+import { Plugin } from '../../core/src/plugin'
+import Storage from './Storage'
+
+type PluginConfig = {}
+
+const LocalStoragePlugin: Plugin<PluginConfig> = config => ({
+  currentUserId,
+}) => {
+  new Storage(currentUserId, 'notes')
+  new Storage(currentUserId, 'folders')
+}
+
+export default LocalStoragePlugin
diff --git a/tsconfig.json b/tsconfig.json
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index 0000000..18c72e3
--- /dev/null
+++ b/tsconfig.json
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+{
+  "compilerOptions": {
+    "target": "es6",
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "forceConsistentCasingInFileNames": true,
+    "module": "esnext",
+    "moduleResolution": "node",
+    "declaration": true,
+    "declarationDir": "./dist",
+    "sourceMap": true,
+    "strict": false
+  },
+  "exclude": [
+    "node_modules",
+    "**/*.test.ts"
+  ],
+  "include": [
+    "**/*.ts"
+  ]
+}