add some methods to permission class

models/permission.js

@@ -1,17 +1,82 @@
 const { Model, DataTypes } = require('sequelize');
 const { sequelize } = require('.');
 
-class Permission extends Model {
+/** @type {{data: Permission[], updated: number, expired: function}} */
+let cached = {
+    data: undefined,
+    updated: 0,
+    expired: () => {
+        return (Date.now() - updated) >= 1000
+    }
+}
 
+class Permission extends Model {
+    static async cache() {
+        if (!cached.expired()) return;
+
+        cached.data = await Permission.findAll();
+        cached.updated = Date.now();
+    }
+
+    /**
+     * Get value from cache
+     * @param {number} user 
+     * @param {string} permission 
+     * @returns {Permission?}
+     */
+    static async findFromCache(user, permission) {
+        await this.cache();
+        for (const perm of cached.data) {
+            if (perm.user == userid && perm.permission == permission)
+                return perm;
+        }
+        return null;
+    }
+
+    /**
+     * Get a permission for user
+     * @param {number} user 
+     * @param {string} permission 
+     * @returns {boolean}
+     */
+    static async forUser(user, permission) {
+        await this.cache();
+        const data = await this.findFromCache(user, permission);
+        if (!data) return false;
+        return data.value != 0;
+    }
+
+    /**
+     * Set a permission for user
+     * @param {number} user
+     * @param {string} permission
+     * @param {number} value
+     * @returns {Permission}
+     */
+    static async set(user, permission, value) {
+        const existing =    await Permission.findOne({where: {user, permission}});
+
+        let perm;
+
+        if (!existing)      perm = await Permission.create({user, permission, value});
+        else                perm = await Permission.update({user, permission, value}, {where: {user, permission}});
+        await this.cache();
+
+        return perm;
+    }
+
+    static async userAllowed(user, permission) {
+        return this.forUser(user, permission);
+    }
 }
 
 Permission.structure = {
-    // id: {
+    id: {
-    //     type: DataTypes.BIGINT,
+        type: DataTypes.BIGINT,
-    //     primaryKey: true,
+        primaryKey: true,
-    //     autoIncrement: true,
+        autoIncrement: true,
-    //     allowNull: false
+        allowNull: false
-    // },
+    },
     user: {
         type: DataTypes.BIGINT,
         allowNull: false