gateway-addon/src/database.ts

Bindings for WebThings Gateway add-ons

/**
 * Wrapper around the gateway's database.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

import fs from 'fs';
import os from 'os';
import path from 'path';
import { verbose, Database as SQLiteDatabase } from 'sqlite3';

const sqlite3 = verbose();

const DB_PATHS = [path.join(os.homedir(), '.webthings', 'config', 'db.sqlite3')];

if (process.env.WEBTHINGS_HOME) {
  DB_PATHS.unshift(path.join(process.env.WEBTHINGS_HOME, 'config', 'db.sqlite3'));
}

if (process.env.WEBTHINGS_DATABASE) {
  DB_PATHS.unshift(process.env.WEBTHINGS_DATABASE);
}

/**
 * An Action represents an individual action on a device.
 */
export class Database {
  private packageName: string;

  private path?: string;

  private conn?: SQLiteDatabase | null;

  /**
   * Initialize the object.
   *
   * @param {String} packageName The adapter's package name
   * @param {String?} path Optional database path
   */
  constructor(packageName: string, path?: string) {
    this.packageName = packageName;
    this.path = path;

    if (!this.path) {
      for (const p of DB_PATHS) {
        if (fs.existsSync(p)) {
          this.path = p;
          break;
        }
      }
    }
  }

  /**
   * Open the database.
   *
   * @returns Promise which resolves when the database has been opened.
   */
  open(): Promise<void> {
    if (this.conn) {
      return Promise.resolve();
    }

    const path = this.path;

    if (!path) {
      return Promise.reject(new Error('Database path unknown'));
    }

    return new Promise((resolve, reject) => {
      this.conn = new sqlite3.Database(path, (err) => {
        if (err) {
          reject(err);
        } else {
          this?.conn?.configure('busyTimeout', 10000);
          resolve();
        }
      });
    });
  }

  /**
   * Close the database.
   */
  close(): void {
    if (this.conn) {
      this.conn.close();
      this.conn = null;
    }
  }

  /**
   * Load the package's config from the database.
   *
   * @returns Promise which resolves to the config object.
   */
  loadConfig(): Promise<Record<string, unknown>> {
    if (!this.conn) {
      return Promise.reject('Database not open');
    }

    const key = `addons.config.${this.packageName}`;

    return new Promise((resolve, reject) => {
      this?.conn?.get('SELECT value FROM settings WHERE key = ?', [key], (error, row) => {
        if (error) {
          reject(error);
        } else if (!row) {
          resolve({});
        } else {
          resolve(JSON.parse(row.value));
        }
      });
    });
  }

  /**
   * Save the package's config to the database.
   */
  saveConfig(config: Record<string, unknown>): Promise<void> {
    if (!this.conn) {
      return Promise.resolve();
    }

    const key = `addons.config.${this.packageName}`;

    return new Promise((resolve, reject) => {
      this?.conn?.run(
        'INSERT OR REPLACE INTO settings (key, value) VALUES (?, ?)',
        [key, JSON.stringify(config)],
        (error) => {
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        }
      );
    });
  }
}