image.js

'use strict'

const sqlite = require('sqlite-async')

/**
 * Class representing images in the database.
 */
class Image {

	/**Constructs database with the appropriate table for article images.
	 * @constructor
	 * @param {string} [dbName=':memory:'] - database for the website
	 */
	constructor(dbName = ':memory:') {
		return (async() => {
			this.db = await sqlite.open(dbName)
			let sql = `CREATE TABLE IF NOT EXISTS images (
				id INTEGER PRIMARY KEY AUTOINCREMENT, 
				image_path TEXT, 
				image_description TEXT);`
			await this.db.run(sql)
			sql = 'INSERT INTO images (image_path) values ("public/avatars/avatar.png")'
			await this.db.run(sql)
			return this
		})()
	}

	/**
	 * Adds filename of selected file to the database.
	 * @param {string} filename
	 * @param {string} [description]
	 * @returns {Promise<integer>} id of image file
	 */
	async add(filename, description) {
		try{
			if(filename.length === 0) throw new Error('filename is missing')
			let sql = `SELECT COUNT(id) as records from images WHERE image_path = '${filename}';`
			const data = await this.db.get(sql)
			if(data.records !== 0) throw new Error('filename is already in use')
			if(description === undefined) sql = `INSERT INTO images (image_path) values ('${filename}');`
			else sql = `INSERT INTO images (image_path, image_description) values ('${filename}', '${description}');`
			await this.db.run(sql)
			sql = 'SELECT last_insert_rowid() as id'
			const result = await this.db.get(sql)
			return result['id']
		} catch(err) {
			throw err
		}
	}

	/**
	 * Retrieves details of an image
	 * @param {Integer} key - id of the image
	 * @returns {Promise<imageData>}
	 */
	async get(key) {
		try{
			if(key === undefined) throw new Error('key is not defined')
			let sql = `SELECT COUNT(id) as records FROM images WHERE id = ${key};`
			let data = await this.db.get(sql)
			if(data.records === 0) throw new Error('file does not exist')
			sql = `SELECT image_path, image_description
				FROM images WHERE id = ${key};`
			data = await this.db.get(sql)
			return data
		} catch(err) {
			throw err
		}
	}

	/**
	 * Retrieves details of all stored images
	 * @returns {Promise<imageData[]>} - array of image data
	 */
	async getAll() {
		const sql = `SELECT image_path as path,
				image_description as description 
				FROM images;`
		const data = await this.db.all(sql)
		return data
	}

	/**
	 * Rename an existing file
	 * @param {string} targetFile - full path of file
	 * @param {string} newName - new filename
	 * @returns {Promise<true>} confirmation for file being renamed
	 */
	async rename(targetFile, newName) {
		try{
			if(targetFile.length === 0) throw new Error('file not selected')
			if(newName.length === 0) throw new Error('new name not stated')
			let sql = `SELECT COUNT(id) as records FROM images WHERE image_path = '${targetFile}';`
			const data = await this.db.get(sql)
			if(data.records === 0) throw new Error('file is not found')
			sql = `UPDATE images SET image_path = '${newName}' WHERE image_path = '${targetFile}';`
			await this.db.run(sql)
			return true
		} catch(err) {
			throw err
		}
	}

	/**
	 * Delete an exisitng image file based on image id
	 * @param {integer} key
	 * @returns {Promise<true>} confirmation for image deleted
	 */
	async delete(key) {
		try{
			if(key === undefined) throw new Error('key is not defined')
			let sql = `SELECT COUNT(id) as records FROM images WHERE id = ${key};`
			const data = await this.db.get(sql)
			if(data.records === 0) throw new Error('file is not found')
			sql = `DELETE FROM images WHERE id = ${key}`
			await this.db.run(sql)
			return true
		} catch(err) {
			throw err
		}
	}

	/**
	 * Count the sum of images
	 * @returns {Promise<integer>} number representing amount of stored images
	 */
	async count() {
		const sql = 'SELECT COUNT(id) as records FROM images'
		const data = await this.db.get(sql)
		return data.records
	}
}

module.exports = Image