const fs = require('fs');
const path = require('path');
const sqlite3 = require('sqlite3').verbose();

class SqliteDatabase {
   constructor(host) {
      this.host = host;
      this.connection = new sqlite3.Database(this.host);
      this.schemaDirectory = path.join(__dirname, 'schemas');
   }

   /**
   * Connect to the database.
   * @returns {Promise} succeeds if connection was established
   */
   // connect() {
   //    let database = ;
   //    this.connection = database;
   //    return database;
   // }

   /**
   * Run a SQL query against the database.
   * @param {String} sql SQL query
   * @param {Array} parameters in the SQL query
   * @returns {Promise}
   */
   run(sql, parameters) {
      return new Promise((resolve, reject) => {
         this.connection.run(sql, parameters, (error, result) => {
            if (error)
               reject(error);
            resolve(result)
         });
      });
   }

   /**
   * Run a SQL query against the database and retrieve all the rows.
   * @param {String} sql SQL query
   * @param {Array} parameters in the SQL query
   * @returns {Promise}
   */
   all(sql, parameters) {
      return new Promise((resolve, reject) => {
         this.connection.all(sql, parameters, (err, rows) => {
            if (err) {
               reject(err);
            }
            resolve(rows);
         })
      })
   }

   /**
   * Run a SQL query against the database and retrieve one row.
   * @param {String} sql SQL query
   * @param {Array} parameters in the SQL query
   * @returns {Promise}
   */
   get(sql, parameters) {
      return new Promise((resolve, reject) => {
         this.connection.get(sql, parameters, (err, rows) => {
            if (err) {
               reject(err);
            }
            resolve(rows);
         })
      })
   }

   /**
   * Run a SQL query against the database and retrieve the status.
   * @param {String} sql SQL query
   * @param {Array} parameters in the SQL query
   * @returns {Promise}
   */
   execute(sql) {
      return new Promise(resolve => {
         this.connection.exec(sql, (err, database) => {
             if (err) {
               console.log('ERROR: ', err);
               reject(err);
            }
            resolve();
         })
      })
   }

   /**
   * Setup the database by running setup.sql file in schemas/.
   * @returns {Promise}
   */
   setUp() {
      const setupSchema = this.readSqlFile('setup.sql');
      return Promise.resolve(this.execute(setupSchema));
   }

   /**
   * Tears down the database by running tearDown.sql file in schemas/.
   * @returns {Promise}
   */
   tearDown() {
      const tearDownSchema = this.readSqlFile('teardown.sql');
      return Promise.resolve(this.execute(tearDownSchema));
   }

   /**
   * Returns the file contents of a SQL file in schemas/.
   * @returns {String}
   */
   readSqlFile(filename) {
      const schemaPath = path.join(this.schemaDirectory, filename);
      const schema = fs.readFileSync(schemaPath).toString('utf-8');
      return schema;
   }
}

module.exports = SqliteDatabase;