const fs = require('fs');

const Q = require('bluebird');

const Loki = require('lokijs');

const Settings = require('./settings');

const log = require('./utils/logger').create('Db');

let db;

exports.init = () => {

const filePath = Settings.dbFilePath;

return Q.try(() => {

// if db file doesn't exist then create it

try {

log.debug(`Check that db exists and it's writeable: ${filePath}`);

fs.accessSync(filePath, fs.R_OK | fs.W_OK);

return Q.resolve();

} catch (err) {

log.info(`Creating db: ${filePath}`);

const tempdb = new Loki(filePath, {

env: 'NODEJS',

autoload: false,

});

return new Q.promisify(tempdb.saveDatabase, { context: tempdb })();

}

})

.then(() => {

log.info(`Loading db: ${filePath}`);

return new Q((resolve, reject) => {

db = new Loki(filePath, {

env: 'NODEJS',

autosave: true,

autosaveInterval: 5000,

autoload: true,

autoloadCallback(err) {

if (err) {

log.error(err);

reject(new Error('Error instantiating db'));

}

resolve();

},

});

});

});

};

exports.getCollection = (name) => {

if (!db.getCollection(name)) {

db.addCollection(name, {

unique: ['_id']

});

}

return db.getCollection(name);

};

exports.close = () => {

return new Q((resolve, reject) => {

db.close((err) => {

if (err) {

reject(err);

} else {

resolve();

}

});

});

};