import dynamoStore = require('dynamodb-datastore');
import cdk = require('@aws-cdk/core');
import lambda = require('@aws-cdk/aws-lambda');

const app = new cdk.App();

class MyStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    this.datastore = new dynamoStore.DataStoreConstruct(this, 'my-datastore');
    
    this.datastore.addObjectType('User', {
      indexes: [
        'id',
        'username',
        'email'
      ]
    });
    
    this.userLamda = .Function(this, 'Singleton', {
      code: new lambda.InlineCode(fs.readFileSync('lambda.js', { encoding: 'utf-8' })),
      handler: 'index.handler',
      timeout: cdk.Duration.seconds(300),
      runtime: lambda.Runtime.JAVASCRIPT,
      env: {
        DATASTORE_TABLE_NAME: this.datastore.tableName
      }
    });
    
    // Helper method similar to the native CDK table.grantReadWriteData(iamRoleBearer)
    // but aware of the object types, and generates the right IAM statements
    this.datastore.grantReadWriteType('User').to(this.userLambda);
  }
}

app.synth();

// In my Lambda:
const dynamoStore = require('dynamodb-datastore');

// Interface that exposes higher level methods that
// automatically generate DynamoDB queries with queries
// that use the right primary key prefix
myDatastore = new dynamoStore.DataStoreInterface({
  tableName: process.env.DATASTORE_TABLE_NAME
})

exports.handler =  async function(event, context) {
  await myDatastore.writeObject({
    type: 'User',
    object: {
      id: 1,
      username: 'foo',
      email: 'foo@bar.com'
    }
  }
  
  let userFoundById = await myDatastore.findObject({
    type: 'User',
    match: {
      id: 1
    }
  });
  
  let userFoundByUsername = await myDatastore.findObject({
    type: 'User',
    match: {
      username: 'foo'
    }
  });
  
  let userFoundByEmail = await myDatastore.findObject({
    type: 'User',
    match: {
      email: 'foo@bar.com'
    }
  });
}