Permissions.js

'use strict';

class LambdaPermissions {

  constructor(provider) {
    this.provider = provider;
  }

  getId(functionName,bucketName) {
    return `exS3-v2-${functionName}-${bucketName.replace(/[\.\:\*]/g,'')}`;
  }

  createPolicy(functionName,bucketName,passthrough){
    const payload = {
      Action: "lambda:InvokeFunction",
      FunctionName: functionName,
      Principal: 's3.amazonaws.com',
      StatementId: this.getId(functionName,bucketName),
      SourceArn: `arn:aws:s3:::${bucketName}`
    }
    return this.provider.request('Lambda', 'addPermission', payload)
      .then( results =>  Object.assign({},{ statement: this.getStatement(this.asJson(results.Policy),passthrough), passthrough }) )
  }

  getPolicy(functionName,passthrough) {
    return this.provider.request('Lambda', 'getPolicy', { FunctionName: functionName })
      .then( results => Object.assign({},{ statement: this.getStatement(this.asJson(results.Policy),passthrough), passthrough }) )
      .catch( error => Object.assign({}, { error:error.message, passthrough } ) );
  }

  getStatement(policy,event) {
    const policyId = this.getId(event.name, event.existingS3.bucket); 
    console.log("policyId",policyId);
    return policy.Statement.find( statement => statement.Sid === policyId );
  }

  asJson(value){
    return typeof value === 'string' ? JSON.parse(value) : value
  }
}

module.exports.Lambda = LambdaPermissions;