Retrieve contents of WAF Logs from S3 bucket in a lambda using Typescript

Question

Requirement - The WAF logs(generated form Kinesis Wire Hose) are stored in to a S3 bucket in a text file format and in a day multiple files are generated which are stored in nested folder structure of year/month/date/multiple files. We want to send these logs to Elastic Search. Each log file contains 3k records and multiple files are generated in a day.

To accomplish this, I am planning to write a lambda to read the contents of each text file, parse them, convert them to json and send to elastic search index using type script.

what would be the best way to accomplish this ? Thanks