Inverted Index is an efficient Information Extraction method for big data in Unstructured text. Consider N $=1$ million documents $($webpages$)$ in various lengths.

You need to build an inverted index for the million documents for the TF $($Term Frequency$)-$IDF $($Inverted Document Frequency$)$ ranking based text analysis in a real time big data application.

$1)$ Describe the data processing flow $($algorithm steps$)$ to build an inverted Index in data pipelining in multiple phases. Specify the data pipelining with common text cleaning processing commonly required for NLP $($Natural Language Processing$)$ methods.