Obtaining/Exporting Font Metrics through a Script

I have a Text Layer consisting of characters with varying font metrics (say Font Height, Typeface, Kerning, Leading etc). Am unable to export out the Font metrics through an AE script.

I was able to get the Font Name, Height, Fill and Stroke properties of the first character from the Text Document.

var textDoc = layer("sourceText") ;

var textDef = textDoc.valueAtTime(0, false) ;

I was able to get the Font Name, height, justification, fill and stroke properties from textDef.

But, I have no clue about getting the other properties like Kerning,  Leading, Tracking etc.

It will be ideal if I can get all the concerned font metrics of each character in the Text Layer (separately).

Thanks in advance.