Where do I find an overview of all python functions for QGIS

I'm making a plug-in for QGIS, using the python language. I've looked everywhere but I can't seem to find a good overview of all the QGIS functions there are usable in the python script.

For example, let's say I selected a Polygon as a geometry. I know I can calculate the area of the polygon using .geometry().area()

But where do I find an overview of ALL the things I can do with this geometry? The QGIS Cookbook gives a few examples but not everything.

There you go:

A diagram of the main PyQGIS relationships (by Thomas Gratier): https://raw.githubusercontent.com/webgeodatavore/qgis-class-diagram/master/diagramme_principal.png

Searchable documentation of QGIS and PyQGIS classes (by SourcePole): http://geoapis.sourcepole.com

For example, properties and methods of the QgsGeometry class are here: http://geoapis.sourcepole.com/qgispyapi-qgsgeometry/