Currently, it is very complicated to add a new report or a new dimension.

For instance to add a new report you basically need to know

• about the entire Piwik platform (eg Events, Menu, Widgets, ReportMetadata, ViewDataTable, DataTable, API, Controller, ...)
• about many data strucutres (eg how a report metadata array structure looks like where not even a documentation about all array keys exists, about goal reports, segment metadata array structure, ...) etc
• the code just for one report is spread across many files.
• A lot of duplicated code. Eg translations for report names, dimensions, etc have to be copied many many times because of the current implementation

For a third party developer this is nearly impossible and would probably take a very long time. Goal is to make this as easy as possible while keeping the platform still performant.

It is a bit easier for plugin developers to add a new dimension although it is still complicated. I think it is not possible add all to add new actions. Even more complex is the part of the core. It is very hard to understand (even for core developers) what is going on during tracking and how everything works. Code is often spread across many files. Only a few people can actually add new dimensions. One problem is that most dimensions are in core although they should be actually in the plugins. Goal is to make it easy to add new dimensions and also easier to understand current dimensions. It would be awesome to have the code for one dimension in one class or whatsoever. Including their MySQL column definition, segments, .... Another goal is to move as much code out of the core as possible for now. Please consider: It would be possible to move a lot out but this would involve the refactoring of many more parts which results in a never ending refactoring.

The last goal is to provide a step by step guide and documentation for core and plugin developers.