The TI bq24725a is a SMBus Smart Battery Charger, with integrated synchronous buck controller. It can be used to charge upto 4-cell Li batteries. It also has dynamic power path management, which dynamically switches the load between AC and battery power. It can also monitor current drawn from the AC source as well as the battery which can be measured by an ADC on the host side.
For this design I am using the BQ24725a evaluation board schematics, but that'd be redrawn in KiCAD. Almost done, and this is how it looks as of now.
Now to design the MCU side of things.