First thing first, I am not native speaker and I am new here.
This schematic is reverse engineered from searchlight PCB traces (which is broken) by me.
D+ and D- terminals connect to the rechargeable battery. I couldn't read the voltage rating of the battery.
"LED"s are white and all of them parallel and voltage drop is about 2.6V.
There is a switch and a button in the middle of the schematic, nothing special.
I have a guess that these two diodes, one transistor and 520Ohm resistor makes up constant current circuit. But simple constant current circuits generally have zener (or at least 2 diodes at base) to implement.
If my guess is not correct, please tell me how this circuits drives the white LEDs.