I'm a pretty lousy guitarist but the earlier two versions made me cry, so 
here's my try:
MAIN RIFF
e|----------------------------------
B|----------------------------------
G|----------------------------------
D|----0-4--0-4--0-4/7-5-4-0---------
A|0h2--2--2-2--2-2--0---------------
E|---------------------(2)--3-------
RIFF 2
The second riff is just the main riff but
with this change compared to the riff above:
             e|---
             B|232   (that is: you hammer on and pull off
                      Just change the  0  part in the main riff)
                                      2 2
PRE-CHORUS
I think they use open chords here: B D A (B) 
CHORUS
Like pre-chorus with a change: B D A G 
The solo part I leave to you...