preg_replace

[Xeef]

hi to all

i know that there are a billion tuts on this but if somebody know how to do it and coud sacrify the 5 minutes woud by great ;)

can some body show me how to do the folowing :


INPUT:
1. Hallo SECRET_20 how are you
2. BlaBla SECRET_202120 BlaBla
3. abc SECRET_1_B

OUTPUT
1. Hallo Xeef = 20 how are you
2. BlaBla Xeef = 2120 BlaBla
3. abc Xeef = 1 + Something

not sure how smart preg_replace is

if it's possible :

input :

Hallo SECRET_1_B --> Hallo Xeef = 1 + BIG ( if 1 then B-> BIG )
Hallo SECRET_2_B --> Hallo Xeef = 2 + SMALL ( if 2 then B-> SMALL )
Hallo SECRET_3 BlaBla SECRET_2 --> Hallo Xeef = 3 BlaBla QQQ ( if there is a SECRET before then QQQ else AAA)

thanks for our time and intrest
1 more thanks if you can help me ;)