regex - Php parse links/emails -

I am thinking that there is a simple snippet that changes any type of link:

  from http://www.cnn.com & lt; A href = "http://www.cnn.com" & gt; Http: //www.cnn.com< / A & gt; From Cnn.com & lt; A href = "http://www.cnn.com" & gt; Cnn.com & lt; / A & gt; From www..cnn.com & lt; A href = "http://www.cnn.com" & gt; Www.cnn.com & lt; / A & gt; From abc@def.com & lt; A href = "mailto: mailto: abc@def.com" & gt; Mail: ABC @ def.com & lt; / A & gt;  

I do not want to use any PHP5 specific library.

Thank you for your time.

UPDATE I want to change the above text to change it. Please note that the href tags and text for episode 2 and 3 are different.

UPDATE2 How does Gmail chat? She is pretty smart and works only for real domain names. Like A.ly works but CCB does not work.

Yes,