What bird is this? Koel or Coucal?

Few days ago, I went to Teluk Intan Riverfront for usual birding practice. My friend CK came along with me. As usual, we will sit on the bench for a while, while waitting for and interesting birds come. Just for few minutes, I saw a few long tailed parakeet flying around. Then they hang around the tree. I managed to snap a few shot of it.

 

That day is a quite an exciting day. I snap a bird that until now no one can determine what species is it. Some say koel, and some say coucal. I have ask many people who loves birds, they also can't give me the right answer. Hopefully I'll get the answer soon. Below is the photo.