Leda and the Swan

Woah! This poem seemed very confusing. All I got out of it was a girl supposedly being raped by a swan. However, I am clueless about the meaning one is supposed to take out of this. After searching for explanations on the internet i discovered that there is greek mythology hidden in this poem, that the swan represents a greek god named zeus and that Agamemnon was a greek king that won the trojan war. Being unfamiliar with greek mythology, this story still  doesn't seem to make sense as far as explanations go.