A 37-year-old woman complains of weakness, feeling unwell, nervousness, mild discharge of dark blood from the vagina before and after menstruation, and periodical pain in her lower abdomen that intensifies during menstruation. Bimanual examination detects enlarged body of the uterus, the appendages cannot be clearly outlined, an uneven surface is detected on the posterior fornix. Laparoscopy detects bluish "eyelets" on the ovaries, peritoneum of the rectouterine pouch, and perirectal fat. What is the most likely diagnosis in this case?