A 32-year-old male patient presented with sore throat and cough 2 weeks ago, followed by edema, oliguria, and fatigue in the past week. Laboratory tests showed hemoglobin (Hb) 90g/L, urinary protein (+++), urine sediment microscopy with 10-15 red blood cells (RBCs)/HP, normal blood C3, serum creatinine 500 μmol/L, blood urea nitrogen (BUN) 23 mmol/L, and ultrasound revealing bilateral enlarged kidneys. The most likely diagnosis is: