A 24-year-old male patient is admitted with 'recurrent gross hematuria for 1 month, oliguria and edema for half a month, and hemoptysis for 2 days'. Physical examination: BP 160/90 mmHg, coarse breath sounds in both lungs with basal rales. Bilateral lower extremity edema. Lab tests: UA shows Pr (++), RBCs 20-25/HPF; CBC shows moderate anemia; anti-GBM antibody (+), ANCA (-). Renal pathology reveals: immunofluorescence IgG (++), IgA (-), IgM (+), C3 (++), C1q (-), Alb (-), with IgG and C3 showing smooth linear deposition along glomerular capillary walls. Light microscopy demonstrates crescentic glomerulonephritis. The definitive diagnosis is: