A young patient presented to casualty with a history of some substance abuse. His pulse was 130 beats per minute and respiratory rate was 30 per minute. Blood gas analysis revealed metabolic acidosis and his urea was 100 mg/dL and creatinine was 4 mg/dL. Urinalysis revealed calcium oxalate crystals. He improved symptomatically after management with intravenous fluids, gastric lavage, sodium bicarbonate, calcium gluconate and 4-methylpyrazole administration. What is the most likely substance that he consumed?