scam_reports = total unique users who report scamming
reports = total positive ratings
btc = total BTC from positive ratings
unique_reports = total unique users who posted positive ratings
oldest = timestamp of the oldest positive trust rating
latest_scam = timestamp of the latest scam rating

scam_multiplier = 1
# recent scam = bigger negative score

if(current_time - latest_scam < 7 days)
    scam_multiplier += 1.5

# new member = bigger negative score
if(current_time - oldest < 60 days)
    scam_multiplier += 3

months = months since oldest
total = reports + btc/50    # 50 BTC = 1 report

# long-term con men
if(total > 0 && scam_reports > 4)
    scam_multiplier += (scam_reports / total) * 50

# Approximately limit the number of points each person can contribute each month
subtotal = min(2*unique_reports * months, total)
# Newer users have smaller point limits
limited_total = min(subtotal, 10*months) / 10

score = min((limited_total * months - scam_reports * scam_multiplier), 150)