「150万〜200万円のUTM機器を置けば安心」という
長期リース営業トークの事実検証と見極め方

#![forbid(unsafe_code)]

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct LeaseProposal {
    pub monthly_payment_yen: u64,
    pub lease_months: u32,
    pub performs_tls13_mitm_inspection: bool,
    pub includes_immutable_backup: bool,
    pub includes_fido2_mfa_setup: bool,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct SecondOpinionVerdict {
    pub total_committed_cost_yen: u64,
    pub effective_risk_reduction_pct: u8,
    pub is_overpriced_lockin: bool,
    pub recommendation: &'static str,
}

pub const fn evaluate_utm_lease_proposal(p: LeaseProposal) -> SecondOpinionVerdict {
    let total_cost = p.monthly_payment_yen * (p.lease_months as u64);

    let mut reduction = 15u8; — Basic L3/L4 NAT & IP blocklist baseline
    if p.performs_tls13_mitm_inspection {
        reduction += 20;
    }
    if p.includes_immutable_backup {
        reduction += 35;
    }
    if p.includes_fido2_mfa_setup {
        reduction += 25;
    }

    let overpriced = total_cost >= 1_200_000 && p.lease_months >= 60 && !p.includes_immutable_backup;

    let rec = if overpriced {
        "WARNING: High-cost long-term hardware lease with low effective coverage against TLS 1.3 threats and ransomware. Prioritize FIDO2 MFA and immutable backups first."
    } else {
        "Acceptable cost structure; verify operational SLA and cancellation terms."
    };

    SecondOpinionVerdict {
        total_committed_cost_yen: total_cost,
        effective_risk_reduction_pct: reduction,
        is_overpriced_lockin: overpriced,
        recommendation: rec,
    }
}