# EVM chains: call totalSupply() on the USDC contract per chain
# Each chain has a separate contract address — verified against Circle docs
USDC_CONTRACTS = {
    "ethereum": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "arbitrum": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "base"    : "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "polygon" : "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174",
}

for chain, rpc_url in RPC_ENDPOINTS.items():
    w3       = Web3(Web3.HTTPProvider(rpc_url))
    contract = w3.eth.contract(
        address=Web3.to_checksum_address(USDC_CONTRACTS[chain]),
        abi=ERC20_ABI
    )
    supply_raw = contract.functions.totalSupply().call()  # raw int, 6 decimals
    supply_usd = Decimal(supply_raw) / Decimal("1e6")     # → USD value
    chain_supplies.append(supply_usd)

# Solana uses a different RPC method — getTokenSupply on the mint account
solana_response = requests.post(SOLANA_RPC_URL, json={
    "method": "getTokenSupply",
    "params": [SOLANA_USDC_MINT]
})
amount   = solana_response.json()["result"]["value"]["amount"]
decimals = solana_response.json()["result"]["value"]["decimals"]
chain_supplies.append(Decimal(amount) / Decimal(10 ** decimals))

# Sum across all chains → on-chain supply for reconciliation bridge
on_chain_total = sum(chain_supplies)   # Control: RCN-02

# TEST 1: On-chain vs issuer ledger variance — RCN-02
# GENIUS Act §7 requires zero variance at the snapshot moment
# Tolerance is $0 — even $1 of unexplained difference is an exception
VARIANCE_TOLERANCE = Decimal("0.00")

variance = abs(on_chain_total - issuer_supply)

if variance > VARIANCE_TOLERANCE:
    # Reconciliation break — log to break log, escalate to Risk Officer
    # Risk Officer must be alerted within 15 minutes (RCN-04)
    raise_exception(
        control="RCN-02",
        message=f"Variance ${variance:,.2f}M exceeds $0 tolerance"
    )
    reconciled = False
else:
    reconciled = True   # On-chain == issuer ledger: PASS

# TEST 2: Coverage ratio — RES-03
# GENIUS Act §4(a)(3): reserve FMV must equal or exceed outstanding supply
# OCC NPRM Part III §3(b): 100% floor, computed daily
COVERAGE_FLOOR = Decimal("1.0000")   # 100.00%

coverage_ratio = (reserve_fmv / on_chain_total).quantize(
    Decimal("0.0001")
)
surplus_usd = reserve_fmv - on_chain_total

if coverage_ratio < COVERAGE_FLOOR:
    # Critical finding — reserves insufficient
    # Monthly RPAF attestation cannot be signed until resolved
    raise_critical(
        control="RES-03",
        message=f"Coverage {coverage_ratio:.2%} below 100% floor"
    )

# March 2026 result: coverage_ratio = 1.0080 (+80 bps) → PASS
# surplus_usd = $359.2M

def escalate_exception(snapshot, control_id, message):
    """
    Log exception to break log and alert Risk Officer.
    OCC NPRM requires Risk Officer notification within 15 minutes.
    Break log entry is the evidence that RCN-04 operated.
    Control: RCN-04
    """
    # Timestamped break log entry — this is the evidence the OCC examiner
    # will request when reviewing the reconciliation control (RCN-04)
    break_entry = {
        "timestamp"    : datetime.now(timezone.utc).isoformat(),
        "snapshot_date": snapshot.snapshot_datetime,
        "control_id"   : control_id,
        "description"  : message,
        "status"       : "OPEN",
        "owner"        : "Risk Officer",
        "disposition"  : None,   # populated on resolution
        "resolved_at"  : None,   # populated on resolution
    }

    # Persist to break log — in production: database write + audit trail
    write_to_break_log(break_entry)

    # Alert Risk Officer — OCC requires notification within 15 minutes
    # In production: email + Slack + PagerDuty
    send_alert(
        recipient=RISK_OFFICER_EMAIL,
        subject=f"[{control_id}] Reconciliation Exception — {snapshot.snapshot_datetime}",
        body=message,
        sla_minutes=15
    )

# ── RESOLUTION WORKFLOW (called when exception is closed) ─────────
def resolve_break(break_id, disposition, resolver, reviewer):
    """
    Record resolution of a reconciliation break.
    Every exception must have: timestamp, disposition code,
    resolver sign-off, and reviewer sign-off.
    This evidence is what the RPAF attestation depends on.
    """
    update_break_log(break_id, {
        "status"      : "CLOSED",
        "disposition" : disposition,   # e.g. "Timing difference — resolved T+1"
        "resolver"    : resolver,      # person who investigated
        "reviewer"    : reviewer,      # independent sign-off
        "resolved_at" : datetime.now(timezone.utc).isoformat(),
    })