# FW Gate — Python SDK
# pip install requests
# © 2026 Flying Whale — zaghmout.btc | ERC-8004 #54

import requests

class FWGate:
    def __init__(self, payment_token=None, base_url="https://fwgate.to", timeout=15):
        self.base_url = base_url.rstrip("/")
        self.timeout = timeout
        self.headers = {"Content-Type": "application/json"}
        if payment_token:
            self.headers["X-PAYMENT"] = payment_token

    def evaluate(self, pair_from, pair_to, amount="1000000", tier="basic"):
        """tier: 'basic' (0.1 STX) | 'enterprise' (1 STX)"""
        if tier == "enterprise":
            resp = requests.post(
                f"{self.base_url}/enterprise/evaluate",
                headers=self.headers,
                json={"pair_from": pair_from, "pair_to": pair_to, "amount": amount},
                timeout=self.timeout
            )
        else:
            resp = requests.get(
                f"{self.base_url}/gate/evaluate",
                headers=self.headers,
                params={"token_in": pair_from, "token_out": pair_to, "amount": amount},
                timeout=self.timeout
            )
        if resp.status_code == 402:
            raise Exception("Payment required — 0.1 STX (basic) or 1 STX (enterprise)")
        resp.raise_for_status()
        return resp.json()

    def guard(self, pair_from, pair_to, execute_fn, **kwargs):
        """Evaluate and call execute_fn only if viable. Raises on halt."""
        allow_degraded = kwargs.pop("allow_degraded", False)
        result = self.evaluate(pair_from, pair_to, **kwargs)
        if not self.is_viable(result, allow_degraded):
            raise Exception(f"FW Gate halted: {result.get('verdict')} — {result.get('execution_feasibility', 0)*100:.0f}%")
        return execute_fn(result)

    def is_viable(self, result, allow_degraded=False):
        v = result.get("verdict") or result.get("gate_verdict", "")
        if v in ("viable", "CLEAR"): return True
        if allow_degraded and v in ("degraded", "CAUTION", "REDUCE"): return True
        return False

    def get_stats(self):
        return requests.get(f"{self.base_url}/scan/stats", timeout=self.timeout).json()

    def get_revenue(self):
        return requests.get(f"{self.base_url}/gate/revenue", timeout=self.timeout).json()

    def get_proof(self, scan_id):
        return requests.get(f"{self.base_url}/proof/{scan_id}?format=json", timeout=self.timeout).json()


# ── Example usage ──────────────────────────────────────────────────────────────
if __name__ == "__main__":
    gate = FWGate(payment_token="your_x402_token_here")

    # One-line guard pattern
    try:
        result = gate.guard(
            "STX", "ALEX",
            lambda r: print("EXECUTE — feasibility:", r["execution_feasibility"])
        )
    except Exception as e:
        print("HALT:", e)

    # Manual check
    r = gate.evaluate("STX", "ALEX", tier="enterprise")
    if not gate.is_viable(r):
        print("HALT:", r["verdict"])
    else:
        print("cert_hash:", r.get("cert_hash"))
        print("audit_id:", r.get("audit_id"))