#!/usr/bin/env python3
"""x402client.py — reference client for paying x402-gated services (basebalance.cloud /rpc).

Pure stdlib. Use from ANY agent that can sign a USDC transfer on Base:
  1. POST /rpc -> free tier serves (10 req/min/IP), check x-quota-* headers.
  2. On HTTP 402, parse the challenge (USDC on Base 8453, amount, payTo, token).
  3. Build + sign a standard ERC20 transfer(USDC, payTo, amount) with YOUR wallet,
     broadcast it on Base, wait for status 0x1.
  4. Retry the request with header  x-paywall-tx: <0x..txhash>.
  5. GET /quota to confirm: tier: "paid", remaining 10,000.

Run:  python3 x402client.py <rpc-gateway-url> [your-address] [rpc-timeout]
"""
import json, sys, time, urllib.request

RPC_URL = "http://localhost:8000/rpc"           # override with argv[1]
QUOTA_URL = RPC_URL.replace("/rpc", "/quota")
BASE_RPCS = ["https://mainnet.base.org", "https://base-rpc.publicnode.com",
             "https://base-rpc.com", "https://1rpc.io/base", "https://base.llamarpc.com"]
UA = {"User-Agent": "Mozilla/5.0 (nexus-x402client)", "Content-Type": "application/json"}


def rpc_call(rpc, method, params):
    req = urllib.request.Request(rpc, data=json.dumps(
        {"jsonrpc": "2.0", "method": method, "params": params, "id": 1}).encode(), headers=UA)
    with urllib.request.urlopen(req, timeout=12) as r:
        return json.load(r).get("result")


def wait_receipt(txhash, chain_rpcs=BASE_RPCS, timeout_s=120):
    """Wait for a Base tx to confirm; return receipt or None."""
    deadline = time.time() + timeout_s
    while time.time() < deadline:
        for rpc in chain_rpcs:
            try:
                rcpt = rpc_call(rpc, "eth_getTransactionReceipt", [txhash])
                if rcpt:
                    return rcpt
            except Exception:
                continue
        time.sleep(4)
    return None


def free_call(url):
    body = json.dumps({"jsonrpc": "2.0", "method": "eth_blockNumber", "params": [], "id": 1}).encode()
    req = urllib.request.Request(url, data=body, headers=UA)
    try:
        with urllib.request.urlopen(req, timeout=15) as r:
            print("  free tier: HTTP %s" % r.status)
            for h in ("x-quota-tier", "x-quota-used", "x-quota-remaining", "x-quota-expiry", "x-rpc-upstream", "x-rpc-cache"):
                if r.headers.get(h):
                    print("  %s: %s" % (h, r.headers.get(h)))
            return json.load(r)
    except urllib.error.HTTPError as e:
        if e.code == 402:
            body = json.load(e)
            ch = body.get("challenge", {})
            print("  HTTP 402 — payment required")
            print("  scheme=%s network=%s amount=%s payTo=%s token=%s" % (
                ch.get("scheme"), ch.get("network"), ch.get("amount"),
                ch.get("payTo"), (ch.get("token") or "")[:10] + "..."))
            return ch
        raise


def dance(gateway_url):
    print("step 1 — free request:")
    ch = free_call(gateway_url)
    if not isinstance(ch, dict) or "payTo" not in ch:
        print("  (free tier sufficed; no payment needed)")
        return True
    print()
    print("step 2 — pay (you sign + broadcast this on Base 8453):")
    print("  USDC token : 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913")
    print("  transfer to: %s" % ch["payTo"])
    print("  amount     : %s USDC (>= %s)" % (ch.get("amount"), ch.get("amount")))
    print("  then:  python3 x402client.py CLAIM %s <txhash>" % gateway_url)
    return False


def claim(gateway_url, txhash):
    print("step 3 — wait for confirmation...")
    rcpt = wait_receipt(txhash)
    if not rcpt or rcpt.get("status") != "0x1":
        print("  not confirmed (yet) — check the tx on Base explorer")
        return False
    print("  confirmed, status 0x1")
    body = json.dumps({"jsonrpc": "2.0", "method": "eth_blockNumber", "params": [], "id": 1}).encode()
    req = urllib.request.Request(gateway_url, data=body,
                                 headers=dict(UA, **{"x-paywall-tx": txhash}))
    with urllib.request.urlopen(req, timeout=15) as r:
        print("  quota tier after claim: %s" % r.headers.get("x-quota-tier"))
        print("  remaining: %s" % r.headers.get("x-quota-remaining"))
    print("done — quota granted (10,000 req or 24h). GET %s to confirm." % QUOTA_URL)


if __name__ == "__main__":
    url = sys.argv[1] if len(sys.argv) > 1 else RPC_URL
    if len(sys.argv) > 2 and sys.argv[2].lower() == "claim":
        claim(url, sys.argv[3])
    else:
        print("x402 client demo — gateway: %s" % url)
        dance(url)