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// The EURC rail against a REAL chain: a €1 donation paid in real (testnet)
// EURC on Ethereum Sepolia, settled by the same balanceOf quorum the mainnet
// rail runs. The fake-rail suites prove the order lifecycle; the unit suites prove
// the decoding; what neither can prove is that the rail's actual RPC
// conversation — eth_chainId verification, the ABI-encoded eth_call, two
// endpoints corroborating a covering balance — works against nodes we do not
// control. A mistake there costs real money on mainnet, which is why this
// suite exists and why it is a MANDATORY deploy gate in CI, network flake and
// all: a deploy that cannot prove the crypto rail settles is not a deploy
// (the operator's call — caution over convenience).
//
// Locally it skips unless EURC_E2E_PRIVATE_KEY is exported, so a train ride
// still runs the rest of the suites. In CI the same missing key is a FAILURE:
// a vanished secret must never quietly turn the gate into a pass.
//
// What it needs (see deploy/README.md "Live payment suites in CI"):
//   EURC_E2E_PRIVATE_KEY  an Ethereum Sepolia key holding testnet EURC
//                         (Circle's faucet, network set to Ethereum Sepolia)
//                         and some Sepolia ETH for gas (the pk910 PoW faucet
//                         mines it, no account). Each run spends 1 EURC + gas.
//   cast                  Foundry's CLI, the only tool in a stock shell that
//                         can sign an ERC-20 transfer. The server itself
//                         deliberately cannot — that is the rail's design.
//
// The receiving pool is generated FRESH here, random addresses nobody holds a
// key for. That is load-bearing, not laziness: CheckPaid compares the
// address's TOTAL balance, so a reused address still holding last run's
// 1 EURC would settle this run's order before any payment — a false pass.
// The 1 EURC sent each run is stranded at the random address, which on a
// testnet costs nothing.
//
// block_tag is "latest" rather than production's "finalized": Sepolia-family
// finality is ~13 minutes, and a reorg un-paying a testnet donation is not a
// risk worth a quarter-hour CI stall. The rail warns about it at load; that
// warning appearing in this suite's server log is expected.

import std;
import Crafter.Network;
import Catcrafts.E2eHarness;

using namespace Catcrafts::E2e;
namespace fs = std::filesystem;

namespace {

// Circle's EURC on Ethereum Sepolia. Verify only against
// https://developers.circle.com/stablecoins/eurc-contract-addresses
constexpr std::string_view kContract = "0x08210F9170F89Ab7658F0B5E3fF39b0E03C594D4";
constexpr std::string_view kChainId  = "11155111";
// Two endpoints from different operators (Allnodes, 1RPC) — the same two
// operators the production ethereum entry uses — because the rule under test
// is "no single node's word settles an order": min_confirmations=2 below
// makes both agree, same as the mainnet chains file.
constexpr std::string_view kRpcPrimary   = "https://ethereum-sepolia-rpc.publicnode.com";
constexpr std::string_view kRpcSecondary = "https://1rpc.io/sepolia";

// €1 donation = 100 cents = 100 × 10^(6-2) EURC base units.
constexpr std::string_view kTransferUnits = "1000000";

bool IsCi() {
    for (const char* v : { "CI", "GITHUB_ACTIONS", "FORGEJO_ACTIONS" }) {
        if (const char* s = std::getenv(v); s && *s) return true;
    }
    return false;
}

// The order token from a checkout redirect's Location header — the EURC rail
// has no hosted page, so the 303 lands back on the order page itself.
std::string TokenOf(const Crafter::HTTPResponse& r) {
    const auto it = r.headers.find("location");
    if (it == r.headers.end()) return {};
    std::smatch m;
    if (std::regex_search(it->second, m, std::regex(R"(/order/([0-9a-f]{32})$)"))) {
        return m[1].str();
    }
    return {};
}

std::string RandomAddress(std::mt19937_64& rng) {
    static constexpr char hex[] = "0123456789abcdef";
    std::string s = "0x";
    for (int i = 0; i < 40; ++i) s += hex[rng() & 0xf];
    return s;
}

std::string Trimmed(std::string s) {
    while (!s.empty() && (s.back() == '\n' || s.back() == '\r' || s.back() == ' ')) {
        s.pop_back();
    }
    return s;
}

} // namespace

int main(int argc, char** argv) {
    if (argc < 2) {
        std::println(std::cerr, "usage: ShouldSettleEurcOnTestnet <server-binary>");
        return 2;
    }

    const char* senderKey = std::getenv("EURC_E2E_PRIVATE_KEY");
    if (!senderKey || !*senderKey) {
        if (IsCi()) {
            std::println(std::cerr,
                "FAIL: EURC_E2E_PRIVATE_KEY is not set. This suite is a mandatory "
                "deploy gate: add the secret in Forgejo (repo Settings -> Actions -> "
                "Secrets) — an Ethereum Sepolia key funded with testnet EURC and gas. "
                "See deploy/README.md \"Live payment suites in CI\".");
            return 1;
        }
        std::println("ShouldSettleEurcOnTestnet: skipped — EURC_E2E_PRIVATE_KEY is not "
                     "set (mandatory in CI, opt-in locally)");
        return 0;
    }
    // The key never enters a command line this process builds: cast reads it
    // from the environment via shell expansion, so it cannot leak through a
    // logged command or the failure output below.
    if (std::system("command -v cast >/dev/null 2>&1") != 0) {
        std::println(std::cerr,
            "FAIL: EURC_E2E_PRIVATE_KEY is set but `cast` (Foundry) is not on PATH — "
            "the suite cannot sign the testnet transfer without it. CI installs it in "
            "the deploy workflow; locally: https://getfoundry.sh");
        return 1;
    }

    // The suite's own scratch dir: the chains file and pool must exist before
    // the server spawns, so they cannot live in TestServer's work dir.
    std::random_device rd;
    std::mt19937_64 rng((static_cast<std::uint64_t>(rd()) << 32) ^ rd());
    const fs::path dir = fs::temp_directory_path()
        / std::format("catcrafts-eurc-testnet-{:016x}", rng());
    std::error_code ec;
    fs::remove_all(dir, ec);
    fs::create_directories(dir);

    const fs::path chains = dir / "chains.json";
    WriteFile(chains, std::format(
        R"({{"chains":[{{"name":"ethereum-sepolia",)"
        R"("rpcs":["{}","{}"],)"
        R"("min_confirmations":2,)"
        R"("contract":"{}","chain_id":{},)"
        R"("block_tag":"latest","note":"testnet"}}]}})",
        kRpcPrimary, kRpcSecondary, kContract, kChainId));

    // Fresh random addresses — see the header for why reuse would false-pass.
    const fs::path pool = dir / "pool.txt";
    {
        std::string lines;
        for (int i = 0; i < 3; ++i) lines += RandomAddress(rng) + "\n";
        WriteFile(pool, lines);
    }

    ServerOptions options;
    // Bank slot on the fake rail so the donation form offers the choice; the
    // crypto slot is the real EURC rail pointed at the testnet chains file.
    options.extraArgs = { "--rail=fake", "--crypto-rail=eurc" };
    options.env = { { "EURC_CHAINS", chains.string() },
                    { "EURC_POOL", pool.string() } };
    TestServer srv(argv[1], 8218, options);

    // ── checkout: a €1 crypto donation ────────────────────────────────
    const auto created = srv.Post("/shop/donation", "amount=1&pay=crypto");
    const std::string token = TokenOf(created);
    Check(created.status == "303" && !token.empty(),
          "a €1 crypto donation 303s to its order page", created.status);
    if (token.empty()) {
        std::println(std::cerr, "server log:\n{}",
                     ReadFile(srv.Work() / "server.log"));
        fs::remove_all(dir, ec);
        return Finish();
    }
    const std::string orderPath = std::format("/order/{}", token);

    // The issued address, from the ledger — the same place the reconciler
    // reads it, so this is the address the rail is actually watching.
    std::string address;
    {
        const std::string ledger = srv.OrdersText();
        std::smatch m;
        if (std::regex_search(ledger, m, std::regex(
                R"lit("id":")lit" + token
                + R"lit(".*?"pay_choice":"crypto".*?"pay_id":"(0x[0-9a-f]{40})@[0-9]+")lit"))) {
            address = m[1].str();
        }
        Check(!address.empty(),
              "the ledger records a crypto order with an address@deadline pay id");
    }
    if (address.empty()) {
        std::println(std::cerr, "ledger was:\n{}\nserver log:\n{}",
                     srv.OrdersText(), ReadFile(srv.Work() / "server.log"));
        fs::remove_all(dir, ec);
        return Finish();
    }
    std::println("issued receiving address: {}", address);

    // ── the order page asks for exactly the right payment ────────────
    {
        const std::string page = srv.Body(orderPath);
        Check(page.find("Pay with EURC") != std::string::npos,
              "the order page renders the self-hosted payment instructions");
        Check(page.find(address) != std::string::npos,
              "the order page shows the issued address");
        // The EIP-681 wallet link carries the amount in base units — the
        // number a wrong scale would corrupt 10,000× in either direction.
        Check(page.find(std::format("uint256={}", kTransferUnits)) != std::string::npos,
              "the wallet link asks for €1 in EURC base units");
        Check(page.find("ethereum-sepolia") != std::string::npos
                  || page.find("Ethereum-sepolia") != std::string::npos,
              "the order page names the watched chain");
    }

    // ── negative control: an unpaid order must not settle ────────────
    // The reconciler has polled the real RPCs at least once by now (first
    // sweep lands ~1 s after the order); a zero balance must read as Pending.
    std::this_thread::sleep_for(std::chrono::seconds(3));
    Check(srv.Body(orderPath).find("awaiting payment") != std::string::npos,
          "an unpaid order stays awaiting after a real RPC poll");

    // ── the customer pays: 1 real EURC on Ethereum Sepolia ────────────
    {
        const fs::path who = dir / "sender.txt";
        std::system(std::format(
            "cast wallet address --private-key \"$EURC_E2E_PRIVATE_KEY\" > \"{}\" 2>&1",
            who.string()).c_str());
        std::println("paying from: {}", Trimmed(ReadFile(who)));
    }
    const fs::path sendLog = dir / "cast-send.log";
    const int sent = std::system(std::format(
        "cast send {} \"transfer(address,uint256)\" {} {} "
        "--rpc-url {} --private-key \"$EURC_E2E_PRIVATE_KEY\" > \"{}\" 2>&1",
        kContract, address, kTransferUnits, kRpcPrimary, sendLog.string()).c_str());
    Check(sent == 0, "cast send transfers 1 testnet EURC and gets a receipt");
    if (sent != 0) {
        std::println(std::cerr,
            "cast send failed — if it reports insufficient funds, top the sender "
            "up: EURC at https://faucet.circle.com (network: Ethereum Sepolia), "
            "gas ETH at https://sepolia-faucet.pk910.de. cast said:\n{}",
            ReadFile(sendLog));
        fs::remove_all(dir, ec);
        return Finish();
    }
    std::println("transfer confirmed on-chain; waiting for the rail to notice");

    // ── the rail notices, both endpoints agreeing ─────────────────────
    // Cadence: the reconciler polls this order every 30 s (the rail's own
    // interval), and both endpoints must see the balance at "latest". 150 s
    // is five polls past the ~12 s block that included the transfer — roomy,
    // tight enough to fail a deploy that would leave real buyers unconfirmed.
    {
        const std::string page = srv.WaitForBody(orderPath, "Thank you", 600);
        Check(page.find("Thank you") != std::string::npos,
              "the paid donation page appears once the balance covers the order");
        Check(page.find("Pay with EURC") == std::string::npos,
              "a settled order stops asking for money");
    }
    {
        const std::string ledger = srv.OrdersText();
        Check(ledger.find("\"status\":\"paid\"") != std::string::npos,
              "the paid transition reached the ledger");
        // The via column must name the chain that settled it — the fact the
        // bookkeeping keeps about where the money lives.
        Check(ledger.find("\"via\":\"eurc-ethereum-sepolia\"") != std::string::npos,
              "the paid event records eurc-ethereum-sepolia as the method");
        Check(ledger.find("\"type\":\"invoice\"") == std::string::npos,
              "a donation settles without an invoice");
    }
    if (failures != 0) {
        std::println(std::cerr, "server log:\n{}",
                     ReadFile(srv.Work() / "server.log"));
    }

    fs::remove_all(dir, ec);
    return Finish();
}