<?php
declare(strict_types=1);

require __DIR__ . '/lib.php';

try {
    $config = faucet_config();
    $network = network_details($config['faucet_address']);

    if ($_SERVER['REQUEST_METHOD'] === 'GET') {
        $ledger = with_ledger_lock(false, static fn(array $ledger): array => $ledger);
        $balance = null;
        if (configuration_ready()) {
            try {
                $balance = faucet_balance_atomic();
            } catch (Throwable $error) {
                error_log('[contractless_faucet] RPC status failed: ' . $error->getMessage());
            }
        }
        json_response([
            'success' => true,
            'online' => configuration_ready() && $balance !== null,
            'network' => $network['network'],
            'symbol' => $network['symbol'],
            'faucet_address' => $config['faucet_address'],
            'claim_amount' => atomic_to_decimal($config['claim_amount_atomic']),
            'cooldown_seconds' => $config['cooldown_seconds'],
            'faucet_balance' => $balance === null ? null : atomic_to_decimal($balance),
            'total_claimed' => atomic_to_decimal((int) $ledger['total_claimed_atomic']),
            'total_addresses' => count($ledger['addresses']),
        ]);
    }

    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        header('Allow: GET, POST');
        json_response(['success' => false, 'error' => 'Method not allowed.'], 405);
    }
    if (!configuration_ready()) {
        json_response([
            'success' => false,
            'error' => 'The faucet is not configured or is temporarily offline.',
        ], 503);
    }

    $rawBody = file_get_contents('php://input');
    if ($rawBody === false || strlen($rawBody) > 4096) {
        json_response(['success' => false, 'error' => 'Invalid request.'], 400);
    }
    $body = json_decode($rawBody, true);
    if (!is_array($body)) {
        json_response(['success' => false, 'error' => 'Request body must be JSON.'], 400);
    }

    $requestedAddress = normalize_requested_address(
        (string) ($body['address'] ?? ''),
        $network['suffix']
    );
    if ($requestedAddress === null) {
        json_response([
            'success' => false,
            'error' => "Enter a valid registered {$network['network']} wallet address.",
        ], 422);
    }

    // REMOTE_ADDR is authoritative. Forwarded headers are intentionally ignored.
    $clientIp = normalized_client_ip((string) ($_SERVER['REMOTE_ADDR'] ?? ''));
    if ($clientIp === null) {
        json_response(['success' => false, 'error' => 'Could not identify the requesting IP.'], 400);
    }

    $now = time();
    $nowMs = (int) floor(microtime(true) * 1000);
    $precheck = with_ledger_lock(true, function (array &$ledger) use (
        $requestedAddress,
        $clientIp,
        $now,
        $nowMs,
        $config
    ): array {
        $lastRequest = (int) $ledger['last_request_timestamp_ms'];
        if ($nowMs - $lastRequest < $config['minimum_request_interval_ms']) {
            return ['allowed' => false, 'status' => 429, 'error' => 'The faucet is busy. Try again.'];
        }
        $ledger['last_request_timestamp_ms'] = $nowMs;

        $addressClaim = active_claim(
            $ledger['addresses'],
            $requestedAddress,
            $now,
            $config['cooldown_seconds']
        );
        $ipClaim = active_claim($ledger['ips'], $clientIp, $now, $config['cooldown_seconds']);
        $claim = $addressClaim ?? $ipClaim;
        if ($claim !== null) {
            return [
                'allowed' => false,
                'status' => 429,
                'error' => 'This wallet address or IP has already claimed recently.',
                'retry_after_seconds' => claim_remaining_seconds(
                    $claim,
                    $now,
                    $config['cooldown_seconds']
                ),
            ];
        }
        return ['allowed' => true];
    });
    if (!$precheck['allowed']) {
        json_response(['success' => false] + $precheck, $precheck['status']);
    }

    $balance = faucet_balance_atomic();
    $requiredBalance = $config['claim_amount_atomic'] + $config['transfer_fee_atomic'];
    if ($balance === null || $balance < $requiredBalance) {
        json_response([
            'success' => false,
            'error' => 'The faucet is temporarily low on funds. Please try again later.',
        ], 503);
    }

    try {
        $transaction = create_faucet_transfer($requestedAddress);
    } catch (InvalidArgumentException $error) {
        json_response(['success' => false, 'error' => $error->getMessage()], 422);
    }
    $canonicalAddress = strtolower(trim((string) $transaction['receiver']));
    $requestId = bin2hex(random_bytes(16));

    $reservation = with_ledger_lock(true, function (array &$ledger) use (
        $canonicalAddress,
        $clientIp,
        $now,
        $requestId,
        $config
    ): array {
        $addressClaim = active_claim(
            $ledger['addresses'],
            $canonicalAddress,
            $now,
            $config['cooldown_seconds']
        );
        $ipClaim = active_claim($ledger['ips'], $clientIp, $now, $config['cooldown_seconds']);
        $claim = $addressClaim ?? $ipClaim;
        if ($claim !== null) {
            return [
                'allowed' => false,
                'retry_after_seconds' => claim_remaining_seconds(
                    $claim,
                    $now,
                    $config['cooldown_seconds']
                ),
            ];
        }

        $entry = [
            'claimed_timestamp' => $now,
            'status' => 'pending',
            'request_id' => $requestId,
            'address' => $canonicalAddress,
            'ip' => $clientIp,
        ];
        $ledger['addresses'][$canonicalAddress] = $entry;
        $ledger['ips'][$clientIp] = $entry;
        return ['allowed' => true];
    });

    if (!$reservation['allowed']) {
        json_response([
            'success' => false,
            'error' => 'This wallet address or IP has already claimed recently.',
            'retry_after_seconds' => $reservation['retry_after_seconds'],
        ], 429);
    }

    try {
        $txid = broadcast_faucet_transfer($transaction);
        with_ledger_lock(true, function (array &$ledger) use (
            $canonicalAddress,
            $clientIp,
            $requestId,
            $txid,
            $config
        ): void {
            foreach ([['addresses', $canonicalAddress], ['ips', $clientIp]] as [$group, $key]) {
                if (($ledger[$group][$key]['request_id'] ?? '') === $requestId) {
                    $ledger[$group][$key]['status'] = 'completed';
                    $ledger[$group][$key]['txid'] = $txid;
                    unset($ledger[$group][$key]['request_id']);
                }
            }
            $ledger['total_claimed_atomic'] += $config['claim_amount_atomic'];
            $ledger['total_claims']++;
        });
    } catch (Throwable $error) {
        with_ledger_lock(true, function (array &$ledger) use (
            $canonicalAddress,
            $clientIp,
            $requestId
        ): void {
            foreach ([['addresses', $canonicalAddress], ['ips', $clientIp]] as [$group, $key]) {
                if (($ledger[$group][$key]['request_id'] ?? '') === $requestId) {
                    unset($ledger[$group][$key]);
                }
            }
        });
        throw $error;
    }

    json_response([
        'success' => true,
        'txid' => $txid,
        'amount' => atomic_to_decimal($config['claim_amount_atomic']),
        'symbol' => $network['symbol'],
        'message' => ucfirst($network['network']) . ' coins were broadcast successfully.',
    ]);
} catch (Throwable $error) {
    error_log('[contractless_faucet] ' . $error->getMessage());
    json_response([
        'success' => false,
        'error' => 'The faucet could not complete this request. Please try again later.',
    ], 500);
}