<?php

declare(strict_types=1);

namespace Drupal\safe_smart_accounts\Service;

use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\Logger\LoggerChannelFactoryInterface;
use Drupal\Core\Logger\LoggerChannelInterface;

/**
 * Service for blockchain interactions related to Safe Smart Accounts.
 *
 * This service handles direct blockchain operations like deploying Safes,
 * submitting transactions, and monitoring transaction status.
 * In Phase 1 (MVP), it uses mock implementations.
 * In Phase 2, it will integrate with actual blockchain via web3p/web3.php.
 */
class SafeBlockchainService {

  /**
   * The config factory.
   *
   * @var \Drupal\Core\Config\ConfigFactoryInterface
   */
  protected ConfigFactoryInterface $configFactory;

  /**
   * The logger channel.
   *
   * @var \Drupal\Core\Logger\LoggerChannelInterface
   */
  protected LoggerChannelInterface $logger;

  /**
   * Constructs a SafeBlockchainService object.
   *
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The config factory.
   * @param \Drupal\Core\Logger\LoggerChannelFactoryInterface $logger_factory
   *   The logger factory.
   */
  public function __construct(
    ConfigFactoryInterface $config_factory,
    LoggerChannelFactoryInterface $logger_factory,
  ) {
    $this->configFactory = $config_factory;
    $this->logger = $logger_factory->get('safe_smart_accounts');
  }

  /**
   * Gets the network configuration for the specified network.
   *
   * @param string $network
   *   The network identifier.
   *
   * @return array|null
   *   Network configuration or NULL if not found.
   */
  protected function getNetworkConfig(string $network): ?array {
    $config = $this->configFactory->get('safe_smart_accounts.settings');
    $network_config = $config->get("network.{$network}");

    if (!$network_config || empty($network_config['enabled'])) {
      return NULL;
    }

    return $network_config;
  }

  /**
   * Generates the setup data for a Safe contract.
   *
   * @param array $owners
   *   Array of owner addresses.
   * @param int $threshold
   *   Threshold for required signatures.
   * @param string $fallback_handler
   *   Fallback handler address.
   *
   * @return string
   *   Encoded setup data.
   */
  protected function encodeSafeSetupData(array $owners, int $threshold, string $fallback_handler): string {
    // Safe contract ABI for setup function.
    $abi = [
      'name' => 'setup',
      'type' => 'function',
      'inputs' => [
        ['name' => '_owners', 'type' => 'address[]'],
        ['name' => '_threshold', 'type' => 'uint256'],
        ['name' => 'to', 'type' => 'address'],
        ['name' => 'data', 'type' => 'bytes'],
        ['name' => 'fallbackHandler', 'type' => 'address'],
        ['name' => 'paymentToken', 'type' => 'address'],
        ['name' => 'payment', 'type' => 'uint256'],
        ['name' => 'paymentReceiver', 'type' => 'address'],
      ],
      'outputs' => [],
    ];

    // Parameters for the setup call.
    $params = [
    // _owners: Array of owner addresses
      $owners,
    // _threshold: Number of required signatures
      $threshold,
    // to: Address for optional setup call (none)
      '0x00000000',
    // data: Data for optional setup call (none)
      '0x',
    // fallbackHandler: Handles unknown calls.
      $fallback_handler,
    // paymentToken: Token for deployment payment (none)
      '0x00000000000000000000',
    // payment: Amount to pay for deployment (0)
      '0',
    // paymentReceiver: Who receives payment (none)
      '0x000000000000000000',
    ];

    // Create a contract instance to encode the function call.
    $contract = new Contract('http://dummy', '');
    $encoded_data = $contract->encodeFunctionCall($abi, $params);
    return $encoded_data;
  }

  /**
   * Deploys a new Safe Smart Account to the blockchain.
   *
   * @param array $safe_config
   *   Safe configuration parameters.
   * @param string $network
   *   The network identifier.
   *
   * @return array|null
   *   Deployment result with transaction hash and Safe address,
   *   or NULL on failure.
   */
  public function deploySafe(array $safe_config, string $network = 'sepolia'): ?array {
    // Phase 1: Mock implementation.
    if ($this->isMockMode()) {
      return $this->getMockSafeDeployment($safe_config, $network);
    }

    // Phase 2: Real blockchain implementation.
    try {
      $config = $this->configFactory->get('safe_smart_accounts.settings');
      $rpc_url = $config->get("network.{$network}.rpc_url");

      if (!$rpc_url) {
        $this->logger->error('No RPC URL configured for network: @network', [
          '@network' => $network,
        ]);
        return NULL;
      }

      // @todo Phase 2 implementation will:
      // 1. Connect to Ethereum RPC using web3p/web3.php
      // 2. Create Safe proxy deployment transaction
      // 3. Submit transaction to network
      // 4. Return transaction hash and predicted Safe address.
      $this->logger->info('Real Safe deployment not yet implemented - using mock for Phase 1');
      return $this->getMockSafeDeployment($safe_config, $network);

    }
    catch (\Exception $e) {
      $this->logger->error('Failed to deploy Safe: @message', [
        '@message' => $e->getMessage(),
      ]);
    }

    return NULL;
  }

  /**
   * Submits a Safe transaction to the blockchain.
   *
   * @param string $safe_address
   *   The Safe Smart Account address.
   * @param array $transaction_data
   *   Transaction data including signatures.
   * @param string $network
   *   The network identifier.
   *
   * @return array|null
   *   Transaction submission result or NULL on failure.
   */
  public function submitTransaction(string $safe_address, array $transaction_data, string $network = 'sepolia'): ?array {
    // Phase 1: Mock implementation.
    if ($this->isMockMode()) {
      return $this->getMockTransactionSubmission($safe_address, $transaction_data, $network);
    }

    // Phase 2: Real blockchain implementation.
    try {
      $config = $this->configFactory->get('safe_smart_accounts.settings');
      $rpc_url = $config->get("network.{$network}.rpc_url");

      if (!$rpc_url) {
        return NULL;
      }

      // @todo Phase 2 implementation will:
      // 1. Connect to Ethereum RPC
      // 2. Build execTransaction call data
      // 3. Submit transaction to network
      // 4. Return transaction hash.
      $this->logger->info('Real transaction submission not yet implemented - using mock for Phase 1');
      return $this->getMockTransactionSubmission($safe_address, $transaction_data, $network);

    }
    catch (\Exception $e) {
      $this->logger->error('Failed to submit Safe transaction: @message', [
        '@message' => $e->getMessage(),
      ]);
    }

    return NULL;
  }

  /**
   * Gets the transaction status from the blockchain.
   *
   * @param string $transaction_hash
   *   The blockchain transaction hash.
   * @param string $network
   *   The network identifier.
   *
   * @return array|null
   *   Transaction status data or NULL on failure.
   */
  public function getTransactionStatus(string $transaction_hash, string $network = 'sepolia'): ?array {
    // Phase 1: Mock implementation.
    if ($this->isMockMode()) {
      return $this->getMockTransactionStatus($transaction_hash, $network);
    }

    // Phase 2: Real blockchain implementation.
    try {
      $config = $this->configFactory->get('safe_smart_accounts.settings');
      $rpc_url = $config->get("network.{$network}.rpc_url");

      if (!$rpc_url) {
        return NULL;
      }

      // @todo Phase 2 implementation will:
      // 1. Connect to Ethereum RPC
      // 2. Get transaction receipt
      // 3. Parse transaction logs
      // 4. Return status, confirmations, gas used, etc.
      return $this->getMockTransactionStatus($transaction_hash, $network);

    }
    catch (\Exception $e) {
      $this->logger->error('Failed to get transaction status: @message', [
        '@message' => $e->getMessage(),
      ]);
    }

    return NULL;
  }

  /**
   * Validates Safe signatures for a transaction.
   *
   * @param string $safe_address
   *   The Safe Smart Account address.
   * @param array $transaction_data
   *   The transaction data.
   * @param array $signatures
   *   Array of signatures to validate.
   * @param string $network
   *   The network identifier.
   *
   * @return bool
   *   TRUE if signatures are valid, FALSE otherwise.
   */
  public function validateSignatures(string $safe_address, array $transaction_data, array $signatures, string $network = 'sepolia'): bool {
    // Phase 1: Mock implementation - always return TRUE for testing.
    if ($this->isMockMode()) {
      $this->logger->debug('Mock signature validation - assuming valid signatures');
      return TRUE;
    }

    // Phase 2: Real implementation will:
    // 1. Recover signer addresses from signatures
    // 2. Check if signers are Safe owners
    // 3. Validate signature format and content
    // 4. Check if enough signatures for threshold.
    return FALSE;
  }

  /**
   * Gets Safe configuration from the blockchain.
   *
   * @param string $safe_address
   *   The Safe Smart Account address.
   * @param string $network
   *   The network identifier.
   *
   * @return array|null
   *   Safe configuration data or NULL on failure.
   */
  public function getSafeConfiguration(string $safe_address, string $network = 'sepolia'): ?array {
    // Phase 1: Mock implementation.
    if ($this->isMockMode()) {
      return $this->getMockSafeConfiguration($safe_address, $network);
    }

    // Phase 2: Real blockchain implementation.
    try {
      $config = $this->configFactory->get('safe_smart_accounts.settings');
      $rpc_url = $config->get("network.{$network}.rpc_url");

      if (!$rpc_url) {
        return NULL;
      }

      // @todo Phase 2 implementation will:
      // 1. Connect to Ethereum RPC
      // 2. Call Safe contract methods (getOwners, getThreshold, etc.)
      // 3. Return current on-chain configuration.
      return $this->getMockSafeConfiguration($safe_address, $network);

    }
    catch (\Exception $e) {
      $this->logger->error('Failed to get Safe configuration: @message', [
        '@message' => $e->getMessage(),
      ]);
    }

    return NULL;
  }

  /**
   * Estimates gas for a Safe transaction.
   *
   * @param string $safe_address
   *   The Safe Smart Account address.
   * @param array $transaction_data
   *   The transaction data.
   * @param string $network
   *   The network identifier.
   *
   * @return int|null
   *   Estimated gas limit or NULL on failure.
   */
  public function estimateGas(string $safe_address, array $transaction_data, string $network = 'sepolia'): ?int {
    // Phase 1: Mock implementation.
    if ($this->isMockMode()) {
      return $this->calculateMockGasEstimate($transaction_data);
    }

    // Phase 2: Real blockchain implementation.
    return NULL;
  }

  /**
   * Checks if the service is in mock mode.
   *
   * @return bool
   *   TRUE if in mock mode, FALSE otherwise.
   */
  protected function isMockMode(): bool {
    $config = $this->configFactory->get('safe_smart_accounts.settings');
    // Default to mock mode in MVP.
    return $config->get('blockchain.mock_mode') ?? TRUE;
  }

  /**
   * Provides mock Safe deployment result.
   *
   * @param array $safe_config
   *   Safe configuration.
   * @param string $network
   *   Network identifier.
   *
   * @return array
   *   Mock deployment result.
   */
  protected function getMockSafeDeployment(array $safe_config, string $network): array {
    // Generate a mock Safe address.
    $mock_safe_address = '0x' . bin2hex(random_bytes(20));
    $mock_tx_hash = '0x' . bin2hex(random_bytes(32));

    $this->logger->info('Mock Safe deployment: address @address, tx @tx', [
      '@address' => $mock_safe_address,
      '@tx' => $mock_tx_hash,
    ]);

    return [
      'safe_address' => $mock_safe_address,
      'transaction_hash' => $mock_tx_hash,
      'network' => $network,
      'status' => 'pending',
      'block_number' => NULL,
      'gas_used' => NULL,
      // Mock cost in ETH.
      'deployment_cost' => '0.001',
    ];
  }

  /**
   * Provides mock transaction submission result.
   *
   * @param string $safe_address
   *   Safe address.
   * @param array $transaction_data
   *   Transaction data.
   * @param string $network
   *   Network identifier.
   *
   * @return array
   *   Mock submission result.
   */
  protected function getMockTransactionSubmission(string $safe_address, array $transaction_data, string $network): array {
    $mock_tx_hash = '0x' . bin2hex(random_bytes(32));

    return [
      'transaction_hash' => $mock_tx_hash,
      'safe_address' => $safe_address,
      'status' => 'pending',
      'network' => $network,
      'submitted_at' => time(),
    ];
  }

  /**
   * Provides mock transaction status.
   *
   * @param string $transaction_hash
   *   Transaction hash.
   * @param string $network
   *   Network identifier.
   *
   * @return array
   *   Mock transaction status.
   */
  protected function getMockTransactionStatus(string $transaction_hash, string $network): array {
    // Simulate different statuses based on hash.
    $statuses = ['pending', 'confirmed', 'failed'];
    $status_index = crc32($transaction_hash) % count($statuses);
    $status = $statuses[$status_index];

    $result = [
      'transaction_hash' => $transaction_hash,
      'status' => $status,
      'network' => $network,
      'confirmations' => 0,
    ];

    if ($status === 'confirmed') {
      $result['confirmations'] = 12;
      $result['block_number'] = 5000000 + (crc32($transaction_hash) % 1000);
      $result['gas_used'] = 21000 + (abs(crc32($transaction_hash)) % 50000);
      $result['block_hash'] = '0x' . bin2hex(random_bytes(32));
    }
    elseif ($status === 'failed') {
      $result['error'] = 'Transaction reverted';
      $result['gas_used'] = 21000;
    }

    return $result;
  }

  /**
   * Provides mock Safe configuration.
   *
   * @param string $safe_address
   *   Safe address.
   * @param string $network
   *   Network identifier.
   *
   * @return array
   *   Mock Safe configuration.
   */
  protected function getMockSafeConfiguration(string $safe_address, string $network): array {
    return [
      'address' => $safe_address,
      'owners' => [
        '0x1234567890123456789012345678901234567890',
        '0x0987654321098765432109876543210987654321',
      ],
      'threshold' => 1,
      'nonce' => 0,
      'version' => '1.4.1',
      'master_copy' => '0xd9Db270c1B5E3Bd161E8c8503c55cEABeE709552',
      'fallback_handler' => '0xf48f2B2d2a534e402487b3ee7C18c33Aec0Fe5e4',
      'modules' => [],
      'network' => $network,
    ];
  }

  /**
   * Calculates mock gas estimate.
   *
   * @param array $transaction_data
   *   Transaction data.
   *
   * @return int
   *   Mock gas estimate.
   */
  protected function calculateMockGasEstimate(array $transaction_data): int {
    // Base transaction cost.
    $base_gas = 21000;
    // Safe execution overhead.
    $safe_overhead = 60000;

    // Add gas for data.
    $data = $transaction_data['data'] ?? '0x';
    // 16 gas per byte
    $data_gas = (strlen($data) - 2) / 2 * 16;

    return (int) ($base_gas + $safe_overhead + $data_gas);
  }

}
