/**
 * Modern MEV Protection Service for Web3.js v2 (2025)
 * Follows Rust SDK architecture patterns
 */

import type { Address } from '@solana/addresses';
import type { Rpc, SolanaRpcApi } from '@solana/rpc';
import type { Commitment } from '@solana/rpc-types';
import type { KeyPairSigner } from '@solana/signers';

/**
 * MEV protection configuration
 */
export interface IMevProtectionConfig {
  usePrivateMempool: boolean;
  enableCommitReveal: boolean;
  fragmentTransaction: boolean;
  useDecoyTransactions: boolean;
  maxSlippage: number;
  priorityFee: bigint;
}

/**
 * MEV protection result
 */
export interface IMevProtectionResult {
  protected: boolean;
  strategy: string;
  estimatedSavings: bigint;
  protectionFee: bigint;
  signature: string;
}

/**
 * Transaction protection status
 */
export interface IProtectionStatus {
  transactionId: string;
  status: 'pending' | 'protected' | 'failed';
  mevDetected: boolean;
  frontRunAttempts: number;
  sandwichAttempts: number;
  protectionApplied: string[];
}

/**
 * Modern MEV Protection Service using Web3.js v2 patterns
 */
export class MevProtectionService {
  constructor(
    private readonly _rpc: Rpc<SolanaRpcApi>,
    private readonly _programId: Address,
    private readonly _commitment: Commitment = 'confirmed'
  ) {}

  /**
   * Apply MEV protection to a transaction
   */
  async protectTransaction(
    transaction: {
      instructions: Array<{
        programAddress: Address;
        accounts: Array<{ address: Address; role: number }>;
        data: Uint8Array;
      }>;
    },
    signer: KeyPairSigner,
    config: IMevProtectionConfig
  ): Promise<IMevProtectionResult> {
    try {
      console.log('🛡️ Applying MEV protection to transaction');

      // Analyze transaction for MEV risks
      const riskLevel = this.analyzeMevRisk(transaction);
      console.log(`📊 MEV Risk Level: ${riskLevel}`);

      // Apply protection strategies based on config
      const strategies = this.selectProtectionStrategies(config, riskLevel);
      console.log(`🔧 Protection Strategies: ${strategies.join(', ')}`);

      // Calculate protection fees
      const protectionFee = this.calculateProtectionFee(riskLevel, strategies);
      const estimatedSavings = this.estimateMevSavings(transaction, strategies);

      // Apply protection
      const protectedTransaction = await this.applyProtection(
        transaction,
        signer,
        strategies
      );

      // Execute protected transaction
      const signature = await this.executeProtectedTransaction(
        protectedTransaction,
        signer
      );

      console.log('✅ Transaction protected and executed:', signature);

      return {
        protected: true,
        strategy: strategies.join(' + '),
        estimatedSavings,
        protectionFee,
        signature,
      };
    } catch (error) {
      console.error('❌ MEV protection failed:', error);
      throw new Error(
        `MEV protection failed: ${error instanceof Error ? error.message : 'Unknown error'}`
      );
    }
  }

  /**
   * Monitor transaction for MEV attempts
   */
  async monitorTransaction(transactionId: string): Promise<IProtectionStatus> {
    try {
      console.log('👁️ Monitoring transaction for MEV:', transactionId);

      // Simulate monitoring
      await new Promise(resolve => setTimeout(resolve, 2000));

      // Mock MEV detection results
      const status: IProtectionStatus = {
        transactionId,
        status: 'protected',
        mevDetected: Math.random() > 0.7, // 30% chance of MEV detection
        frontRunAttempts: Math.floor(Math.random() * 3),
        sandwichAttempts: Math.floor(Math.random() * 2),
        protectionApplied: ['private-mempool', 'commit-reveal'],
      };

      console.log('📊 MEV Monitoring Result:', status);
      return status;
    } catch (error) {
      console.error('❌ MEV monitoring failed:', error);
      throw new Error(
        `MEV monitoring failed: ${error instanceof Error ? error.message : 'Unknown error'}`
      );
    }
  }

  /**
   * Get MEV protection statistics
   */
  async getProtectionStats(timeframe: '24h' | '7d' | '30d' = '24h'): Promise<{
    totalTransactions: number;
    protectedTransactions: number;
    mevBlocked: number;
    totalSavings: bigint;
    averageProtectionFee: bigint;
  }> {
    try {
      console.log(`📈 Getting MEV protection stats for ${timeframe}`);

      // Mock statistics based on timeframe
      const multiplier = timeframe === '24h' ? 1 : timeframe === '7d' ? 7 : 30;

      return {
        totalTransactions: 150 * multiplier,
        protectedTransactions: 142 * multiplier,
        mevBlocked: 18 * multiplier,
        totalSavings: BigInt(2500000 * multiplier), // in lamports
        averageProtectionFee: BigInt(5000), // in lamports
      };
    } catch (error) {
      console.error('❌ Failed to get protection stats:', error);
      throw new Error(
        `Stats retrieval failed: ${error instanceof Error ? error.message : 'Unknown error'}`
      );
    }
  }

  /**
   * Analyze MEV risk level for a transaction
   */
  private analyzeMevRisk(transaction: any): 'low' | 'medium' | 'high' {
    // Simplified risk analysis
    const instructionCount = transaction.instructions.length;
    
    if (instructionCount >= 5) return 'high';
    if (instructionCount >= 3) return 'medium';
    return 'low';
  }

  /**
   * Select protection strategies based on config and risk
   */
  private selectProtectionStrategies(
    config: IMevProtectionConfig,
    riskLevel: string
  ): string[] {
    const strategies: string[] = [];

    if (config.usePrivateMempool) strategies.push('private-mempool');
    if (config.enableCommitReveal) strategies.push('commit-reveal');
    if (config.fragmentTransaction && riskLevel !== 'low') strategies.push('fragmentation');
    if (config.useDecoyTransactions && riskLevel === 'high') strategies.push('decoy-transactions');

    // Always include priority fee protection
    strategies.push('priority-fee');

    return strategies;
  }

  /**
   * Calculate protection fee based on risk and strategies
   */
  private calculateProtectionFee(riskLevel: string, strategies: string[]): bigint {
    let baseFee = BigInt(5000); // Base fee in lamports

    // Risk level multiplier
    const riskMultiplier = riskLevel === 'high' ? 3 : riskLevel === 'medium' ? 2 : 1;
    baseFee = baseFee * BigInt(riskMultiplier);

    // Strategy fee
    const strategyFee = BigInt(strategies.length * 2000);

    return baseFee + strategyFee;
  }

  /**
   * Estimate MEV savings
   */
  private estimateMevSavings(_transaction: any, strategies: string[]): bigint {
    // Simplified savings calculation
    let savings = BigInt(0);

    if (strategies.includes('private-mempool')) savings += BigInt(15000);
    if (strategies.includes('commit-reveal')) savings += BigInt(25000);
    if (strategies.includes('fragmentation')) savings += BigInt(35000);
    if (strategies.includes('decoy-transactions')) savings += BigInt(45000);

    return savings;
  }

  /**
   * Apply protection to transaction
   */
  private async applyProtection(
    transaction: any,
    _signer: KeyPairSigner,
    strategies: string[]
  ): Promise<any> {
    console.log('🔧 Applying protection strategies:', strategies.join(', '));

    // Simulate protection application
    await new Promise(resolve => setTimeout(resolve, 1500));

    // Return modified transaction (mock)
    return {
      ...transaction,
      protected: true,
      strategies,
      timestamp: Date.now(),
    };
  }

  /**
   * Execute protected transaction
   */
  private async executeProtectedTransaction(
    _protectedTransaction: any,
    signer: KeyPairSigner
  ): Promise<string> {
    console.log('⚡ Executing protected transaction');

    // Simulate execution
    await new Promise(resolve => setTimeout(resolve, 2000));

    return `protected_sig_${Date.now()}_${signer.address.slice(0, 8)}`;
  }
}