# Configuration Package Documentation

## Overview

The configuration package provides a centralized configuration management system for the MEV Bot application. It handles loading configuration from YAML files, expanding environment variables, and validating configuration parameters.

## Core Components

### `Config` Structure

The main configuration structure contains all application settings:

1. **Arbitrum** - Arbitrum node configuration
2. **Bot** - Bot operational parameters
3. **Uniswap** - Uniswap protocol settings
4. **Log** - Logging configuration
5. **Database** - Database settings
6. **Ethereum** - Ethereum account configuration
7. **Contracts** - Smart contract addresses
8. **Arbitrage** - Arbitrage service configuration

### Configuration Loading

The package provides a `Load` function that:

1. Reads configuration from a YAML file
2. Expands environment variables in the configuration
3. Applies environment variable overrides
4. Returns a validated configuration structure

### Environment Variable Expansion

The package supports two formats for environment variable expansion:
- `${VARIABLE_NAME}` - Standard format
- `$VARIABLE_NAME` - Simplified format

When environment variables are not set, they expand to empty strings to prevent invalid YAML.

### Environment Variable Overrides

The package provides automatic overrides for key configuration parameters through environment variables:

- **ARBITRUM_RPC_ENDPOINT** - Primary RPC endpoint
- **ARBITRUM_WS_ENDPOINT** - WebSocket endpoint
- **ARBITRUM_FALLBACK_ENDPOINTS** - Comma-separated fallback endpoints
- **RPC_REQUESTS_PER_SECOND** - Rate limit requests per second
- **RPC_MAX_CONCURRENT** - Maximum concurrent requests
- **BOT_MAX_WORKERS** - Maximum bot workers
- **BOT_CHANNEL_BUFFER_SIZE** - Channel buffer size
- **ETHEREUM_PRIVATE_KEY** - Private key for transactions
- **ETHEREUM_ACCOUNT_ADDRESS** - Account address
- **ETHEREUM_GAS_PRICE_MULTIPLIER** - Gas price multiplier
- **CONTRACT_ARBITRAGE_EXECUTOR** - Arbitrage executor contract
- **CONTRACT_FLASH_SWAPPER** - Flash swapper contract

## Configuration Structures

### `ArbitrumConfig`
- **RPCEndpoint** - Primary RPC endpoint URL
- **WSEndpoint** - WebSocket endpoint URL
- **ChainID** - Chain identifier (42161 for Arbitrum)
- **RateLimit** - Rate limiting configuration
- **FallbackEndpoints** - List of fallback RPC endpoints

### `EndpointConfig`
- **URL** - RPC endpoint URL
- **RateLimit** - Rate limiting for this endpoint

### `RateLimitConfig`
- **RequestsPerSecond** - Maximum requests per second
- **MaxConcurrent** - Maximum concurrent requests
- **Burst** - Burst size for rate limiting

### `BotConfig`
- **Enabled** - Enable/disable bot
- **PollingInterval** - Polling interval in seconds
- **MinProfitThreshold** - Minimum profit threshold in USD
- **GasPriceMultiplier** - Gas price multiplier
- **MaxWorkers** - Maximum concurrent workers
- **ChannelBufferSize** - Channel buffer size
- **RPCTimeout** - RPC call timeout in seconds

### `UniswapConfig`
- **FactoryAddress** - Uniswap factory contract address
- **PositionManagerAddress** - Position manager address
- **FeeTiers** - Supported fee tiers
- **Cache** - Cache configuration

### `CacheConfig`
- **Enabled** - Enable/disable caching
- **Expiration** - Cache expiration in seconds
- **MaxSize** - Maximum cache size

### `LogConfig`
- **Level** - Log level (debug, info, warn, error)
- **Format** - Log format (json, text)
- **File** - Log file path

### `DatabaseConfig`
- **File** - Database file path
- **MaxOpenConnections** - Maximum open connections
- **MaxIdleConnections** - Maximum idle connections

### `EthereumConfig`
- **PrivateKey** - Private key for transactions
- **AccountAddress** - Account address
- **GasPriceMultiplier** - Gas price multiplier

### `ContractsConfig`
- **ArbitrageExecutor** - Arbitrage executor contract address
- **FlashSwapper** - Flash swapper contract address
- **AuthorizedCallers** - Authorized caller addresses
- **AuthorizedDEXes** - Authorized DEX addresses

### `ArbitrageConfig`
- **Enabled** - Enable/disable arbitrage service
- **ArbitrageContractAddress** - Arbitrage contract address
- **FlashSwapContractAddress** - Flash swap contract address
- **MinProfitWei** - Minimum profit in wei
- **MinROIPercent** - Minimum ROI percentage
- **MinSignificantSwapSize** - Minimum significant swap size
- **SlippageTolerance** - Slippage tolerance
- **MinScanAmountWei** - Minimum scan amount in wei
- **MaxScanAmountWei** - Maximum scan amount in wei
- **MaxGasPriceWei** - Maximum gas price in wei
- **MaxConcurrentExecutions** - Maximum concurrent executions
- **MaxOpportunitiesPerEvent** - Maximum opportunities per event
- **OpportunityTTL** - Opportunity time-to-live
- **MaxPathAge** - Maximum path age
- **StatsUpdateInterval** - Statistics update interval
- **PoolDiscoveryConfig** - Pool discovery configuration

### `PoolDiscoveryConfig`
- **Enabled** - Enable/disable pool discovery
- **BlockRange** - Block range for scanning
- **PollingInterval** - Polling interval
- **FactoryAddresses** - DEX factory addresses
- **MinLiquidityWei** - Minimum liquidity threshold
- **CacheSize** - Cache size
- **CacheTTL** - Cache time-to-live

## Functions

### `Load(filename string) (*Config, error)`
Loads configuration from a YAML file:
1. Reads the file
2. Expands environment variables
3. Parses YAML
4. Applies environment variable overrides
5. Returns validated configuration

### `expandEnvVars(s string) string`
Expands environment variables in a string using regex pattern matching.

### `OverrideWithEnv()`
Applies environment variable overrides to the configuration.

### `ValidateEnvironmentVariables() error`
Validates all required environment variables:
- Checks for required variables
- Validates RPC endpoint URLs
- Validates numeric values
- Ensures proper formatting

### `validateRPCEndpoint(endpoint string) error`
Validates RPC endpoint URLs:
- Checks for valid schemes (http, https, ws, wss)
- Validates hostname
- Restricts localhost in production
- Prevents empty endpoints

## Security Features

### Environment Variable Validation
- Validates all required environment variables
- Checks RPC endpoint URL formats
- Ensures proper numeric value ranges
- Prevents invalid configuration states

### RPC Endpoint Security
- Validates URL schemes
- Restricts localhost usage in production
- Checks for valid hostnames
- Prevents empty endpoints

### Private Key Protection
- Ensures private key is provided
- Validates account address format
- Prevents empty private key values

## Best Practices

### Configuration Management
1. Use environment-specific configuration files
2. Store sensitive data in environment variables
3. Validate configuration at startup
4. Document all configuration parameters
5. Provide sensible defaults

### Security
1. Never store private keys in configuration files
2. Use secure RPC endpoints (https, wss)
3. Validate all external inputs
4. Restrict localhost usage in production
5. Regularly audit configuration access

### Performance
1. Tune rate limiting based on provider limits
2. Adjust worker pool sizes for hardware
3. Optimize cache settings for memory usage
4. Monitor resource utilization
5. Scale configuration with network conditions

## Error Handling

### Configuration Loading Errors
- File read failures
- YAML parsing errors
- Environment variable expansion issues
- Validation failures

### Validation Errors
- Missing required variables
- Invalid URL formats
- Out-of-range numeric values
- Empty required fields

## Testing

### Unit Tests
- Configuration loading and parsing
- Environment variable expansion
- Validation logic
- Override functionality

### Integration Tests
- End-to-end configuration loading
- Environment variable integration
- Security validation
- Performance testing

## Future Improvements

### Enhanced Features
1. Configuration hot reloading
2. Remote configuration sources
3. Configuration versioning
4. Advanced validation rules
5. Configuration migration tools

### Security Enhancements
1. Encrypted configuration values
2. Configuration signing and verification
3. Role-based configuration access
4. Audit logging for configuration changes
5. Secure configuration distribution