using Microsoft.Extensions.Options;

namespace LittleShop.Services;

/// <summary>
/// Validates critical configuration settings on startup to prevent security issues
/// </summary>
public class ConfigurationValidationService
{
    private readonly IConfiguration _configuration;
    private readonly IWebHostEnvironment _environment;
    private readonly ILogger<ConfigurationValidationService> _logger;

    public ConfigurationValidationService(
        IConfiguration configuration,
        IWebHostEnvironment environment,
        ILogger<ConfigurationValidationService> logger)
    {
        _configuration = configuration;
        _environment = environment;
        _logger = logger;
    }

    /// <summary>
    /// Validates all critical configuration settings on startup
    /// Throws exceptions for security-critical misconfigurations
    /// </summary>
    public void ValidateConfiguration()
    {
        _logger.LogInformation("🔍 Validating application configuration...");

        // JWT validation is critical in production, optional in development/testing
        if (_environment.IsProduction() || !string.IsNullOrEmpty(_configuration["Jwt:Key"]))
        {
            ValidateJwtConfiguration();
        }
        else if (_environment.IsDevelopment())
        {
            _logger.LogWarning("⚠️ JWT validation skipped in development. Configure Jwt:Key for production readiness.");
        }

        ValidateSilverPayConfiguration();
        ValidateProductionSafeguards();
        ValidateEnvironmentConfiguration();

        _logger.LogInformation("✅ Configuration validation completed successfully");
    }

    private void ValidateJwtConfiguration()
    {
        var jwtKey = _configuration["Jwt:Key"];

        if (string.IsNullOrEmpty(jwtKey))
        {
            throw new InvalidOperationException("🚨 CRITICAL: JWT Key not configured. Set Jwt:Key in appsettings.json");
        }

        // Check for the old hardcoded key
        if (jwtKey.Contains("ThisIsASuperSecretKey"))
        {
            throw new InvalidOperationException("🚨 CRITICAL: Default JWT key detected. Generate a new secure key!");
        }

        // Require minimum key length for security
        if (jwtKey.Length < 32)
        {
            throw new InvalidOperationException("🚨 CRITICAL: JWT key too short. Must be at least 32 characters.");
        }

        _logger.LogInformation("✅ JWT configuration validated");
    }

    private void ValidateSilverPayConfiguration()
    {
        var baseUrl = _configuration["SilverPay:BaseUrl"];
        var apiKey = _configuration["SilverPay:ApiKey"];

        if (string.IsNullOrEmpty(baseUrl))
        {
            throw new InvalidOperationException("🚨 CRITICAL: SilverPay BaseUrl not configured");
        }

        if (string.IsNullOrEmpty(apiKey))
        {
            throw new InvalidOperationException("🚨 CRITICAL: SilverPay ApiKey not configured");
        }

        // Check for test/mock indicators in production
        if (_environment.IsProduction())
        {
            if (baseUrl.Contains("localhost") || baseUrl.Contains("127.0.0.1"))
            {
                throw new InvalidOperationException("🚨 CRITICAL: SilverPay configured with localhost in production!");
            }

            if (apiKey.Contains("test") || apiKey.Contains("mock") || apiKey.Contains("demo"))
            {
                _logger.LogWarning("⚠️ WARNING: SilverPay API key contains test/mock indicators in production");
            }
        }

        _logger.LogInformation("✅ SilverPay configuration validated");
    }

    private void ValidateProductionSafeguards()
    {
        // Ensure no mock services can be accidentally enabled
        var mockServiceConfig = _configuration.GetSection("SilverPay").GetChildren()
            .Where(x => x.Key.ToLower().Contains("mock") || x.Key.ToLower().Contains("test"))
            .ToList();

        if (mockServiceConfig.Any())
        {
            foreach (var config in mockServiceConfig)
            {
                _logger.LogWarning("⚠️ Found mock/test configuration: {Key} = {Value}", config.Key, config.Value);
            }
        }

        // In production, absolutely no mock configurations should exist
        if (_environment.IsProduction())
        {
            var useMockService = _configuration.GetValue<bool>("SilverPay:UseMockService", false);
            if (useMockService)
            {
                throw new InvalidOperationException("🚨 CRITICAL: Mock service enabled in production! Set SilverPay:UseMockService to false");
            }

            // Check for any configuration that might enable testing/mocking
            var dangerousConfigs = new[]
            {
                "Testing:Enabled",
                "Mock:Enabled",
                "Development:MockPayments",
                "Debug:MockServices"
            };

            foreach (var configKey in dangerousConfigs)
            {
                if (_configuration.GetValue<bool>(configKey, false))
                {
                    throw new InvalidOperationException($"🚨 CRITICAL: Dangerous test configuration enabled in production: {configKey}");
                }
            }
        }

        _logger.LogInformation("✅ Production safeguards validated");
    }

    private void ValidateEnvironmentConfiguration()
    {
        // Log current environment for verification
        _logger.LogInformation("🌍 Environment: {Environment}", _environment.EnvironmentName);

        // Validate database connection
        var connectionString = _configuration.GetConnectionString("DefaultConnection");
        if (string.IsNullOrEmpty(connectionString))
        {
            throw new InvalidOperationException("🚨 CRITICAL: Database connection string not configured");
        }

        // Check for development database in production
        if (_environment.IsProduction() && connectionString.Contains("littleshop.db"))
        {
            _logger.LogWarning("⚠️ WARNING: Using SQLite database in production. Consider PostgreSQL/SQL Server for production.");
        }

        _logger.LogInformation("✅ Environment configuration validated");
    }
}