fengling-risk-control/Fengling.RiskControl.Client/Evaluation/RiskEvaluator.cs

using Fengling.RiskControl.Domain.Aggregates.RiskRules;
using Fengling.RiskControl.Configuration;
using Fengling.RiskControl.Counter;
using Fengling.RiskControl.Rules;
using Microsoft.Extensions.Logging;

namespace Fengling.RiskControl.Evaluation;

public interface IRiskEvaluator
{
    Task<RiskEvaluationResult> EvaluateAsync(RiskEvaluationRequest request);
    Task<bool> IsAllowedAsync(RiskEvaluationRequest request);
}

public class RiskEvaluator : IRiskEvaluator
{
    private readonly IRuleLoader _ruleLoader;
    private readonly IRiskCounterService _counterService;
    private readonly RiskControlClientOptions _options;
    private readonly ILogger<RiskEvaluator> _logger;

    public RiskEvaluator(
        IRuleLoader ruleLoader,
        IRiskCounterService counterService,
        RiskControlClientOptions options,
        ILogger<RiskEvaluator> logger)
    {
        _ruleLoader = ruleLoader;
        _counterService = counterService;
        _options = options;
        _logger = logger;
    }

    public async Task<RiskEvaluationResult> EvaluateAsync(RiskEvaluationRequest request)
    {
        var rules = await _ruleLoader.GetActiveRulesAsync();
        var factors = new List<RiskFactorResult>();
        var totalScore = 0;

        foreach (var rule in rules)
        {
            var factor = await EvaluateRuleAsync(rule, request);
            if (factor != null)
            {
                factors.Add(factor);
                totalScore += factor.Points;
            }
        }

        var riskLevel = DetermineRiskLevel(totalScore);
        var recommendedAction = DetermineAction(riskLevel);
        var blocked = recommendedAction == RiskRuleAction.Block;

        return new RiskEvaluationResult
        {
            TotalScore = totalScore,
            RiskLevel = riskLevel,
            RecommendedAction = recommendedAction,
            Blocked = blocked,
            Message = blocked ? "操作被风险控制系统拒绝" : "操作已通过风险评估",
            Factors = factors,
            EvaluatedAt = DateTime.UtcNow
        };
    }

    public Task<bool> IsAllowedAsync(RiskEvaluationRequest request)
    {
        return EvaluateAsync(request).ContinueWith(t => !t.Result.Blocked);
    }

    private async Task<RiskFactorResult?> EvaluateRuleAsync(RiskRule rule, RiskEvaluationRequest request)
    {
        return rule.RuleType switch
        {
            RiskRuleType.FrequencyLimit => await EvaluateFrequencyLimitAsync(rule, request),
            RiskRuleType.AmountLimit => EvaluateAmountLimit(rule, request),
            RiskRuleType.Blacklist => EvaluateBlacklist(rule, request),
            RiskRuleType.DeviceFingerprint => EvaluateDeviceFingerprint(rule, request),
            RiskRuleType.VelocityCheck => EvaluateVelocityCheck(rule, request),
            _ => null
        };
    }

    private async Task<RiskFactorResult?> EvaluateFrequencyLimitAsync(RiskRule rule, RiskEvaluationRequest request)
    {
        var config = rule.GetConfig<FrequencyLimitConfig>();
        if (config == null)
        {
            _logger.LogWarning("Rule {RuleId} has invalid FrequencyLimitConfig", rule.Id);
            return null;
        }

        var metricKey = $"{request.EventType.ToLower()}_count";
        var currentCount = await _counterService.GetValueAsync(request.MemberId, metricKey);
        var limit = config.MaxCount;

        if (currentCount >= limit)
        {
                    return new RiskFactorResult
                    {
                        RuleName = rule.Name,
                        RuleType = rule.RuleType.ToString(),
                        Points = rule.Priority,
                        Detail = $"已超过{request.EventType}次数限制({currentCount}/{limit})"
                    };
        }

        await _counterService.IncrementAsync(request.MemberId, metricKey);

        return null;
    }

    private RiskFactorResult? EvaluateAmountLimit(RiskRule rule, RiskEvaluationRequest request)
    {
        if (!request.Amount.HasValue)
            return null;

        var config = rule.GetConfig<AmountLimitConfig>();
        if (config == null)
            return null;

        var metricKey = $"{request.EventType.ToLower()}_amount";
        var currentAmount = _counterService.GetValueAsync(request.MemberId, metricKey).GetAwaiter().GetResult();

        if (currentAmount + request.Amount.Value > config.MaxAmount)
        {
            return new RiskFactorResult
            {
                RuleName = rule.Name,
                RuleType = rule.RuleType.ToString(),
                Points = rule.Priority,
                Detail = $"已超过{request.EventType}金额限制({currentAmount + request.Amount.Value}/{config.MaxAmount})"
            };
        }

        _counterService.IncrementAsync(request.MemberId, metricKey, request.Amount.Value).GetAwaiter().GetResult();

        return null;
    }

    private RiskFactorResult? EvaluateBlacklist(RiskRule rule, RiskEvaluationRequest request)
    {
        var config = rule.GetConfig<BlacklistConfig>();
        if (config == null)
            return null;

        var memberValues = _counterService.GetAllValuesAsync(request.MemberId).GetAwaiter().GetResult();

        if (memberValues.TryGetValue("is_blacklisted", out var isBlacklisted) && isBlacklisted == 1)
        {
            return new RiskFactorResult
            {
                RuleName = rule.Name,
                RuleType = rule.RuleType.ToString(),
                Points = rule.Priority,
                Detail = "用户已被加入黑名单"
            };
        }

        return null;
    }

    private RiskFactorResult? EvaluateDeviceFingerprint(RiskRule rule, RiskEvaluationRequest request)
    {
        if (string.IsNullOrEmpty(request.DeviceFingerprint))
            return null;

        var config = rule.GetConfig<DeviceFingerprintConfig>();
        if (config == null)
            return null;

        return null;
    }

    private RiskFactorResult? EvaluateVelocityCheck(RiskRule rule, RiskEvaluationRequest request)
    {
        var config = rule.GetConfig<VelocityCheckConfig>();
        if (config == null)
            return null;

        return null;
    }

    private RiskLevel DetermineRiskLevel(int totalScore)
    {
        if (totalScore >= _options.Evaluation.HighRiskThreshold)
            return RiskLevel.High;
        if (totalScore >= _options.Evaluation.MediumRiskThreshold)
            return RiskLevel.Medium;
        return RiskLevel.Low;
    }

    private RiskRuleAction DetermineAction(RiskLevel riskLevel)
    {
        return riskLevel switch
        {
            RiskLevel.High => RiskRuleAction.Block,
            RiskLevel.Medium => RiskRuleAction.RequireVerification,
            _ => RiskRuleAction.Allow
        };
    }
}

public class FrequencyLimitConfig
{
    public int MaxCount { get; set; } = 10;
    public string TimeWindow { get; set; } = "Day";
}

public class AmountLimitConfig
{
    public int MaxAmount { get; set; } = 1000;
}

public class BlacklistConfig
{
    public List<string> BlockedMembers { get; set; } = new();
}

public class DeviceFingerprintConfig
{
    public int MaxAccountsPerDevice { get; set; } = 3;
}

public class VelocityCheckConfig
{
    public int MaxRequestsPerMinute { get; set; } = 100;
}