telecom-platform/apps/api-server/internal/handlers/security_handlers.go

package handlers

import (
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
)

// SecurityHandler handles security-related HTTP requests
type SecurityHandler struct{}

// NewSecurityHandler creates a new security handler
func NewSecurityHandler() *SecurityHandler {
	return &SecurityHandler{}
}

// FraudAlert represents a fraud alert
type FraudAlert struct {
	ID           string         `json:"id"`
	Type         string         `json:"type"`
	Severity     string         `json:"severity"`
	ProfileID    string         `json:"profile_id"`
	Description  string         `json:"description"`
	RiskScore    float64        `json:"risk_score"`
	Evidence     []string       `json:"evidence"`
	IPAddress    string         `json:"ip_address"`
	Timestamp    time.Time      `json:"timestamp"`
	Status       string         `json:"status"`
	ActionsTaken []string       `json:"actions_taken"`
	Metadata     map[string]any `json:"metadata"`
}

// FraudMetrics represents fraud detection metrics
type FraudMetrics struct {
	Period            string           `json:"period"`
	TotalAlerts       int64            `json:"total_alerts"`
	ResolvedAlerts    int64            `json:"resolved_alerts"`
	FalsePositives    int64            `json:"false_positives"`
	ResolutionRate    float64          `json:"resolution_rate_pct"`
	FalsePositiveRate float64          `json:"false_positive_rate_pct"`
	ByType            map[string]int64 `json:"by_type"`
	BySeverity        map[string]int64 `json:"by_severity"`
	GeneratedAt       time.Time        `json:"generated_at"`
}

// AnalyzeTransaction analyzes a transaction for fraud
func (h *SecurityHandler) AnalyzeTransaction(c *gin.Context) {
	var req map[string]any
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	profileID, _ := req["profile_id"].(string)
	ipAddress, _ := req["ip_address"].(string)

	// Simulated fraud analysis
	riskScore := 25.0 // Low risk by default

	// Check for suspicious patterns
	if amount, ok := req["amount"].(float64); ok && amount > 1000 {
		riskScore += 20
	}

	alert := FraudAlert{
		ID:          "alert-" + time.Now().Format("20060102150405"),
		Type:        "transaction_analysis",
		Severity:    getSeverityFromScore(riskScore),
		ProfileID:   profileID,
		Description: "Transaction analyzed for fraud indicators",
		RiskScore:   riskScore,
		Evidence: []string{
			"Transaction amount within normal range",
			"IP address matches historical pattern",
			"Device fingerprint recognized",
		},
		IPAddress:    ipAddress,
		Timestamp:    time.Now(),
		Status:       "analyzed",
		ActionsTaken: []string{"Logged for monitoring"},
		Metadata:     req,
	}

	c.JSON(http.StatusOK, alert)
}

// GetFraudAlerts returns fraud alerts with filtering
func (h *SecurityHandler) GetFraudAlerts(c *gin.Context) {
	var filter struct {
		Type     string `json:"type"`
		Severity string `json:"severity"`
		Status   string `json:"status"`
		Limit    int    `json:"limit"`
	}
	c.ShouldBindJSON(&filter)

	if filter.Limit == 0 || filter.Limit > 100 {
		filter.Limit = 50
	}

	// Simulated alerts
	alerts := []FraudAlert{
		{
			ID:          "alert-001",
			Type:        "account_takeover",
			Severity:    "high",
			ProfileID:   "profile-123",
			Description: "Multiple failed login attempts from new IP",
			RiskScore:   85.0,
			Evidence:    []string{"10 failed logins", "New IP address", "Different country"},
			IPAddress:   "192.168.1.100",
			Timestamp:   time.Now().Add(-2 * time.Hour),
			Status:      "new",
		},
		{
			ID:          "alert-002",
			Type:        "payment_fraud",
			Severity:    "medium",
			ProfileID:   "profile-456",
			Description: "Unusual payment pattern detected",
			RiskScore:   55.0,
			Evidence:    []string{"Large transaction", "New payment method"},
			IPAddress:   "10.0.0.50",
			Timestamp:   time.Now().Add(-5 * time.Hour),
			Status:      "investigating",
		},
		{
			ID:          "alert-003",
			Type:        "sim_swap",
			Severity:    "critical",
			ProfileID:   "profile-789",
			Description: "SIM swap attempt detected",
			RiskScore:   95.0,
			Evidence:    []string{"SIM change request", "No prior notification", "High-value account"},
			IPAddress:   "172.16.0.25",
			Timestamp:   time.Now().Add(-30 * time.Minute),
			Status:      "blocked",
		},
	}

	// Filter alerts
	filtered := make([]FraudAlert, 0)
	for _, alert := range alerts {
		if filter.Type != "" && alert.Type != filter.Type {
			continue
		}
		if filter.Severity != "" && alert.Severity != filter.Severity {
			continue
		}
		if filter.Status != "" && alert.Status != filter.Status {
			continue
		}
		filtered = append(filtered, alert)
		if len(filtered) >= filter.Limit {
			break
		}
	}

	c.JSON(http.StatusOK, filtered)
}

// UpdateAlertStatus updates a fraud alert status
func (h *SecurityHandler) UpdateAlertStatus(c *gin.Context) {
	alertID := c.Param("id")

	var req struct {
		Status  string   `json:"status" binding:"required"`
		Actions []string `json:"actions"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"id":            alertID,
		"status":        req.Status,
		"actions_taken": req.Actions,
		"updated_at":    time.Now(),
	})
}

// GetFraudMetrics returns fraud detection metrics
func (h *SecurityHandler) GetFraudMetrics(c *gin.Context) {
	period := c.DefaultQuery("period", "monthly")

	metrics := FraudMetrics{
		Period:            period,
		TotalAlerts:       1250,
		ResolvedAlerts:    1100,
		FalsePositives:    125,
		ResolutionRate:    88.0,
		FalsePositiveRate: 10.0,
		ByType: map[string]int64{
			"account_takeover":   350,
			"subscription_fraud": 200,
			"payment_fraud":      400,
			"usage_anomaly":      200,
			"sim_swap":           100,
		},
		BySeverity: map[string]int64{
			"low":      400,
			"medium":   500,
			"high":     250,
			"critical": 100,
		},
		GeneratedAt: time.Now(),
	}

	c.JSON(http.StatusOK, metrics)
}

// GetFraudPatterns returns detected fraud patterns
func (h *SecurityHandler) GetFraudPatterns(c *gin.Context) {
	patterns := []map[string]any{
		{
			"id":          "pattern-1",
			"name":        "Velocity Attack",
			"description": "Multiple rapid transactions from same source",
			"frequency":   "high",
			"indicators":  []string{"High transaction rate", "Same IP", "Different accounts"},
			"mitigation":  "Rate limiting, IP blocking",
		},
		{
			"id":          "pattern-2",
			"name":        "Account Enumeration",
			"description": "Systematic probing of account existence",
			"frequency":   "medium",
			"indicators":  []string{"Sequential account checks", "Automated requests"},
			"mitigation":  "CAPTCHA, rate limiting",
		},
		{
			"id":          "pattern-3",
			"name":        "SIM Swap Attack",
			"description": "Unauthorized SIM card replacement",
			"frequency":   "low",
			"indicators":  []string{"Sudden SIM change", "No customer contact", "High-value target"},
			"mitigation":  "Multi-factor verification, cooling period",
		},
	}

	c.JSON(http.StatusOK, gin.H{"patterns": patterns})
}

// VerifySIMSwap verifies a SIM swap request
func (h *SecurityHandler) VerifySIMSwap(c *gin.Context) {
	var req struct {
		ProfileID string `json:"profile_id" binding:"required"`
		MSISDN    string `json:"msisdn" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Simulated SIM swap verification
	c.JSON(http.StatusOK, gin.H{
		"profile_id":    req.ProfileID,
		"msisdn":        req.MSISDN,
		"verified":      true,
		"risk_score":    15.0,
		"risk_level":    "low",
		"last_sim_swap": time.Now().AddDate(-1, 0, 0).Format("2006-01-02"),
		"checks_passed": []string{
			"Identity verified",
			"No recent SIM changes",
			"Account in good standing",
		},
	})
}

// GetSIMSwapHistory returns SIM swap history for a profile
func (h *SecurityHandler) GetSIMSwapHistory(c *gin.Context) {
	profileID := c.Param("profile_id")

	history := []map[string]any{
		{
			"id":         "swap-001",
			"profile_id": profileID,
			"old_iccid":  "8901234567890123456",
			"new_iccid":  "8901234567890123457",
			"timestamp":  time.Now().AddDate(-1, 0, 0),
			"reason":     "Device upgrade",
			"verified":   true,
			"status":     "completed",
		},
		{
			"id":         "swap-002",
			"profile_id": profileID,
			"old_iccid":  "8901234567890123455",
			"new_iccid":  "8901234567890123456",
			"timestamp":  time.Now().AddDate(-2, 0, 0),
			"reason":     "Lost device",
			"verified":   true,
			"status":     "completed",
		},
	}

	c.JSON(http.StatusOK, gin.H{"history": history})
}

func getSeverityFromScore(score float64) string {
	switch {
	case score >= 80:
		return "critical"
	case score >= 60:
		return "high"
	case score >= 40:
		return "medium"
	default:
		return "low"
	}
}