#!/bin/bash
# Diagnostic script for 502 Bad Gateway error

set -e

NAMESPACE=${1:-production}
APP_NAME="peikarband"

echo "🔍 Diagnosing 502 Bad Gateway for $APP_NAME in namespace $NAMESPACE"
echo "=========================================="
echo ""

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# 1. Check Pods
echo "1️⃣ Checking Pods..."
echo "-------------------"
PODS=$(kubectl get pods -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME --no-headers 2>/dev/null || echo "")
if [ -z "$PODS" ]; then
    echo -e "${RED}❌ No pods found!${NC}"
    exit 1
fi

kubectl get pods -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME
echo ""

# Check pod status
POD_STATUS=$(kubectl get pods -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME -o jsonpath='{.items[0].status.phase}' 2>/dev/null || echo "Unknown")
POD_NAME=$(kubectl get pods -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")

if [ "$POD_STATUS" != "Running" ]; then
    echo -e "${RED}❌ Pod is not Running! Status: $POD_STATUS${NC}"
    echo ""
    echo "Pod events:"
    kubectl describe pod -n $NAMESPACE $POD_NAME | tail -20
    echo ""
fi

# 2. Check Service
echo "2️⃣ Checking Service..."
echo "----------------------"
kubectl get svc -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME
echo ""

# 3. Check Ingress
echo "3️⃣ Checking Ingress..."
echo "-----------------------"
kubectl get ingress -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME
echo ""

# 4. Check Pod Logs
if [ -n "$POD_NAME" ]; then
    echo "4️⃣ Recent Pod Logs (last 30 lines)..."
    echo "--------------------------------------"
    kubectl logs -n $NAMESPACE $POD_NAME --tail=30 || echo "Could not fetch logs"
    echo ""
fi

# 5. Check Readiness/Liveness
if [ -n "$POD_NAME" ]; then
    echo "5️⃣ Checking Probe Status..."
    echo "----------------------------"
    READY=$(kubectl get pod -n $NAMESPACE $POD_NAME -o jsonpath='{.status.conditions[?(@.type=="Ready")].status}' 2>/dev/null || echo "Unknown")
    echo "Ready: $READY"
    
    # Check container status
    CONTAINER_STATUS=$(kubectl get pod -n $NAMESPACE $POD_NAME -o jsonpath='{.status.containerStatuses[0].ready}' 2>/dev/null || echo "Unknown")
    echo "Container Ready: $CONTAINER_STATUS"
    echo ""
fi

# 6. Test from inside pod
if [ -n "$POD_NAME" ] && [ "$POD_STATUS" == "Running" ]; then
    echo "6️⃣ Testing /ping endpoint from inside pod..."
    echo "---------------------------------------------"
    kubectl exec -n $NAMESPACE $POD_NAME -- curl -s http://localhost:8000/ping || echo -e "${RED}❌ /ping failed!${NC}"
    echo ""
fi

# 7. Check Service Endpoints
echo "7️⃣ Checking Service Endpoints..."
echo "---------------------------------"
SVC_NAME=$(kubectl get svc -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")
if [ -n "$SVC_NAME" ]; then
    kubectl get endpoints -n $NAMESPACE $SVC_NAME
    ENDPOINTS=$(kubectl get endpoints -n $NAMESPACE $SVC_NAME -o jsonpath='{.subsets[0].addresses[*].ip}' 2>/dev/null || echo "")
    if [ -z "$ENDPOINTS" ]; then
        echo -e "${RED}❌ No endpoints! Service cannot route traffic.${NC}"
        echo "This is likely because readiness probe is failing."
    fi
    echo ""
fi

# 8. Check Resources
if [ -n "$POD_NAME" ]; then
    echo "8️⃣ Checking Resource Usage..."
    echo "------------------------------"
    kubectl top pod -n $NAMESPACE $POD_NAME 2>/dev/null || echo "Metrics not available"
    echo ""
fi

# 9. Check Events
echo "9️⃣ Recent Events..."
echo "-------------------"
kubectl get events -n $NAMESPACE --sort-by='.lastTimestamp' | grep $APP_NAME | tail -10 || echo "No recent events"
echo ""

# 10. NetworkPolicy check
echo "🔟 Checking NetworkPolicy..."
echo "---------------------------"
kubectl get networkpolicy -n $NAMESPACE -l app.kubernetes.io/name=$APP_NAME || echo "No NetworkPolicy found"
echo ""

echo "=========================================="
echo "✅ Diagnosis complete!"
echo ""
echo "Common fixes:"
echo "1. If pod is CrashLoopBackOff: Check logs and resource limits"
echo "2. If no endpoints: Readiness probe is failing - check /ping endpoint"
echo "3. If NetworkPolicy exists: Check if it allows ingress traffic"
echo "4. If resources exhausted: Increase limits in values-production.yaml"