#!/bin/bash

# Fix Docker DNS resolution issues in WSL2
# This script addresses the "dial tcp: lookup registry-1.docker.io" error

set -e

echo "=========================================="
echo "Docker DNS Fix for WSL2"
echo "=========================================="

# Check if running as root
if [ "$EUID" -ne 0 ]; then 
    echo "Please run as root or with sudo"
    echo "Usage: sudo ./fix-docker-dns.sh"
    exit 1
fi

# Step 1: Fix WSL2 DNS resolution
echo ""
echo "Step 1: Configuring WSL2 DNS..."
if [ ! -f /etc/wsl.conf ]; then
    echo "Creating /etc/wsl.conf..."
    cat > /etc/wsl.conf <<EOF
[network]
generateResolvConf = false
EOF
fi

# Backup existing resolv.conf
if [ -f /etc/resolv.conf ]; then
    cp /etc/resolv.conf /etc/resolv.conf.backup.$(date +%Y%m%d_%H%M%S)
fi

# Create new resolv.conf with reliable DNS servers
echo "Updating /etc/resolv.conf with reliable DNS servers..."
cat > /etc/resolv.conf <<EOF
# DNS configuration for WSL2
# Generated by fix-docker-dns.sh

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 1.1.1.1
nameserver 10.255.255.254
EOF

chattr +i /etc/resolv.conf 2>/dev/null || echo "Note: chattr not available, resolv.conf may be regenerated"

# Step 2: Configure Docker daemon DNS
echo ""
echo "Step 2: Configuring Docker daemon DNS..."

# Check if Docker Desktop is being used (common in WSL2)
if command -v docker &> /dev/null; then
    DOCKER_CONTEXT=$(docker context show 2>/dev/null || echo "default")
    echo "Docker context: $DOCKER_CONTEXT"
fi

# Create Docker daemon.json directory if it doesn't exist
mkdir -p /etc/docker

# Backup existing daemon.json if it exists
if [ -f /etc/docker/daemon.json ]; then
    cp /etc/docker/daemon.json /etc/docker/daemon.json.backup.$(date +%Y%m%d_%H%M%S)
    echo "Backed up existing daemon.json"
fi

# Create or update daemon.json with DNS configuration
echo "Creating/updating /etc/docker/daemon.json..."
cat > /etc/docker/daemon.json <<EOF
{
  "dns": ["8.8.8.8", "8.8.4.4", "1.1.1.1"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  }
}
EOF

# Step 3: Restart Docker service (if systemd is available)
echo ""
echo "Step 3: Restarting Docker service..."
if systemctl is-active --quiet docker 2>/dev/null; then
    echo "Restarting Docker daemon..."
    systemctl restart docker
    echo "Waiting for Docker to be ready..."
    sleep 5
elif command -v docker &> /dev/null; then
    echo "Docker Desktop detected. Please restart Docker Desktop manually."
    echo "Or run: wsl --shutdown (from Windows PowerShell) and restart WSL"
fi

# Step 4: Test DNS resolution
echo ""
echo "Step 4: Testing DNS resolution..."
echo "Testing registry-1.docker.io resolution..."
if nslookup registry-1.docker.io > /dev/null 2>&1; then
    echo "✓ DNS resolution working!"
else
    echo "⚠ DNS resolution still failing. Trying alternative approach..."
    # Try with dig if available
    if command -v dig &> /dev/null; then
        dig registry-1.docker.io +short || echo "Still failing"
    fi
fi

# Step 5: Test Docker connectivity
echo ""
echo "Step 5: Testing Docker connectivity..."
if command -v docker &> /dev/null; then
    echo "Testing Docker pull (dry-run)..."
    if docker pull hello-world:latest > /dev/null 2>&1; then
        echo "✓ Docker connectivity working!"
    else
        echo "⚠ Docker pull test failed. This might be normal if images are already cached."
    fi
fi

echo ""
echo "=========================================="
echo "Fix completed!"
echo "=========================================="
echo ""
echo "Next steps:"
echo "1. If using Docker Desktop, restart it from Windows"
echo "2. Or restart WSL: wsl --shutdown (from Windows PowerShell)"
echo "3. Try running your Quorum network again: ./run.sh"
echo ""
echo "If issues persist, try:"
echo "  - Check Windows firewall settings"
echo "  - Verify internet connectivity"
echo "  - Check Docker Desktop settings for network configuration"
echo ""