#!/bin/bash
# Automatically switch to fallback IPs when primary IPs fail

HOSTS_FILE="inventories/production/hosts"
TIMEOUT=3
CHANGED=false

# Colors
GREEN='\033[0;32m'
RED='\033[0;31m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

echo -e "${BLUE}Auto-fallback: Testing and switching to fallback IPs when needed...${NC}"
echo "=================================================================="

# Function to test IP connectivity
test_ip() {
    local ip="$1"
    if ping -c 1 -W "$TIMEOUT" "$ip" >/dev/null 2>&1; then
        return 0
    else
        return 1
    fi
}

# Function to test SSH connectivity
test_ssh() {
    local host="$1"
    local ip="$2"
    local user="$3"
    
    if timeout 5 ssh -o ConnectTimeout=3 -o BatchMode=yes "$user@$ip" exit >/dev/null 2>&1; then
        return 0
    else
        return 1
    fi
}

# Function to switch to fallback IP
switch_to_fallback() {
    local hostname="$1"
    local primary_ip="$2"
    local fallback_ip="$3"
    
    echo -e "  ${YELLOW}→ Switching $hostname to fallback IP: $fallback_ip${NC}"
    
    # Use sed to replace the primary IP with fallback IP
    sed -i "s/$hostname ansible_host=$primary_ip/$hostname ansible_host=$fallback_ip/" "$HOSTS_FILE"
    
    # Remove the fallback attribute since we're now using it as primary
    sed -i "s/ ansible_host_fallback=$fallback_ip//" "$HOSTS_FILE"
    
    CHANGED=true
}

# Parse hosts file and test connectivity
while IFS= read -r line; do
    # Skip empty lines and comments
    [[ -z "$line" || "$line" =~ ^# ]] && continue
    
    # Skip group headers
    [[ "$line" =~ ^\[.*\]$ ]] && continue
    
    # Parse host entry
    if [[ "$line" =~ ansible_host= ]]; then
        hostname=$(echo "$line" | awk '{print $1}')
        primary_ip=$(echo "$line" | grep -oP 'ansible_host=\K[^\s]+')
        fallback_ip=$(echo "$line" | grep -oP 'ansible_host_fallback=\K[^\s]+' || echo "")
        user=$(echo "$line" | grep -oP 'ansible_user=\K[^\s]+' || echo "root")
        
        echo -n "Testing $hostname ($primary_ip)... "
        
        # Test primary IP
        if test_ip "$primary_ip"; then
            # Test SSH on primary IP
            if test_ssh "$hostname" "$primary_ip" "$user"; then
                echo -e "${GREEN}✓ OK${NC}"
            else
                echo -e "${YELLOW}⚠ Ping OK, SSH failed${NC}"
                if [[ -n "$fallback_ip" ]]; then
                    echo -e "  ${BLUE}→ Trying fallback IP...${NC}"
                    if test_ip "$fallback_ip" && test_ssh "$hostname" "$fallback_ip" "$user"; then
                        switch_to_fallback "$hostname" "$primary_ip" "$fallback_ip"
                    else
                        echo -e "  ${RED}✗ Fallback also failed${NC}"
                    fi
                fi
            fi
        else
            echo -e "${RED}✗ Primary IP failed${NC}"
            if [[ -n "$fallback_ip" ]]; then
                echo -e "  ${BLUE}→ Trying fallback IP...${NC}"
                if test_ip "$fallback_ip" && test_ssh "$hostname" "$fallback_ip" "$user"; then
                    switch_to_fallback "$hostname" "$primary_ip" "$fallback_ip"
                else
                    echo -e "  ${RED}✗ Fallback also failed${NC}"
                fi
            fi
        fi
    fi
done < "$HOSTS_FILE"

echo ""
if [[ "$CHANGED" == "true" ]]; then
    echo -e "${GREEN}✓ Hosts file updated with working IPs!${NC}"
    echo -e "${BLUE}You can now run your Ansible commands.${NC}"
else
    echo -e "${GREEN}✓ All primary IPs are working - no changes needed.${NC}"
fi