#!/bin/bash
#
# Node Failover Simulation Script
# Simulates node shutdown and verifies network continues operating
# Uses RPC endpoints only, no SSH access (check logic only)
#

set -e

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "${SCRIPT_DIR}/../.." && pwd)"

# Node Configuration
NODES=(
    "aitbc:10.1.223.93"
    "aitbc1:10.1.223.40"
    "aitbc2:10.1.223.98"
)

RPC_PORT=8006
LOG_DIR="/var/log/aitbc"
LOG_FILE="${LOG_DIR}/failover-simulation.log"

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

# Logging functions
log() {
    local level="$1"
    shift
    local message="$@"
    local timestamp=$(date '+%Y-%m-%d %H:%M:%S')
    echo "[${timestamp}] [${level}] ${message}" | tee -a "${LOG_FILE}"
}

log_success() {
    log "SUCCESS" "$@"
    echo -e "${GREEN}$@${NC}"
}

log_error() {
    log "ERROR" "$@"
    echo -e "${RED}$@${NC}"
}

log_warning() {
    log "WARNING" "$@"
    echo -e "${YELLOW}$@${NC}"
}

# Check RPC endpoint health
check_rpc_health() {
    local node_name="$1"
    local node_ip="$2"
    
    if curl -f -s --max-time 5 "http://${node_ip}:${RPC_PORT}/health" > /dev/null 2>&1; then
        log_success "RPC healthy on ${node_name}"
        return 0
    else
        log_error "RPC unhealthy on ${node_name}"
        return 1
    fi
}

# Simulate node shutdown (check logic only)
simulate_node_shutdown() {
    local node_name="$1"
    local node_ip="$2"
    
    log "=== SIMULATING shutdown of ${node_name} ==="
    log "Note: This is a simulation - no actual service shutdown"
    log "Marking ${node_name} as unavailable in test logic"
    
    # In a real scenario, we would stop the service here
    # For simulation, we just mark it as unavailable in our logic
    return 0
}

# Simulate node reconnection (check logic only)
simulate_node_reconnection() {
    local node_name="$1"
    local node_ip="$2"
    
    log "=== SIMULATING reconnection of ${node_name} ==="
    log "Note: This is a simulation - no actual service restart"
    log "Marking ${node_name} as available in test logic"
    
    # Check if RPC is actually available
    if check_rpc_health "$node_name" "$node_ip"; then
        log_success "${node_name} reconnected (RPC available)"
        return 0
    else
        log_error "${node_name} failed to reconnect (RPC unavailable)"
        return 1
    fi
}

# Verify network continues with node down
verify_network_continues() {
    local down_node="$1"
    
    log "=== Verifying network continues with ${down_node} down ==="
    
    local available_nodes=0
    
    for node_config in "${NODES[@]}"; do
        IFS=':' read -r node_name node_ip <<< "$node_config"
        
        # Skip the simulated down node
        if [ "$node_name" = "$down_node" ]; then
            log "Skipping ${node_name} (simulated down)"
            continue
        fi
        
        if check_rpc_health "$node_name" "$node_ip"; then
            ((available_nodes++))
        fi
    done
    
    log "Available nodes: ${available_nodes} / 3"
    
    if [ $available_nodes -ge 2 ]; then
        log_success "Network continues operating with ${available_nodes} nodes"
        return 0
    else
        log_error "Network not operating with insufficient nodes (${available_nodes})"
        return 1
    fi
}

# Verify consensus with reduced node count
verify_consensus() {
    local down_node="$1"
    
    log "=== Verifying consensus with ${down_node} down ==="
    
    # Get block heights from available nodes
    local heights=()
    
    for node_config in "${NODES[@]}"; do
        IFS=':' read -r node_name node_ip <<< "$node_config"
        
        # Skip the simulated down node
        if [ "$node_name" = "$down_node" ]; then
            continue
        fi
        
        local height=$(curl -s --max-time 5 "http://${node_ip}:${RPC_PORT}/rpc/head" 2>/dev/null | grep -o '"height":[0-9]*' | grep -o '[0-9]*' || echo "0")
        
        if [ "$height" != "0" ]; then
            heights+=("${node_name}:${height}")
            log "Block height on ${node_name}: ${height}"
        fi
    done
    
    # Check if heights are consistent
    if [ ${#heights[@]} -lt 2 ]; then
        log_error "Not enough nodes to verify consensus"
        return 1
    fi
    
    local first_height=$(echo "${heights[0]}" | cut -d':' -f2)
    local consistent=true
    
    for height_info in "${heights[@]}"; do
        local h=$(echo "$height_info" | cut -d':' -f2)
        if [ "$h" != "$first_height" ]; then
            consistent=false
            log_warning "Height mismatch: ${height_info}"
        fi
    done
    
    if [ "$consistent" = true ]; then
        log_success "Consensus verified (all nodes at height ${first_height})"
        return 0
    else
        log_error "Consensus failed (heights inconsistent)"
        return 1
    fi
}

# Measure recovery time (simulated)
measure_recovery_time() {
    local node_name="$1"
    local node_ip="$2"
    
    log "=== Measuring recovery time for ${node_name} ==="
    
    local start=$(date +%s)
    
    # Simulate reconnection check
    if simulate_node_reconnection "$node_name" "$node_ip"; then
        local end=$(date +%s)
        local recovery_time=$((end - start))
        log "Recovery time for ${node_name}: ${recovery_time}s"
        echo "${recovery_time}"
        return 0
    else
        log_error "Recovery failed for ${node_name}"
        echo "failed"
        return 1
    fi
}

# Main execution
main() {
    log "=== Node Failover Simulation Started ==="
    
    # Create log directory if it doesn't exist
    mkdir -p "${LOG_DIR}"
    
    local total_failures=0
    
    # Check initial network health
    log "=== Checking initial network health ==="
    for node_config in "${NODES[@]}"; do
        IFS=':' read -r node_name node_ip <<< "$node_config"
        if ! check_rpc_health "$node_name" "$node_ip"; then
            ((total_failures++))
        fi
    done
    
    if [ ${total_failures} -gt 0 ]; then
        log_error "Initial network health check failed"
        exit 1
    fi
    
    # Simulate shutdown of each node sequentially
    for node_config in "${NODES[@]}"; do
        IFS=':' read -r node_name node_ip <<< "$node_config"
        
        log ""
        log "=== Testing failover for ${node_name} ==="
        
        # Simulate shutdown
        simulate_node_shutdown "$node_name" "$node_ip"
        
        # Verify network continues
        if ! verify_network_continues "$node_name"; then
            log_error "Network failed to continue without ${node_name}"
            ((total_failures++))
        fi
        
        # Verify consensus
        if ! verify_consensus "$node_name"; then
            log_error "Consensus failed without ${node_name}"
            ((total_failures++))
        fi
        
        # Simulate reconnection
        local recovery_time=$(measure_recovery_time "$node_name" "$node_ip")
        
        if [ "$recovery_time" = "failed" ]; then
            log_error "Recovery failed for ${node_name}"
            ((total_failures++))
        fi
    done
    
    log "=== Node Failover Simulation Completed ==="
    log "Total failures: ${total_failures}"
    
    if [ ${total_failures} -eq 0 ]; then
        log_success "Node Failover Simulation passed"
        exit 0
    else
        log_error "Node Failover Simulation failed with ${total_failures} failures"
        exit 1
    fi
}

# Run main function
main "$@"