#!/bin/bash
# =============================================================================
# sld_watchdog.sh - Monitors SLD service health and restarts if needed
# =============================================================================

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SCRIPT_NAME="sld_watchdog"

# Source configuration and library
source "$SCRIPT_DIR/hana.conf"
source "$SCRIPT_DIR/hana_lib.sh"

# SLD-specific configuration
SLD_URL="${SLD_URL:-https://localhost:40000/sld/sld0100.svc}"
SLD_TIMEOUT="${SLD_TIMEOUT:-5}"

# Acquire lock
if ! acquire_lock "$SCRIPT_NAME"; then
    exit 0
fi
trap 'release_lock "$SCRIPT_NAME"' EXIT

# Function to check SLD health
# Returns HTTP status code or "0" for connection errors
check_sld_health() {
    local http_status
    http_status=$(curl -k -s -o /dev/null -w "%{http_code}" -m "$SLD_TIMEOUT" --connect-timeout "$SLD_TIMEOUT" "$SLD_URL" 2>/dev/null)
    
    # Handle curl errors (returns 000 on connection failure)
    if [ -z "$http_status" ] || [ "$http_status" == "000" ]; then
        echo "0"
    else
        echo "$http_status"
    fi
}

# Function to restart SLD service
restart_sld_service() {
    log_message "$SCRIPT_NAME" "Attempting to restart SLD service..."
    
    # Try systemctl first
    if command -v systemctl &> /dev/null; then
        systemctl restart sapb1servertools 2>&1
        local restart_status=$?
        if [ $restart_status -eq 0 ]; then
            log_message "$SCRIPT_NAME" "Service restart command executed successfully"
            return 0
        else
            log_message "$SCRIPT_NAME" "Service restart failed with exit code ${restart_status}"
            return 1
        fi
    else
        log_message "$SCRIPT_NAME" "systemctl not available, trying alternative restart methods"
        # Fallback: try service command
        service sapb1servertools restart 2>&1
        return $?
    fi
}

# Main monitoring logic
main() {
    log_message "$SCRIPT_NAME" "Checking SLD service health at ${SLD_URL}..."
    
    local http_status
    http_status=$(check_sld_health)
    
    # 200 OK or 401 Unauthorized indicate the Tomcat layer is actively processing
    if [[ $http_status == 200 || $http_status == 401 ]]; then
        log_message "$SCRIPT_NAME" "[OK] SLD service healthy (HTTP Status: $http_status)"
        return 0
    fi
    
    # Service is down or unresponsive
    local status_detail
    if [ "$http_status" == "0" ]; then
        status_detail="Connection failed or timeout"
    else
        status_detail="HTTP Status: ${http_status}"
    fi
    
    log_message "$SCRIPT_NAME" "[ALERT] SLD dead or hung (${status_detail}). Restarting service..."
    
    # Send notification
    send_alert "$SCRIPT_NAME" "SLD Service Critical" "SLD service is down (${status_detail}). Restarting ${SLD_URL}"
    
    # Restart the service
    if ! restart_sld_service; then
        log_message "$SCRIPT_NAME" "[CRITICAL] Failed to restart SLD service"
        send_alert "$SCRIPT_NAME" "SLD Service Critical" "Failed to restart SLD service"
        return 1
    fi
    
    # Allow service to spin up, then log recovery status
    log_message "$SCRIPT_NAME" "Waiting 15 seconds for service to restart..."
    sleep 15
    
    local recovery_status
    recovery_status=$(check_sld_health)
    
    if [[ $recovery_status == 200 || $recovery_status == 401 ]]; then
        log_message "$SCRIPT_NAME" "[RECOVERY] SLD service recovered successfully (HTTP Status: $recovery_status)"
    else
        local recovery_detail
        if [ "$recovery_status" == "0" ]; then
            recovery_detail="Connection failed after restart"
        else
            recovery_detail="HTTP Status: $recovery_status"
        fi
        log_message "$SCRIPT_NAME" "[CRITICAL] SLD service failed to recover after restart (${recovery_detail})"
        send_alert "$SCRIPT_NAME" "SLD Service Critical" "SLD service FAILED to recover after restart (${recovery_detail})"
        return 1
    fi
    
    return 0
}

# Run main function
main
exit_code=$?

log_message "$SCRIPT_NAME" "SLD watchdog check complete."
exit $exit_code