#!/usr/bin/env bash
#
# qvm-stop - Gracefully shut down the QEMU VM
#
# This script stops the running VM by sending SIGTERM first for graceful
# shutdown, waiting up to 30 seconds, then sending SIGKILL if necessary.
# It cleans up state files (vm.pid, ssh.port) after shutdown completes.
#
# Usage: qvm stop
#

set -euo pipefail

# Source common library
readonly QVM_LIB_DIR="${QVM_LIB_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/../lib" && pwd)}"
source "${QVM_LIB_DIR}/common.sh"

# Timeout for graceful shutdown in seconds
readonly SHUTDOWN_TIMEOUT=30

#
# wait_for_process_exit - Wait for process to terminate
# Args: $1 - PID to wait for
#       $2 - timeout in seconds
# Returns: 0 if process exits, 1 on timeout
#
wait_for_process_exit() {
    local pid="$1"
    local timeout="$2"
    local elapsed=0
    
    while (( elapsed < timeout )); do
        if ! kill -0 "$pid" 2>/dev/null; then
            return 0
        fi
        sleep 1
        (( elapsed++ ))
    done
    
    return 1
}

#
# main - Main shutdown orchestration
#
main() {
    # Check if VM is running
    if ! is_vm_running; then
        log_info "VM is not running"
        exit 0
    fi
    
    # Get VM process PID
    local vm_pid
    vm_pid=$(cat "$QVM_PID_FILE")
    
    log_info "Shutting down VM (PID: $vm_pid)..."
    
    # Send SIGTERM for graceful shutdown
    if kill -TERM "$vm_pid" 2>/dev/null; then
        log_info "Sent SIGTERM, waiting up to ${SHUTDOWN_TIMEOUT}s for graceful shutdown..."
        
        if wait_for_process_exit "$vm_pid" "$SHUTDOWN_TIMEOUT"; then
            log_info "VM shut down gracefully"
        else
            log_warn "Graceful shutdown timeout, forcefully terminating..."
            
            # Send SIGKILL to force termination
            if kill -KILL "$vm_pid" 2>/dev/null; then
                # Wait briefly to ensure process is dead
                sleep 1
                
                # Verify process is actually dead
                if kill -0 "$vm_pid" 2>/dev/null; then
                    die "Failed to kill VM process $vm_pid"
                fi
                
                log_info "VM forcefully terminated"
            else
                log_warn "Process $vm_pid already terminated"
            fi
        fi
    else
        log_warn "Process $vm_pid already terminated (could not send SIGTERM)"
    fi
    
    # Clean up state files
    log_info "Cleaning up state files..."
    rm -f "$QVM_PID_FILE" "$QVM_SSH_PORT_FILE"
    
    log_info "VM stopped successfully"
}

main "$@"