#!/usr/bin/env bash
# Hot-adjust Apache MPM Event settings and graceful reload.
# Usage: tune-mpm.sh [--max-workers N] [--server-limit N] [--start-servers N]
#                     [--min-spare-threads N] [--max-spare-threads N]
#                     [--max-connections-per-child N]

set -euo pipefail

# Read current values from the config as defaults
CONFIG_FILE="/etc/httpd/conf.d/mpm-tuning.conf"

if [ ! -f "$CONFIG_FILE" ]; then
  echo "Error: $CONFIG_FILE not found. Run detect-memory.sh first."
  exit 1
fi

# Parse current values from config
current_start=$(grep -oP 'StartServers\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "1")
current_min_spare=$(grep -oP 'MinSpareThreads\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "5")
current_max_spare=$(grep -oP 'MaxSpareThreads\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "15")
current_max_workers=$(grep -oP 'MaxRequestWorkers\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "50")
current_server_limit=$(grep -oP 'ServerLimit\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "2")
current_max_conn=$(grep -oP 'MaxConnectionsPerChild\s+\K\d+' "$CONFIG_FILE" 2>/dev/null || echo "3000")

# Parse arguments
START_SERVERS=$current_start
MIN_SPARE_THREADS=$current_min_spare
MAX_SPARE_THREADS=$current_max_spare
MAX_REQUEST_WORKERS=$current_max_workers
SERVER_LIMIT=$current_server_limit
MAX_CONNECTIONS_PER_CHILD=$current_max_conn

while [[ $# -gt 0 ]]; do
  case $1 in
    --max-workers) MAX_REQUEST_WORKERS="$2"; shift 2 ;;
    --server-limit) SERVER_LIMIT="$2"; shift 2 ;;
    --start-servers) START_SERVERS="$2"; shift 2 ;;
    --min-spare-threads) MIN_SPARE_THREADS="$2"; shift 2 ;;
    --max-spare-threads) MAX_SPARE_THREADS="$2"; shift 2 ;;
    --max-connections-per-child) MAX_CONNECTIONS_PER_CHILD="$2"; shift 2 ;;
    --help|-h)
      echo "Usage: $0 [--max-workers N] [--server-limit N] [--start-servers N]"
      echo "          [--min-spare-threads N] [--max-spare-threads N]"
      echo "          [--max-connections-per-child N]"
      echo ""
      echo "Current values:"
      echo "  StartServers:           $current_start"
      echo "  MinSpareThreads:        $current_min_spare"
      echo "  MaxSpareThreads:        $current_max_spare"
      echo "  MaxRequestWorkers:      $current_max_workers"
      echo "  ServerLimit:            $current_server_limit"
      echo "  MaxConnectionsPerChild: $current_max_conn"
      exit 0
      ;;
    *) echo "Unknown option: $1"; exit 1 ;;
  esac
done

# Write updated config
cat <<EOF > "$CONFIG_FILE"
<IfModule mpm_event_module>
    StartServers            ${START_SERVERS}
    MinSpareThreads         ${MIN_SPARE_THREADS}
    MaxSpareThreads         ${MAX_SPARE_THREADS}
    ThreadLimit             64
    ThreadsPerChild         25
    MaxRequestWorkers       ${MAX_REQUEST_WORKERS}
    ServerLimit             ${SERVER_LIMIT}
    MaxConnectionsPerChild  ${MAX_CONNECTIONS_PER_CHILD}
</IfModule>
EOF

echo "MPM config updated:"
echo "  StartServers=$START_SERVERS ServerLimit=$SERVER_LIMIT MaxRequestWorkers=$MAX_REQUEST_WORKERS"
echo "  MinSpareThreads=$MIN_SPARE_THREADS MaxSpareThreads=$MAX_SPARE_THREADS MaxConnectionsPerChild=$MAX_CONNECTIONS_PER_CHILD"

# Graceful reload
/usr/sbin/httpd -k graceful
echo "Apache graceful reload triggered."