#!/bin/bash

set -o nounset

# Check if directory for monit logs exists
if [ ! -d "$HOME/.bigchaindb-monit" ]; then
  mkdir -p "$HOME/.bigchaindb-monit"
fi

monit_pid_path=${MONIT_PID_PATH:=$HOME/.bigchaindb-monit/monit_processes}
monit_script_path=${MONIT_SCRIPT_PATH:=$HOME/.bigchaindb-monit/monit_script}
monit_log_path=${MONIT_LOG_PATH:=$HOME/.bigchaindb-monit/logs}
monitrc_path=${MONITRC_PATH:=$HOME/.monitrc}

function usage() {
        cat <<EOM

    Usage: ${0##*/} [-h]

    Configure Monit for BigchainDB and Tendermint process management.

    ENV[MONIT_PID_PATH] || --monit-pid-path PATH

    Absolute path to directory where the the program's pid-file will reside. 
    The pid-file contains the ID(s) of the process(es). (default: ${monit_pid_path})

    ENV[MONIT_SCRIPT_PATH] || --monit-script-path PATH

    Absolute path to the directory where the executable program or
    script is present. (default: ${monit_script_path})

    ENV[MONIT_LOG_PATH] || --monit-log-path PATH

    Absolute path to the directory where all the logs for processes
    monitored by Monit are stored. (default: ${monit_log_path})

    ENV[MONITRC_PATH] || --monitrc-path PATH

    Absolute path to the monit control file(monitrc). (default: ${monitrc_path})

    -h|--help
        Show this help and exit.

EOM
}

while [[ $# -gt 0 ]]; do
    arg="$1"
    case $arg in
        --monit-pid-path)
            monit_pid_path="$2"
            shift
        ;;
        --monit-script-path)
            monit_script_path="$2"
            shift
        ;;
        --monit-log-path)
            monit_log_path="$2"
            shift
        ;;
        --monitrc-path)
            monitrc_path="$2"
            shift
        ;;
        -h|--help)
            usage
            exit
        ;;
        *)
            echo "Unknown option: $1"
            usage
            exit 1
        ;;
    esac
    shift
done

# Check if directory for monit logs exists
if [ ! -d "$monit_log_path" ]; then
  mkdir -p "$monit_log_path"
fi

# Check if directory for monit pid files exists
if [ ! -d "$monit_pid_path" ]; then
  mkdir -p "$monit_pid_path"
fi

cat >${monit_script_path} <<EOF
#!/bin/bash
case \$1 in

  start_bigchaindb)

    pushd \$4
      nohup bigchaindb -l DEBUG start >> \$3/bigchaindb.out.log 2>> \$3/bigchaindb.err.log &

      echo \$! > \$2
    popd

    ;;

  stop_bigchaindb)

    kill -2 \`cat \$2\`
    rm -f \$2

    ;;

  start_tendermint)

    pushd \$4
      nohup tendermint node --consensus.create_empty_blocks=false >> \$3/tendermint.out.log 2>> \$3/tendermint.err.log &

      echo \$! > \$2
    popd

    ;;

  stop_tendermint)

    kill -2 \`cat \$2\`
    rm -f \$2

    ;;

esac
exit 0
EOF
chmod +x ${monit_script_path}

# Handling overwriting of control file interactively
if [ -f "$monitrc_path" ]; then
    echo "$monitrc_path already exists."
    read -p "Overwrite[Y]? " -n 1 -r
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]; then
        echo "Overriding $monitrc_path/.monitrc"
    else
        read -p "Enter absolute path to store Monit control file: " monitrc_path
        eval monitrc_path="$monitrc_path"
        if [ ! -d "$(dirname $monitrc_path)" ]; then
            echo "Failed to save monit control file '$monitrc_path': No such file or directory."
            exit 1
        fi
    fi
fi

# configure monitrc
cat >${monitrc_path} <<EOF
set httpd
  port 2812
  allow localhost

check process bigchaindb
    with pidfile ${monit_pid_path}/bigchaindb.pid
    start program "${monit_script_path} start_bigchaindb $monit_pid_path/bigchaindb.pid ${monit_log_path} ${monit_log_path}"
    restart program "${monit_script_path} start_bigchaindb $monit_pid_path/bigchaindb.pid ${monit_log_path} ${monit_log_path}"
    stop program "${monit_script_path} stop_bigchaindb $monit_pid_path/bigchaindb.pid ${monit_log_path} ${monit_log_path}"

check process tendermint
    with pidfile ${monit_pid_path}/tendermint.pid
    start program "${monit_script_path} start_tendermint ${monit_pid_path}/tendermint.pid ${monit_log_path} ${monit_log_path}"
    restart program "${monit_script_path} start_bigchaindb ${monit_pid_path}/bigchaindb.pid ${monit_log_path} ${monit_log_path}"
    stop program "${monit_script_path} stop_tendermint ${monit_pid_path}/tendermint.pid ${monit_log_path} ${monit_log_path}"
    depends on bigchaindb
EOF

# Setting permissions for control file
chmod 0700 ${monitrc_path}

echo -e "BigchainDB process manager configured!"
set -o errexit