#!/bin/bash

set -o pipefail

set +e

# Script trace mode
if [ "${DEBUG_MODE}" == "true" ]; then
    set -o xtrace
fi

# Default Zabbix installation name
# Used only by Zabbix web-interface
: ${ZBX_SERVER_NAME:="Zabbix docker"}
# Default Zabbix server host
: ${ZBX_SERVER_HOST:="zabbix-server"}
# Default Zabbix server port number
: ${ZBX_SERVER_PORT:="10051"}

# Default timezone for web interface
: ${PHP_TZ:="Europe/Riga"}

# Default directories
# Configuration files directory
ZABBIX_ETC_DIR="/etc/zabbix"
# Web interface www-root directory
ZABBIX_WWW_ROOT="/usr/share/zabbix"

# usage: file_env VAR [DEFAULT]
# as example: file_env 'MYSQL_PASSWORD' 'zabbix'
#    (will allow for "$MYSQL_PASSWORD_FILE" to fill in the value of "$MYSQL_PASSWORD" from a file)
# unsets the VAR_FILE afterwards and just leaving VAR
file_env() {
    local var="$1"
    local fileVar="${var}_FILE"
    local defaultValue="${2:-}"

    if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
        echo "**** Both variables $var and $fileVar are set (but are exclusive)"
        exit 1
    fi

    local val="$defaultValue"

    if [ "${!var:-}" ]; then
        val="${!var}"
        echo "** Using ${var} variable from ENV"
    elif [ "${!fileVar:-}" ]; then
        if [ ! -f "${!fileVar}" ]; then
            echo "**** Secret file \"${!fileVar}\" is not found"
            exit 1
        fi
        val="$(< "${!fileVar}")"
        echo "** Using ${var} variable from secret file"
    fi
    export "$var"="$val"
    unset "$fileVar"
}

# Check prerequisites for MySQL database
check_variables() {
    : ${DB_SERVER_HOST:="mysql-server"}
    : ${DB_SERVER_PORT:="3306"}
    USE_DB_ROOT_USER=false
    CREATE_ZBX_DB_USER=false
    file_env MYSQL_USER
    file_env MYSQL_PASSWORD

    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
        echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
        exit 1
    fi

    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
        echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
        exit 1
    fi

    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
        USE_DB_ROOT_USER=true
        DB_SERVER_ROOT_USER="root"
        DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
    fi

    [ -n "${MYSQL_USER}" ] && CREATE_ZBX_DB_USER=true

    # If root password is not specified use provided credentials
    : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
    DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
    DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}

    DB_SERVER_DBNAME=${MYSQL_DATABASE:-"zabbix"}
}

check_db_connect() {
    echo "********************"
    echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
    echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
    echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
    if [ "${DEBUG_MODE}" == "true" ]; then
        if [ "${USE_DB_ROOT_USER}" == "true" ]; then
            echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
            echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
        fi
        echo "* DB_SERVER_ZBX_USER: ${DB_SERVER_ZBX_USER}"
        echo "* DB_SERVER_ZBX_PASS: ${DB_SERVER_ZBX_PASS}"
    fi
    echo "********************"

    WAIT_TIMEOUT=5

    export MYSQL_PWD="${DB_SERVER_ROOT_PASS}"

    while [ ! "$(mysqladmin ping -h ${DB_SERVER_HOST} -P ${DB_SERVER_PORT} -u ${DB_SERVER_ROOT_USER} \
                --silent --connect_timeout=10)" ]; do
        echo "**** MySQL server is not available. Waiting $WAIT_TIMEOUT seconds..."
        sleep $WAIT_TIMEOUT
    done

    unset MYSQL_PWD
}

prepare_web_server() {
    APACHE_SITES_DIR="/etc/apache2/sites-enabled"

    echo "** Adding Zabbix virtual host (HTTP)"
    if [ -f "$ZABBIX_ETC_DIR/apache.conf" ]; then
        ln -s "$ZABBIX_ETC_DIR/apache.conf" "$APACHE_SITES_DIR/zabbix.conf"
    else
        echo "**** Impossible to enable HTTP virtual host"
    fi

    if [ -f "/etc/ssl/apache2/ssl.crt" ] && [ -f "/etc/ssl/apache2/ssl.key" ]; then
        echo "** Adding Zabbix virtual host (HTTPS)"
        if [ -f "$ZABBIX_ETC_DIR/apache_ssl.conf" ]; then
            ln -s "$ZABBIX_ETC_DIR/apache_ssl.conf" "$APACHE_SITES_DIR/zabbix_ssl.conf"
        else
            echo "**** Impossible to enable HTTPS virtual host"
        fi
    else
        echo "**** Impossible to enable SSL support for Apache2. Certificates are missed."
    fi
}

prepare_zbx_web_config() {
    echo "** Preparing Zabbix frontend configuration file"

    export ZBX_MAXEXECUTIONTIME=${ZBX_MAXEXECUTIONTIME:-"600"}
    export ZBX_MEMORYLIMIT=${ZBX_MEMORYLIMIT:-"128M"}
    export ZBX_POSTMAXSIZE=${ZBX_POSTMAXSIZE:-"16M"}
    export ZBX_UPLOADMAXFILESIZE=${ZBX_UPLOADMAXFILESIZE:-"2M"}
    export ZBX_MAXINPUTTIME=${ZBX_MAXINPUTTIME:-"300"}
    export PHP_TZ=${PHP_TZ:-"Europe/Riga"}

    export DB_SERVER_TYPE="MYSQL"
    export DB_SERVER_HOST=${DB_SERVER_HOST}
    export DB_SERVER_PORT=${DB_SERVER_PORT}
    export DB_SERVER_DBNAME=${DB_SERVER_DBNAME}
    export DB_SERVER_SCHEMA=${DB_SERVER_SCHEMA}
    export DB_SERVER_USER=${DB_SERVER_ZBX_USER}
    export DB_SERVER_PASS=${DB_SERVER_ZBX_PASS}
    export ZBX_SERVER_HOST=${ZBX_SERVER_HOST}
    export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
    export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}

    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
        sed -ri \
            -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
            "/etc/apache2/apache2.conf"
        sed -ri \
            -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
            "/etc/apache2/conf-available/other-vhosts-access-log.conf"
    fi
}

#################################################

echo "** Deploying Zabbix web-interface (Apache) with MySQL database"

check_variables
check_db_connect
prepare_web_server
prepare_zbx_web_config

echo "########################################################"

if [ "$1" != "" ]; then
    echo "** Executing '$@'"
    exec "$@"
elif [ -f "/usr/sbin/httpd" ]; then
    echo "** Executing HTTPD"
    exec /usr/sbin/httpd -D FOREGROUND
else
    echo "Unknown instructions. Exiting..."
    exit 1
fi

#################################################