#!/bin/bash

set -o pipefail

set +e

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

# Default Zabbix installation name
# Default Zabbix server host
: ${ZBX_SERVER_HOST:="zabbix-server"}
# Default Zabbix server port number
: ${ZBX_SERVER_PORT:="10051"}

# Default directories
# User 'zabbix' home directory
ZABBIX_USER_HOME_DIR="/var/lib/zabbix"
# Configuration files directory
ZABBIX_ETC_DIR="/etc/zabbix"

escape_spec_char() {
    local var_value=$1

    var_value="${var_value//\\/\\\\}"
    var_value="${var_value//[$'\n']/}"
    var_value="${var_value//\//\\/}"
    var_value="${var_value//./\\.}"
    var_value="${var_value//\*/\\*}"
    var_value="${var_value//^/\\^}"
    var_value="${var_value//\$/\\\$}"
    var_value="${var_value//\&/\\\&}"
    var_value="${var_value//\[/\\[}"
    var_value="${var_value//\]/\\]}"

    echo "$var_value"
}

update_config_var() {
    local config_path=$1
    local var_name=$2
    local var_value=$3
    local is_multiple=$4

    if [ ! -f "$config_path" ]; then
        echo "**** Configuration file '$config_path' does not exist"
        return
    fi

    echo -n "** Updating '$config_path' parameter \"$var_name\": '$var_value'... "

    # Remove configuration parameter definition in case of unset parameter value
    if [ -z "$var_value" ]; then
        sed -i -e "/^$var_name=/d" "$config_path"
        echo "removed"
        return
    fi

    # Remove value from configuration parameter in case of double quoted parameter value
    if [ "$var_value" == '""' ]; then
        sed -i -e "/^$var_name=/s/=.*/=/" "$config_path"
        echo "undefined"
        return
    fi

    # Use full path to a file for TLS related configuration parameters
    if [[ $var_name =~ ^TLS.*File$ ]]; then
        var_value=$ZABBIX_USER_HOME_DIR/enc/$var_value
    fi

    # Escaping characters in parameter value and name
    var_value=$(escape_spec_char "$var_value")
    var_name=$(escape_spec_char "$var_name")

    if [ "$(grep -E "^$var_name=" $config_path)" ] && [ "$is_multiple" != "true" ]; then
        sed -i -e "/^$var_name=/s/=.*/=$var_value/" "$config_path"
        echo "updated"
    elif [ "$(grep -Ec "^# $var_name=" $config_path)" -gt 1 ]; then
        sed -i -e  "/^[#;] $var_name=$/i\\$var_name=$var_value" "$config_path"
        echo "added first occurrence"
    else
        sed -i -e "/^[#;] $var_name=/s/.*/&\n$var_name=$var_value/" "$config_path"
        echo "added"
    fi

}

update_config_multiple_var() {
    local config_path=$1
    local var_name=$2
    local var_value=$3

    var_value="${var_value%\"}"
    var_value="${var_value#\"}"

    local IFS=,
    local OPT_LIST=($var_value)

    for value in "${OPT_LIST[@]}"; do
        update_config_var $config_path $var_name $value true
    done
}

prepare_zbx_agent_config() {
    echo "** Preparing Zabbix agent configuration file"
    ZBX_AGENT_CONFIG=$ZABBIX_ETC_DIR/zabbix_agentd.conf

    : ${ZBX_PASSIVESERVERS:=""}
    : ${ZBX_ACTIVESERVERS:=""}

    [ -n "$ZBX_PASSIVESERVERS" ] && ZBX_PASSIVESERVERS=","$ZBX_PASSIVESERVERS

    ZBX_PASSIVESERVERS=$ZBX_SERVER_HOST$ZBX_PASSIVESERVERS

    [ -n "$ZBX_ACTIVESERVERS" ] && ZBX_ACTIVESERVERS=","$ZBX_ACTIVESERVERS

    ZBX_ACTIVESERVERS=$ZBX_SERVER_HOST":"$ZBX_SERVER_PORT$ZBX_ACTIVESERVERS

    update_config_var $ZBX_AGENT_CONFIG "PidFile"
    update_config_var $ZBX_AGENT_CONFIG "LogType" "console"
    update_config_var $ZBX_AGENT_CONFIG "LogFile"
    update_config_var $ZBX_AGENT_CONFIG "LogFileSize"
    update_config_var $ZBX_AGENT_CONFIG "DebugLevel" "${ZBX_DEBUGLEVEL}"
    update_config_var $ZBX_AGENT_CONFIG "SourceIP"
    update_config_var $ZBX_AGENT_CONFIG "EnableRemoteCommands" "${ZBX_ENABLEREMOTECOMMANDS}"
    update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"

    : ${ZBX_PASSIVE_ALLOW:="true"}
    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
        echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
        update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
    else
        update_config_var $ZBX_AGENT_CONFIG "Server"
    fi

    update_config_var $ZBX_AGENT_CONFIG "ListenPort" "${ZBX_LISTENPORT}"
    update_config_var $ZBX_AGENT_CONFIG "ListenIP" "${ZBX_LISTENIP}"
    update_config_var $ZBX_AGENT_CONFIG "StartAgents" "${ZBX_STARTAGENTS}"

    : ${ZBX_ACTIVE_ALLOW:="true"}
    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
        echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
        update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
    else
        update_config_var $ZBX_AGENT_CONFIG "ServerActive"
    fi

    update_config_var $ZBX_AGENT_CONFIG "HostInterface" "${ZBX_HOSTINTERFACE}"
    update_config_var $ZBX_AGENT_CONFIG "HostInterfaceItem" "${ZBX_HOSTINTERFACEITEM}"

    update_config_var $ZBX_AGENT_CONFIG "Hostname" "${ZBX_HOSTNAME}"
    update_config_var $ZBX_AGENT_CONFIG "HostnameItem" "${ZBX_HOSTNAMEITEM}"
    update_config_var $ZBX_AGENT_CONFIG "HostMetadata" "${ZBX_METADATA}"
    update_config_var $ZBX_AGENT_CONFIG "HostMetadataItem" "${ZBX_METADATAITEM}"
    update_config_var $ZBX_AGENT_CONFIG "RefreshActiveChecks" "${ZBX_REFRESHACTIVECHECKS}"
    update_config_var $ZBX_AGENT_CONFIG "BufferSend" "${ZBX_BUFFERSEND}"
    update_config_var $ZBX_AGENT_CONFIG "BufferSize" "${ZBX_BUFFERSIZE}"
    update_config_var $ZBX_AGENT_CONFIG "MaxLinesPerSecond" "${ZBX_MAXLINESPERSECOND}"
    # Please use include to enable Alias feature
#    update_config_multiple_var $ZBX_AGENT_CONFIG "Alias" ${ZBX_ALIAS}
    update_config_var $ZBX_AGENT_CONFIG "Timeout" "${ZBX_TIMEOUT}"
    update_config_var $ZBX_AGENT_CONFIG "Include" "/etc/zabbix/zabbix_agentd.d/"
    update_config_var $ZBX_AGENT_CONFIG "UnsafeUserParameters" "${ZBX_UNSAFEUSERPARAMETERS}"
    update_config_var $ZBX_AGENT_CONFIG "LoadModulePath" "$ZABBIX_USER_HOME_DIR/modules/"
    update_config_multiple_var $ZBX_AGENT_CONFIG "LoadModule" "${ZBX_LOADMODULE}"
    update_config_var $ZBX_AGENT_CONFIG "TLSConnect" "${ZBX_TLSCONNECT}"
    update_config_var $ZBX_AGENT_CONFIG "TLSAccept" "${ZBX_TLSACCEPT}"
    update_config_var $ZBX_AGENT_CONFIG "TLSCAFile" "${ZBX_TLSCAFILE}"
    update_config_var $ZBX_AGENT_CONFIG "TLSCRLFile" "${ZBX_TLSCRLFILE}"
    update_config_var $ZBX_AGENT_CONFIG "TLSServerCertIssuer" "${ZBX_TLSSERVERCERTISSUER}"
    update_config_var $ZBX_AGENT_CONFIG "TLSServerCertSubject" "${ZBX_TLSSERVERCERTSUBJECT}"
    update_config_var $ZBX_AGENT_CONFIG "TLSCertFile" "${ZBX_TLSCERTFILE}"
    update_config_var $ZBX_AGENT_CONFIG "TLSKeyFile" "${ZBX_TLSKEYFILE}"
    update_config_var $ZBX_AGENT_CONFIG "TLSPSKIdentity" "${ZBX_TLSPSKIDENTITY}"
    update_config_var $ZBX_AGENT_CONFIG "TLSPSKFile" "${ZBX_TLSPSKFILE}"

    if [ "$(id -u)" != '0' ]; then
        update_config_var $ZBX_AGENT_CONFIG "User" "$(whoami)"
    else
        update_config_var $ZBX_AGENT_CONFIG "AllowRoot" "1"
    fi
}

prepare_agent() {
    echo "** Preparing Zabbix agent"
    prepare_zbx_agent_config
}

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

if [ "${1#-}" != "$1" ]; then
    set -- /usr/sbin/zabbix_agentd "$@"
fi

if [ "$1" == '/usr/sbin/zabbix_agentd' ]; then
    prepare_agent
fi

exec "$@"

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