#!/bin/bash

#------------------
# variables
#------------------

def_dirname=/tmp
def_filename=full_export.dmp
ora_dirname=temporarydirectoryforexport
overwrite_dumpfile=n
tmpfile=JustATemporaryFile

#------------------
# functions
#------------------

function readDBConn() {
        ok=false
        while ! $ok; do
                # read username and password
                read -p "Please enter a username with privileges to export the database [leave empty to use '/ as sysdba']: " dbuser
                if [ -z "${dbuser}" ]; then
                        conn_string="/ as sysdba"
                        # the extra_sql is needed for cases when we connect with sysdba but the instance is not open
                        extra_sql="select 1 from dba_data_files where rownum=1;"
                else
                        read -s -p "Please enter ${dbuser}'s password: " dbpwd
                        conn_string=${dbuser}/${dbpwd}
                        extra_sql=""
                        echo
                fi
                # try to connect to Oracle
                $ORACLE_HOME/bin/sqlplus -s /nolog <<- EOF > /dev/null 2>&1
                        set feedback off pages 0
                        whenever sqlerror exit 1
                        conn ${conn_string}
                        ${extra_sql}
                        exit
		EOF
                if [ $? -ne 0 ]; then
                        # can't connect, try again
                        echo "Cannot connect to Oracle"
                        echo
                else
                        # connected
                        ok=true
                fi
        done
}

function readInput() {
        # read input from user
        read -p "Please enter Oracle Home to use for export [leave empty to use '${ORACLE_HOME}']: " ORA_HOME
        export ORACLE_HOME=${ORA_HOME:=${ORACLE_HOME}}
        read -p "Please enter database SID [leave empty to use '${ORACLE_SID}']: " ORA_SID
        export ORACLE_SID=${ORA_SID:=${ORACLE_SID}}
        readDBConn
        read -p "Please enter directory for the dump file [leave empty to use '${def_dirname}']: " dirname
        dirname=${dirname:=${def_dirname}}
        read -p "Please enter dump file name [leave empty to use '${def_filename}']: " filename
        filename=${filename:=${def_filename}}
        # append .dmp if there isn't
        filename=${filename/%\.dmp/}.dmp
        # generate log file name with the same name as the dump file but .log
        logfilename=${filename/%\.dmp/\.log}
}

function confirm() {
        # list all input and ask for confirmation
        echo
        echo "Export will use the following:"
        echo "------------------------------"
        echo "Oracle home:              ${ORACLE_HOME}"
        echo "Oracle SID:               ${ORACLE_SID}"
        echo "Export will be done by:   ${dbuser:=sys as sysdba}"
        echo "Export file:              ${dirname}/${filename}"
        echo "Log file:                 ${dirname}/${logfilename}"
        echo
        read -p "Is this ok? [y for yes, anything else to abort]: " v_confirm
        if [ "${v_confirm}" != "y" ]; then
                echo "Export aborted!"
                exit
        fi
        echo
}

function checkDir() {
        # check if the directory exists and if we can write to it
        if [ -d ${dirname} ]; then
                # directory exists
                touch ${dirname}/${tmpfile} > /dev/null 2>&1
                if [ $? -eq 0 ]; then
                        # can write to the firectory
                        rm ${dirname}/${tmpfile}
                else
                        # cannot write to the directory
                        echo "Cannot create a file in '${dirname}'"
                        exit 1
                fi
        else
                # direcroty does not exist
                read -p "Directory '${dirname}' does not exist, create it? [y for yes, anything else to abort]: " v_confirm
                if [ "${v_confirm}" != "y" ]; then
                        echo "Export aborted!"
                        exit
                else
                        # create the directory
                        mkdir -p ${dirname} > /dev/null 2>&1
                        if [ $? -ne 0 ]; then
                                echo "Cannot create directory '${dirname}'"
                                exit 1
                        fi
                fi
        fi
}

function checkFile() {
        # check if the file exists
        if [ -f ${dirname}/${filename} ]; then
                # file exists
                read -p "File '${dirname}/${filename}' already exist, overwrite? [y for yes, anything else to abort]: " v_confirm
                if [ "${v_confirm}" != "y" ]; then
                        echo "Export aborted!"
                        exit
                else
                        overwrite_dumpfile=y
                fi
        fi
}

function createOracleDir() {
        # creating directory in Oracle for the export
        $ORACLE_HOME/bin/sqlplus -s /nolog <<- EOF > /dev/null 2>&1
                set feedback off
                whenever sqlerror exit 1
                conn ${conn_string}
                create directory ${ora_dirname} as '${dirname}';
                exit
				EOF
        if [ $? -ne 0 ]; then
                echo "Cannot create Oracle directory"
                exit 1
        fi
}

function runExport() {
        # generate the overwrite clause for data pump
        overwrite_clause=""
        [[ "${overwrite_dumpfile}" == "y" ]] && overwrite_clause="reuse_dumpfiles=Y"

        # run the export and save the exit code
        echo
        echo -n "Exporting the database... "
        $ORACLE_HOME/bin/expdp \"${conn_string}\" full=y directory=${ora_dirname} dumpfile=${filename} logfile=${logfilename} ${overwrite_clause} > /dev/null 2>&1
        export_rc=$?
        echo "Done"
}

function dropOracleDir() {
        # delete the  directory in Oracle
        $ORACLE_HOME/bin/sqlplus -s /nolog <<- EOF > /dev/null 2>&1
                set feedback off
                whenever sqlerror exit 1
                conn ${conn_string}
                drop  directory ${ora_dirname};
                exit
				EOF
        if [ $? -ne 0 ]; then
                echo "Cannot drop Oracle directory"
                exit 1
        fi
}

#------------------
# main
#------------------

echo
echo "Welcome to the export assistant"
echo "==============================="
echo

readInput
confirm
checkDir
checkFile
createOracleDir
runExport
dropOracleDir

echo
if [ ${export_rc} -ne 0 ]; then
        echo "Export failed!"
        exit 1
else
        echo "Export completed successfully!"
fi