#!/usr/bin/env bash

# Mail Installer
# Min. Requirement  : GNU/Linux Ubuntu 14.04
# Last Build        : 12/07/2019
# Author            : ESLabs.ID (eslabs.id@gmail.com)
# Since Version     : 1.0.0

# Include helper functions.
if [ "$(type -t run)" != "function" ]; then
    BASEDIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )
    # shellchechk source=scripts/helper.sh
    # shellcheck disable=SC1090
    . "${BASEDIR}/helper.sh"
fi

# Make sure only root can run this installer script.
requires_root

##
# Install Postfix mail server.
#
function install_postfix() {
    if "${AUTO_INSTALL}"; then
        DO_INSTALL_POSTFIX="y"
    else
        while [[ "${DO_INSTALL_POSTFIX}" != "y" && "${DO_INSTALL_POSTFIX}" != "n" ]]; do
            read -rp "Do you want to install Postfix Mail Transfer Agent? [y/n]: " -i y -e DO_INSTALL_POSTFIX
        done
    fi

    if [[ ${DO_INSTALL_POSTFIX} == y* && "${INSTALL_MAILER}" == true ]]; then
        echo "Installing Postfix Mail Transfer Agent..."

        if hash apt 2>/dev/null; then
            run apt install -qq -y mailutils postfix
        else
            fail "Unable to install NGiNX, this GNU/Linux distribution is not supported."
        fi

        # Configure Postfix.
        run postconf -e "inet_interfaces = all"
        run postconf -e "inet_protocols = all"
        run postconf -e "alias_maps = hash:/etc/aliases"
        run postconf -e "alias_database = hash:/etc/aliases"
        run postconf -e "home_mailbox = Maildir/"
        run postconf -e "myhostname = ${HOSTNAME}"
        #run postconf -e "mydomain = eslabs.id"
        run postconf -e "myorigin = localhost"
        run postconf -e "mydestination = \$myhostname, localhost, localhost.localdomain"

        # Setting up SMTP authentication.
        run postconf -e "smtpd_sasl_type = dovecot"
        run postconf -e "smtpd_sasl_path = private/auth"
        run postconf -e "smtpd_sasl_local_domain ="
        run postconf -e "smtpd_sasl_security_options = noanonymous"
        run postconf -e "broken_sasl_auth_clients = yes"
        run postconf -e "smtpd_sasl_auth_enable = yes"
        run postconf -e "smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination,reject_invalid_hostname,reject_non_fqdn_hostname,reject_non_fqdn_sender,reject_non_fqdn_recipient,reject_unknown_sender_domain,reject_rbl_client sbl.spamhaus.org,reject_rbl_client cbl.abuseat.org"

        # Getting Let's Encrypt certificates.
        local CERTPATH=""

        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true \
        && $(dig "${SENDER_DOMAIN}" +short) = "${SERVER_IP}" ]]; then
            run certbot certonly --standalone --agree-tos --preferred-challenges http -d "${SENDER_DOMAIN}"
            CERTPATH="/etc/letsencrypt/live/${SENDER_DOMAIN}"
        elif [[ $(dig "${HOSTNAME}" +short) = "${SERVER_IP}" ]]; then
            run certbot certonly --standalone --agree-tos --preferred-challenges http --webroot-path=/usr/share/nginx/html -d "${HOSTNAME}"
            CERTPATH="/etc/letsencrypt/live/${HOSTNAME}"
        fi

        # Enable Postfix secure.
        if [ -n "${CERTPATH}" ]; then
            run postconf -e "smtpd_tls_cert_file = ${CERTPATH}/fullchain.pem"
            run postconf -e "smtpd_tls_key_file = ${CERTPATH}/privkey.pem"
            run postconf -e "smtp_tls_security_level = may"
            run postconf -e "smtpd_tls_security_level = may"
            run postconf -e "smtp_tls_note_starttls_offer = yes"
            run postconf -e "smtpd_tls_loglevel = 1"
            run postconf -e "smtpd_tls_received_header = yes"
        fi

        # Multiple domain, multiple user settings.
        # Ref: https://debian-administration.org/article/243/Handling_mail_for_multiple_virtual_domains_with_postfix

        # Virtual alias mapping.
        [ ! -d /etc/postfix/virtual ] && run mkdir -p /etc/postfix/virtual
        [ ! -f /etc/postfix/virtual/addresses ] && run touch /etc/postfix/virtual/addresses
        run bash -c "echo '${HOSTNAME}   DOMAIN
${LEMPER_USERNAME}@${HOSTNAME}    ${LEMPER_USERNAME}
postmaster@${HOSTNAME}    ${LEMPER_USERNAME}
root@${HOSTNAME}  ${LEMPER_USERNAME}
wordpress@${HOSTNAME}  ${LEMPER_USERNAME}' > /etc/postfix/virtual/addresses"

        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            run bash -c "echo '${SENDER_DOMAIN}    DOMAIN
@${SENDER_DOMAIN}    ${LEMPER_USERNAME}' > /etc/postfix/virtual/addresses"
        fi

        postmap /etc/postfix/virtual/addresses
        run postconf -e "virtual_alias_maps = hash:/etc/postfix/virtual/addresses"

        # Virtual domain mapping.
        [ ! -f /etc/postfix/virtual/domains ] && touch /etc/postfix/virtual/domains
        run bash -c "echo '${HOSTNAME}' > /etc/postfix/virtual/domains"

        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            run bash -c "echo '${SENDER_DOMAIN}' >> /etc/postfix/virtual/domains"
        fi

        run postconf -e "virtual_alias_domains = /etc/postfix/virtual/domains"

        # Installation status.
        if "${DRYRUN}"; then
            info "Postfix reloaded in dry run mode."
        else
            if [[ $(pgrep -c postfix) -gt 0 ]]; then
                run systemctl reload postfix
                success "Postfix reloaded successfully."
            elif [[ -n $(command -v postfix) ]]; then
                run systemctl start postfix

                if [[ $(pgrep -c postfix) -gt 0 ]]; then
                    success "Postfix started successfully."
                else
                    error "Something goes wrong with Postfix installation."
                fi
            fi
        fi
    fi
}


##
# Install Dovecot
#
function install_dovecot() {
    if "${AUTO_INSTALL}"; then
        DO_INSTALL_DOVECOT="y"
    else
        while [[ "${DO_INSTALL_DOVECOT}" != "y" && "${DO_INSTALL_DOVECOT}" != "n" ]]; do
            read -rp "Do you want to install Dovecot IMAP and POP3 email server? [y/n]: " -i y -e DO_INSTALL_DOVECOT
        done
    fi

    if [[ ${DO_INSTALL_DOVECOT} == y* && "${INSTALL_MAILER}" == true ]]; then
        echo "Installing Dovecot IMAP and POP3 email server..."

        if hash apt 2>/dev/null; then
            run apt install -qq -y dovecot-core dovecot-common dovecot-imapd dovecot-pop3d
        else
            fail "Unable to install NGiNX, this GNU/Linux distribution is not supported."
        fi

        # Configure Dovecot.
        run maildirmake.dovecot /etc/skel/Maildir
        run maildirmake.dovecot /etc/skel/Maildir/.Drafts
        run maildirmake.dovecot /etc/skel/Maildir/.Sent
        run maildirmake.dovecot /etc/skel/Maildir/.Trash
        run maildirmake.dovecot /etc/skel/Maildir/.Templates
        run cp -r /etc/skel/Maildir "/home/${LEMPER_USERNAME}"
        run chown -R lemper:lemper "/home/${LEMPER_USERNAME}/Maildir"
        run chmod -R 700 "/home/${LEMPER_USERNAME}/Maildir"

        # Add LEMPer default user to mail group.
        run adduser "${LEMPER_USERNAME}" mail

        # Include the Maildir location in terminal and mail profiles.
        run bash -c "echo -e '\nexport MAIL=~/Maildir' >> /etc/bash.bashrc"
        run bash -c "echo -e '\nexport MAIL=~/Maildir' >> /etc/profile.d/mail.sh"

        # User authentication (with SASL).
        if [ -f /etc/dovecot/conf.d/10-auth.conf ]; then
            # Disabling the plaintext authentication.
            if grep -qwE "^#disable_plaintext_auth\ =\ [a-zA-Z]*" /etc/dovecot/conf.d/10-auth.conf; then
                run sed -i "/^#disable_plaintext_auth/a disable_plaintext_auth\ =\ yes" \
                    /etc/dovecot/conf.d/10-auth.conf
            else
                run sed -i "s/disable_plaintext_auth\ =\ [a-zA-Z]*/disable_plaintext_auth\ =\ yes/g" \
                    /etc/dovecot/conf.d/10-auth.conf
            fi

            # Enabling login authentication mechanism.
            if grep -qwE "^#auth_mechanisms\ =\ [a-zA-Z]*" /etc/dovecot/conf.d/10-auth.conf; then
                run sed -i "/^#auth_mechanisms/a auth_mechanisms = plain login" \
                    /etc/dovecot/conf.d/10-auth.conf
            else
                run sed -i "s/auth_mechanisms\ =\ [a-zA-Z]*/auth_mechanisms\ =\ plain\ login/g" \
                    /etc/dovecot/conf.d/10-auth.conf
            fi
        fi

        # Set the mail directory to use the same format as Postfix.
        if [ -f /etc/dovecot/conf.d/10-mail.conf ]; then
            # Maildir.
            if grep -qwE "^mail_location\ =\ [^[:digit:]]*$" /etc/dovecot/conf.d/10-mail.conf; then
                run sed -i "s/^mail_location\ =\ [^[:digit:]]*$/mail_location\ =\ maildir:~\/Maildir/g" \
                    /etc/dovecot/conf.d/10-mail.conf
            else
                run sed -iE "/^#mail_location\ =\ [^[:digit:]]*$/a mail_location\ =\ maildir:~\/Maildir" \
                    /etc/dovecot/conf.d/10-mail.conf
            fi
        fi

        # Enable IMAP and POP3 protocols for email clients.
        if [ -f /etc/dovecot/conf.d/10-master.conf ]; then
            # IMAP
            run sed -i "s/#port\ =\ 143/port\ =\ 143/g" /etc/dovecot/conf.d/10-master.conf
            # IMAPS
            run sed -i "s/#port\ =\ 993/port\ =\ 993/g" /etc/dovecot/conf.d/10-master.conf
            run sed -i "s/#ssl\ =\ yes/ssl\ =\ yes/g" /etc/dovecot/conf.d/10-master.conf

            # POP3
            run sed -i "s/#port\ =\ 110/port\ =\ 110/g" /etc/dovecot/conf.d/10-master.conf
            # IMAPS
            run sed -i "s/#port\ =\ 995/port\ =\ 995/g" /etc/dovecot/conf.d/10-master.conf
            run sed -i "s/#ssl\ =\ yes/ssl\ =\ yes/g" /etc/dovecot/conf.d/10-master.conf

            # Postfix SMTP auth.
            run sed -i "s/#mode\ =\ 0666/mode\ =\ 0666/g" /etc/dovecot/conf.d/10-master.conf
            run sed -i "s/#user\ =\ postfix/user\ =\ postfix/g" /etc/dovecot/conf.d/10-master.conf
            run sed -i "s/#group\ =\ postfix/group\ =\ postfix/g" /etc/dovecot/conf.d/10-master.conf
        fi

        # Installation status.
        if "${DRYRUN}"; then
            info "Dovecot installed in dryrun mode."
        else
            if [[ $(pgrep -c dovecot) -gt 0 ]]; then
                run systemctl reload dovecot
                success "Dovecot reloaded successfully."
            elif [[ -n $(command -v dovecot) ]]; then
                run systemctl start dovecot

                if [[ $(pgrep -c dovecot) -gt 0 ]]; then
                    success "Dovecot started successfully."
                else
                    error "Something goes wrong with Dovecot installation."
                fi
            fi
        fi
    fi
}

## TODO: Postfix and Dovecot default configuration
# https://www.linode.com/docs/email/postfix/email-with-postfix-dovecot-and-mysql/


## 
# Install SPF + DKIM
# Ref: https://www.linuxbabe.com/mail-server/setting-up-dkim-and-spf
#
function install_spf_dkim() {
    if "${AUTO_INSTALL}"; then
        DO_INSTALL_SPFDKIM="y"
    else
        while [[ "${DO_INSTALL_SPFDKIM}" != "y" && "${DO_INSTALL_SPFDKIM}" != "n" ]]; do
            read -rp "Do you want to install Postfix Policy Agent and OpenDKIM? [y/n]: " -i y -e DO_INSTALL_SPFDKIM
        done
    fi

    if [[ ${DO_INSTALL_SPFDKIM} == y* && "${INSTALL_SPFDKIM}" == true ]]; then
        echo "Installing SPF + DKIM email server..."

        # Installing SPF Policy Agent & OpenDKIM.
        if hash apt 2>/dev/null; then
            run apt install -qq -y postfix-policyd-spf-python opendkim opendkim-tools
        else
            fail "Unable to install NGiNX, this GNU/Linux distribution is not supported."
        fi

        # Update postfix master conf.
        run bash -c "echo 'policyd-spf  unix  -       n       n       -       0       spawn
user=policyd-spf argv=/usr/bin/policyd-spf' >> /etc/postfix/master.cf"

        # Update postfix main conf.
        run postconf -e 'policyd-spf_time_limit = 3600'
        run postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination,reject_invalid_hostname,reject_non_fqdn_hostname,reject_non_fqdn_sender,reject_non_fqdn_recipient,reject_unknown_sender_domain,reject_rbl_client sbl.spamhaus.org,reject_rbl_client cbl.abuseat.org,check_policy_service unix:private/policyd-spf'

        # Add postfix user to opendkim group.
        run adduser postfix opendkim

        # Connect Postfix to OpenDKIM.
        # Ubuntu ships Postfix in chrooted jail, 
        # need to update OpenDKIM socket to be able to communicate with OpenDKIM.
        # Create a directory to hold the OpenDKIM socket file and only allow opendkim user and postfix group to access it.
        run mkdir -p /var/spool/postfix/opendkim
        run chown opendkim:postfix /var/spool/postfix/opendkim

        # Update OpenDKIM default socket configuration file.
        if [ -f /etc/default/opendkim ]; then
            run sed -i "s/^RUNDIR=\/var\/run\/opendkim/#RUNDIR=\/var\/run\/opendkim/g" /etc/default/opendkim
            run sed -i "/^#RUNDIR=\/var\/spool\/postfix\/var\/run\/opendkim/s/^#//" /etc/default/opendkim
        fi

        # Update OpenDKIM socket config.
        local OPENDKIM_SOCKET="local:/var/spool/postfix/opendkim/opendkim.sock"
        run sed -i "/^Socket\s[^[:digit:]]*$/s//#&/" /etc/opendkim.conf
        run sed -i "/^#Socket\s[^[:digit:]]*$/a Socket\    ${OPENDKIM_SOCKET}" /etc/opendkim.conf

        # Postfix Milter configuration.
        run postconf -e "milter_default_action = accept"
        run postconf -e "milter_protocol = 6"
        run postconf -e "smtpd_milters = local:/opendkim/opendkim.sock"
        run postconf -e "non_smtpd_milters = \$smtpd_milters"

        # Adjusts OpenDKIM config.
        #run sed -i "/^#Canonicalization/a Canonicalization\       relaxed\/simple" /etc/opendkim.conf
        run sed -i "/^#Canonicalization/a Canonicalization\       relaxed\/relaxed" /etc/opendkim.conf
        run sed -i "/^#Mode/a Mode\                   sv" /etc/opendkim.conf
        run sed -i "/^#SubDomains/a SubDomains\             no" /etc/opendkim.conf
        run sed -i "/^SubDomains/a #ADSPAction\ continue\nAutoRestart\         yes\nAutoRestartRate\     10\/1M\nBackground\          yes\nDNSTimeout\          5\nSignatureAlgorithm\  rsa-sha256" /etc/opendkim.conf

        # Add opendkim user id.
        if ! grep -qwE "^UserID\                opendkim" /etc/opendkim.conf; then
            run bash -c "echo 'UserID                opendkim' >> /etc/opendkim.conf"
        fi

        # Add domains keys.
        if ! "${DRYRUN}"; then 
            cat >> /etc/opendkim.conf <<EOL
# Map domains in From addresses to keys used to sign messages
KeyTable           refile:/etc/opendkim/key.table
SigningTable       refile:/etc/opendkim/signing.table

# Hosts to ignore when verifying signatures
ExternalIgnoreList  /etc/opendkim/trusted.hosts

# A set of internal hosts whose mail should be signed
InternalHosts       /etc/opendkim/trusted.hosts
EOL
        fi

        # Create a directory structure for OpenDKIM.
        [ ! -d /etc/opendkim ] && \
        run mkdir -p /etc/opendkim && \
        run chown -hR opendkim:opendkim /etc/opendkim

        [ ! -d /etc/opendkim/keys ] && \
        run mkdir -p /etc/opendkim/keys && \
        run chmod go-rw /etc/opendkim/keys

        # Create the signing table.
        [ ! -f /etc/opendkim/signing.table ] && run touch /etc/opendkim/signing.table

        #DOMAIN_SIGNING="*@your-domain.com    default._domainkey.your-domain.com"
        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            DOMAIN_SIGNING="*@${SENDER_DOMAIN}    lemper._domainkey.${SENDER_DOMAIN}"
            run bash -c "echo '${DOMAIN_SIGNING}' > /etc/opendkim/signing.table"
        fi

        # Create the key table.
        [ ! -f /etc/opendkim/key.table ] && run touch /etc/opendkim/key.table

        #DOMAIN_KEY="default._domainkey.your-domain.com     your-domain.com:default:/etc/opendkim/keys/your-domain.com/default.private"
        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            DOMAIN_KEY="lemper._domainkey.${SENDER_DOMAIN}    ${SENDER_DOMAIN}:lemper:/etc/opendkim/keys/${SENDER_DOMAIN}/lemper.private"
            run bash -c "echo '${DOMAIN_KEY}' > /etc/opendkim/key.table"
        fi

        # Create trusted hosts.
        [ ! -f /etc/opendkim/trusted.hosts ] && run touch /etc/opendkim/trusted.hosts
        run bash -c "echo -e '127.0.0.1\nlocalhost' > /etc/opendkim/trusted.hosts"

        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            run bash -c "echo -e '\n*.${SENDER_DOMAIN}' >> /etc/opendkim/trusted.hosts"
        fi

        # Generate Private/Public Keypair for sender domain.

        if [[ $(validate_fqdn "${SENDER_DOMAIN}") = true && "${SENDER_DOMAIN}" != "example.com" ]]; then
            # Create a separate folder for the domain.
            run mkdir -p "/etc/opendkim/keys/${SENDER_DOMAIN}"

            # Generate keys using opendkim-genkey tool.
            #opendkim-genkey -b 2048 -d your-domain.com -D /etc/opendkim/keys/your-domain.com -s default -v
            local HASH_LENGTH=${HASH_LENGTH:-2048}
            run opendkim-genkey -b "${HASH_LENGTH}" -d "${SENDER_DOMAIN}" -D "/etc/opendkim/keys/${SENDER_DOMAIN}" -s lemper -v

            # Make opendkim as the owner of the private key.
            #chown opendkim:opendkim /etc/opendkim/keys/your-domain.com/default.private
            run chown opendkim:opendkim "/etc/opendkim/keys/${SENDER_DOMAIN}/lemper.private"

            # Publish Your Public Key in DNS Records.
            DKIM_KEY=$(cat "/etc/opendkim/keys/${SENDER_DOMAIN}/lemper.txt")

            echo -e "Add this DKIM key to your DNS TXT record!\nDKIM Key: ${DKIM_KEY}"

            # Test DKIM Key.
            #run opendkim-testkey -d "${SENDER_DOMAIN}" -s lemper -vvv
            echo -e "\nAfter then run this command to check your DNS record"
            echo "opendkim-testkey -d ${SENDER_DOMAIN} -s lemper -vvv"
        fi
    fi
}


echo "[Mail Server Installation]"

# Start running things from a call at the end so if this script is executed
# after a partial download it doesn't do anything.
if [[ -n $(command -v postfix) ]]; then
    info "Postfix already exists. Installation skipped..."
else
    install_postfix "$@"
fi

if [[ -n $(command -v dovecot) ]]; then
    info "Dovecot already exists. Installation skipped..."
else
    install_dovecot "$@"
fi

install_spf_dkim