install

#!/bin/bash

# This script will install from a local git clone or it can be run from
# Github directly, like this:
#
#     BRANCH=master GROUP=famzah && curl -s https://raw.githubusercontent.com/${GROUP}/aws-dyndns/${BRANCH}/install | sudo bash -s ${BRANCH} ${GROUP}
#
# Only supply arguments when installing directly from GitHub. Relevant
# configuration values in the current install are imported from previous
# installs.

# https://stackoverflow.com/a/246128/185257
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
PROJECT="aws-dyndns"

REPO_DIR=
download() {
    if [[ -n "$1" ]] ; then
        local BRANCH="$1"
        local GROUP="$2"

        REPO_DIR=$(mktemp -d)
        pushd "${REPO_DIR}" &>/dev/null

        echo "Downloading project archive..."
        set -e
        curl -LJO https://github.com/"${GROUP}"/${PROJECT}/archive/refs/heads/"${BRANCH}".zip
        set +e

        # Some embedded Linux systems, like EdgeOS, do not seem to deliver with
        # the capability to easily unpack zip files, so attempt to do it with
        # Python instead.
        if ! type unzip &>/dev/null ; then
            set -e
            python -c "import zipfile; zipfile.ZipFile('${PROJECT}-${BRANCH}.zip', 'r').extractall('./')"
            set +e
        else
            set -e
            unzip "${PROJECT}-${BRANCH}.zip"
            set +e
        fi

        popd &>/dev/null
        SCRIPT_DIR="${REPO_DIR}/${PROJECT}-${BRANCH}"
    fi
}

systemd() {
    echo
    echo "Installing ${PROJECT} systemd unit..."
    cp "${SCRIPT_DIR}/systemd/${PROJECT}.service" /lib/systemd/system
    chmod 644 /lib/systemd/system/${PROJECT}.service
    systemctl daemon-reload
    systemctl enable ${PROJECT}.service
    systemctl cat ${PROJECT}.service
}

script() {
    echo
    echo "Installing ${PROJECT} script..."
    mkdir -p /usr/local/sbin
    cp "${SCRIPT_DIR}/${PROJECT}" /usr/local/sbin
    chmod 755 /usr/local/sbin/${PROJECT}
}

configuration() {
    echo
    echo "Installing configuration file..."
    if [[ -r /etc/${PROJECT}.conf ]]; then
        echo "Prior configuration found, migrating prior values..."
        cp "${SCRIPT_DIR}/systemd/${PROJECT}.conf" /tmp
        while IFS= read -r VAR ; do
            VAL=$(grep "${VAR}=" /etc/${PROJECT}.conf | cut -d'=' -f2)
            echo "${VAR}=${VAL}"
            sed -i "s#${VAR}=.*#${VAR}=${VAL}#" /tmp/${PROJECT}.conf
        done < <(grep -E '^[_A-Za-z][_A-Za-z0-9]*=' /tmp/${PROJECT}.conf | cut -d'=' -f1)
        mv /tmp/${PROJECT}.conf /etc/${PROJECT}.conf
    else
        cp "${SCRIPT_DIR}/systemd/${PROJECT}.conf" /etc
    fi

    chmod 644 /etc/${PROJECT}.conf
}

cleanup() {
    echo
    echo "Install Complete"
    echo "Review /etc/${PROJECT}.conf before starting ${PROJECT} service."

    if [[ -n "${REPO_DIR}" ]] ; then
        rm -rf "${REPO_DIR}"
    fi
}

main() {
    # If arguments are supplied assume we are pulling the install script from
    # GitHub. Otherwise we are installing from a local Git clone.
    if [[ -n "$1" ]] ; then
        download "$@"
    fi

    systemd
    script
    configuration
    cleanup
}

main "$@"