prelude.sh

#!/bin/bash

# TODO write a naming convention and set up shfmt accordingly
# TODO make this into the library so that the
# testing of distro version can be used in if/else
#
# TODO refactor and rewrite this whole file, it is a bit ugly and buggy
# TODO use just one bash function notation not two

if [[ "${__INITPC_PRELUDE_SOURCED__}" != "true" ]]; then
    __INITPC_PRELUDE_SOURCED__='true'

    # Enable strict mode
    set -euo pipefail

    # TODO toread:
    # https://linuxopsys.com/topics/customizing-bash-prompt-in-linux-changing-colors
    # https://gist.github.com/vratiu/9780109
    # https://tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html
    # https://opensource.com/article/19/9/linux-terminal-colors
    # https://linuxopsys.com/topics/customizing-bash-prompt-in-linux-changing-colors
    # https://www.cyberciti.biz/faq/bash-shell-change-the-color-of-my-shell-prompt-under-linux-or-unix/
    # https://unix.stackexchange.com/questions/148/colorizing-your-terminal-and-shell-environment
    # https://dev.to/ifenna__/adding-colors-to-bash-scripts-48g4

    # shellcheck disable=SC2034
    readonly RED='\033[0;31m'
    # shellcheck disable=SC2034
    readonly IYELLOW='\033[0;93m' # high intensity yellow
    # shellcheck disable=SC2034
    readonly GREEN='\033[0;32m'
    # shellcheck disable=SC2034
    readonly NC='\033[0m' # No Color

    # makes the echo prompt yellow to improve readability
    export PS4="\[${IYELLOW}\]+ \[${NC}\]"

    # TODO renumber the exit codes according to the docs bellow
    # SEE: https://manpages.ubuntu.com/manpages/lunar/man3/sysexits.h.3head.html
    # SEE: https://tldp.org/LDP/abs/html/exitcodes.html
    # shellcheck disable=SC2034
    readonly EXIT_SUCCESS=0
    # shellcheck disable=SC2034
    readonly EXIT_FILE_IO_ERROR=50
    # TODO - consider even better error code number (guaranteed to be unique)
    # apt-get install returns 100 if a package was not found... 100 is not a good error code. >IMPORTANT<
    # shellcheck disable=SC2034
    readonly EXIT_INCORRECT_PLATFORM=99
    # shellcheck disable=SC2034
    readonly EXIT_INVALID_ARGUMENT=10
    # TODO - finish
    #

    set -x # turn logging on here to avoid polluting logs with the obvious

    # @param $1 - distro ID
    function distro_is
    {
        # TODO test the test... and make sure it is correct/valid/general enough
        # TODO see:
        # https://www.freedesktop.org/software/systemd/man/os-release.html
        # https://0pointer.de/blog/projects/os-release.html
        # https://manpages.ubuntu.com/manpages/focal/man5/os-release.5.html
        # https://docs.oracle.com/cd/E88353_01/html/E37852/os-release-5.html
        # https://github.com/chef/os_release
        # https://man.archlinux.org/man/os-release.5.en
        # https://manpages.debian.org/testing/systemd/os-release.5.en.html
        # https://www.commandlinux.com/man-page/man5/os-release.5.html
        # https://unix.stackexchange.com/questions/351557/on-what-linux-distributions-can-i-rely-on-the-presence-of-etc-os-release

        if [[ ! -f /etc/os-release ]]; then
            echo "/etc/os-release file not found."
            echo "Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        local ID
        # shellcheck disable=SC1091
        ID=$(source /etc/os-release && echo "${ID}")
        echo "Distro ID=${ID}"

        if [[ "${ID}" != "$1" ]]; then
            echo "Error: The distro ID is ${ID} but it should be $1! Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi
    }

    function get_major_distro_version
    {
        if [[ ! -f /etc/os-release ]]; then
            echo "/etc/os-release file not found."
            echo "Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        local VERSION_ID
        # shellcheck disable=SC1091
        VERSION_ID="$(source /etc/os-release && echo "${VERSION_ID}")"

        if [[ ${VERSION_ID} == "" ]]; then
            return
        fi

        echo "${VERSION_ID}" | grep -o "^[0-9]\+"
    }

    # @param $1 - minimal distro major version
    function distro_version_ge
    {
        local MAJOR_VERSION

        if ! MAJOR_VERSION="$(get_major_distro_version)"; then
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        # An empty VERSION_ID is interpretted as the (positive) infinity.
        if [[ "${MAJOR_VERSION}" == "" ]]; then
            echo "Warning: The version ID is empty."
            return
        fi

        if [[ "${MAJOR_VERSION}" -lt "$1" ]]; then
            echo "Error: Major distro version is ${MAJOR_VERSION} but it should be at least $1! Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi
    }

    function distro_version_le
    {
        local MAJOR_VERSION

        if ! MAJOR_VERSION="$(get_major_distro_version)"; then
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        # An empty VERSION_ID is interpretted as the (positive) infinity.
        if [[ "${MAJOR_VERSION}" == "" ]]; then
            echo "Warning: The version ID is empty."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        if [[ "${MAJOR_VERSION}" -gt "$1" ]]; then
            echo "Error: Major distro version is ${MAJOR_VERSION} but it should be at most $1! Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi
    }
    # TODO is this robust enough? What about sth. more robust?
    function gnome_present
    {
        local GNOME_PRESENT="no"

        if gnome-extensions --version; then
            GNOME_PRESENT="yes"
            echo "gnome-extensions executable found."
            echo "Assuming that GNOME is present"
        fi

        if [[ ${GNOME_PRESENT} != "$1" ]]; then
            echo "GNOME_PRESENT != $1. Aborting."
            return "${EXIT_INCORRECT_PLATFORM}"
        fi

        return 0
    }

    print0()
    {
        [ "$#" -eq 0 ] || printf '%s\0' "$@"
    }

    # Appends a prefix in the first parameter to every line from stdin and executes
    # the resulting command. Ignores comments and empty lines.
    for_each()
    {
        set +x
        local prefix="$1"
        local line
        while read -r line; do # Read a line and strip leading and trailing spaces
            # Skip empty lines and comments
            [[ "$line" =~ ^[[:space:]]*(#|$) ]] && continue
            # TODO try rewriting this with eval so that the colors and
            # debug msgs are printed correctly. I am using subshell instead of eval
            # because of the debugging output being displayed incorrectly otherwise.
            bash -cx "$prefix$line"
        done
        set -x
    }
    err()
    {
        echo "[$(date +'%Y-%m-%dT%H:%M:%S%z')]: $*" >&2
    }
    my_run_parts()
    {
        # TODO add pushd and popd here?
        # maybe run-parts can also execute everything from main
        # and the platform check would be a firtst file in the folder
        # i.e. 00 and I would call it platform_check or sth like that
        # what about that?
        echo "Not implemented"
        # run-parts for generic filenames (including dot)
        # as a test run first
        # run-parts --regex='^[^/]+$' --test . | grep files not matching the regex below
        run-parts --regex='^[0-9][0-9][\.A-Za-z0-9_-]+$' .
        # but filter the filenames and exit if there is a filename
        # that does not match [0-9][0-9]*.sh
        # Then run the real run and only filter by the strict regex
        exit 1
        # run-parts --regex='' --exit-on-error --verbose
    }
    ensure_line()
    {
        local line="$1"
        local file="$2"

        grep -Fxq -- "$line" "$file" 2> /dev/null \
            || printf '%s\n' "$line" >> "$file"
    }
fi