Alchemy/ingredients/lead

#!/bin/sh
# Bare Metal Alchemist, 2022

############################################# 
#                Lead - ♄                   # 
############################################# 

# The most basic ingredient in an Alchemy recipe, lead is used in all
# recipes in this repository to standardize some simple things that I
# rely on to make scripts concise and pleasant to use

# --------------- Escape Codes ---------------
# These constants are used to add color and text formatting to the
# terminal's output -- Further reading: ANSI Escape Codes
RED="\e[0;31m"
GREEN="\e[0;32m"
BLUE="\e[0;34m"
BOLD="\e[1m"
ULINE="\e[4m"
RESET="\e[0m"

# --------------- Traps ---------------

# Traps, in the case of shell scripting, listen for certain signals 
# that are broadcast by the system and execute a command in response

# We only want these to activate if we're running a recipe
if [[ $SHLVL -gt 1 ]]; then
    # Make sure that ctrl+C consistently exits the script
    trap "exit" INT 
    # Give informative error messages when we receive ERR
    trap 'echo -e "${RED}Oops...${RESET} Something went wrong on line $LINENO of this script. Exit code was $?" >&2' ERR
fi


# --------------- Environment Setup ---------------

# If there's an env file, export it's contents to the environment
if [ -f .env ]; then
    export $(grep -v '^#' .env | xargs)
else
    if [ -z $ALCHEMY ]; then
        echo "No .env file, this might cause some issues..."
    fi
fi


# --------------- Functions ---------------

# Coding Moment: generally, whenever you see something with brackets
# at the end of it, like this() or like(this), it's a function!
# It takes inputs and gives (or does) something as an output

# Checks to see if we can use a command or not
check_exists() {
    command -v "$1" >/dev/null
}

# This one installs utilities to your OS (If you need them!)
install_if_needed() {
    for package in "$@" # $@ means "all the arguments you passed 
    do
        case $DISTRO in
            "debian")
                # TODO Better installation detection than check_exists
                if [ -z $(check_exists $package) ]; then
                    echo "installing" $package
                    sudo apt install -y $package
                else
                    echo $package 'already installed!'
                fi
                ;;
            "arch")
                if pacman -Qi $package &>/dev/null; then
                    echo $package 'already installed!'
                else
                    echo "installing" $package
                    sudo pacman -S $package --noconfirm --needed
                fi
                ;;
            "fedora")
                # TODO Better installation detection than "check_exists"
                if [ -z $(check_exists $package) ]; then
                    echo "installing" $package
                    sudo dnf install -y $package
                else
                    echo $package 'already installed!'
                fi
                ;;
            "mac")
                # TODO Better installation detection than "check_exists"
                if [ -z $(check_exists $package) ]; then
                    echo "installing" $package
                    brew install $package
                else
                    echo $package 'already installed!'
                fi
                ;;
        esac
    done
}

# These two might look like gibberish because we're using regex, don't worry.
# It takes values and stores them away in the env for later reference
forget() {
    unset ${1}
    sed -i "/^${1}.*$/d" .env
}

remember() {
    KEY=$(echo ${1} | cut -d'=' -f 1)
    VALUE=$(echo ${1} | cut -d'=' -f 2)

    if [[ ! $KEY =~ ^[A-Z_]+$ ]]; then
        echo "Keys must consist only of capital letters and underscores"
    fi

    if [[ ! $VALUE =~ ^[A-Za-z0-9/_.]+$ ]]; then
        echo "Valid characters for env values: letters, numbers, \".\",\"/\",\"_\""
    fi

    # If we're setting a valid key/value pair
    if [[ ${1} =~ ^[A-Z_]+\=[A-Za-z0-9/._]*$ ]]; then

        # If we're trying to set the value to something new
        if [[ ! $(env | grep ${KEY}) = $1 ]]; then
            echo -e "${BLUE}${KEY}${RESET} has already been defined in the env!"
            echo -en "would you like to overwrite it? ${BLUE}(y/n)${RESET} "
            read overwrite
            case $overwrite in
                "y" | "Y")
                    unset ${KEY}
                    sed -i "/^${KEY}.*$/d" .env
                    echo "${1}" >> .env
                    export ${1}
                    ;;
            esac
        else
            forget ${KEY}
            echo "${1}" >> .env
            export ${1}
        fi
    fi
}


LEAD=1