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"
ITALIC="\e[3m"
ULINE="\e[4m"
RESET="\e[0m"

# TODO -- there are actually a lot of ANSI codes that can be used
# 0 - Reset (normal attributes)
# 1 - Bold or increased intensity
# 2 - Faint (opposite of bold)
# 3 - Italic
# 4 - Underline
# 5 - Blink slowly
# 6 - Blink quickly
# 7 - Swap foreground and background
# 8 - Conceal
# 9 - Cross-out
# 10 - Default font
# 11-19 - Alternate fonts
# 20 - Fraktur font
# 21 - Bold off or double underline
# 22 - Bold and faint off
# 23 - Italic and fraktur off
# 24 - Underline off
# 25 - Blink off
# 27 - Undo foreground and background swapping
# 28 - Conceal off
# 29 - Cross-out off
# 39 - Default text color
# 49 - Default background color
# 51 - Framed
# 52 - Encircled
# 53 - Overlined
# 54 - Frame and encircle off
# 55 - Overline off

# TODO -- these should be implemented as part of the syntax for "say"

# --------------- 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, so we
# check to see if we're running a "shell inside of a shell"
if [[ $SHLVL -gt 1 ]]; then
    # Make sure that ctrl+C consistently exits the script
    trap "exit" INT 
    # Give informative error messages when we receive ERR
    trap 'say "${RED}Oops...${RESET} Something went wrong on line $LINENO of this script. Exit code was $?" >&2' ERR
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

# --------------- Input/Output ---------------

# 'say' is a simple function that imitates "echo"
# This needs to be built out way more! Replace echo for POSIX compatibility
say() {
    printf "%b\n" "${1}"
}

ask_for() { 
    if [ ${#} -eq 0 ]; then
        say "To use this command, you need to pass the variable you want,"
        say "and then add as string of text to ask for it if you want. Example:\n"
        say "ask_for RESPONSE \"Could you give me a RESPONSE please?\""
        say ""
        say "Afterwards, you'll be able to use \$RESPONSE as a variable,"
        say "and ${ITALIC}say \$RESPONSE${RESET} will respond with your entry"
        return 0
    fi

    if [ -n "${2}" ]; then
        printf "%b" "${2}"
    fi

    read ${1}
}

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

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

# This is how we call a function that we have already defined.
# This one takes no arguments (words after the function name
source_env

# --------------- Program Installation ---------------

# Checks to see if we can use a command or not
check_for() {
    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_for
                if [ -z $(check_for $package) ]; then
                    say "installing $package"
                    sudo apt install -y $package
                else
                    say "$package already installed!"
                fi
                ;;
            "arch")
                if pacman -Qi $package &>/dev/null; then
                    say "$package already installed!"
                else
                    say "installing $package"
                    sudo pacman -S $package --noconfirm --needed
                fi
                ;;
            "fedora")
                # TODO Better installation detection than "check_for"
                if [ -z $(check_for $package) ]; then
                    say "installing $package"
                    sudo dnf install -y $package
                else
                    say "$package already installed!"
                fi
                ;;
            "mac")
                # TODO Better installation detection than "check_for"
                if [ -z $(check_for $package) ]; then
                    say "installing $package"
                    brew install $package
                else
                    say "$package already installed!"
                fi
                ;;
        esac
    done
}


# --------------- Memory ---------------
# These two functions might look like gibberish because we're using regex,
# short for REGular EXpression. It's a form of matching text to a pattern.


# It takes values and stores them away in the env for later reference
forget() {
    DOTENV_ENTRY=$(cat .env | grep ^${1}\=)
    if [ -n "$DOTENV_ENTRY" ]; then
        unset ${1}
        sed -i "/^${1}.*$/d" .env
    else
        say "I already don't remember ${BLUE}${1}${RESET}..."
    fi

    # Once we've made changes, we need to make sure we're up to date
    source_env
}

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

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

    if [[ ! $VALUE =~ ^[A-Za-z0-9/_.:]+$ ]]; then
        say "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

        DOTENV_ENTRY=$(cat .env | grep ${KEY})
        # If something already exists and we're trying to set it to something new
        if [ -n "$DOTENV_ENTRY" ] && [ "$DOTENV_ENTRY" != "$1" ]; then
            say "I'm trying to remember ${BLUE}${1}${RESET}, but..."
            say ""
            say "${BLUE}${DOTENV_ENTRY}${RESET}"
            say "This has already been defined in the .env file!"
            say ""
            ask_for overwrite "would you like to overwrite it? ${BLUE}(y/n)${RESET} "
            case $overwrite in
                "y" | "Y")
                    unset ${KEY}
                    sed -i "/^${KEY}.*$/d" .env
                    echo "${1}" >> .env
                    export ${1}
                    ;;
            esac
        elif [ -z "$DOTENV_ENTRY" ]; then
            unset ${KEY}
            echo "${1}" >> .env
            export ${1}
        fi
    fi

    # Once we've made changes, we need to make sure we're up to date
    source_env
}

LEAD=1