bash_profile_switcher.sh

# shellcheck shell=bash
# Bash profile switcher

# bash-profile-switcher.sh
#
# Manage multiple environments using profile files
# and loading dynamically with bash shell.
#
# Append or source this snippet at the end of your ~/.bashrc
# Use switch_profile function to load custom profiles
#
# Source repository: https://github.com/gianluca-mascolo/bash-profile-switcher
#
# Copyright (C) 2022-2023 Gianluca Mascolo
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

### GENERAL CONFIGURATION ###

# Setup default directory
export SWITCH_PROFILE_DIRECTORY=".bash_profile.d"
[[ -d "$HOME/$SWITCH_PROFILE_DIRECTORY" ]] || mkdir "$HOME/$SWITCH_PROFILE_DIRECTORY"
[[ -d "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets" ]] || mkdir "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets"

# Setup save profile filename
export SWITCH_PROFILE_SAVED=".bash_saved_profile"

# List of loaded snippets separated by colon
export SWITCH_PROFILE_SNIPPETS=""

# shellcheck source=/dev/null
[[ -f "$HOME/$SWITCH_PROFILE_DIRECTORY/.version" ]] && source "$HOME/$SWITCH_PROFILE_DIRECTORY/.version"

### FUNCTION DECLARATION ###

# __switch_profile_parse
# To be used with mapfile
# Every line in the file is parsed and checked for a corresponding snippet to be loaded

__switch_profile_parse() {
    local VALUE
    local SNIPPET
    VALUE="$2"
    if [[ "$VALUE" =~ ^[[:blank:]]*([^# ]+)([[:blank:]]|$) ]]; then
        {
            SNIPPET="${BASH_REMATCH[1]}"
            if [[ -f "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets/$SNIPPET.sh" ]] && ! __switch_profile_snippet search "$SNIPPET"; then
                # shellcheck source=/dev/null
                source "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets/$SNIPPET.sh" load && __switch_profile_snippet push "$SNIPPET"
            fi
        }
    fi
    return 0
}

# __switch_profile_snippet [push|pop|search] <snippet name>
# Manage the status of snippets storing it in SWITCH_PROFILE_SNIPPETS if it has loaded or unloaded.
# - push the snippet name into SWITCH_PROFILE_SNIPPETS only if the value is not already present
# - pop the snippet name from SWITCH_PROFILE_SNIPPETS
# - search if a snippet name is present in SWITCH_PROFILE_SNIPPETS
__switch_profile_snippet() {
    local -r snippet_cmd="${1:-}"
    local -r snippet_name="${2:-}"
    local -r REGEX="(^|.*:)(${snippet_name})(:.*|$)"

    case "$snippet_cmd" in
    push)
        if [[ "$SWITCH_PROFILE_SNIPPETS" =~ $REGEX ]]; then return 0; else SWITCH_PROFILE_SNIPPETS="${SWITCH_PROFILE_SNIPPETS}:${snippet_name}"; fi
        export SWITCH_PROFILE_SNIPPETS=${SWITCH_PROFILE_SNIPPETS#:}
        ;;
    pop)
        if [[ "$SWITCH_PROFILE_SNIPPETS" =~ $REGEX ]]; then SWITCH_PROFILE_SNIPPETS="${BASH_REMATCH[1]%:}:${BASH_REMATCH[3]#:}"; else return 0; fi
        SWITCH_PROFILE_SNIPPETS=${SWITCH_PROFILE_SNIPPETS%:}
        export SWITCH_PROFILE_SNIPPETS=${SWITCH_PROFILE_SNIPPETS#:}
        ;;
    search)
        if [[ "$SWITCH_PROFILE_SNIPPETS" =~ $REGEX ]]; then return 0; else return 1; fi
        ;;
    *)
        echo "${SWITCH_PROFILE_SNIPPETS:-}"
        ;;
    esac
    return 0
}

# Create list of profiles from .profile files
__switch_profile_list() {
    local PROFILE_LIST
    # Note: If there are no matching files, echo *.profile output literally "*.profile"
    PROFILE_LIST="$(echo "$HOME/$SWITCH_PROFILE_DIRECTORY/"*.profile)"
    PROFILE_LIST="${PROFILE_LIST//$HOME\/$SWITCH_PROFILE_DIRECTORY\//}"
    PROFILE_LIST="${PROFILE_LIST//.profile/}"
    [[ "$PROFILE_LIST" = '*' ]] && PROFILE_LIST=""
    echo "$PROFILE_LIST"
}

SWITCH_PROFILE_LIST=$(__switch_profile_list)
export SWITCH_PROFILE_LIST

__switch_profile_help() {
    cat <<EOF
switch_profile [options] profile

OPTIONS
  -k
    Keep env. Load selected profile without unloading current environment.
  -d
    Don't load profile. Unload current profile and don't load any profile in new bash shells
  -t
    Temporary profile. Load selected profile in current shell without starting it in new bash shells
  -l
    List available profiles
  -v
    Display switch_profile version
  -h Show help instructions (this help)

PROFILE
  A profile to load in ~/$SWITCH_PROFILE_DIRECTORY. Profile files end with extension '.profile' and contains a list of snippets to be loaded.
  Current profile is stored in environment variable SWITCH_PROFILE_CURRENT and in file ~/$SWITCH_PROFILE_SAVED

SNIPPETS

  Snippets are .sh files located in ~/$SWITCH_PROFILE_DIRECTORY/snippets that accept load or unload as first positional parameter (\$1)
  Each snippet will be included with source in your shell.

EXAMPLE

  Given the following setup ~/$SWITCH_PROFILE_DIRECTORY
  ~]$ tree ~/.bash_profile.d/
    $HOME/.bash_profile.d/
    ├── dev.profile
    └── snippets
        ├── snip1.sh
        └── snip2.sh

  ~]$ cat ~/.bash_profile.d/dev.profile
    snip1
    snip2

  ~]$ switch_profile dev

  snip1.sh and snip2.sh will be included into your bash shell.

ADDENDUM

  - Snippets will be loaded in the order the are listed into profile file.
  - When you switch into a profile snippets are loaded with source command e.g. 'source snip1 load'
  - When you change profile, current snippets are unloaded (except if you use -k) in reverse order
    they are listed into profile file with source e.g. 'source snip1 unload'


EOF
}

switch_profile() {
    local OPTIND OPTARG SELECTED_PROFILE KEEP_ENV TEMP_PROFILE RESET_PROFILE
    local -a SNIPPET_ARRAY
    KEEP_ENV=0
    TEMP_PROFILE=0
    RESET_PROFILE=0
    while getopts ":tkdhlv" Option; do
        case $Option in
        k)
            KEEP_ENV=1
            ;;
        t)
            TEMP_PROFILE=1
            ;;
        l)
            SWITCH_PROFILE_LIST=$(__switch_profile_list)
            export SWITCH_PROFILE_LIST
            [[ -n "$SWITCH_PROFILE_LIST" ]] && complete -o nospace -W "$SWITCH_PROFILE_LIST" switch_profile
            echo -e "${SWITCH_PROFILE_LIST// /\\n}"
            return 0
            ;;
        h)
            __switch_profile_help
            return 0
            ;;
        v)
            echo "${SWITCH_PROFILE_VERSION:-unknown}"
            return 0
            ;;
        d)
            RESET_PROFILE=1
            ;;
        *)
            __switch_profile_help
            return 1
            ;;
        esac
    done
    shift $((OPTIND - 1))

    if ! [[ $KEEP_ENV -eq 1 ]]; then
        IFS=':' read -r -a SNIPPET_ARRAY <<<"$SWITCH_PROFILE_SNIPPETS"
        for ((n = -1; n >= -${#SNIPPET_ARRAY[*]}; n--)); do
            if [[ -f "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets/${SNIPPET_ARRAY[$n]}.sh" ]]; then
                # shellcheck source=/dev/null
                source "$HOME/$SWITCH_PROFILE_DIRECTORY/snippets/${SNIPPET_ARRAY[$n]}.sh" unload && __switch_profile_snippet pop "${SNIPPET_ARRAY[$n]}"
            fi
        done
    fi
    if [[ $RESET_PROFILE -eq 1 ]]; then
        echo "unset SWITCH_PROFILE_CURRENT" >"$HOME/$SWITCH_PROFILE_SAVED"
        exec bash
    fi

    SELECTED_PROFILE="$1"
    if [[ -f "${HOME}/${SWITCH_PROFILE_DIRECTORY}/${SELECTED_PROFILE}.profile" ]]; then {
        if [[ $TEMP_PROFILE -eq 0 ]]; then
            echo "export SWITCH_PROFILE_CURRENT=$SELECTED_PROFILE" >"$HOME/$SWITCH_PROFILE_SAVED"
        else
            export SWITCH_PROFILE_NEXT="$SELECTED_PROFILE"
        fi
        exec bash
    }; else
        {
            __switch_profile_help
            echo "Selected profile does not exist."
            switch_profile -l
            echo ""
            return 1
        }
    fi
}

### MAIN SCRIPT ###
[[ -n "$SWITCH_PROFILE_LIST" ]] && complete -o nospace -W "$SWITCH_PROFILE_LIST" switch_profile

if [[ -z ${SWITCH_PROFILE_NEXT+is_set} ]]; then {
    if [[ -f "$HOME/$SWITCH_PROFILE_SAVED" ]]; then
        {
            # shellcheck source=/dev/null
            source "$HOME/$SWITCH_PROFILE_SAVED"
        }
    fi
}; else
    {
        export SWITCH_PROFILE_CURRENT="$SWITCH_PROFILE_NEXT"
        unset SWITCH_PROFILE_NEXT
    }
fi

if [[ -n "${SWITCH_PROFILE_CURRENT+is_set}" ]]; then
    mapfile -c 1 -C __switch_profile_parse -t <"${HOME}/${SWITCH_PROFILE_DIRECTORY}/${SWITCH_PROFILE_CURRENT}.profile"
fi