A shell script for single file branch version control (sfbvc)

sfbvc

# sfbvc stands for single file branch version control.
#
# By Modar Alfadly <https://modar.me> on the 24th Jan 2019
#
# sfbvc is a convention to create an orphan branch for each file in a repository
# and the master branch will be the merge of all the other branches.
# This is a niche convention which is trying to simulate file history
# in applications similar to cloud storages like Google Drive and Dropbox.
# We are using git under the hood and assuming that it is installed and in PATH.
#
# The limitation here becomes in the naming of the branches.
# See: https://wincent.com/wiki/Legal_Git_branch_names
# and: https://www.spinics.net/lists/git/msg133704.html
# Legal file names can not:
# - Have a path component that begins with "."
# - Have a double dot "…"
# - Have an ASCII control character, "~", "^", ":" or SP, anywhere
# - End with a "/"
# - End with ".lock"
# - Contain a "\" (backslash)
# - Contain "*", "?", "[" or "@{"
# - Be "master" and placed in the root directory
#
# To use these commands, run the following:
# source sfbvc
#
# To disable them, run the following:
# nosfbvc
#
# Please, don't use git directly on an sfbvc repositry.
# Instead, use the commands defined by this file.
# The commands are commit, push and pull.
#############################################


#############################################
# Helper commands
#############################################

# get the directory of the repository
repo-dir () {
    git rev-parse --show-toplevel
}

# get the branch name of the given file
branch-name () {
    # allow only one passed argument
    if [ "$#" -ne 1 ]; then
        echo "You should pass a single file"
    else
        local repodir=$(repo-dir)
        local filedir=$(realpath $1)
        # local offset=$((${#repodir} + 1))
        # echo ${filedir:offset}
        echo ${filedir#$repodir/}
    fi
}

# list modified and untracked files
# this will unstage any staged changes
ls-files () {
    # unstage all staged files
    git reset > /dev/null 2>&1  # > /dev/null 2>&1 suppresses stdout & stderr
    # git reset > /dev/null 2>/dev/null  # equivalent to the above line
    # list modified and untracted files
    git ls-files --modified --others --full-name $(repo-dir)
}


#############################################
# Main commands
#############################################

# commit a single file
commit () {
    # allow only one passed argument
    if [ "$#" -ne 1 ]; then
        echo "You should pass a single file to commit"
    else
        # unstage all staged files
        git reset > /dev/null 2>&1
        # stash all changes
        git stash > /dev/null 2>&1
        # get branch name
        local branch=$(branch-name $1)
        # try to create an orphan branch and capture output
        local message=$((git checkout --orphan $branch --) 2>&1)

        # check if invalid branch name
        if [[ $message == *"is not a valid branch name." ]]; then 
            echo "$branch is an invalid file name and will not be saved"
        else
            # check if new file
            if [[ $message == "Switched to a new branch"* ]]; then
                # clear the index and the working tree
                git rm -rf $(repo-dir) > /dev/null 2>&1
                # stage and commit new file
                git add $1 && git commit -m "add file" > /dev/null 2>&1
            else
                # checkout to the branch
                git checkout $branch -- > /dev/null 2>&1
                # unstash the changes
                git checkout stash -- $1 && git stash drop > /dev/null 2>&1
                # commit the file
                git commit -m "changes" > /dev/null 2>&1
            fi
            # checkout back to master
            git checkout master -- > /dev/null 2>&1
            # merge branch and fast forward
            git merge $branch --no-commit --ff > /dev/null 2>&1
        fi
    fi
}

# push everything to remote
push () {
    git push --all origin
}

# pull all changes from remote
pull () {
    # track all remote branches
    for remote in `git branch -r | grep -v '\->'`; do
        git branch --track ${remote#origin/} $remote > /dev/null 2>&1
    done
    # pull all the branches
    git pull --all
}

# unset and deactivate these commands
nosfbvc () {
    unset -f repo-dir branch-name ls-files
    unset commit push pull
    unset -f nosfbvc
}