dotfiles

#!/bin/sh
# vim: fdm=marker
#
#   dotfiles - track dotfiles in git directly from your home directory
#
#   Copyright (c) 2017-2019 by Eli Schwartz <eschwartz@archlinux.org>
#
#   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 2 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/>.
#

[ -f "${XDG_CONFIG_HOME:-$HOME/.config}"/dotfiles.conf ] && . "${XDG_CONFIG_HOME:-$HOME/.config}"/dotfiles.conf

usage() {
	cat <<- _EOF_
		Usage: dotfiles [-h|--help] <COMMAND>
		Thin wrapper around git to version dotfiles. Most commands are passed
		straight through to git with a custom GIT_DIR to store dotfiles metadata
		outside of the top-level home directory.

		OPTIONS
		    -h, --help      Show this usage message

		CUSTOM COMMANDS
		    init            Init a bare git repository and set it up as an
		                      empty dotfiles repository
		    clone           Clone an existing dotfiles repository and integrate
		                      it with \$HOME. If existing files clash with repository
		                      files, they must be manually resolved.
		    ignore          Add new strings to gitignore, or edit the gitignore
		                      directly, without using ~/.gitignore
		    readme          Edit the repository README.md without using ~/README.md
_EOF_
}

error() {
    local mesg="${1:-An unknown error occurred.}"
    printf "==> ERROR: %s\nAborting...\n" "$mesg" 1>&2
    exit 1
}

sparse_tree() {
    cat <<- _EOF_
	/*
	!README.md
	!LICENSE
	!.gitattributes
	!.gitignore
_EOF_
}

# gitignore {{{
base_gitignore() {
    cat <<- _EOF_
	# XDG user dirs
	Desktop/
	Documents/
	Downloads/
	Music/
	Pictures/
	Public/
	Templates/
	Videos/

	# Security
	.gnupg/*
	!.gnupg/*.conf
	.ssh/

	# Common caches
	.adobe/
	.atom/
	.*cache/
	.gem/
	.macromedia/
	.node-gyp/
	.npm/
	.cargo/
	.thumbnails/
	.wget-hsts
	.v8flags*

	# Misc commonly generated files
	.bash_history
	.zsh_history
	.bazaar/
	.dbus/
	.dropbox/
	.ICEauthority
	.lesshst
	.python_history
	.sqlite_history
	.psql_history
	.subversion/
	.wine/
	.Xauthority
	.xsession-errors

	# Misc junk files
	*~
	*.bak
	*.log
	*.swp
	*.tmp

	# Automatically appended
_EOF_
}
# }}}

# Init {{{
init_setup() {
    mkdir -p "${XDG_CONFIG_HOME:-$HOME/.config}"
    echo "dotfiles_dir=$dotfiles_dir" > "${XDG_CONFIG_HOME:-$HOME/.config}"/dotfiles.conf
    sparse_tree > "$dotfiles_dir"/info/sparse-checkout
    git --git-dir "$dotfiles_dir" config --local core.bare false
    git --git-dir "$dotfiles_dir" config --local core.worktree ~
    git --git-dir "$dotfiles_dir" config --local core.sparseCheckout true
    git --git-dir "$dotfiles_dir" config --local status.showUntrackedFiles no
}

init() {
    if ! dotfiles_dir="$("$readlink" -m "${1:-.}")"; then
        error "failed to resolve directory '$1'"
    fi
    git init --bare "$dotfiles_dir" || error "failed to init repository in '$1'"
    init_setup
    base_gitignore > "$dotfiles_dir"/info/exclude
}

clone() {
    if ! dotfiles_dir="$("$readlink" -m "${2:-dotfiles}")"; then
        error "failed to resolve directory '$2'"
    fi
    git clone --bare "$1" "$dotfiles_dir" || error "failed to clone '$1'"
    init_setup
    # If there is no .gitignore yet, this will just clobber some comments
    git --git-dir "$dotfiles_dir" show HEAD:.gitignore > "$dotfiles_dir"/info/exclude 2>/dev/null
    git --git-dir "$dotfiles_dir" show HEAD:.gitattributes > "$dotfiles_dir"/info/attributes 2>/dev/null
    git --git-dir "$dotfiles_dir" checkout
}
# }}}

edit_info() {
    local infofile="$dotfiles_dir/info/$1" dotfile="$2"; shift 2

    if [ $# -eq 0 ]; then
        ${EDITOR:-vim} "$infofile"
    else
        printf '%s\n' "$@" >> "$infofile"
    fi
    git --git-dir="$dotfiles_dir" update-index --add --cacheinfo 10064,$(git --git-dir="$dotfiles_dir" hash-object -w "$infofile"),"$dotfile"
    git --git-dir "$dotfiles_dir" checkout --quiet
}

readme() {
    local readme_file="$(mktemp -dt dotfiles.XXXXXX)/README.md"
    git --git-dir="$dotfiles_dir" show :README.md > "$readme_file"
    ${EDITOR:-vim} "$readme_file"
    git --git-dir="$dotfiles_dir" update-index --add --cacheinfo 10064,$(git --git-dir="$dotfiles_dir" hash-object -w "$readme_file"),README.md
    rm -r "${readme_file%README.md}"
    git --git-dir "$dotfiles_dir" checkout --quiet
}

# Main

# prefer GNU-prefixed readlink for macOS
readlink=$(command -v greadlink || command -v readlink)

if [ -n "$1" ]; then
    # POSIX shift complains if there is nothing to pop.
    dot_cmd="$1"
    shift
fi

case $dot_cmd in
    -h|--help|help)
        usage
        exit
        ;;
    init|clone)
        $dot_cmd "$@"
        ;;
    ignore)
        edit_info exclude .gitignore "$@"
        ;;
    attributes)
        edit_info attributes .gitattributes "$@"
        ;;
    readme)
        $dot_cmd
        ;;
    *)
        git --git-dir="$dotfiles_dir" $dot_cmd "$@"
esac