install

#!/bin/sh

# TODO: add -v for debugging
# TODO: only install the supplied argument if supplied

beverbose=1

# comment_line checks if a line is a comment 🐸
comment_line() {
    case "$1" in
    \#*) return 0 ;;
    esac
    return 1
}

# empty_line checks if a line is empty 😆
empty_line() {
    test -z "$1" && return 0

    return 1
}

# log prints information to stderr
log() {
    local msg="$1"

    printf '%s\n' "$msg" 1>&2
}

# error logs the error and exit immediately
error() {
    printf '\033[1;31m'
    log "$1"
    printf '\033[0m'
    exit 1
}

symlink() {
    ln -nsf "$1" "$2"
}

main() {
    cd "${0%/*}" || error "could not change directory to ${0%/*}"

    counter=0
    while read -r line; do
        counter=$((counter + 1))
        comment_line "$line" && continue
        empty_line "$line" && continue

        read -r src dst _ <<-EOL
            $line
EOL

        if ! test -e "$src"; then
            error "line $counter: $src: no such file or directory"
        fi
        if test -z "$dst"; then
            error "Error on line $counter: destination is missing"
        fi

        src="$PWD/$src"
        dst="$HOME/$dst"
        # make sure the parent directory exists
        if ! test -d "${dst%/*}"; then
            test $beverbose && log "CREATING A DIRECTORY ${dst%/*} FOR $src"
            mkdir -p "${dst%/*}"
        fi

        test $beverbose && log "SYMLINK $src AT $dst"
        symlink "$src" "$dst"
    done <rules.txt
}

main "$@"