#!/bin/sh
## dictver -- dictionary versioning
## by C. Duckworth
#
# DICTVER is a new versioning scheme that I've just decided I will use
# everywhere.  It works like this:
#
# - Versions are words.
# - If version A comes after version B in the dictionary, it's a later
#   version.
# - If the first letter of version A is different than the first
#   letter of version B, it's a major (possibly backward-incompatible)
#   upgrade.
# - Otherwise, it's a minor upgrade.
#
# This program will, when given the current version of a project, bump
# that version to another one.  See usage() for details.

usage() {
    cat >&2 <<EOF
dictver --- upgrade the dictionary versioning of a project
USAGE:  dictver [-m] [-d DISTANCE-SPEC] VERSION
OPTIONS:
 -m	Declare this is a MAJOR version update.
 -d DISTANCE-SPEC
	Specify the distance from the current VERSION to stray
	when creating the new VERSION.  Can be one of (MAX|MIN,MAX),
	where MAX is the maximum distance to stray and MIN the minimum.
PARAMETERS:
 VERSION
	The current version of the project.
EOF
    exit ${1:-0}
}

do_opts() {
    MAJORP=false
    MIN=1
    MAX=10
    DICT=/usr/share/dict/words
    while getopts hmd: OPT
    do case "$OPT" in
           (h) usage ;;
           (m) MAJORP=true ;;
           (d) case "$OPT" in
                   (*,*) MIN="${OPTARG%,*}"
                         MAX="${OPTARG#*,}"
                         ;;
                   (*) MAX="$OPTARG" ;;
               esac
               ;;
           (*) usage 1 ;;
       esac
    done
}

get_context() {
    if "$MAJORP"
    then word="$(next_letter "$1")"
    else word="$1"
    fi

    test -n "$word" || exit 2   # doesn't actually exit b/c pipelines

    # echo >&2 "$word"
    until grep -q "^$word" "$DICT"
    do word="${word%?}" #; echo >&2 "$word"
    done
    # echo >&2 "$word"

    grep -i -A "$MAX" "^$word" "$DICT" |
        head -n "$MAX" |
        while read -r line
        do test $((MIN--)) -ge 0 ||  echo "$line"
        done
}

next_letter() {
    case "$1" in
        (a*|A*) echo ^b ;;
        (b*|B*) echo ^c ;;
        (c*|C*) echo ^d ;;
        (d*|D*) echo ^e ;;
        (e*|E*) echo ^f ;;
        (f*|F*) echo ^g ;;
        (g*|G*) echo ^h ;;
        (h*|H*) echo ^i ;;
        (i*|I*) echo ^j ;;
        (j*|J*) echo ^k ;;
        (k*|K*) echo ^l ;;
        (l*|L*) echo ^m ;;
        (m*|M*) echo ^n ;;
        (n*|N*) echo ^o ;;
        (o*|O*) echo ^p ;;
        (p*|P*) echo ^q ;;
        (q*|Q*) echo ^r ;;
        (r*|R*) echo ^s ;;
        (s*|S*) echo ^t ;;
        (t*|T*) echo ^u ;;
        (u*|U*) echo ^v ;;
        (v*|V*) echo ^w ;;
        (w*|W*) echo ^x ;;
        (x*|X*) echo ^y ;;
        (y*|Y*) echo ^z ;;
        (*) echo >&2 "No more letters?!" ;;
    esac
}

main() {
    do_opts "$@"; shift $((OPTIND-1))
    test -n "$1" || usage 1
    get_context "$1" | sort -R | head -n1
}

# set -x
main "$@"