#!/bin/bash

#
# Bottles of Beer song in Bash
#
# A way-overcomplicated implementation of the bottles of beer song in bash.
# Optional argument:
#
#  *  `--careless` - Generate the "happen to fall" version
#
# NOTE:  This is an altered version of a "99 bottles of beer" song
# Bash script by Bill Brown.  The intent of the altered version is
# to show the style, so the above text is preserved from [the
# original][99b].
#
#   [99b]: http://99-bottles-of-beer.net/language-bash-1831.html
#

pred() {
    #
    # Get predecessor to a number $1
    #
    case $1 in
        *nine)      echo ${1%nine}eight;;
        *eight)     echo ${1%eight}seven;;
        *seven)     echo ${1%seven}six;;
        *six)       echo ${1%six}five;;
        *five)      echo ${1%five}four;;
        *four)      echo ${1%four}three;;
        *three)     echo ${1%three}two;;
        *two)       echo ${1%two}one;;
        one)        echo zero;;
        *-one)      echo ${1%-one};;
        *one)       echo ${1%one};;
        ten)        echo nine;;
        eleven)     echo ten;;
        twelve)     echo eleven;;
        *teen)      teenpred $1;;
        *ty)        tenspred $1;;
        zero)       echo "";  #to terminate
    esac
}

teenpred() {
    #
    # Get predecessor of a teen $1
    #
    case $1 in
        thirteen)   echo twelve;;
        *)          echo $(crunchprefix $(pred $(uncrunchprefix ${1%teen})))teen;;
    esac
}

tenspred() {
    #
    # Get predecessor of a multiple of ten $1
    #
    case $1 in
        twenty)     echo nineteen;;
        *) echo $(crunchprefix --tens $(pred $(uncrunchprefix ${1%ty})))ty-nine;;
    esac
}

crunchprefix() {
    #
    # Crunch number prefix $1 to its conventional form
    #
    # ...such as `three` --> `thir`
    #
    # option `--tens` - multiples of ten are a bit different
    #
    [ $1 = --tens ] && { tensop=true; shift; }
    case $1 in
        two)    [ -n "$tensop" ] && echo twen || echo $1;;
        three)  echo thir;;
        four)   [ -n "$tensop" ] && echo 'for' || echo $1;;
        five)   echo fif;;
        eight)  [ -n "$tensop" ] && echo eigh || echo $1;;
        *)      echo $1;;
    esac
}

uncrunchprefix() {
    #
    # Reverse crunchprefix $1
    #
    case $1 in
        twen)   echo two;;
        thir)   echo three;;
        'for')  echo four;;
        fif)    echo five;;
        eigh)   echo eight;;
        *)      echo $1;;
    esac
}

grammar() {
    #
    # Apply peculiarities of English grammar to text on stdin
    #
    local oneBottle=false  #can effect the following line
    while read line; do
        line="${line/one more bottles/one more bottle}"
        case "$line" in
            *"one of those bottles"*)   line="$([ $oneBottle = true ] &&
                                        echo ${line/one of those bottles/that lone bottle} ||
                                        echo $line )"
                                        ;;
            *"one down"*)               line="$([ $oneBottle = true ] &&
                                        echo ${line/one down/it down} ||
                                        echo $line )"
                                        ;;
            *bottles*)                  oneBottle=false;;
            *bottle*)                   oneBottle=true;;
        esac
        #Some say the twenties should have no hyphen
        line="${line/twenty-/twenty }"
        echo $line
    done
}

capitalize() {
    #
    # Fix capitalization of each line on stdin
    #
    while read line; do
        echo -n ${line:0:1} | tr '[:lower:]' '[:upper:]'
        echo ${line#?}
    done
}

punctuate() {
    #
    # Add punctuation to each line on stdin
    #
    while read line; do
        case "${line}" in
            [Ii]f*)     echo ${line},;;
            '')         echo;;
            *)          echo ${line}.;;
        esac
    done
}

verse() {
    #
    # Write one verse with number $1
    #
    local nb=$1
    echo $nb bottles of beer on the wall
    echo $nb bottles of beer
    if [ $nb = zero ]; then
        echo Go to the store and buy some more
        nb=ninety-nine
    else
        echo $breakLine
        nb=$(pred $nb)
    fi
    echo $nb bottles of beer on the wall
}

poeticize() {
    #
    # Make text on stdin nice
    #
    while read first rest; do
        case "$rest" in
            *beer*)
                first=${first/zero/no}
                local syl=$(syllables ${first% *})
                case $syl in  #improve meter
                    1|2)    echo $first 'more' $rest;;
                    *)      echo $first $rest;;
                esac
                ;;
            *)  echo $first $rest
        esac
    done
}

syllables() {
    #
    # Estimate number of syllables in word $1
    #
    local n=1
    case $1 in
        eleven)     n=2;; #sounds better if not considered 3
        *teen)      n=2;;
        *ty)        n=2;;
        *-*)        n=3;; #don't care about more than 3
    esac
    case $1 in
        *seven*)    let $((n = n+1));;
    esac
    echo $n
}

main() {
    standardBreakLine="Take one down and pass it around"
    wastefulBreakLine="If one of those bottles should happen to fall"
    breakLine=$([ "$1" = --careless ] \
     && echo $wastefulBreakLine \
     || echo $standardBreakLine)

    nb=ninety-nine

    while [ -n "$nb" ]; do
        verse $nb
        echo
        nb=$(pred $nb)
    done | poeticize | grammar | punctuate | capitalize
}

main "$@"