#!/bin/bash
VERSION="0.3.5+lite"

# History:
#   0.3.5+lite: strip mkost 0.3.5+ost down to essentials.

set -e 
set -u

function showVersion() {
    echo "$0 Version $VERSION"
}

MINLENGTH=120
MAXLENGTH=600
DEBUG_LEVEL=0

function showHelp() {
cat << FEOF
$0 [args] > out-file.ly

Arguments include:
    -m|--min SECONDS ($MINLENGTH) : Require songs to be SECONDS long.
        Will clear MAX setting, if greater.
    -M|--max SECONDS ($MAXLENGTH) : Prevent songs from being over SECONDS long.
        Will clear MIN setting, if lesser.
    --epic : Same as: -m 180 -M 235
        Song length 3:00 to 3:55
    --song : Same as: -m 120 -M 180
        Song length 2:00 to 3:00
    --ringtone : Same as: -m 45 -M 75
        Song length: 0:45 to 1:15
    --alert : Same as: -m 25 -M 35
        Song length: 0:25 to 0:35
    -h|--help : show this help message
    --version : show the version number 
FEOF
}

while [ $# -gt 0 ] ; do
    case "$1" in
    -h|--help) showHelp ; exit 0 ;;
    --version) showVersion ; exit 0 ;;
    --feat-bridge) FEAT_BRIDGE=1 ;;
    --no-feat-bridge) FEAT_BRIDGE=0 ;;
    --epic)
        MINLENGTH=180
        MAXLENGTH=235
        FEAT_BRIDGE=0
	;;
    --song)
        MINLENGTH=120
        MAXLENGTH=180
        FEAT_BRIDGE=1
        ;;
    --ringtone)
        MINLENGTH=45
        MAXLENGTH=75
        FEAT_BRIDGE=0
        ;;
    --alert)
        MINLENGTH=25
        MAXLENGTH=35
        FEAT_BRIDGE=0
        ;;
    -m|--min)
        shift
        MINLENGTH="$1"
        if [ $MINLENGTH -ne 0 -a $MINLENGTH -gt $MAXLENGTH ] ; then
            MAXLENGTH=0
        fi
        ;;
    -M|--max)
        shift
        MAXLENGTH="$1"
        if [ $MAXLENGTH -ne 0 -a $MAXLENGTH -lt $MINLENGTH ] ; then
            MINLENGTH=0
        fi
        ;;
    *) echo "ERROR: Unknown argument: $1" 1>&2 ; exit 1 ;;
    esac
    shift
done

function warning() {
    echo "$@" 1>&2
}

warning "Requested: Song length $MINLENGTH to $MAXLENGTH"
warning

function randomNote() {
    local N=$(( $RANDOM % $# ))
    local -a ARR=( "$@" )
    echo "${ARR[$N]} "
}

function bassLine() {
    local -a ARR1=( a4 b4 c4 d4 e4 f4 g4 )
    local -a ARR2=( e2 f2 g2 a2 b2 c2 d2 )
    CNT="$1"
    while [ $CNT -gt 0 ] ; do
        local N=$(( $RANDOM % 7 ))
        local A="${ARR1[$N]}"
        local B="${ARR2[$N]}"
        echo -n "$A $A $B "
        CNT=$(( $CNT - 1 ))
    done
}

function random8Tune() {
    CNT="$1"
    while [ $CNT -gt 0 ] ; do
        local I
        for I in 1 2 3 4 5 6 7 8 ; do
            randomNote a\'8 b\'8 c\'8 d\'8 e\'8 f\'8 g\'8 
        done
        CNT=$(( $CNT - 1 ))
    done
}

T=$(( $RANDOM % 6 ))
TEMPO=$(( 110 + 10 * $T ))
unset T

MinBars=$(( $MINLENGTH * $TEMPO / 60 / 4 ))
MaxBars=$(( $MAXLENGTH * $TEMPO / 60 / 4 ))
BarOff=$(( $MaxBars - $MinBars ))

barcnt=$(( $RANDOM % $BarOff + $MinBars ))
sec=$(( $barcnt * 4 * 60 / $TEMPO ))

BASS=`bassLine $barcnt`
TUNE=`random8Tune $barcnt`

nfo="$(( $sec / 60 )) minutes, $(( $sec % 60 )) seconds, or $barcnt bars at $TEMPO"

warning "Generated: ${barcnt} bars"
warning "    Length: $nfo"

cat << FEOF
\\version "2.14.2"

% ${nfo}

% Bar Count: ${barcnt}

tuneGlobal = {
    \\key c \\major
    \\time 4/4
    \\tempo 4 = ${TEMPO}
}

bassMusic = \\absolute {
    ${BASS}
}

tuneMusic = \\absolute {
    ${TUNE}
}

\\score {
    <<
        \\new Staff {
            \\set Staff.instrumentName = #"Bass"
            \\new Voice = "bass" { \\tuneGlobal \\bassMusic }
        } 
        \\new Staff <<
            \\set Staff.midiInstrument = #"flute" 
            \\new Voice = "tune" { \\tuneGlobal \\tuneMusic }
        >>
    >>

    \\midi { }
}

FEOF
warning "Done."