#!/bin/bash

############################
##### SET YOUR OPTIONS #####
############################

# The chance of any given file to be selected is 1 in $CHANCE
CHANCE=100

# The location of your music
MUSICDIR=/cygdrive/d/media/mp3

# The list of file extensions to include
MUSICXTNS=( MP3 FLAC OGG M4A )

######################################
##### OKAY WE'RE DOING STUFF NOW #####
######################################

mscan()
{
	shopt -s dotglob								# this makes globs grab files beginning with . 
	shopt -s nocaseglob								# this makes globs case-insensitive

	local DIRSTACK[0]=$1								# create a local directory stack

	while [ ${#DIRSTACK[*]} -gt 0 ]; do
		local WDIR=${DIRSTACK[${#DIRSTACK[*]}-1]}				# grab whatever directory is on top of the stack
		unset DIRSTACK[${#DIRSTACK[*]}-1]					# and remove it from the stack

		for DIR in "$WDIR"*/; do						# this matches only directories
			if [ -x "$DIR" ]; then						# if the directory is +x we can read it
				DIRSTACK[${#DIRSTACK[*]}]=$DIR				# so put it into the stack
			fi
		done

		for EXT in ${MUSICXTNS[*]}; do						# go through the list of extensions
			for FILE in "$WDIR"*.$EXT; do					# go through the files matching this extension (works because of nocaseglob)
				if [ ! -f "$FILE" ] || [ -d "$FILE" ]; then		# if this file doesn't exist, we probably got no matching files and had the glob returned; also make sure this isn't a directory
					continue					# if either of those bad things happened, skip the rest
				fi
				if [ -r "$FILE" ] && (( $RANDOM % $CHANCE == 0 )); then	# if the file is readable and passes the random check
					echo $FILE					# add it to the playlist
				fi
			done
		done
	done
}

mscan $MUSICDIR | sort -R 								# pipe the whole thing through sort -R to make it more random