Shuffle XSPF file by album using xsltproc for e.g. Clementine

shuffle.sh

#!/bin/bash

cd $(dirname $0)

playlist=shuffled.xspf

cat >$playlist <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<playlist version="1" xmlns="http://xspf.org/ns/0/">
  <trackList>
EOF

albums=$(xsltproc.exe tracks2albums.xsl Alle\ Titel.xspf)
xsltproc <(cat <<EOF
<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xspf="http://xspf.org/ns/0/">
    <xsl:output method="xml" indent="yes" omit-xml-declaration="yes" />
    <xsl:template match="albums">
    $(for index in $(echo "$albums" | shuf -i 1-$(xmllint --xpath "string((//album)[last()]/@index)" -)); do echo '<xsl:apply-templates select="//album[@index = '$index']" />'; done)
    </xsl:template>
    <xsl:template match="album">
        <xsl:for-each select="xspf:track">
            <xsl:copy-of select="." />
        </xsl:for-each>
    </xsl:template>
</xsl:stylesheet>
EOF
) <(echo "$albums") >>$playlist

cat >>$playlist <<EOF
  </trackList>
</playlist>
EOF

tracks2albums.xsl

<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xspf="http://xspf.org/ns/0/">
    <xsl:output method="xml" indent="yes" />
    <xsl:key name="album" match="xspf:track" use="xspf:album" />
    <xsl:template match="xspf:trackList">
        <xsl:element name="albums">
            <xsl:apply-templates select="xspf:track[generate-id(.)=generate-id(key('album',xspf:album)[1])]" />
        </xsl:element>
    </xsl:template>
    <xsl:template match="xspf:track">
        <xsl:element name="album">
            <xsl:if test="xspf:album != '' and xspf:album != 'No Album'">
                <xsl:variable name="i" select="position()" />
                <xsl:attribute name="index">
                    <xsl:value-of select="$i" />
                </xsl:attribute>
                <xsl:for-each select="key('album', xspf:album)">
                    <xsl:copy-of select="." />
                </xsl:for-each>
            </xsl:if>
        </xsl:element>
    </xsl:template>
    <!-- <xsl:template match="xspf:track">
        <xsl:if test="xspf:album != ''">
            <album><xsl:value-of select="xspf:album" /></album>
        </xsl:if>
    </xsl:template>
-->
</xsl:stylesheet>