Grouping based on the node value if only it exists

My requirement is slightly complex one.I have to use only XSLT 1.0. I could able to get the solution using XSLT 2.0, but I need the solution using 1.0.

I have the following input xml:

   <?xml version="1.0" encoding="UTF-8"?>
    <results>
       <row>
          <CASEID>C1</CASEID>
          <CASEBA>MEDICAID</CASEBA>
          <ISSUEID>I1</ISSUEID>
          <ISSUEBA>MEDICAID</ISSUEBA>
          <OBJECTID>1</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
       <row>
          <CASEID>C1</CASEID>
          <CASEBA>MEDICAID</CASEBA>
          <ISSUEID>I2</ISSUEID>
          <ISSUEBA>MEDICAID</ISSUEBA>
          <OBJECTID>2</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
       <row>
          <CASEID>C1</CASEID>
          <CASEBA>MEDICAID</CASEBA>
          <ISSUEID>I1</ISSUEID>
          <ISSUEBA>MEDICAID</ISSUEBA>
          <OBJECTID>extra</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
       <row>
          <CASEID>C2</CASEID>
          <CASEBA>MEDICAID</CASEBA>
          <ISSUEID>I3</ISSUEID>
          <ISSUEBA>MEDICAID</ISSUEBA>
          <OBJECTID>3</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
       <row>
          <ISSUEID>I6</ISSUEID>
          <ISSUEBA>MEDICAID</ISSUEBA>
          <OBJECTID>10</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
       <row>
          <CASEID>C11</CASEID>
          <CASEBA>MEDICAID</CASEBA>
          <OBJECTID>11</OBJECTID>
          <OBJECTBA>MEDICAID</OBJECTBA>
       </row>
    </results>

I have to transform the above xml to simpler one using XSLT by following the below conditions:

If I have the <CASEID>, then <CASE> tag should be there. If I have the <ISSUEID>, then <ISSUE> tag should be there. If I have the <OBJECT>, then <OBJECTID> tag should be there. The reason behind this is some of the row elements might have <CASEID> <ISSUEID> <OBJECTID> and some not. A <CASE> can directly have a <SOURCE> under it if there is no <ISSUE>.

1)First target is to move all the <CASEID>'s whose values are same under the new <CASE> tag along with <CASEBA> node.

For Example:

<CASE>
   <CASEID>C1</CASEID>
   <CASEBA>MEDICAID</CASEBA>
</CASE>

2)List out all the <ISSUEID> &<ISSUEBA> whose <CASEID>'s are equal in different <row>'s and move them under the new tag<ISSUE> within the recently created <CASE> tag.

For example:

 <CASE>
     <CASEID>C1</CASEID>
     <CASEBA>MEDICAID</CASEBA>
     <ISSUE>
        <ISSUEID>I1</ISSUEID>
        <ISSUEBA>MEDICAID</ISSUEBA>
     </ISSUE>
     <ISSUE>
        <ISSUEID>I2</ISSUEID>
        <ISSUEBA>MEDICAID</ISSUEBA>
     </ISSUE>
  </CASE>

3)List out all the <OBJECTID>'s whose <ISSUEID>'s are equal in different <row>'s and move them under the new <SOURCE> tag within <ISSUE>tag which will be definitely under the <CASE> . For example:

<CASE>
         <CASEID>C1</CASEID>
         <CASEBA>MEDICAID</CASEBA>
         <ISSUE>
            <ISSUEID>I1</ISSUEID>
            <ISSUEBA>MEDICAID</ISSUEBA>
            <SOURCE>
               <OBJECTID>1</OBJECTID>
               <OBJECTBA>MEDICAID</OBJECTBA>
            </SOURCE>
            <SOURCE>
               <OBJECTID>extra</OBJECTID>
                <OBJECTBA>MEDICAID</OBJECTBA>
            </SOURCE>
         </ISSUE>
         <ISSUE>
            <ISSUEID>I2</ISSUEID>
            <ISSUEBA>MEDICAID</ISSUEBA>
            <SOURCE>
               <OBJECTID>2</OBJECTID>
               <OBJECTBA>MEDICAID</OBJECTBA>
            </SOURCE>
         </ISSUE>
      </CASE>

The final output xml should be as below:

 <?xml version="1.0" encoding="UTF-8"?>
<results>
   <CASE>
      <CASEID>C1</CASEID>
      <CASEBA>MEDICAID</CASEBA>
      <ISSUE>
         <ISSUEID>I1</ISSUEID>
         <ISSUEBA>MEDICAID</ISSUEBA>
         <SOURCE>
            <OBJECTID>1</OBJECTID>
            <OBJECTBA>MEDICAID</OBJECTBA>
         </SOURCE>
         <SOURCE>
            <OBJECTID>extra</OBJECTID>
            <OBJECTBA>MEDICAID</OBJECTBA>
         </SOURCE>
      </ISSUE>
      <ISSUE>
         <ISSUEID>I2</ISSUEID>
         <ISSUEBA>MEDICAID</ISSUEBA>
         <SOURCE>
            <OBJECTID>2</OBJECTID>
            <OBJECTBA>MEDICAID</OBJECTBA>
         </SOURCE>
      </ISSUE>
   </CASE>
   <CASE>
      <CASEID>C2</CASEID>
      <CASEBA>MEDICAID</CASEBA>
      <ISSUE>
         <ISSUEID>I3</ISSUEID>
         <ISSUEBA>MEDICAID</ISSUEBA>
         <SOURCE>
            <OBJECTID>3</OBJECTID>
            <OBJECTBA>MEDICAID</OBJECTBA>
         </SOURCE>
      </ISSUE>
   </CASE>
   <ISSUE>
      <ISSUEID>I6</ISSUEID>
      <ISSUEBA>MEDICAID</ISSUEBA>
      <SOURCE>
         <OBJECTID>10</OBJECTID>
         <OBJECTBA>MEDICAID</OBJECTBA>
      </SOURCE>
   </ISSUE>
   <CASE>
      <CASEID>C11</CASEID>
      <CASEBA>MEDICAID</CASEBA>
      <SOURCE>
         <OBJECTID>11</OBJECTID>
         <OBJECTBA>MEDICAID</OBJECTBA>
      </SOURCE>
   </CASE>
</results>

Please forgive me if I didn't explain my requirement properly. Please do ask me if you need any additional information. It would be really great if someone helps me out.

You can still solve this using Muenchian Grouping. If you are grouping by CASEID initially, but CASEID may not be present, you can define the first key like so

 <xsl:key name="case" match="row" use="string(CASEID)" />

So, for the first key, row elements with no CASEID will be matched by an empty string and grouped together.

To group by INDEXID within CASEID, you can use a key like this, as this will still work with no CASEID (as concat returns a string)

<xsl:key name="issue" match="row" use="concat(CASEID, '|', ISSUEID)" />

To select the distinct CASEID records you would then do this:

<xsl:apply-templates select="row[generate-id() = generate-id(key('case', string(CASEID))[1])]" mode="case" />

However, in the template that matched the row elements for this mode, you would need a xsl:choose statement, to check whether CASEID existed or not. If they did exist, you would create <CASE> element. If not, you would apply the next level key.

    <xsl:choose>
        <xsl:when test="CASEID">
            <CASE>
                <!-- Apply next key -->
            </CASE>
        </xsl:when>
        <xsl:otherwise>
              <!-- Apply next key -->
        </xsl:otherwise>
    </xsl:choose>

Try this XSLT

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:output method="xml" indent="yes" />

    <xsl:key name="case" match="row" use="string(CASEID)" />
    <xsl:key name="issue" match="row" use="concat(CASEID, '|', ISSUEID)" />
    <xsl:key name="object" match="row" use="concat(CASEID, '|', ISSUEID, '|', OBJECTID)" />

    <xsl:template match="results">
        <xsl:copy>
            <xsl:apply-templates select="row[generate-id() = generate-id(key('case', string(CASEID))[1])]" mode="case" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="row" mode="case">
        <xsl:choose>
            <xsl:when test="CASEID">
                <CASE>
                    <xsl:apply-templates select="CASEID|CASEBA" />
                    <xsl:apply-templates select="key('case', string(CASEID))[generate-id() = generate-id(key('issue', concat(CASEID, '|', ISSUEID))[1])]" mode="issue" />
                </CASE>
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates select="key('case', concat('', CASEID))[generate-id() = generate-id(key('issue', concat(CASEID, '|', ISSUEID))[1])]" mode="issue" />
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

    <xsl:template match="row" mode="issue">
        <xsl:choose>
            <xsl:when test="ISSUEID">
                <ISSUE>
                    <xsl:apply-templates select="ISSUEID|ISSUEBA" />
                    <xsl:apply-templates select="key('issue', concat(CASEID, '|', ISSUEID))[generate-id() = generate-id(key('object', concat(CASEID, '|', ISSUEID, '|', OBJECTID))[1])]" mode="object" />
                </ISSUE>
            </xsl:when>
            <xsl:otherwise>
                <xsl:apply-templates select="key('issue', concat(CASEID, '|', ISSUEID))[generate-id() = generate-id(key('object', concat(CASEID, '|', ISSUEID, '|', OBJECTID))[1])]" mode="object" />            
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

    <xsl:template match="row" mode="object">
        <xsl:if test="OBJECTID">
            <SOURCE>
                <xsl:apply-templates select="OBJECTID|OBJECTBA" />
            </SOURCE>
        </xsl:if>
    </xsl:template>

    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>