Getting the deepest node and calculating relative path

Greetings,

I need to transform an XML that looks like:

<Root>
	<Paths>
		<Path value="/Catalog/Department/Product/SKU"/>
		<Path value="/Catalog/Department/@dept_id"/>
		<Path value="/Catalog/Department/Product/Name"/>
		<Path value="/Catalog/Department/Product/Price"/>
		<Path value="/Catalog/Department/Product/Variant/Name"/>
	</Paths>
</Root>

to something that looks like:

<Root>
	<LongestPath>/Catalog/Department/Product/Variant/Name</LongestPath>
	<RelPaths>
		<RelPath value="../../SKU"/>
		<RelPath value="../../../@dept_id"/>
		<RelPath value="../../Name"/>
		<RelPath value="../../Price"/>
		<RelPath value="."/>
	</RelPaths>
</Root>

The basic idea is to get the <Path> element whose value attribute holds the
XPath expression that, if evaluated, would result in nodes at the deepest
level, relative to other paths specified in the value attributes of sibling
<Path> elements. The XPath expressions themselves are meant to be used on
another XML; only their string values are important here. A simple logic
that would work for me would be to cut each XPath string to the rightmost
"/" character, and simply return the longest string out of all such cut
strings (If you notice carefully, these XPath expressions are defined such
that in a given context, the parent nodes of the resulting node-set of each
XPath expression belong to the same branch of an arbitrary tree).

After getting the longest path, I need to output a <RelPath> node
corresponding to each <Path> node such that the value attribute contains the
relative path of the corresponding Path element, relative to the longest
path. This should be pretty clear from the output xml I've provided above.

Is this kind of complex(?) transformation possible in xslt. Theoretically I
have all the information I need in the source XML that should be required to
perform the required transformation, but I'm just not able to figure out
how. It'll be a pity if I have to "manually" perform this transformation
using Java.

Please let me know if any solutions exist.

Thanks,
Iresh

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