def addSource(File sourceFile) {
        sources.appendNode("ClCompile", [Include: toPath(sourceFile)]).appendNode('Filter', 'Source Files')
    }

    def addHeader(File headerFile) {
        headers.appendNode("ClInclude", [Include: toPath(headerFile)]).appendNode('Filter', 'Header Files')
    }

    def getFilters() {
        return xml.ItemGroup.findAll({ it.'@Label' == 'Filters' })[0]
    }

    private Node getSources() {

        assert source.Filter[0].text() == 'Source Files'
        return source.'@Include'
    }

    private String headerFile(int index) {
        def header = itemGroup('Headers').ClInclude[index]
        assert header.Filter[0].text() == 'Header Files'
        return header.'@Include'
    }

    private Node itemGroup(String label) {
        return filtersXml.ItemGroup.find({it.'@Label' == label}) as Node

        resources.appendNode("ResourceCompile", [Include: toPath(it)])
    }

    def addHeaderFile(File it) {
        def headers = xml.ItemGroup.find({ it.'@Label' == 'Headers' }) as Node
        headers.appendNode("ClInclude", [Include: toPath(it)])
    }

    def addConfiguration(VisualStudioProjectConfiguration configuration) {
        def configNode = configurations.appendNode("ProjectConfiguration", [Include: configuration.name])

        def sources = itemGroup('References').ResourceCompile
        return normalise(sources*.'@Include')
    }

    List<String> getHeaderFiles() {
        def sources = itemGroup('Headers').ClInclude
        return normalise(sources*.'@Include')
    }

    private static List<String> normalise(List<String> files) {
        return files.collect({ TextUtil.normaliseFileSeparators(it)}).sort()
    }