How do I get parameter data from Php method under current offset?

GetTemplateReferenceContributor.kt

package cz.k2.eshop

import com.intellij.patterns.PlatformPatterns.psiElement
import com.intellij.patterns.PsiNamePatternCondition
import com.intellij.patterns.StandardPatterns
import com.intellij.psi.PsiElement
import com.intellij.psi.PsiReferenceContributor
import com.intellij.psi.PsiReferenceRegistrar
import com.jetbrains.php.lang.parser.PhpElementTypes
import com.jetbrains.php.lang.psi.elements.FunctionReference

class GetTemplateReferenceContributor : PsiReferenceContributor() {
    override fun registerReferenceProviders(registrar: PsiReferenceRegistrar) {
        val templateMethodPattern = object : PsiNamePatternCondition<PsiElement>("withFunctionName", StandardPatterns.string().matches("GetTemplate")) {
            override fun getPropertyValue(o: Any): String? {
                return if (o is FunctionReference) o.name else null
            }
        }

        val elementPattern = psiElement().withElementType(PhpElementTypes.STRING).
                withParent(psiElement().withElementType(PhpElementTypes.PARAMETER_LIST).withParent(psiElement().
                        withElementType(PhpElementTypes.FUNCTION_CALL).with(templateMethodPattern)))

        registrar.registerReferenceProvider(elementPattern, GetTemplateReferenceProvider(), PsiReferenceRegistrar.DEFAULT_PRIORITY)
    }
}

GetTemplateReferenceProvider.kt

package cz.k2.eshop

import com.intellij.psi.PsiElement
import com.intellij.psi.PsiReference
import com.intellij.psi.PsiReferenceProvider
import com.intellij.util.ProcessingContext

class GetTemplateReferenceProvider : PsiReferenceProvider() {
    override fun getReferencesByElement(element: PsiElement, context: ProcessingContext): Array<PsiReference> {
        val specialGetTemplateReference = SpecialGetTemplateReference(element)
        val standardGetTemplateReference = StandardGetTemplateReference(element)
        val result: MutableList<PsiReference> = mutableListOf<PsiReference>()

        if (specialGetTemplateReference.psiFile != null) {
            result.add(specialGetTemplateReference)
        }

        if (standardGetTemplateReference.psiFile != null) {
            result.add(standardGetTemplateReference)
        }

        return if (result.size > 0) result.toTypedArray() else PsiReference.EMPTY_ARRAY
    }
}

SpecialGetTemplateReference.kt

package cz.k2.eshop

import com.intellij.psi.PsiElement
import com.intellij.psi.PsiManager
import com.intellij.psi.PsiReferenceBase

class SpecialGetTemplateReference internal constructor(element: PsiElement) : PsiReferenceBase<PsiElement>(element) {
    val project = myElement.project
    val parameterData = myElement.text.substring(1, myElement.textLength - 1)
    val destinationString = "special/views/$parameterData.phtml"
    val virtualFile = project.baseDir.findFileByRelativePath(destinationString)
    val psiFile = virtualFile?.let { PsiManager.getInstance(project).findFile(it) }

    override fun resolve(): PsiElement? = psiFile

    override fun getVariants(): Array<Any?> {
        return arrayOfNulls(0)
    }
}

StandardGetTemplateReference.kt

package cz.k2.eshop

import com.intellij.psi.PsiElement
import com.intellij.psi.PsiFile
import com.intellij.psi.PsiManager
import com.intellij.psi.PsiReferenceBase

class StandardGetTemplateReference internal constructor(element: PsiElement) : PsiReferenceBase<PsiElement>(element) {
    val project = myElement.project
    val parameterData = myElement.text.substring(1, myElement.textLength - 1)
    val destinationString = "standard/views/$parameterData.phtml"
    val virtualFile = project.baseDir.findFileByRelativePath(destinationString)
    val psiFile: PsiFile? = virtualFile?.let { PsiManager.getInstance(project).findFile(it) }

    override fun resolve(): PsiElement? = psiFile

    // Used for autocompletion
    override fun getVariants(): Array<Any?> {
        return arrayOfNulls(0)
    }
}