plugins/gradle/java/src/service/resolve/GradleActionDelegatesToProvider.kt

// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package org.jetbrains.plugins.gradle.service.resolve

import com.intellij.psi.PsiClassType
import com.intellij.psi.PsiWildcardType
import groovy.lang.Closure
import org.jetbrains.plugins.groovy.lang.psi.api.GrFunctionalExpression
import org.jetbrains.plugins.groovy.lang.psi.api.GroovyMethodResult
import org.jetbrains.plugins.groovy.lang.resolve.api.ExpressionArgument
import org.jetbrains.plugins.groovy.lang.resolve.delegatesTo.DelegatesToInfo
import org.jetbrains.plugins.groovy.lang.resolve.delegatesTo.GrDelegatesToProvider
import org.jetbrains.plugins.groovy.lang.resolve.delegatesTo.getContainingCall


class GradleActionDelegatesToProvider : GrDelegatesToProvider {
  override fun getDelegatesToInfo(expression: GrFunctionalExpression): DelegatesToInfo? {
    val call = getContainingCall(expression) ?: return null
    val result = call.advancedResolve() as? GroovyMethodResult ?: return null
    val argumentMapping = result.candidate?.argumentMapping ?: return null
    val type = argumentMapping.expectedType(ExpressionArgument(expression)) as? PsiClassType ?: return null
    val clazz = type.resolve() ?: return null
    if (clazz.qualifiedName != "org.gradle.api.Action") {
      return null
    }
    val substitutedType = result.substitutor.substitute(type) as? PsiClassType ?: return null
    val typeArgument = substitutedType.parameters.singleOrNull() ?: return null
    val delegateType = if (typeArgument is PsiWildcardType && typeArgument.isSuper) {
      typeArgument.bound
    }
    else {
      typeArgument
    }
    return DelegatesToInfo(delegateType, Closure.DELEGATE_FIRST)
  }
}