package org.example.smalljava.typing

import com.google.common.base.Predicates
import com.google.inject.Inject
import org.eclipse.emf.ecore.EObject
import org.eclipse.emf.ecore.EcoreFactory
import org.eclipse.xtext.naming.QualifiedName
import org.eclipse.xtext.scoping.IGlobalScopeProvider
import org.example.smalljava.lib.SmallJavaLib
import org.example.smalljava.smallJava.SJAssignment
import org.example.smalljava.smallJava.SJBoolConstant
import org.example.smalljava.smallJava.SJClass
import org.example.smalljava.smallJava.SJExpression
import org.example.smalljava.smallJava.SJHere
import org.example.smalljava.smallJava.SJIntConstant
import org.example.smalljava.smallJava.SJMemberSelection
import org.example.smalljava.smallJava.SJMethod
import org.example.smalljava.smallJava.SJNew
import org.example.smalljava.smallJava.SJNull
import org.example.smalljava.smallJava.SJReturn
import org.example.smalljava.smallJava.SJStringConstant
import org.example.smalljava.smallJava.SJSuper
import org.example.smalljava.smallJava.SJSymbolRef
import org.example.smalljava.smallJava.SJThis
import org.example.smalljava.smallJava.SJVariableDeclaration
import org.example.smalljava.smallJava.SmallJavaFactory
import org.example.smalljava.smallJava.SmallJavaPackage

import static extension org.example.smalljava.util.SmallJavaModelUtil.*
import org.eclipse.emf.ecore.util.EcoreUtil

class SmallJavaTypeProvider {
	
	@Inject extension SmallJavaLib
	
	@Inject IGlobalScopeProvider globalScopeProvider
	
	val ep = SmallJavaPackage::eINSTANCE
	
	public static val stringType = 
		SmallJavaFactory::eINSTANCE.createSJClass => [name = 'stringType']
	public static val intType = 
		SmallJavaFactory::eINSTANCE.createSJClass => [name = 'intType']
	public static val booleanType = 
		SmallJavaFactory::eINSTANCE.createSJClass => [name = 'booleanType']

	public static val nullType = 
		SmallJavaFactory::eINSTANCE.createSJClass => [name = 'nullType']
	
	def typeFor(SJExpression e) {
		switch (e) {
			SJThis : e.containingClass
			SJHere : e.here
			SJSuper : e.containingClass.getSuperclassOrObject
			SJSymbolRef: e.symbol?.type
			SJNew: e.type
			SJMemberSelection: e.member?.type
			SJNull: nullType
			SJStringConstant: stringType
			SJIntConstant: intType
			SJBoolConstant: booleanType
		}
	}
	
	def SJClass getHere(EObject e) {
		var result = globalScopeProvider.getScope(e.eResource, EcoreFactory.eINSTANCE.createEReference => [EType = SmallJavaPackage.Literals.SJ_CLASS] , Predicates.alwaysTrue).getSingleElement(QualifiedName.create("Here")).EObjectOrProxy as SJClass
		return EcoreUtil.resolve(result, e.eResource.resourceSet) as SJClass
	}

	def expectedType(SJExpression e) {
		val c = e.eContainer
		val f = e.eContainingFeature
		switch (c) {
			SJVariableDeclaration case f == ep.SJVariableDeclaration_Expression : 
				c.type
			SJAssignment case f == ep.SJAssignment_Right : 
				c.left.typeFor
			SJReturn case f == ep.SJReturn_Expression :
				c.containingMethod.type
			SJMemberSelection case f == ep.SJMemberSelection_Args : {
				// assume that it refers to a method and that there
				// is a parameter corresponding to the argument
				try {
					(c.member as SJMethod).params.get(c.args.indexOf(e)).type
				} catch (Throwable t) {
					null // otherwise there is no specific expected type
				}
			}
			case f == ep.SJIfStatement_Expression: booleanType
		}
	}

	def argsTypesAsStrings(SJMemberSelection sel) {
		"(" + sel.args.map[typeFor?.name].join(", ") + ")"
	}

	def isPrimitive(SJClass c) {
		c.eResource == null
	}
}