package lombok.javac.handlers;

import static lombok.javac.handlers.PKG.chainDots;

import java.util.ArrayList;
import java.util.Collection;

import lombok.SneakyThrows;
import lombok.core.AnnotationValues;
import lombok.javac.JavacAnnotationHandler;
import lombok.javac.JavacAST.Node;

import org.mangosdk.spi.ProviderFor;

import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.tree.JCTree.JCAnnotation;
import com.sun.tools.javac.tree.JCTree.JCAssign;
import com.sun.tools.javac.tree.JCTree.JCBlock;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCNewArray;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.util.List;

@ProviderFor(JavacAnnotationHandler.class)
public class HandleSneakyThrows implements JavacAnnotationHandler<SneakyThrows> {
	@Override public boolean handle(AnnotationValues<SneakyThrows> annotation, JCAnnotation ast, Node annotationNode) {
		Collection<String> exceptionNames = annotation.getRawExpressions("value");
		
		List<JCExpression> memberValuePairs = ast.getArguments();
		if ( memberValuePairs == null || memberValuePairs.size() == 0 ) return false;
		
		JCExpression arrayOrSingle = ((JCAssign)memberValuePairs.get(0)).rhs;
		final List<JCExpression> exceptionNameNodes;
		if ( arrayOrSingle instanceof JCNewArray ) {
			exceptionNameNodes = ((JCNewArray)arrayOrSingle).elems;
		} else exceptionNameNodes = List.of(arrayOrSingle);
		
		if ( exceptionNames.size() != exceptionNameNodes.size() ) {
			annotationNode.addError(
					"LOMBOK BUG: The number of exception classes in the annotation isn't the same pre- and post- guessing.");
		}
		
		java.util.List<String> exceptions = new ArrayList<String>();
		for ( String exception : exceptionNames ) {
			if ( exception.endsWith(".class") ) exception = exception.substring(0, exception.length() - 6);
			exceptions.add(exception);
		}
		
		Node owner = annotationNode.up();
		switch ( owner.getKind() ) {
		case METHOD:
			return handleMethod(annotationNode, (JCMethodDecl)owner.get(), exceptions);
		default:
			annotationNode.addError("@SneakyThrows is legal only on methods and constructors.");
			return true;
		}
	}
	
	private boolean handleMethod(Node annotation, JCMethodDecl method, Collection<String> exceptions) {
		Node methodNode = annotation.up();
		
		if ( (method.mods.flags & Flags.ABSTRACT) != 0 ) {
			annotation.addError("@SneakyThrows can only be used on concrete methods.");
			return true;
		}
		
		if ( method.body == null ) return false;
		
		List<JCStatement> contents = method.body.stats;
		
		for ( String exception : exceptions ) {
			contents = List.of(buildTryCatchBlock(methodNode, contents, exception));
		}
		
		method.body.stats = contents;
		methodNode.rebuild();
		
		return true;
	}

	private JCStatement buildTryCatchBlock(Node node, List<JCStatement> contents, String exception) {
		TreeMaker maker = node.getTreeMaker();
		
		JCBlock tryBlock = maker.Block(0, contents);
		
		JCExpression varType = chainDots(maker, node, exception.split("\\."));
		
		JCVariableDecl catchParam = maker.VarDef(maker.Modifiers(0), node.toName("$ex"), varType, null);
		JCExpression lombokLombokSneakyThrowNameRef = chainDots(maker, node, "lombok", "Lombok", "sneakyThrow");
		JCBlock catchBody = maker.Block(0, List.<JCStatement>of(maker.Throw(maker.Apply(
				List.<JCExpression>nil(), lombokLombokSneakyThrowNameRef,
				List.<JCExpression>of(maker.Ident(node.toName("$ex")))))));
		
		return maker.Try(tryBlock, List.of(maker.Catch(catchParam, catchBody)), null);
	}
}