////////////////////////////////////////////////////////////////////////////////
// Copyright 2019 Prominic.NET, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License
//
// Author: Prominic.NET, Inc.
// No warranty of merchantability or fitness of any kind.
// Use this software at your own risk.
////////////////////////////////////////////////////////////////////////////////
package net.prominic.groovyls.providers;

import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CompletableFuture;

import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.Variable;
import org.eclipse.lsp4j.Hover;
import org.eclipse.lsp4j.MarkedString;
import org.eclipse.lsp4j.Position;
import org.eclipse.lsp4j.TextDocumentIdentifier;
import org.eclipse.lsp4j.jsonrpc.messages.Either;

import net.prominic.groovyls.compiler.ast.ASTNodeVisitor;
import net.prominic.groovyls.compiler.util.GroovyASTUtils;
import net.prominic.groovyls.util.GroovyNodeToStringUtils;

public class HoverProvider {
	private ASTNodeVisitor ast;

	public HoverProvider(ASTNodeVisitor ast) {
		this.ast = ast;
	}

	public CompletableFuture<Hover> provideHover(TextDocumentIdentifier textDocument, Position position) {
		Hover hover = new Hover();
		List<Either<String, MarkedString>> contents = new ArrayList<>();
		hover.setContents(contents);

		if (ast == null) {
			//this shouldn't happen, but let's avoid an exception if something
			//goes terribly wrong.
			return CompletableFuture.completedFuture(hover);
		}

		URI uri = URI.create(textDocument.getUri());
		ASTNode offsetNode = ast.getNodeAtLineAndColumn(uri, position.getLine(), position.getCharacter());
		if (offsetNode == null) {
			return CompletableFuture.completedFuture(hover);
		}

		ASTNode definitionNode = GroovyASTUtils.getDefinition(offsetNode, false, ast);
		if (definitionNode == null) {
			return CompletableFuture.completedFuture(hover);
		}

		String content = getContent(definitionNode);
		if (content == null) {
			return CompletableFuture.completedFuture(hover);
		}

		contents.add(Either.forRight(new MarkedString("groovy", content)));
		return CompletableFuture.completedFuture(hover);
	}

	private String getContent(ASTNode hoverNode) {
		if (hoverNode instanceof ClassNode) {
			ClassNode classNode = (ClassNode) hoverNode;
			return GroovyNodeToStringUtils.classToString(classNode, ast);
		} else if (hoverNode instanceof MethodNode) {
			MethodNode methodNode = (MethodNode) hoverNode;
			return GroovyNodeToStringUtils.methodToString(methodNode, ast);
		} else if (hoverNode instanceof Variable) {
			Variable varNode = (Variable) hoverNode;
			return GroovyNodeToStringUtils.variableToString(varNode, ast);
		} else {
			System.err.println("*** hover not available for node: " + hoverNode);
		}
		return null;
	}
}