package no.uio.ifi.refaktor.utils;

import static no.uio.ifi.refaktor.RefaktorAssert.assertThat;
import static org.hamcrest.CoreMatchers.instanceOf;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.NodeFinder;
import org.eclipse.jdt.internal.core.dom.NaiveASTFlattener;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.TextSelection;

@SuppressWarnings("restriction")
public class ParseUtils {

	public static CompilationUnit parse(ICompilationUnit unit) {
		return CompilationUnitCacheManager.getParsedCompilationUnitFor(unit);
	}

	public static CompilationUnit parse(IDocument document) {
		return ParseUtils.parse(document.get().toCharArray());
	}

	private static CompilationUnit parse(char[] chars) {
		ASTParser parser = ParseUtils.createParser();
		parser.setSource(chars);
		return (CompilationUnit) parser.createAST(null);
	}

	public static ASTParser createParser() {
		ASTParser parser = ASTParser.newParser(AST.JLS4);
		parser.setKind(ASTParser.K_COMPILATION_UNIT);
		parser.setResolveBindings(true);
		return parser;
	}

	public static TextSelection stripTextSelection(IDocument document, TextSelection textSelection) {
		final String text = getSelectedTextFromDocument(textSelection, document);

		if (text.isEmpty())
			return null; // VS was here, TODO: return textSelection? EK was here

		int lstrip = numberOfPrecedingWhitespaceCharacters(text);
		int rstrip = numberOfSuccessiveWhitespaceCharacters(text);

		int newOffset = textSelection.getOffset() + lstrip;
		int newLength = textSelection.getLength() - (lstrip + rstrip);

		return new TextSelection(document, newOffset, newLength);
	}

	private static String getSelectedTextFromDocument(TextSelection textSelection, IDocument document) {
		try {
			return document.get(textSelection.getOffset(), textSelection.getLength());
		} catch (BadLocationException e) {
			throw new RuntimeException(e);
		}
	}

	private static int numberOfPrecedingWhitespaceCharacters(final String text) {
		int lstrip = 0;
		while (lstrip < text.length() && Character.isWhitespace(text.charAt(lstrip)))
			lstrip++;
		return lstrip;
	}

	private static int numberOfSuccessiveWhitespaceCharacters(final String text) {
		if (textContainsOnlyWhitespace(text))
			return 0;
			
		int rstrip = 0;
		int rIndex = text.length() - 1;
		while (rstrip < text.length() && Character.isWhitespace(text.charAt(rIndex--)))
			rstrip++;
		return rstrip;
	}

	private static boolean textContainsOnlyWhitespace(final String text) {
		return text.trim().length() == 0;
	}

	public static String getNodeDebugText(ASTNode node) {
		NaiveASTFlattener printer = new NaiveASTFlattener();
		node.accept(printer);
		return printer.getResult();
	}

	public static String getNodeText(ASTNode node) {
		try {
			return getCompilationUnitAndGetTextFromSource(node);
		} catch (JavaModelException e) {
			throw new RuntimeException(e);
		} catch (BadLocationException e) {
			throw new RuntimeException(e);
		}
	}

	private static String getCompilationUnitAndGetTextFromSource(ASTNode node) 
			throws JavaModelException, BadLocationException {
		IDocument document = getDocument(getCompilationUnit(node));
		return document.get(node.getStartPosition(), node.getLength());
	}

	private static CompilationUnit getCompilationUnit(ASTNode node) {
		ASTNode rootNode = node.getRoot();
		assertThat(rootNode, instanceOf(CompilationUnit.class));
		return (CompilationUnit) rootNode;
	}

	private static IDocument getDocument(CompilationUnit compilationUnit) throws JavaModelException {
		return new Document(compilationUnit.getTypeRoot().getSource());
	}

	static NodeFinder createNodeFinder(CompilationUnit cu, ITextSelection selection) {
		return new NodeFinder(cu.getRoot(), selection.getOffset(), selection.getLength());
	}
}