package no.uio.ifi.refaktor.utils;

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

import org.eclipse.core.resources.IProject;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.AbstractTypeDeclaration;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.NodeFinder;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.TextSelection;

/**
 * A custom TextSelection that enforces the presence of
 * a compilation unit to back the selection.
 */
public class CompilationUnitTextSelection extends TextSelection implements ITextSelection {

	private ICompilationUnit compilationUnit;
	private NodeFinder nodeFinder;

	public CompilationUnitTextSelection(ICompilationUnit compilationUnit, int offset, int length) {
		super(offset, length);
		if (compilationUnit == null)
			throw new NullPointerException(this.getClass().getCanonicalName() + ": given compilation unit cannot be null");
		this.compilationUnit = compilationUnit;
	}

	public CompilationUnitTextSelection(ICompilationUnit compilationUnit, ITextSelection selection) {
		this(compilationUnit, selection.getOffset(), selection.getLength());
	}

	@Override
	public IDocument getDocument() {
		return DocumentUtils.getDocumentFromCompilationUnit(compilationUnit);
	}

	public int getEnd() {
		return getOffset() + getLength();
	}

	public IProject getProject() {
		return compilationUnit.getJavaProject().getProject();
	}

	public ICompilationUnit getCompilationUnit() {
		return compilationUnit;
	}

	public ASTNode getCoveringNode() {
		return getNodeFinder().getCoveringNode();
	}

	public ASTNode getCoveredNode() {
		return getNodeFinder().getCoveredNode();
	}

	private NodeFinder getNodeFinder() {
		if (nodeFinder == null)
			nodeFinder = ParseUtils.createNodeFinder(ParseUtils.parse(compilationUnit), this);
		return nodeFinder;
	}

	public boolean surroundsNode(ASTNode node) {
		return getOffset() <= node.getStartPosition() && endOfNode(node) <= getEnd();
	}

	private int endOfNode(ASTNode node) {
		return node.getStartPosition() + node.getLength();
	}

	public String getPackageName() {
		return getConcreteCompilationUnit().getPackage().getName().getFullyQualifiedName();
	}

	public String getNameOfSurroundingType() {
		for (Object type: getConcreteCompilationUnit().types()) {
			assertThat(type, instanceOf(AbstractTypeDeclaration.class));
			AbstractTypeDeclaration absTypeDecl = (AbstractTypeDeclaration) type;
			if (isSurroundedBy(absTypeDecl))
				return absTypeDecl.getName().getFullyQualifiedName();
		}
		return null;
	}

	private boolean isSurroundedBy(AbstractTypeDeclaration absTypeDecl) {
		return absTypeDecl.getStartPosition() <= getOffset() && getLength() <= absTypeDecl.getLength();
	}

	private CompilationUnit getConcreteCompilationUnit() {
		ASTNode root = getCoveringNode().getRoot();
		assertThat(root, instanceOf(CompilationUnit.class));
		return (CompilationUnit) root;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof CompilationUnitTextSelection)
			return super.equals(obj) && compilationUnit.equals(((CompilationUnitTextSelection)obj).compilationUnit);
		return false;
	}
	
	@Override
	public int hashCode() {
		return (getOffset() << 24) | (getLength() << 16) | compilationUnit.hashCode();
	}
	
	@Override
	public String toString() {
		return "Offset: " + getOffset() + "; Length: " + getLength() + "; End: " + getEnd() + "; CU handle identifier: " + compilationUnit.getHandleIdentifier();
	}
	
	@Override
	public int getStartLine() {
		return createTextSelectionWithDocument().getStartLine();
	}
	
	@Override
	public int getEndLine() {
		return createTextSelectionWithDocument().getEndLine();
	}
	
	@Override
	public String getText() {
		return createTextSelectionWithDocument().getText();
	}
	
	private TextSelection createTextSelectionWithDocument() {
		return new TextSelection(getDocument(), getOffset(), getLength());
	}
}