package org.eclipse.jst.jsp.ui.internal.hyperlink;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.Path;
import org.eclipse.jdt.core.IField;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.ILocalVariable;
import org.eclipse.jdt.core.IMethod;
import org.eclipse.jdt.core.ISourceRange;
import org.eclipse.jdt.core.ISourceReference;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.hyperlink.IHyperlink;
import org.eclipse.jface.text.hyperlink.IHyperlinkDetector;
import org.eclipse.jst.jsp.core.internal.java.IJSPTranslation;
import org.eclipse.jst.jsp.core.internal.java.JSPTranslation;
import org.eclipse.jst.jsp.core.internal.java.JSPTranslationAdapter;
import org.eclipse.jst.jsp.ui.internal.Logger;
import org.eclipse.wst.sse.core.IStructuredModel;
import org.eclipse.wst.sse.core.StructuredModelManager;
import org.eclipse.wst.xml.core.document.XMLDocument;
import org.eclipse.wst.xml.core.document.XMLModel;

/**
 * Detects hyperlinks in JSP Java content
 */
public class JSPJavaHyperlinkDetector implements IHyperlinkDetector {

	private IHyperlink createHyperlink(IJavaElement element, IRegion region, IDocument document) {
		IHyperlink link = null;
		if (region != null) {
			// open local variable in the JSP file...
			if (element instanceof ISourceReference) {
				IFile file = null;
				int jspOffset = 0;
				IStructuredModel sModel = null;

				// try to locate the file in the workspace
				try {
					sModel = StructuredModelManager.getModelManager().getExistingModelForRead(document);
					if (sModel != null) {
						String uriString = sModel.getResolver().getFileBaseLocation();
						file = getFile(uriString);
					}
				}
				finally {
					if (sModel != null)
						sModel.releaseFromRead();
				}

				// get Java range, translate coordinate to JSP

				try {
					ISourceRange range = null;
					IJSPTranslation jspTranslation = getJSPTranslation(document);
					if (jspTranslation != null) {
						// link to local variable definitions
						if (element instanceof ILocalVariable) {
							range = ((ILocalVariable) element).getNameRange();
						}
						// linking to fields of the same compilation unit
						else if (element.getElementType() == IJavaElement.FIELD) {
							Object cu = ((IField) element).getCompilationUnit();
							if (cu != null && cu.equals(jspTranslation.getCompilationUnit()))
								range = ((ISourceReference) element).getSourceRange();
						}
						// linking to methods of the same compilation unit
						else if (element.getElementType() == IJavaElement.METHOD) {
							Object cu = ((IMethod) element).getCompilationUnit();
							if (cu != null && cu.equals(jspTranslation.getCompilationUnit()))
								range = ((ISourceReference) element).getSourceRange();
						}
					}

					if (range != null && file != null && file.exists()) {
						jspOffset = jspTranslation.getJspOffset(range.getOffset());
						if (jspOffset >= 0) {
							link = new WorkspaceFileHyperlink(region, file, new Region(jspOffset, range.getLength()));
						}
					}
				}
				catch (JavaModelException jme) {
					Logger.log(Logger.WARNING_DEBUG, jme.getMessage(), jme);
				}
			}
			if (link == null) {
				link = new JSPJavaHyperlink(region, element);
			}
		}
		return link;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.hyperlink.IHyperlinkDetector#detectHyperlinks(org.eclipse.jface.text.ITextViewer,
	 *      org.eclipse.jface.text.IRegion, boolean)
	 */
	public IHyperlink[] detectHyperlinks(ITextViewer textViewer, IRegion region, boolean canShowMultipleHyperlinks) {
		List hyperlinks = new ArrayList(0);

		if (region != null && textViewer != null) {
			IDocument document = textViewer.getDocument();

			// check and make sure this is a valid Java type
			JSPTranslation jspTranslation = getJSPTranslation(document);
			if (jspTranslation != null) {
				// check if we are in JSP Java content
				int javaOffset = jspTranslation.getJavaOffset(region.getOffset());
				if (javaOffset > -1) {
					// check that we are not in indirect Java content (like
					// included files)
					if (!jspTranslation.isIndirect(javaOffset)) {
						// get Java elements
						IJavaElement[] elements = jspTranslation.getElementsFromJspRange(region.getOffset(), region.getOffset() + region.getLength());
						if (elements != null && elements.length > 0) {
							// create a JSPJavaHyperlink for each Java element
							for (int i = 0; i < elements.length; ++i) {
								IJavaElement element = elements[i];

								// find hyperlink range for Java element
								IRegion hyperlinkRegion = selectWord(document, region.getOffset());
								IHyperlink link = createHyperlink(element, hyperlinkRegion, document);
								if (link != null) {
									hyperlinks.add(link);
								}
							}
						}
					}
				}
			}
		}

		if (hyperlinks.size() == 0)
			return null;
		return (IHyperlink[]) hyperlinks.toArray(new IHyperlink[0]);
	}

	/**
	 * Returns an IFile from the given uri if possible, null if cannot find
	 * file from uri.
	 * 
	 * @param fileString
	 *            file system path
	 * @return returns IFile if fileString exists in the workspace
	 */
	private IFile getFile(String fileString) {
		IFile file = null;

		if (fileString != null) {
			IFile[] files = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocation(new Path(fileString));
			for (int i = 0; i < files.length && file == null; i++)
				if (files[i].exists())
					file = files[i];
		}

		return file;
	}
	/**
	 * Get JSP translation object
	 * 
	 * @return JSPTranslation if one exists, null otherwise
	 */
	private JSPTranslation getJSPTranslation(IDocument document) {
		JSPTranslation translation = null;

		XMLModel xmlModel = null;
		try {
			xmlModel = (XMLModel) StructuredModelManager.getModelManager().getExistingModelForRead(document);
			if (xmlModel != null) {
				XMLDocument xmlDoc = xmlModel.getDocument();
				JSPTranslationAdapter adapter = (JSPTranslationAdapter) xmlDoc.getAdapterFor(IJSPTranslation.class);
				if (adapter != null) {
					translation = adapter.getJSPTranslation();
				}
			}
		}
		finally {
			if (xmlModel != null)
				xmlModel.releaseFromRead();
		}
		return translation;
	}

	/**
	 * Java always selects word when defining region
	 * 
	 * @param document
	 * @param anchor
	 * @return IRegion
	 */
	private IRegion selectWord(IDocument document, int anchor) {

		try {
			int offset = anchor;
			char c;

			while (offset >= 0) {
				c = document.getChar(offset);
				if (!Character.isJavaIdentifierPart(c))
					break;
				--offset;
			}

			int start = offset;

			offset = anchor;
			int length = document.getLength();

			while (offset < length) {
				c = document.getChar(offset);
				if (!Character.isJavaIdentifierPart(c))
					break;
				++offset;
			}

			int end = offset;

			if (start == end)
				return new Region(start, 0);

			return new Region(start + 1, end - start - 1);

		}
		catch (BadLocationException x) {
			return null;
		}
	}
}