plugins/org.eclipse.gmf.xpand.migration/src/org/eclipse/gmf/internal/xpand/build/WorkspaceModelRegistry.java

package org.eclipse.gmf.internal.xpand.build;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EPackage;
import org.eclipse.emf.ecore.plugin.EcorePlugin;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;

class WorkspaceModelRegistry implements MetaModelSource {
	private static class Descriptor {
		final String workspacePath;
		final String nsURI;
		final Resource resource;

		public Descriptor(String workspacePath, String nsURI, Resource res) {
			assert workspacePath != null && nsURI != null && res != null;
			this.workspacePath = workspacePath;
			this.nsURI = nsURI;
			this.resource = res;
		}
	}

	private final Map<String, Descriptor> pathToDescriptor = new TreeMap<String, Descriptor>();
	private final Map<String, Descriptor> uriToDescriptor = new TreeMap<String, Descriptor>();

//	void DEBUG_DUMP() {
//		System.err.println(">>> " + WorkspaceModelRegistry.class.getSimpleName());
//		for (Map.Entry<String, Descriptor> e : uriToDescriptor.entrySet()) {
//			assert e.getKey().equals(e.getValue().nsURI);
//			System.err.println(e.getKey() + " ==> " + e.getValue().workspacePath);
//		}
//		System.err.println("<<< " + WorkspaceModelRegistry.class.getSimpleName());
//	}
	
	public WorkspaceModelRegistry() {
		resourceSet.getURIConverter().getURIMap().putAll(EcorePlugin.computePlatformURIMap());
		
	}

	public EPackage find(String nsURI) {
		Descriptor d = uriToDescriptor.get(nsURI);
		return d == null ? null : (EPackage) d.resource.getContents().get(0);
	}

	public void build(IProject project, IProgressMonitor monitor) throws CoreException {
		EcoreModelResourceVisitor visitor = new EcoreModelResourceVisitor(monitor);
		project.accept(visitor);
		handleCollectedData(visitor);
	}

	public void build(IProject project, IResourceDelta delta, IProgressMonitor monitor) throws CoreException {
		EcoreModelResourceVisitor visitor = new EcoreModelResourceVisitor(monitor);
		delta.accept(visitor);
		handleCollectedData(visitor);
	}

	private void handleCollectedData(EcoreModelResourceVisitor visitor) {
		for (IFile f : visitor.getRemovedModelFiles()) {
			String workspacePath = getKeyPath(f);
			Descriptor d = pathToDescriptor.remove(workspacePath);
			if (d != null) {
				Descriptor d2 = uriToDescriptor.remove(d.nsURI);
				assert d2 == d;
			}
			delist(d);
		}
		Set<IFile> filesToAdd = new HashSet<IFile>(visitor.getNewModelFiles());
		for (IFile f : visitor.getChangedModelFiles()) {
			Descriptor d = pathToDescriptor.remove(getKeyPath(f));
			if (d != null) {
				Descriptor d2 = uriToDescriptor.remove(d.nsURI); // uri might be changed, let alone Descriptor is not modifyable
				assert d2 == d;
				delist(d);
			}
			filesToAdd.add(f);
		}
		for (IFile f : filesToAdd) {
			try {
				Resource r = attemptLoad(f);
				if (r != null && hasSuitableContent(r)) {
					Descriptor d = createDescriptor(f, r);
					assert d != null;
					pathToDescriptor.put(d.workspacePath, d);
					uriToDescriptor.put(d.nsURI, d);
				}
			} catch (Exception ex) {
				ex.printStackTrace();
				// ignore
			}
		}
	}

	// TODO per-project?
	private final ResourceSet resourceSet = new ResourceSetImpl();

	private Resource attemptLoad(IFile file) throws IOException {
		URI uri = URI.createPlatformResourceURI(file.getFullPath().toString(), false);
		Resource res = getResourceSet(file).getResource(uri, true);
		if (res == null) {
			throw new FileNotFoundException("Can't load model from " + file.getFullPath());
		}
		return res;
	}

	private ResourceSet getResourceSet(IFile file) {
		return resourceSet;
	}

	// works in pair with #createDescriptor - may extract these as interface to support models other than Ecore
	private boolean hasSuitableContent(Resource r) {
		assert r != null;
		return r.getContents().get(0) instanceof EPackage;
	}

	private Descriptor createDescriptor(IFile f, Resource res) {
		final String path = getKeyPath(f);
		EPackage p = (EPackage) res.getContents().get(0);
		final String nsURI = p.getNsURI();
		if (nsURI == null) {
			throw new IllegalArgumentException("Invalid model file (missed nsURI) " + path);
		}
		return new Descriptor(path, nsURI, res);
	}

	private void delist(Descriptor d) {
		d.resource.unload();
		d.resource.getResourceSet().getResources().remove(d.resource);
	}

	private String getKeyPath(IFile f) {
		return f.getFullPath().toString();
	}
}