package org.eclipse.jdt.internal.core;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
import org.eclipse.core.resources.*;
import org.eclipse.core.runtime.IStatus;

import org.eclipse.jdt.core.*;
import org.eclipse.jdt.core.jdom.IDOMCompilationUnit;
import org.eclipse.jdt.core.jdom.DOMFactory;
import org.eclipse.jdt.core.jdom.IDOMImport;
import org.eclipse.jdt.core.jdom.IDOMNode;

/**
 * <p>This operation adds an import declaration to an existing compilation unit.
 * If the compilation unit already includes the specified import declaration,
 * the import is not generated (it does not generate duplicates).
 * Note that it is valid to specify both a single-type import and an on-demand import
 * for the same package, for example <code>"java.io.File"</code> and
 * <code>"java.io.*"</code>, in which case both are preserved since the semantics
 * of this are not the same as just importing <code>"java.io.*"</code>.
 * Importing <code>"java.lang.*"</code>, or the package in which the compilation unit
 * is defined, are not treated as special cases.  If they are specified, they are
 * included in the result.
 *
 * <p>Required Attributes:<ul>
 *  <li>Compilation unit
 *  <li>Import name - the name of the import to add to the
 *      compilation unit. For example: <code>"java.io.File"</code> or <code>"java.awt.*"</code>
 * </ul>
 */
public class CreateImportOperation extends CreateElementInCUOperation {

	/**
	 * The name of the import to be created.
	 */
	protected String fImportName;
/**
 * When executed, this operation will add an import to the given compilation unit.
 */
public CreateImportOperation(String importName, ICompilationUnit parentElement) {
	super(parentElement);
	fImportName = importName;
}
/**
 * @see CreateTypeMemberOperation#generateElementDOM
 */
protected IDOMNode generateElementDOM() throws JavaModelException {
	if (fCUDOM.getChild(fImportName) == null) {
		DOMFactory factory = new DOMFactory();
		//not a duplicate
		IDOMImport imp = factory.createImport();
		imp.setName(fImportName);
		return imp;
	}
	
	//no new import was generated
	fCreationOccurred = false;
	//all the work has already been done
	return null;
}
/**
 * @see CreateElementInCUOperation#generateResultHandle
 */
protected IJavaElement generateResultHandle() {
	return getCompilationUnit().getImport(fImportName);
}
/**
 * @see CreateElementInCUOperation#getMainTaskName()
 */
public String getMainTaskName(){
	return Util.bind("operation.createImportsProgress"); //$NON-NLS-1$
}
/**
 * Sets the correct position for the new import:<ul>
 * <li> after the last import
 * <li> if no imports, before the first type
 * <li> if no type, after the package statement
 * <li> and if no package statement - first thing in the CU
 */
protected void initializeDefaultPosition() {
	try {
		ICompilationUnit cu = getCompilationUnit();
		IImportDeclaration[] imports = cu.getImports();
		if (imports.length > 0) {
			createAfter(imports[imports.length - 1]);
			return;
		}
		IType[] types = cu.getTypes();
		if (types.length > 0) {
			createBefore(types[0]);
			return;
		}
		IJavaElement[] children = cu.getChildren();
		//look for the package declaration
		for (int i = 0; i < children.length; i++) {
			if (children[i].getElementType() == IJavaElement.PACKAGE_DECLARATION) {
				createAfter(children[i]);
				return;
			}
		}
	} catch (JavaModelException npe) {
	}
}
/**
 * Possible failures: <ul>
 *  <li>NO_ELEMENTS_TO_PROCESS - the compilation unit supplied to the operation is
 * 		<code>null</code>.
 *  <li>INVALID_NAME - not a valid import declaration name.
 * </ul>
 * @see IJavaModelStatus
 * @see JavaConventions
 */
public IJavaModelStatus verify() {
	IJavaModelStatus status = super.verify();
	if (!status.isOK()) {
		return status;
	}
	if (JavaConventions.validateImportDeclaration(fImportName).getSeverity() == IStatus.ERROR) {
		return new JavaModelStatus(IJavaModelStatusConstants.INVALID_NAME, fImportName);
	}
	return JavaModelStatus.VERIFIED_OK;
}
}