package org.antlr.jetbrains.sample;

import com.intellij.core.CoreASTFactory;
import com.intellij.lang.ParserDefinition;
import com.intellij.psi.impl.source.tree.CompositeElement;
import com.intellij.psi.impl.source.tree.LeafElement;
import com.intellij.psi.impl.source.tree.LeafPsiElement;
import com.intellij.psi.impl.source.tree.PsiCoreCommentImpl;
import com.intellij.psi.tree.IElementType;
import org.antlr.intellij.adaptor.lexer.TokenIElementType;
import org.antlr.jetbrains.sample.parser.SampleLanguageLexer;
import org.antlr.jetbrains.sample.psi.IdentifierPSINode;
import org.jetbrains.annotations.NotNull;

/** How to create parse tree nodes (Jetbrains calls them AST nodes). Later
 *  non-leaf nodes are converted to PSI nodes by the {@link ParserDefinition}.
 *  Leaf nodes are already considered PSI nodes.  This is mostly just
 *  {@link CoreASTFactory} but with comments on the methods that you might want
 *  to override.
 */
public class SampleASTFactory extends CoreASTFactory {
	/** Create an internal parse tree node. FileElement for root or a parse tree CompositeElement (not
	 *  PSI) for the token.
	 *  The FileElement is a parse tree node, which is converted to a PsiFile
	 *  by {@link ParserDefinition#createFile}.
	 */
	@NotNull
    @Override
    public CompositeElement createComposite(IElementType type) {
	    return super.createComposite(type);
    }

	/** Create a parse tree (AST) leaf node from a token. Doubles as a PSI leaf node.
	 *  Does not see whitespace tokens.  Default impl makes {@link LeafPsiElement}
	 *  or {@link PsiCoreCommentImpl} depending on {@link ParserDefinition#getCommentTokens()}.
	 */
	@NotNull
	@Override
	public LeafElement createLeaf(@NotNull IElementType type, CharSequence text) {
		if ( type instanceof TokenIElementType &&
			 ((TokenIElementType) type).getANTLRTokenType()==SampleLanguageLexer.ID)
		{
			// found an ID node; here we do not distinguish between definitions and references
			// because we have no context information here. All we know is that
			// we have an identifier node that will be connected somewhere in a tree.
			//
			// You can only rename, find usages, etc... on leaves implementing PsiNamedElement
			//
			// TODO: try not to create one for IDs under def subtree roots like vardef, function
			return new IdentifierPSINode(type, text);
		}
		LeafElement leaf = super.createLeaf(type, text);
		return leaf;
    }
}
