package no.uio.ifi.refaktor.analyze.analyzers;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import no.uio.ifi.refaktor.utils.CompilationUnitTextSelection;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.dom.Statement;

class TextSelectionsGeneratorHelper {

	private final Set<CompilationUnitTextSelection> textSelections;
	private final ICompilationUnit compilationUnit;
	
	private TextSelectionsGeneratorHelper(ICompilationUnit compilationUnit) {
		this.compilationUnit = compilationUnit;
		textSelections = new HashSet<CompilationUnitTextSelection>();
	}

	static Set<CompilationUnitTextSelection> generateSelectionsFromList(List<Statement> statements, ICompilationUnit compilationUnit) {
		return new TextSelectionsGeneratorHelper(compilationUnit).generateSelectionsFromList(statements);
	}

	private Set<CompilationUnitTextSelection> generateSelectionsFromList(List<Statement> statements) {
		for (Statement statement: statements)
			generateSelectionsFor(statement);
		return textSelections;
	}

	private void generateSelectionsFor(Statement statement) {
		Set<CompilationUnitTextSelection> newSelections = new HashSet<CompilationUnitTextSelection>();
		CompilationUnitTextSelection textSelectionFromStatement = createTextSelectionFromStatement(statement);
		newSelections.add(textSelectionFromStatement);

		for (CompilationUnitTextSelection textSelection: textSelections)
			newSelections.add(addTextSelections(textSelection, textSelectionFromStatement));

		textSelections.addAll(newSelections);
	}

	private CompilationUnitTextSelection createTextSelectionFromStatement(Statement statement) {
		return new CompilationUnitTextSelection(compilationUnit, statement.getStartPosition(), statement.getLength());
	}

	private static CompilationUnitTextSelection addTextSelections(
			CompilationUnitTextSelection textSelectionOne, CompilationUnitTextSelection textSelectionTwo) {
		int offset = Math.min(textSelectionOne.getOffset(), textSelectionTwo.getOffset());
		int length = Math.max(textSelectionOne.getEnd(), textSelectionTwo.getEnd()) - offset;
		return new CompilationUnitTextSelection(textSelectionOne.getCompilationUnit(), offset, length);
	}

}