package org.matheclipse.core.eval.util;

import static org.matheclipse.core.expression.F.List;
import static org.matheclipse.core.expression.F.Options;
import static org.matheclipse.core.expression.F.ReplaceAll;

import org.matheclipse.core.expression.F;
import org.matheclipse.core.interfaces.IAST;
import org.matheclipse.core.interfaces.IExpr;
import org.matheclipse.core.interfaces.ISymbol;

/**
 * Managing Options associated with a function symbol.
 * 
 */
public class Options {
	private IAST fDefaultOptionsList;

	private IAST fCurrentOptionsList;

	/**
	 * 
	 * @param symbol
	 *            the options symbol for determining "default option values"
	 * @param currentOptionsList
	 *            the AST where the option could be defined starting at position startIndex
	 * @param startIndex
	 *            the index from which tolook for options defined in currentOptionsList
	 */
	public Options(final ISymbol symbol, final IAST currentOptionsList, final int startIndex) {
		// get the List of pre-defined options:
		final IExpr temp = F.eval(Options(symbol));
		if ((temp != null) && (temp instanceof IAST) && temp.isList()) {
			fDefaultOptionsList = (IAST) temp;
		} else {
			fDefaultOptionsList = null;
		}
		this.fCurrentOptionsList = null;
		if (currentOptionsList != null && startIndex < currentOptionsList.size()) {
			this.fCurrentOptionsList = List();
			for (int i = startIndex; i < currentOptionsList.size(); i++) {
				this.fCurrentOptionsList.add(1, currentOptionsList.get(i));
			}
		}
	}

	public Options(final ISymbol symbol, final IExpr optionExpr) {
		// get the List of pre-defined options:
		final IExpr temp = F.eval(Options(symbol));
		if ((temp != null) && (temp instanceof IAST) && temp.isList()) {
			fDefaultOptionsList = (IAST) temp;
		} else {
			fDefaultOptionsList = null;
		}
		this.fCurrentOptionsList = List();
		this.fCurrentOptionsList.add(optionExpr);
	}

	/**
	 * Get the option from the internal option list and check if it's true or false.
	 * 
	 * @param optionString
	 *            the option string
	 * @return true if the option is set to True or false otherwise.
	 */
	public boolean isOption(final String optionString) {
		IExpr temp = getOption(optionString);
		return temp.equals(F.True);
	}

	/**
	 * Get the option from the internal option list.
	 * 
	 * @param optionString
	 *            the option string
	 * @return the found option value or null if the option is not available
	 */
	public IExpr getOption(final String optionString) {
		IAST rule = null;
		if (fCurrentOptionsList != null) {
			try {
				for (int i = 1; i < fCurrentOptionsList.size(); i++) {
					if (fCurrentOptionsList.get(i).isAST()) {
						rule = (IAST) fCurrentOptionsList.get(i);
						if (rule.isRuleAST() && rule.get(1).toString().equalsIgnoreCase(optionString)) {
							return rule.get(2);
						}
					}
				}
			} catch (Exception e) {

			}
		}
		if (fDefaultOptionsList != null) {
			try {
				for (int i = 1; i < fDefaultOptionsList.size(); i++) {
					if (fDefaultOptionsList.get(i).isAST()) {
						rule = (IAST) fDefaultOptionsList.get(i);
						if (rule.isRuleAST() && rule.get(1).toString().equalsIgnoreCase(optionString)) {
							return rule.get(2);
						}
					}
				}
			} catch (Exception e) {

			}
		}
		return null;
	}

	public IAST replaceAll(final IAST options) {
		IAST result = options.clone();
		if (fCurrentOptionsList != null) {
			result = (IAST) F.eval(ReplaceAll(result, fCurrentOptionsList));
		}
		if (fDefaultOptionsList != null) {
			result = (IAST) F.eval(ReplaceAll(result, fDefaultOptionsList));
		}
		return result;
	}

}