package org.matheclipse.core.reflection.system;

import static org.matheclipse.core.expression.F.$p;
import static org.matheclipse.core.expression.F.$s;
import static org.matheclipse.core.expression.F.C0;
import static org.matheclipse.core.expression.F.C1;
import static org.matheclipse.core.expression.F.CI;
import static org.matheclipse.core.expression.F.CInfinity;
import static org.matheclipse.core.expression.F.CN1;
import static org.matheclipse.core.expression.F.Cos;
import static org.matheclipse.core.expression.F.E;
import static org.matheclipse.core.expression.F.List;
import static org.matheclipse.core.expression.F.Log;
import static org.matheclipse.core.expression.F.Power;
import static org.matheclipse.core.expression.F.Set;
import static org.matheclipse.core.expression.F.SetDelayed;
import static org.matheclipse.core.expression.F.Times;

import org.matheclipse.core.eval.interfaces.AbstractArg12;
import org.matheclipse.core.eval.interfaces.AbstractFunctionEvaluator;
import org.matheclipse.core.eval.interfaces.INumeric;
import org.matheclipse.core.expression.ComplexNum;
import org.matheclipse.core.expression.ComplexUtils;
import org.matheclipse.core.expression.F;
import org.matheclipse.core.expression.Num;
import org.matheclipse.core.interfaces.IAST;
import org.matheclipse.core.interfaces.IComplexNum;
import org.matheclipse.core.interfaces.IExpr;
import org.matheclipse.core.interfaces.IInteger;
import org.matheclipse.core.interfaces.INum;
import org.matheclipse.core.interfaces.ISymbol;
import org.matheclipse.parser.client.SyntaxError;

/**
 * See Wikipedia - Logarithm
 * 
 */
public class Log extends AbstractArg12 implements INumeric {

	/*
	 * 
 { Log[1]=0, Log[E]=1, Log[E^(x_Integer)]:=x, Log[E^(x_Rational)]:=x, Log[E^(I)]=I, Log[Exp[-I]]=(-I),
	 * Log[0]=(-Infinity) } 
	 */
	final static IAST RULES = List(Set(Log(Power(E, Times(CN1, CI))), Times(CN1, CI)), Set(Log(Power(E, CI)), CI),
			Set(Log(C0), Times(CN1, CInfinity)), Set(Log(C1), C0), Set(Log(E), C1),
			SetDelayed(Log(Power(E, $p("x", $s("Integer")))), $s("x")), SetDelayed(Log(Power(E, $p("x", $s("Rational")))), $s("x")));

	@Override
	public IAST getRuleAST() {
		return RULES;
	}

	public Log() {
	}

	@Override
	public IExpr e1DblArg(final INum arg1) {
		return Num.valueOf(Math.log(arg1.getRealPart()));
	}

	@Override
	public IExpr e1DblComArg(final IComplexNum arg1) {
		return ComplexUtils.log((ComplexNum) arg1);
	}

	@Override
	public IExpr e2DblArg(final INum arg1, final INum arg2) {
		return Num.valueOf(Math.log(arg2.getRealPart()) / Math.log(arg1.getRealPart()));
	}

	@Override
	public IExpr e2IntArg(final IInteger arg1, final IInteger arg2) {
		try {
			long l1 = arg1.toLong();
			long l2 = arg2.toLong();
			double res = Math.log(l2) / Math.log(l1);
			if (F.isNumIntValue(res)) {
				int r = Double.valueOf(Math.round(res)).intValue();
				if (arg2.equals(arg1.pow(r))) {
					return F.integer(r);
				}
			}
		} catch (ArithmeticException ae) {
			// toLong() method failed
		}
		return null;
	}

	public double evalReal(final double[] stack, final int top, final int size) {
		if (size != 1) {
			throw new UnsupportedOperationException();
		}
		return Math.log(stack[top]);
	}

	@Override
	public void setUp(ISymbol symbol) throws SyntaxError {
		symbol.setAttributes(ISymbol.LISTABLE | ISymbol.NUMERICFUNCTION);
		super.setUp(symbol);
	}

	@Override
	public IExpr e1ObjArg(IExpr arg1) {
		if (AbstractFunctionEvaluator.isNegativeExpression(arg1)) {
			IExpr temp = F.eval(Times(CN1, arg1));
			if (temp.isPositive()) {
				return F.Plus(Log(temp), Times(CI, F.Pi));
			}
		}
		return null;
	}
}