package com.fr.plugin.function.fib;

import com.fr.general.GeneralUtils;
import com.fr.intelli.record.Focus;
import com.fr.intelli.record.Original;
import com.fr.record.analyzer.EnableMetrics;
import com.fr.script.AbstractFunction;
import com.fr.stable.ArrayUtils;
import com.fr.stable.Primitive;

@EnableMetrics
public class Fibonacci extends AbstractFunction {

    @Override
    @Focus(id = "com.fr.plugin.function.fib", text = "", source = Original.PLUGIN)
    public Object run(Object[] args) {
        if (ArrayUtils.isEmpty(args)) {
            return Primitive.ERROR_VALUE;
        }
        int n = GeneralUtils.objectToNumber(args[0]).intValue();
        if (n < 0) {
            return Primitive.ERROR_VALUE;
        }
        return getFib(n);
    }

    private int getFib(int n) {
        if (n < 0) {
            return -1;
        } else if (n == 0) {
            return 0;
        } else if (n == 1 || n == 2) {
            return 1;
        } else {
            int[] fibAry = new int[n + 1];
            fibAry[0] = 0;
            fibAry[1] = fibAry[2] = 1;
            for (int i = 3; i <= n; i++) {
                fibAry[i] = fibAry[i - 1] + fibAry[i - 2];
            }
            return fibAry[n];
        }
    }
}