package algs11;

import stdlib.StdDraw;
import stdlib.StdOut;
import stdlib.StdRandom;
import stdlib.Trace;

import java.util.Arrays;

/**
 * This is a skeleton file for your homework. Edit the sections marked TODO. You
 * may add new functions. You may also edit the function "main" to test your
 * code.
 *
 * You must not add static variables. You MAY add static functions, just not
 * static variables.
 *
 * It is okay to add functions, such as
 *
 * <pre>
 *     public static double sumHelper (double[] list, int i, double sumSoFar) {
 * </pre>
 *
 * but it is NOT okay to add static variables, such as
 *
 * <pre>
 * public static int x;
 * </pre>
 *
 * As for homework 1, you must not change the declaration of any method.
 * 
 * You can edit the main function all you want. I will not run your main
 * function when grading.
 */
public class MyRecursion {

  /**
   * As a model, here is a minValue function, both iteratively and recursively
   */
  /** iterative version */
  public static double minValueI (double[] list) {
    double result = list[0];
    int i = 1;
    while (i < list.length) {
      if (list[i] < result) result = list[i];
      i = i + 1;
    }
    return result;
  }

  /** recursive version */
  public static double minValue (double[] list) {
    return minValueHelper (list, 1, list[0]);
  }
  private static double minValueHelper (double[] list, int i, double result) {
    if (i < list.length) {
      if (list[i] < result) result = list[i];
      result = minValueHelper (list, i + 1, result);
    }
    return result;
  }

  /**
   * PROBLEM 1: Translate the following sum function from iterative to
   * recursive.
   *
   * You should write a helper method. You may not use any "fields" to solve
   * this problem (a field is a variable that is declared "outside" of the
   * function declaration --- either before or after).
   */
  public static double sumI (double[] a) {
    double result = 0.0;
    int i = 0;
    while (i < a.length) {
      result = result + a[i];
      i = i + 1;
    }
    return result;
  }
  public static double sum (double[] a) {
    // TODO
    return StdRandom.uniform ();
  }

  /**
   * PROBLEM 2: Do the same translation for this in-place reverse function
   *
   * You should write a helper method. You may not use any "fields" to solve
   * this problem (a field is a variable that is declared "outside" of the
   * function declaration --- either before or after).
   */
  public static void reverseI (double[] a) {
    int hi = a.length - 1;
    int lo = 0;
    while (lo < hi) {
      double loVal = a[lo];
      double hiVal = a[hi];
      a[hi] = loVal;
      a[lo] = hiVal;
      lo = lo + 1;
      hi = hi - 1;
    }
  }
  public static void reverse (double[] a) {
    // TODO
  }

  /**
   * PROBLEM 3: The following function draws mickey mouse, if you call it like
   * this from main:
   *
   * <pre>
   * draw (.5, .5, .25);
   * </pre>
   *
   * Change the code to draw mickey moose instead. Your solution should be
   * recursive.
   * 
   * Before picture:
   * http://reed.cs.depaul.edu/efredericks/ds1/images/MickeyMouse.png After picture:
   * http://reed.cs.depaul.edu/efredericks/ds1/images/MickeyMoose.png
   *
   * You may not use any "fields" to solve this problem (a field is a variable
   * that is declared "outside" of the function declaration --- either before
   * or after).
   */
  public static void draw (double centerX, double centerY, double radius) {
    // TODO 
    if (radius < .0005) return;

    StdDraw.setPenColor (StdDraw.LIGHT_GRAY);
    StdDraw.filledCircle (centerX, centerY, radius);
    StdDraw.setPenColor (StdDraw.BLACK);
    StdDraw.circle (centerX, centerY, radius);

    double change = radius * 0.90;

    StdDraw.setPenColor (StdDraw.LIGHT_GRAY);
    StdDraw.filledCircle (centerX + change, centerY + change, radius / 2);
    StdDraw.setPenColor (StdDraw.BLACK);
    StdDraw.circle (centerX + change, centerY + change, radius / 2);

    StdDraw.setPenColor (StdDraw.LIGHT_GRAY);
    StdDraw.filledCircle (centerX - change, centerY + change, radius / 2);
    StdDraw.setPenColor (StdDraw.BLACK);
    StdDraw.circle (centerX - change, centerY + change, radius / 2);
  }

  /**
   * PROBLEM 4: Run runTerribleLoop for one hour. You can stop the program
   * using the red "stop" square in eclipse. Fill in the OUTPUT line below
   * with the numbers you saw LAST --- edit the line, replacing the two ...
   * with what you saw:
   *
   * OUTPUT: terribleFibonacci(...)=... // TODO
   *
   * Comment: the code uses "long" variables, which are like "int", but
   * bigger. It's because fibonacci numbers get really big really fast.
   */
  public static void runTerribleLoop () {
    for (int N = 0; N < 100; N++)
      StdOut.format ("terribleFibonacci(%2d)=%d\n", N, terribleFibonacci (N));
  }
  public static long terribleFibonacci (int n) {
    if (n <= 1) return n;
    return terribleFibonacci (n - 1) + terribleFibonacci (n - 2);
  }

  /**
   * PROBLEM 5: The implementation of terribleFibonacci is TERRIBLE! Write a
   * more efficient version of fibonacci. Do not change runFibonacciLoop or
   * runFibonacciSomeValues.
   *
   * To make fibonacci run faster, you want it so that each call to
   * fibonacci(n) computes the fibonacci numbers between 0 and n once, not
   * over and over again.
   *
   * Comment: You will want to use a local variable of type "long" rather than
   * type "int", for the reasons discussed above.
   *
   * Comment: At some point, your fibonacci numbers might become negative.
   * This is normal and expected.
   * http://en.wikipedia.org/wiki/Integer_overflow We discuss this at length
   * in our systems classes.
   *
   * You may not use any "fields" to solve this problem (a field is a variable
   * that is declared "outside" of the function declaration --- either before
   * or after).
   * 
   * You may use a loop on this problem.
   * You do not need to use recursion.
   */
  public static void runFibonacciLoop () {
    for (int N = 0; N < 100; N++)
      StdOut.format ("fibonacci(%2d)=%d\n", N, fibonacci (N));
  }
  public static long fibonacci (int n) {
    return 0; // TODO
  }

  /**
   * A test program, using private helper functions.  See below.
   * To make typing tests a little easier, I've written a function to convert strings to arrays.  See below.
   * You can modify this -- it is not graded.
   */
  public static void main (String[] args) {
    testSum ("11 21 81 -41 51 61");
    testSum ("11 21 81 -41 51");
    testSum ("11 21 81 -41");
    testSum ("11 21 81");
    testSum ("11 21");
    testSum ("11");
    testSum ("");

    testReverse ("11 21 81 -41 51 61");
    testReverse ("11 21 81 -41 51");
    testReverse ("11 21 81 -41");
    testReverse ("11 21 81");
    testReverse ("11 21");
    testReverse ("11");
    testReverse ("");

    testFibonacci (0, 0);
    testFibonacci (1, 1);
    testFibonacci (1, 2);
    testFibonacci (2, 3);
    testFibonacci (21, 8);
    testFibonacci (233, 13);
    testFibonacci (75025, 25);
    testFibonacci (             1_836_311_903L, 46);
    testFibonacci (             2_971_215_073L, 47);
    testFibonacci (       308_061_521_170_129L, 71); 
    testFibonacci (       498_454_011_879_264L, 72);
    testFibonacci ( 7_540_113_804_746_346_429L, 92);
    testFibonacci (-6_246_583_658_587_674_878L, 93);
    testFibonacci (  -813_251_414_217_914_645L, 376);
    StdOut.println ("Finished tests");

    draw (.5, .5, .25);

    // TODO: uncomment these temporarily when you want to see the output of your Fibonacci functions
    //runTerribleLoop (); 
    //runFibonacciLoop();   
  }
  
  /*
   * A main function for debugging -- change the name to "main" to run it (and
   * rename the existing main method to something else). Change the test as
   * appropriate.
   */
  public static void main1 (String[] args) {
    Trace.drawStepsOfMethod ("minValueI");
    Trace.drawStepsOfMethod ("minValue");
    Trace.drawStepsOfMethod ("minValueHelper");
    Trace.run ();
    testMinValue ("11 21 9 31 41");
  }

  /* Test functions --- lot's of similar code! */
  private static void testSum (String list) {
    double[] aList = doublesFromString (list);
    double expected = sumI (aList);
    double actual = sum (aList);
    if (! Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed sum([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed sum([%s]): Expecting (%.1f) Actual (%.1f)\n", list, expected, actual);
    }
  }
  private static void testMinValue (String list) {
    double[] aList = doublesFromString (list);
    double expected = minValueI (aList);
    double actual = minValue (aList);
    if (! Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed minValue([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed minValue([%s]): Expecting (%.1f) Actual (%.1f)\n", list, expected, actual);
    }
  }
  private static void testReverse (String list) {
    double[] expected = doublesFromString (list);
    reverseI (expected);
    double[] actual = doublesFromString (list);
    reverse (actual);
    // != does not do what we want on arrays
    if (! Arrays.equals (expected, actual)) {
      StdOut.format ("Failed reverse([%s]): Expecting (%s) Actual (%s)\n", list, Arrays.toString (expected), Arrays.toString (actual));
    }
  }
  private static void testFibonacci (long expected, int n) {
    long actual = fibonacci (n);
    if (expected != actual) {
      StdOut.format ("Failed fibonacci(%d): Expecting (%d) Actual (%d)\n", n, expected, actual);
    }
  }

  /* A utility function to create an array of doubles from a string. */
  // The string should include a list of numbers, separated by single spaces.
  private static double[] doublesFromString (String s) {
    if ("".equals (s)) return new double [0]; // empty array is a special case
    String[] nums = s.split (" ");
    double[] result = new double[nums.length];
    for (int i = nums.length-1; i >= 0; i--) {
      try { 
        result[i] = Double.parseDouble (nums[i]); 
      } catch (NumberFormatException e) { 
        throw new IllegalArgumentException (String.format ("Bad argument \"%s\": could not parse \"%s\" as a double", s, nums[i]));
      }
    }
    return result;
  }
}