/*  Starshatter: The Open Source Project
    Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
    Copyright (c) 1997-2006, Destroyer Studios LLC.

    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    Utility functions for generating random numbers and locations.
*/

#include "Random.h"

// +----------------------------------------------------------------------+

void RandomInit()
{
    srand(timeGetTime());
}

// +----------------------------------------------------------------------+

Point RandomDirection()
{
    Point p = Point(rand() - 16384, rand() - 16384, 0);
    p.Normalize();
    return p;
}

// +----------------------------------------------------------------------+

Point RandomPoint()
{
    Point p = Point(rand() - 16384, rand() - 16384, 0);
    p.Normalize();
    p *= 15e3 + rand()/3;
    return p;
}

// +----------------------------------------------------------------------+

Vec3 RandomVector(double radius)
{
    Vec3 v = Vec3(rand() - 16384, rand() - 16384, rand() - 16384);
    v.Normalize();

    if (radius > 0)
    v *= (float) radius;
    else
    v *= (float) Random(radius/3, radius);

    return v;
}

// +----------------------------------------------------------------------+

double Random(double min, double max)
{
    double delta = max - min;
    double r     = delta * rand() / 32768.0;

    return min + r;
}

// +----------------------------------------------------------------------+

int RandomIndex()
{
    static int index     = 0;
    static int table[16] = { 0, 9, 4, 7, 14, 11, 2, 12, 1, 5, 13, 8, 6, 10, 3, 15 };

    int r = 1 + ((rand() & 0x0700) >> 8);
    index += r;
    if (index > 1e7) index = 0;
    return table[index % 16];
}

// +----------------------------------------------------------------------+

bool RandomChance(int wins, int tries)
{
    double fraction = 256.0 * wins / tries;
    double r        = (rand() >> 4) & 0xFF;

    return r < fraction;
}

// +----------------------------------------------------------------------+

int RandomSequence(int current, int range)
{
    if (range > 1) {
        int step = (int) Random(1, range-1);
        return (current + step) % range;
    }

    return current;
}

// +----------------------------------------------------------------------+

int RandomShuffle(int count)
{
    static int  set_size = -1;
    static BYTE set[256];
    static int  index    = -1;

    if (count < 0 || count > 250)
    return 0;

    if (set_size != count) {
        set_size = count;
        index    = -1;
    }

    // need to reshuffle
    if (index < 0 || index > set_size-1) {
        // set up the deck
        int tmp[256];
        for (int i = 0; i < 256; i++)
        tmp[i] = i;

        // shuffle the cards
        for (int i = 0; i < set_size; i++) {
            int n     = (int) Random(0, set_size);
            int tries = set_size;
            while (tmp[n] < 0 && tries--) {
                n = (n+1) % set_size;
            }

            if (tmp[n] >= 0) {
                set[i] = tmp[n];
                tmp[n] = -1;
            }
            else {
                set[i] = 0;
            }
        }

        index = 0;
    }

    return set[index++];
}