#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

//' Example RNG Draws with sitmo
//' 
//' Shows a basic setup and use case for sitmo. 
//' 
//' @param n A \code{unsigned int} is a .
//' @return A \code{vec} with random sequences. 
//' @examples
//' n = 10
//' sitmo_draws(n)
// [[Rcpp::export]]
Rcpp::NumericVector sitmo_draws(unsigned int n) {
  
  Rcpp::NumericVector o(n);
  
  // Create a prng engine
  sitmo::prng eng;
  
  // Draw from base engine
  for (unsigned int i=0; i< n ; ++i){
    o(i) = eng();  
  }

  return o;
}

#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

//' Example Seed Set and RNG Draws with sitmo
//' 
//' Shows how to set a seed in sitmo. 
//' 
//' @param n    An \code{unsigned int} that dictates how many realizations occur.
//' @param seed An \code{unsigned int} that controls the rng seed. 
//' @return A \code{vector} with random sequences. 
//' @examples
//' n = 10
//' a = sitmo_engine_seed(n, 1337)
//' b = sitmo_engine_seed(n, 1337)
//' c = sitmo_engine_seed(n, 1338)
//' 
//' isTRUE(all.equal(a,b))
//' isTRUE(all.equal(a,c))
// [[Rcpp::export]]
Rcpp::NumericVector sitmo_engine_seed(unsigned int n, unsigned int seed) {
  
  // Create Rcpp Matrix
  Rcpp::NumericVector o(n);
  
  // Create a prng engine with a specific seed
  sitmo::prng eng(static_cast<uint32_t>(seed));
  
  // Draw from base engine
  for (unsigned int i=0; i < n; ++i){
    o(i) = eng();        
  }

  return o;
}

#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

//' Example Seed Set and RNG Draws with sitmo
//' 
//' Shows how to set a seed in sitmo. 
//' 
//' @param n    An \code{unsigned int} that dictates how many realizations occur.
//' @param seed An \code{unsigned int} that controls the rng seed. 
//' @return A \code{matrix} with random sequences. 
//' @examples
//' n = 10
//' a = sitmo_engine_seed(n, 1337)
//' 
//' isTRUE(all.equal(a[,1],a[,2]))
// [[Rcpp::export]]
Rcpp::NumericMatrix sitmo_engine_reset(unsigned int n, unsigned int seed) {
  
  // Create Rcpp Vector
  Rcpp::NumericMatrix o(n,2);
  
  // Create a prng engine with a specific seed
  sitmo::prng eng(static_cast<uint32_t>(seed));
  
  // Draw from base engine
  for (unsigned int i=0; i < n ; ++i){
    o(i,0) = eng();        
  }
  
  // Reset seed
  eng.seed();
  
  // Draw from base engine
  for (unsigned int i=0; i< n ; ++i){
    o(i,1) = eng();        
  }  
  
  return o;
}

#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

//' Two RNG engines running side-by-side
//' 
//' Shows how to create two separate RNGs and increase them together. 
//' 
//' @param n     An \code{unsigned int} that dictates how many realizations occur.
//' @param seeds A \code{vec} containing two integers greater than 0. 
//' @return A \code{matrix} with random sequences. 
//' @examples
//' n = 10
//' a = sitmo_two_seeds(n, c(1337,1338))
//' 
//' b = sitmo_two_seeds(n, c(1337,1337))
//' 
//' isTRUE(all.equal(a[,1],a[,2]))
//' 
//' isTRUE(all.equal(b[,1],b[,2]))
//' 
//' isTRUE(all.equal(a[,1],b[,1]))
// [[Rcpp::export]]
Rcpp::NumericMatrix sitmo_two_seeds(unsigned int n, Rcpp::NumericVector seeds) {
  
  if(seeds.size() != 2) Rcpp::stop("Need exactly two seeds for this example.");
  
  // Create Rcpp Matrix
  Rcpp::NumericMatrix o(n,2);
  
  // Create a prng engine with a specific seed
  sitmo::prng eng1;
  eng1.seed(seeds(0));
  
  sitmo::prng eng2;
  eng2.seed(seeds(1));

  // Draw from base engine
  for (unsigned int i=0; i< n ; ++i){
    o(i,0) = eng1();      
    o(i,1) = eng2();        
  }  
  
  return o;
}

#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

//' Random Uniform Number Generator with sitmo
//' 
//' The function provides an implementation of sampling from a random uniform distribution
//' 
//' @param n    An \code{unsigned integer} denoting the number of realizations to generate.
//' @param min  A \code{double} indicating the minimum \eqn{a} value 
//'               in the uniform's interval \eqn{\left[a,b\right]}
//' @param max  A \code{double} indicating the maximum \eqn{b} value 
//'               in the uniform's interval \eqn{\left[a,b\right]}
//' @param seed A special \code{unsigned integer} containing a single seed.
//' @return A \code{vec} containing the realizations.
//' @export
//' @examples
//' a = runif_sitmo(10)
// [[Rcpp::export]]
Rcpp::NumericVector runif_sitmo(unsigned int n, double min = 0.0, double max = 1.0, uint32_t seed = 1) {
  Rcpp::NumericVector o(n);
  
  // Create a prng engine
  sitmo::prng eng(seed);
  // Obtain the range between max and min
  double dis = max - min; 
  
  for(int i = 0; i < n; ++i) {
    // Sample from the RNG and divide it by the maximum value possible (can also use SITMO_RAND_MAX, which is 4294967295)
    // Apply appropriate scale (MAX-MIN)
    o[i] = min + ((double) eng() / (sitmo::prng::max())) * (dis);
  }
  
  return o;
}

#ifdef _OPENMP
#include <omp.h>
#endif

#ifdef _OPENMP
// multithreaded OpenMP version of code
#else
// single-threaded version of code
#endif

#include <Rcpp.h>
#include <sitmo.h> // SITMO PPRNG

// [[Rcpp::depends(sitmo)]]

#ifdef _OPENMP
#include <omp.h>
#endif

// [[Rcpp::plugins(openmp)]]

//' Test Generation using sitmo and C++11
//' 
//' The function provides an implementation of creating realizations from the default engine.
//' 
//' @param n An \code{unsigned integer} denoting the number of realizations to generate.
//' @param seeds A \code{vec} containing a list of seeds. Each seed is run on its own core.
//' @return A \code{vec} containing the realizations.
//' @details
//' The following function's true power is only accessible on platforms that support OpenMP (e.g. Windows and Linux).
//' However, it does provide a very good example as to how to make ones code applicable across multiple platforms.
//' 
//' With this being said, how we determine how many cores to split the generation to is governed by the number of seeds supplied.
//' In the event that one is using OS X, only the first seed supplied is used. 
//' 
//' @export
//' @examples
//' a = sitmo_parallel(10, 5.0, c(1))
//' 
//' b = sitmo_parallel(10, 5.0, c(1))
//' 
//' c = sitmo_parallel(10, 5.0, c(2))
//' 
//' isTRUE(all.equal(a,b))
//' 
//' isTRUE(all.equal(a,c))
// [[Rcpp::export]]
Rcpp::NumericVector sitmo_parallel(unsigned int n, Rcpp::NumericVector& seeds){ 
  
  unsigned int ncores = seeds.size();

  Rcpp::NumericVector q(n);
  
  #ifdef _OPENMP
  #pragma omp parallel num_threads(ncores) if(ncores > 1)
  {
  #endif
  
    // Engine requires uint32_t inplace of unsigned int
    uint32_t active_seed;
      
    // Write the active seed per core or just write one of the seeds.
    #ifdef _OPENMP
      active_seed = static_cast<uint32_t>(seeds[omp_get_thread_num()]);
    #else
      active_seed = static_cast<uint32_t>(seeds[0]);
    #endif
    
    sitmo::prng eng( active_seed );
  
    // Parallelize the Loop
    #ifdef _OPENMP
    #pragma omp for schedule(static)
    #endif
    for (unsigned int i = 0; i < n; i++){
      q[i] = eng(). 
    }

  #ifdef _OPENMP
  }
  #endif
  
  return q;
}