/*
 * Demo: exercise libflame compiled to WebAssembly.
 *
 * 1. Native FLAME/C API: Cholesky factorization of an SPD matrix.
 * 2. LAPACK compatibility layer (lapack2flame): solve A x = b with dgesv_.
 */
#include <stdio.h>
#include <math.h>
#include "FLAME.h"

/* LAPACK-style prototype provided by the lapack2flame layer. */
extern int dgesv_( int* n, int* nrhs, double* a, int* lda,
                   int* ipiv, double* b, int* ldb, int* info );

static int test_flame_cholesky( void )
{
  int    n = 4, i, j;
  FLA_Obj A;
  double* buf;

  /* SPD matrix: A = M^T M + n*I built by hand (column-major). */
  double A0[16] = {
    4.16, -3.12,  0.56, -0.10,
   -3.12,  5.03, -0.83,  1.18,
    0.56, -0.83,  0.76,  0.34,
   -0.10,  1.18,  0.34,  1.18
  };

  FLA_Obj_create( FLA_DOUBLE, n, n, 0, 0, &A );
  buf = (double*) FLA_Obj_buffer_at_view( A );
  for ( j = 0; j < n; j++ )
    for ( i = 0; i < n; i++ )
      buf[ j * n + i ] = A0[ j * n + i ];

  if ( FLA_Chol( FLA_LOWER_TRIANGULAR, A ) != FLA_SUCCESS ) {
    printf( "FLA_Chol: FAILED (matrix not SPD?)\n" );
    FLA_Obj_free( &A );
    return 1;
  }

  /* Check L(0,0) = sqrt(4.16) */
  double expect = sqrt( 4.16 );
  double got    = buf[0];
  printf( "FLA_Chol:  L(0,0) = %.6f (expected %.6f)  %s\n",
          got, expect, fabs( got - expect ) < 1e-12 ? "OK" : "MISMATCH" );

  FLA_Obj_free( &A );
  return fabs( got - expect ) >= 1e-12;
}

static int test_lapack_dgesv( void )
{
  /* Solve A x = b where A = [[2,1],[1,3]], b = [3,5] -> x = [0.8, 1.4] */
  int    n = 2, nrhs = 1, lda = 2, ldb = 2, info = 0;
  int    ipiv[2];
  double A[4] = { 2.0, 1.0,   /* column 0 */
                  1.0, 3.0 }; /* column 1 */
  double b[2] = { 3.0, 5.0 };

  dgesv_( &n, &nrhs, A, &lda, ipiv, b, &ldb, &info );

  printf( "dgesv_:    info = %d, x = [%.6f, %.6f] (expected [0.8, 1.4])  %s\n",
          info, b[0], b[1],
          ( info == 0 && fabs( b[0] - 0.8 ) < 1e-12
                      && fabs( b[1] - 1.4 ) < 1e-12 ) ? "OK" : "MISMATCH" );

  return !( info == 0 && fabs( b[0] - 0.8 ) < 1e-12
                      && fabs( b[1] - 1.4 ) < 1e-12 );
}

int main( void )
{
  int failures = 0;

  FLA_Init();
  printf( "libflame WASM demo\n" );

  failures += test_flame_cholesky();
  failures += test_lapack_dgesv();

  FLA_Finalize();

  printf( failures == 0 ? "ALL TESTS PASSED\n" : "%d TEST(S) FAILED\n",
          failures );
  return failures;
}