#include "rb_lapack.h"

extern VOID sgetri_(integer* n, real* a, integer* lda, integer* ipiv, real* work, integer* lwork, integer* info);


static VALUE
rblapack_sgetri(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_a;
  real *a; 
  VALUE rblapack_ipiv;
  integer *ipiv; 
  VALUE rblapack_lwork;
  integer lwork; 
  VALUE rblapack_work;
  real *work; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_a_out__;
  real *a_out__;

  integer lda;
  integer n;

  VALUE rblapack_options;
  if (argc > 0 && TYPE(argv[argc-1]) == T_HASH) {
    argc--;
    rblapack_options = argv[argc];
    if (rb_hash_aref(rblapack_options, sHelp) == Qtrue) {
      printf("%s\n", "USAGE:\n  work, info, a = NumRu::Lapack.sgetri( a, ipiv, [:lwork => lwork, :usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SGETRI( N, A, LDA, IPIV, WORK, LWORK, INFO )\n\n*  Purpose\n*  =======\n*\n*  SGETRI computes the inverse of a matrix using the LU factorization\n*  computed by SGETRF.\n*\n*  This method inverts U and then computes inv(A) by solving the system\n*  inv(A)*L = inv(U) for inv(A).\n*\n\n*  Arguments\n*  =========\n*\n*  N       (input) INTEGER\n*          The order of the matrix A.  N >= 0.\n*\n*  A       (input/output) REAL array, dimension (LDA,N)\n*          On entry, the factors L and U from the factorization\n*          A = P*L*U as computed by SGETRF.\n*          On exit, if INFO = 0, the inverse of the original matrix A.\n*\n*  LDA     (input) INTEGER\n*          The leading dimension of the array A.  LDA >= max(1,N).\n*\n*  IPIV    (input) INTEGER array, dimension (N)\n*          The pivot indices from SGETRF; for 1<=i<=N, row i of the\n*          matrix was interchanged with row IPIV(i).\n*\n*  WORK    (workspace/output) REAL array, dimension (MAX(1,LWORK))\n*          On exit, if INFO=0, then WORK(1) returns the optimal LWORK.\n*\n*  LWORK   (input) INTEGER\n*          The dimension of the array WORK.  LWORK >= max(1,N).\n*          For optimal performance LWORK >= N*NB, where NB is\n*          the optimal blocksize returned by ILAENV.\n*\n*          If LWORK = -1, then a workspace query is assumed; the routine\n*          only calculates the optimal size of the WORK array, returns\n*          this value as the first entry of the WORK array, and no error\n*          message related to LWORK is issued by XERBLA.\n*\n*  INFO    (output) INTEGER\n*          = 0:  successful exit\n*          < 0:  if INFO = -i, the i-th argument had an illegal value\n*          > 0:  if INFO = i, U(i,i) is exactly zero; the matrix is\n*                singular and its inverse could not be computed.\n*\n\n*  =====================================================================\n*\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  work, info, a = NumRu::Lapack.sgetri( a, ipiv, [:lwork => lwork, :usage => usage, :help => help])\n");
      return Qnil;
    } 
  } else
    rblapack_options = Qnil;
  if (argc != 2 && argc != 3)
    rb_raise(rb_eArgError,"wrong number of arguments (%d for 2)", argc);
  rblapack_a = argv[0];
  rblapack_ipiv = argv[1];
  if (argc == 3) {
    rblapack_lwork = argv[2];
  } else if (rblapack_options != Qnil) {
    rblapack_lwork = rb_hash_aref(rblapack_options, ID2SYM(rb_intern("lwork")));
  } else {
    rblapack_lwork = Qnil;
  }

  if (!NA_IsNArray(rblapack_a))
    rb_raise(rb_eArgError, "a (1th argument) must be NArray");
  if (NA_RANK(rblapack_a) != 2)
    rb_raise(rb_eArgError, "rank of a (1th argument) must be %d", 2);
  lda = NA_SHAPE0(rblapack_a);
  n = NA_SHAPE1(rblapack_a);
  if (NA_TYPE(rblapack_a) != NA_SFLOAT)
    rblapack_a = na_change_type(rblapack_a, NA_SFLOAT);
  a = NA_PTR_TYPE(rblapack_a, real*);
  if (!NA_IsNArray(rblapack_ipiv))
    rb_raise(rb_eArgError, "ipiv (2th argument) must be NArray");
  if (NA_RANK(rblapack_ipiv) != 1)
    rb_raise(rb_eArgError, "rank of ipiv (2th argument) must be %d", 1);
  if (NA_SHAPE0(rblapack_ipiv) != n)
    rb_raise(rb_eRuntimeError, "shape 0 of ipiv must be the same as shape 1 of a");
  if (NA_TYPE(rblapack_ipiv) != NA_LINT)
    rblapack_ipiv = na_change_type(rblapack_ipiv, NA_LINT);
  ipiv = NA_PTR_TYPE(rblapack_ipiv, integer*);
  if (rblapack_lwork == Qnil)
    lwork = n;
  else {
    lwork = NUM2INT(rblapack_lwork);
  }
  {
    na_shape_t shape[1];
    shape[0] = MAX(1,lwork);
    rblapack_work = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  work = NA_PTR_TYPE(rblapack_work, real*);
  {
    na_shape_t shape[2];
    shape[0] = lda;
    shape[1] = n;
    rblapack_a_out__ = na_make_object(NA_SFLOAT, 2, shape, cNArray);
  }
  a_out__ = NA_PTR_TYPE(rblapack_a_out__, real*);
  MEMCPY(a_out__, a, real, NA_TOTAL(rblapack_a));
  rblapack_a = rblapack_a_out__;
  a = a_out__;

  sgetri_(&n, a, &lda, ipiv, work, &lwork, &info);

  rblapack_info = INT2NUM(info);
  return rb_ary_new3(3, rblapack_work, rblapack_info, rblapack_a);
}

void
init_lapack_sgetri(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
  sHelp = sH;
  sUsage = sU;
  rblapack_ZERO = zero;

  rb_define_module_function(mLapack, "sgetri", rblapack_sgetri, -1);
}
