/*
    Copyright (C) 2021 William Hart

    This file is part of FLINT.

    FLINT is free software: you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
*/

#include "fq_default.h"

void fq_default_ctx_init_modulus_nmod_type(fq_default_ctx_t ctx,
                         const nmod_poly_t modulus, const char * var, int type)
{
   ulong p = modulus->mod.n;
   int bits = FLINT_BIT_COUNT(p);
   int d = nmod_poly_degree(modulus);

   if (type == 1 ||
       (type == 0 && bits*d <= 16 &&
        n_pow(p, d) < (UWORD(1) << 16)))
   {
      fq_nmod_ctx_struct * fq_nmod_ctx =
                                     flint_malloc(sizeof(fq_nmod_ctx_struct));
      ctx->type = 1;
      fq_nmod_ctx_init_modulus(fq_nmod_ctx, modulus, var);
      if (fq_zech_ctx_init_fq_nmod_ctx_check(ctx->ctx.fq_zech, fq_nmod_ctx))
         ctx->ctx.fq_zech->owns_fq_nmod_ctx = 1;
      else
      {
         *ctx->ctx.fq_nmod = *fq_nmod_ctx;
         flint_free(fq_nmod_ctx);
         ctx->type = 2;
      }
   } else if (type == 2 || type == 0)
   {
      ctx->type = 2;
      fq_nmod_ctx_init_modulus(ctx->ctx.fq_nmod, modulus, var);
   } else
   {
      fmpz_mod_ctx_t fmod_ctx;
      fmpz_mod_poly_t fmod;
      fmpz_t p;
      ctx->type = 3;
      fmpz_init_set_ui(p, modulus->mod.n);
      fmpz_mod_ctx_init(fmod_ctx, p);
      fmpz_mod_poly_init(fmod, fmod_ctx);
      fmpz_mod_poly_set_nmod_poly(fmod, modulus);
      fq_ctx_init_modulus(ctx->ctx.fq, fmod, fmod_ctx, var);
      fmpz_mod_poly_clear(fmod, fmod_ctx);
      fmpz_mod_ctx_clear(fmod_ctx);
      fmpz_clear(p);
   }
}

void fq_default_ctx_init_modulus_nmod(fq_default_ctx_t ctx,
                                   const nmod_poly_t modulus, const char * var)
{
   fq_default_ctx_init_modulus_nmod_type(ctx, modulus, var, 0);
}