/*
  Copyright(C) 2015  Brazil
  Copyright(C) 2020-2022  Sutou Kouhei <kou@clear-code.com>

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "../grn_ctx_impl.h"
#include "../grn_ii.h"
#include "../grn_db.h"
#include "../grn_expr_executor.h"
#include "../grn_posting.h"

#ifdef GRN_WITH_MRUBY
#include <mruby.h>
#include <mruby/class.h>
#include <mruby/data.h>
#include <mruby/string.h>
#include <mruby/hash.h>
#include <mruby/variable.h>

#include "mrb_ctx.h"
#include "mrb_index_cursor.h"
#include "mrb_converter.h"
#include "mrb_options.h"

static struct mrb_data_type mrb_grn_index_cursor_type = {
  "Groonga::IndexCursor",
  NULL
};

static mrb_value
mrb_grn_index_cursor_class_open_raw(mrb_state *mrb, mrb_value klass)
{
  grn_ctx *ctx = (grn_ctx *)mrb->ud;
  mrb_value mrb_table_cursor;
  mrb_value mrb_index;
  mrb_value mrb_options = mrb_nil_value();
  grn_obj *index_cursor;
  grn_table_cursor *table_cursor;
  grn_obj *index;
  grn_id rid_min = GRN_ID_NIL;
  grn_id rid_max = GRN_ID_MAX;
  int flags = 0;
  mrb_value mrb_index_cursor;

  mrb_get_args(mrb, "oo|H", &mrb_table_cursor, &mrb_index, &mrb_options);

  table_cursor = DATA_PTR(mrb_table_cursor);
  index = DATA_PTR(mrb_index);
  if (!mrb_nil_p(mrb_options)) {
    /* TODO */
  }
  index_cursor = grn_index_cursor_open(ctx, table_cursor, index,
                                       rid_min, rid_max, flags);
  grn_mrb_ctx_check(mrb);

  mrb_index_cursor = mrb_funcall(mrb, klass, "new", 1,
                                 mrb_cptr_value(mrb, index_cursor));
  mrb_iv_set(mrb, mrb_index_cursor, mrb_intern_lit(mrb, "@index"), mrb_index);
  return mrb_index_cursor;
}

static mrb_value
mrb_grn_index_cursor_initialize(mrb_state *mrb, mrb_value self)
{
  mrb_value mrb_index_cursor_ptr;

  mrb_get_args(mrb, "o", &mrb_index_cursor_ptr);
  DATA_TYPE(self) = &mrb_grn_index_cursor_type;
  DATA_PTR(self) = mrb_cptr(mrb_index_cursor_ptr);

  return self;
}

static mrb_value
mrb_grn_index_cursor_close(mrb_state *mrb, mrb_value self)
{
  grn_ctx *ctx = (grn_ctx *)mrb->ud;
  grn_obj *index_cursor;

  index_cursor = DATA_PTR(self);
  if (index_cursor) {
    DATA_PTR(self) = NULL;
    grn_obj_close(ctx, index_cursor);
    grn_mrb_ctx_check(mrb);
  }

  return mrb_nil_value();
}

static mrb_value
mrb_grn_index_cursor_count(mrb_state *mrb, mrb_value self)
{
  grn_ctx *ctx = (grn_ctx *)mrb->ud;
  grn_id term_id;
  int n_records = 0;

  while (grn_index_cursor_next(ctx, DATA_PTR(self), &term_id)) {
    n_records++;
  }

  return mrb_int_value(mrb, n_records);
}

static mrb_value
mrb_grn_index_cursor_select(mrb_state *mrb, mrb_value self)
{
  grn_ctx *ctx = (grn_ctx *)mrb->ud;
  mrb_value mrb_result_set;
  mrb_value mrb_options;
  grn_obj *index_cursor;
  grn_obj *expr = NULL;
  grn_obj *expr_variable = NULL;
  int offset = 0;
  int limit = 10;
  int max_n_unmatched_records = -1;
  grn_expr_executor executor;
  int n_matched_records = 0;
  int n_unmatched_records = 0;
  mrb_value mrb_index;
  grn_obj *index;
  grn_obj *lexicon;
  grn_obj *data_table;
  grn_hash *result_set;
  grn_posting *posting;
  grn_id term_id;
  grn_operator op = GRN_OP_OR;

  mrb_get_args(mrb, "o|H", &mrb_result_set, &mrb_options);

  index_cursor = DATA_PTR(self);
  result_set = DATA_PTR(mrb_result_set);

  if (!mrb_nil_p(mrb_options)) {
    mrb_value mrb_expr;
    mrb_value mrb_offset;
    mrb_value mrb_limit;
    mrb_value mrb_max_n_unmatched_records;

    mrb_expr = grn_mrb_options_get_lit(mrb, mrb_options, "expression");
    if (!mrb_nil_p(mrb_expr)) {
      expr = DATA_PTR(mrb_expr);
      expr_variable = grn_expr_get_var_by_offset(ctx, expr, 0);
    }

    mrb_offset = grn_mrb_options_get_lit(mrb, mrb_options, "offset");
    if (!mrb_nil_p(mrb_offset)) {
      offset = (int)mrb_integer(mrb_offset);
    }

    mrb_limit = grn_mrb_options_get_lit(mrb, mrb_options, "limit");
    if (!mrb_nil_p(mrb_limit)) {
      limit = (int)mrb_integer(mrb_limit);
    }

    mrb_max_n_unmatched_records =
      grn_mrb_options_get_lit(mrb, mrb_options, "max_n_unmatched_records");
    if (!mrb_nil_p(mrb_max_n_unmatched_records)) {
      max_n_unmatched_records = (int)mrb_integer(mrb_max_n_unmatched_records);
    }
  }

  if (limit <= 0) {
    return mrb_int_value(mrb, n_matched_records);
  }

  mrb_index = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "@index"));
  index = DATA_PTR(mrb_index);
  lexicon = ((grn_ii *)index)->lexicon;
  data_table = grn_ctx_at(ctx, grn_obj_get_range(ctx, index));

  if (max_n_unmatched_records < 0) {
    max_n_unmatched_records = INT32_MAX;
  }
  if (expr) {
    grn_expr_executor_init(ctx, &executor, expr);
    grn_mrb_ctx_check(mrb);
  }
  while ((posting = grn_index_cursor_next(ctx, index_cursor, &term_id))) {
    if (expr) {
      bool matched_raw = false;
      grn_obj *matched;

      matched = grn_expr_executor_exec(ctx, &executor, posting->rid);
      if (matched) {
        matched_raw = grn_obj_is_true(ctx, matched);
      } else {
        grn_mrb_ctx_check(mrb);
      }

      if (!matched_raw) {
        n_unmatched_records++;
        if (n_unmatched_records > max_n_unmatched_records) {
          grn_expr_executor_fin(ctx, &executor);
          grn_obj_unref(ctx, data_table);
          return mrb_int_value(mrb, -1);
        }
        continue;
      }
    }
    n_matched_records++;
    if (offset > 0) {
      offset--;
      continue;
    }
    grn_posting_internal add_posting = *((grn_posting_internal *)posting);
    add_posting.weight_float += 1;
    grn_ii_posting_add_float(ctx,
                             (grn_posting *)(&add_posting),
                             result_set,
                             op);
    limit--;
    if (limit == 0) {
      break;
    }
  }
  if (expr) {
    grn_expr_executor_fin(ctx, &executor);
  }
  grn_ii_resolve_sel_and(ctx, result_set, op);

  grn_obj_unref(ctx, data_table);

  return mrb_int_value(mrb, n_matched_records);
}

void
grn_mrb_index_cursor_init(grn_ctx *ctx)
{
  grn_mrb_data *data = &(ctx->impl->mrb);
  mrb_state *mrb = data->state;
  struct RClass *module = data->module;
  struct RClass *klass;

  klass = mrb_define_class_under(mrb, module, "IndexCursor", mrb->object_class);
  MRB_SET_INSTANCE_TT(klass, MRB_TT_DATA);

  mrb_define_class_method(mrb, klass, "open_raw",
                          mrb_grn_index_cursor_class_open_raw,
                          MRB_ARGS_ARG(2, 1));

  mrb_define_method(mrb, klass, "initialize",
                    mrb_grn_index_cursor_initialize, MRB_ARGS_REQ(1));
  mrb_define_method(mrb, klass, "close",
                    mrb_grn_index_cursor_close, MRB_ARGS_NONE());
  mrb_define_method(mrb, klass, "count",
                    mrb_grn_index_cursor_count, MRB_ARGS_NONE());
  mrb_define_method(mrb, klass, "select",
                    mrb_grn_index_cursor_select, MRB_ARGS_ARG(1, 1));
}
#endif
