/* Copyright (c) 2018, SequoiaDB and/or its affiliates. All rights reserved.

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; version 2 of the License.

  This program 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 General Public License for more details.

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

#ifndef MYSQL_SERVER
#define MYSQL_SERVER
#endif

#include "sdb_condition.h"
#include "sdb_errcode.h"

Sdb_cond_ctx::Sdb_cond_ctx() {
  cur_item = NULL;
  status = SDB_COND_SUPPORTED;
}

Sdb_cond_ctx::~Sdb_cond_ctx() {
  clear();
}

void Sdb_cond_ctx::clear() {
  Sdb_item *item_tmp = NULL;

  if (cur_item != NULL) {
    delete cur_item;
    cur_item = NULL;
  }

  while ((item_tmp = item_list.pop()) != NULL) {
    delete item_tmp;
  }
}

void Sdb_cond_ctx::pop_all() {
  Sdb_item *item_tmp = NULL;

  if (SDB_COND_UNSUPPORTED == status) {
    clear();
    goto done;
  }

  while (!item_list.is_empty()) {
    if (NULL == cur_item) {
      cur_item = item_list.pop();
      continue;
    }

    if (!cur_item->finished()) {
      if (Item_func::COND_AND_FUNC == cur_item->type()) {
        cur_item->push((Item *)NULL);
      } else {
        delete cur_item;
        cur_item = NULL;
        update_stat(SDB_ERR_COND_INCOMPLETED);
        continue;
      }
    }

    item_tmp = cur_item;
    cur_item = item_list.pop();
    if (0 != cur_item->push(item_tmp)) {
      delete item_tmp;
    }
  }

done:
  return;
}

void Sdb_cond_ctx::pop() {
  int rc = SDB_ERR_OK;
  Sdb_item *item_tmp = NULL;

  if (!keep_on() || item_list.is_empty()) {
    goto done;
  }

  while (!item_list.is_empty()) {
    if (NULL == cur_item) {
      cur_item = item_list.pop();
      continue;
    }

    item_tmp = cur_item;
    cur_item = item_list.pop();
    rc = cur_item->push(item_tmp);
    if (0 != rc) {
      delete item_tmp;
      goto error;
    }

    if (cur_item->finished()) {
      pop();
    }
    break;
  }

done:
  return;
error:
  update_stat(rc);
  goto done;
}

void Sdb_cond_ctx::update_stat(int rc) {
  if (SDB_ERR_OK == rc) {
    goto done;
  }

  if (SDB_COND_UNSUPPORTED == status || SDB_COND_BEFORE_SUPPORTED == status) {
    goto done;
  }

  if (NULL == cur_item || Item_func::COND_OR_FUNC == cur_item->type()) {
    status = SDB_COND_UNSUPPORTED;
    goto done;
  }

  if (Item_func::COND_AND_FUNC == cur_item->type() &&
      SDB_ERR_COND_PART_UNSUPPORTED == rc) {
    status = SDB_COND_PART_SUPPORTED;
  } else {
    status = SDB_COND_BEFORE_SUPPORTED;
  }

done:
  return;
}

bool Sdb_cond_ctx::keep_on() {
  if (SDB_COND_UNSUPPORTED == status || SDB_COND_BEFORE_SUPPORTED == status) {
    return FALSE;
  }
  return true;
}

void Sdb_cond_ctx::push(Item *item) {
  int rc = SDB_ERR_OK;
  Sdb_item *item_tmp = NULL;

  // get the real item
  // see aslo Item_ref
  Item *cond_item = (NULL == item) ? NULL : item->real_item();

  if (!keep_on()) {
    goto done;
  }

  if (NULL != cur_item) {
    if (NULL == cond_item || (Item::FUNC_ITEM != cond_item->type() &&
                              Item::COND_ITEM != cond_item->type())) {
      rc = cur_item->push(cond_item);
      if (0 != rc) {
        goto error;
      }

      if (cur_item->finished()) {
        // finish the current item
        pop();
        if (!keep_on()) {
          // Occur unsupported scene while finish the current item.
          // the status will be set in pop(), so keep rc=0 and skip
          // update_stat()
          goto error;
        }
      }

      goto done;
    }
  }

  if (Item::FUNC_ITEM != cond_item->type() &&
      Item::COND_ITEM != cond_item->type()) {
    // 1. When execute `select * from tb where a`, the first
    //    item will be FIELD_ITEM. This condition has not been handled yet.
    // 2. Subselect always can't be pushed down.
    //
    // This assert is to find out others condition that never be considered.
    DBUG_ASSERT(Item::FIELD_ITEM == cond_item->type() ||
                Item::SUBSELECT_ITEM == cond_item->type());
    rc = SDB_ERR_COND_UNSUPPORTED;
    goto error;
  }
  item_tmp = create_sdb_item((Item_func *)cond_item);
  if (NULL == item_tmp) {
    rc = SDB_ERR_COND_UNSUPPORTED;
    goto error;
  }
  if (cur_item != NULL) {
    item_list.push_front(cur_item);  // netsted func
  }
  cur_item = item_tmp;
  if (cur_item->finished()) {
    // func has no parameter
    pop();
    if (!keep_on()) {
      goto error;
    }
  }

done:
  return;
error:
  update_stat(rc);
  goto done;
}

Sdb_item *Sdb_cond_ctx::create_sdb_item(Item_func *cond_item) {
  Sdb_item *item = NULL;
  switch (cond_item->functype()) {
    case Item_func::COND_AND_FUNC: {
      item = new Sdb_and_item();
      break;
    }
    case Item_func::COND_OR_FUNC: {
      item = new Sdb_or_item();
      break;
    }
    case Item_func::EQ_FUNC:
    case Item_func::EQUAL_FUNC: {
      item = new Sdb_func_eq(cond_item);
      break;
    }
    case Item_func::NE_FUNC: {
      item = new Sdb_func_ne();
      break;
    }
    case Item_func::LT_FUNC: {
      item = new Sdb_func_lt();
      break;
    }
    case Item_func::LE_FUNC: {
      item = new Sdb_func_le();
      break;
    }
    case Item_func::GT_FUNC: {
      item = new Sdb_func_gt();
      break;
    }
    case Item_func::GE_FUNC: {
      item = new Sdb_func_ge();
      break;
    }
    case Item_func::BETWEEN: {
      item = new Sdb_func_between(((Item_func_between *)cond_item)->negated);
      break;
    }
    case Item_func::ISNULL_FUNC: {
      item = new Sdb_func_isnull();
      break;
    }
    case Item_func::ISNOTNULL_FUNC: {
      item = new Sdb_func_isnotnull();
      break;
    }
    case Item_func::IN_FUNC: {
      Item_func_in *item_func = (Item_func_in *)cond_item;
      item = new Sdb_func_in(item_func->negated, item_func->arg_count);
      break;
    }
    case Item_func::LIKE_FUNC: {
      item = new Sdb_func_like((Item_func_like *)cond_item);
      break;
    }
    default: {
      item = new Sdb_func_unkown(cond_item);
      break;
    }
  }
  return item;
}

int Sdb_cond_ctx::to_bson(bson::BSONObj &obj) {
  static bson::BSONObj empty_obj;
  int rc = 0;
  if (NULL != cur_item) {
    rc = cur_item->to_bson(obj);
    if (0 == rc) {
      goto done;
    }
    update_stat(rc);
  }
  obj = empty_obj;

done:
  return rc;
}

static void sdb_traverse_cond(const Item *cond_item, void *arg) {
  Sdb_cond_ctx *sdb_ctx = (Sdb_cond_ctx *)arg;

  if (SDB_COND_UNSUPPORTED == sdb_ctx->status ||
      SDB_COND_BEFORE_SUPPORTED == sdb_ctx->status) {
    // skip all while occured unsupported-condition
    goto done;
  }

  sdb_ctx->push((Item *)cond_item);
done:
  return;
}

void sdb_parse_condtion(const Item *cond_item, Sdb_cond_ctx *sdb_ctx) {
  ((Item *)cond_item)
      ->traverse_cond(&sdb_traverse_cond, (void *)sdb_ctx, Item::PREFIX);
  sdb_ctx->pop_all();
}