/*  Copyright (c) 2015, Oracle 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 */

#include "my_global.h"

#include <mysql/service_parser.h>

#include "item.h"
#include "mysqld.h"
#include "select_lex_visitor.h"
#include "sp_cache.h"
#include "sql_class.h"
#include "sql_digest.h"
#include "sql_error.h"
#include "sql_lex.h"
#include "sql_list.h"
#include "sql_parse.h"
#include "sql_string.h"
#include "transaction.h" // trans_commit_stmt
#include "sql_base.h" // close_thread_tables
#include "mysqld_thd_manager.h"
#include "template_utils.h"

/**
  This class implements the parse tree visiting service.
  @see mysql_parser_visit_tree
*/
class Service_visitor: public Select_lex_visitor
{
  parse_node_visit_function m_processor;
  uchar *m_arg;

public:
  /**
    @param processor This function will be called for each literal (Item) in
    the parse tree, along with the Item's type and arg. If the function
    returns non-zero, parse tree traversal will terminate.

    @param arg Will be passed to processor on every call.
  */
  Service_visitor(parse_node_visit_function processor, uchar *arg) :
    m_processor(processor),
    m_arg(arg)
  {}

protected:
  bool visit_item(Item *item)
  {
    switch(item->type())
    {
      // These are all the literals.
    case Item::PARAM_ITEM:
    case Item::STRING_ITEM:
    case Item::INT_ITEM:
    case Item::DECIMAL_ITEM:
    case Item::REAL_ITEM:
    case Item::NULL_ITEM:
    case Item::VARBIN_ITEM:
    case Item::CACHE_ITEM:
      return m_processor(item, m_arg);
    default:
      break;
    }
    return false;
  }
};


/**
  This class implements the framework needed for the callback function that
  handles conditions that may arise during parsing via the parser service.

  @see mysql_parser_visit_tree
*/
class Plugin_error_handler: public Internal_error_handler
{
  THD *m_thd;
  const char *m_message;
  const sql_condition_handler_function m_handle_error;
  void *m_state;

public:
  Plugin_error_handler(THD *thd,
                       sql_condition_handler_function handle_error,
                       void *state)
    : m_thd(thd), m_message(NULL), m_handle_error(handle_error), m_state(state)
  {
    if (handle_error != NULL)
      thd->push_internal_handler(this);
  }

  virtual bool handle_condition(THD *thd,
                                uint sql_errno_u,
                                const char* sqlstate,
                                Sql_condition::enum_severity_level *,
                                const char* msg)
  {
    int sql_errno= static_cast<int>(sql_errno_u);
    if (m_handle_error != NULL)
      return m_handle_error(sql_errno, sqlstate, msg, m_state) != 0;
    return false;
  }

  const char *get_message() { return m_message; }

  ~Plugin_error_handler()
  {
    if (m_handle_error != NULL)
      m_thd->pop_internal_handler();
  }
};


extern "C"
MYSQL_THD mysql_parser_current_session()
{
  return current_thd;
}

extern "C"
MYSQL_THD mysql_parser_open_session()
{
  THD *old_thd= current_thd;

  // See create_thd()
  THD *thd= new (std::nothrow) THD;
  if (thd == NULL)
    return NULL;

  thd->security_context()->set_host_ptr(STRING_WITH_LEN(my_localhost));
  thd->lex= new LEX;
  thd->lex->set_current_select(NULL);

  thd->variables.character_set_client= old_thd->variables.character_set_client;

  return thd;
}


namespace {

struct thread_args
{
  thread_args(MYSQL_THD thd, callback_function fun, void *arg)
    : m_thd(thd), m_fun(fun), m_arg(arg)
  {}
  MYSQL_THD m_thd;
  callback_function m_fun;
  void *m_arg;
};

extern "C"
void *parser_service_start_routine(void *arg)
{
  thread_args *tt= pointer_cast<thread_args*>(arg);
  THD *thd= tt->m_thd;
  my_thread_init();

  DBUG_ENTER("parser_service_start_routine");

  Global_THD_manager *thd_manager= Global_THD_manager::get_instance();
  thd->thread_stack= reinterpret_cast<char*>(&thd);
  thd->set_new_thread_id();
  mysql_thread_set_psi_id(thd->thread_id());
  thd->store_globals();
  thd->set_time();

  thd_manager->add_thd(thd);
  (tt->m_fun)(tt->m_arg);

  trans_commit_stmt(thd);
  close_thread_tables(thd);
  thd->mdl_context.release_transactional_locks();
  close_mysql_tables(thd);

  thd->release_resources();
  thd->restore_globals();
  thd_manager->remove_thd(thd);

  LEX *lex= thd->lex;
  delete thd;
  delete lex;
  delete tt;

  DBUG_LEAVE;
  my_thread_end();
  my_thread_exit(0);
  return 0;
}

} // namespace


extern "C"
void mysql_parser_start_thread(THD *thd, callback_function fun, void *arg,
                               my_thread_handle *thread_handle)
{
  my_thread_handle handle;
  my_thread_attr_t attr;
  my_thread_attr_init(&attr);

  thread_args *args = new thread_args(thd, fun, arg);
  mysql_thread_create(key_thread_parser_service,
                      &handle, &attr,
                      parser_service_start_routine, args);
  *thread_handle= handle;
}


extern "C"
void mysql_parser_join_thread(my_thread_handle *thread_id)
{
  my_thread_join(thread_id, NULL);
}


extern "C"
void mysql_parser_set_current_database(MYSQL_THD thd, const MYSQL_LEX_STRING db)
{
  if (db.length == 0)
  {
    LEX_CSTRING db_const = { NULL, 0 };
    thd->set_db(db_const);
  }
  else
  {
    LEX_CSTRING db_const = { db.str, db.length };
    thd->set_db(db_const);
  }
}


extern "C"
int mysql_parser_parse(MYSQL_THD thd, const MYSQL_LEX_STRING query,
                       unsigned char is_prepared,
                       sql_condition_handler_function handle_condition,
                       void *condition_handler_state)
{
  /*
    Clean up parse- and item trees in case this function was called before for
    the same THD.
  */
  if (thd->lex->is_lex_started)
  {
    thd->end_statement();
    thd->cleanup_after_query();
  }

  lex_start(thd);

  if (alloc_query(thd, query.str, query.length))
    return 1; // Fatal error flag set

  Parser_state parser_state;
  if (parser_state.init(thd, query.str, query.length))
    return 1;

  parser_state.m_input.m_compute_digest= true;
  thd->m_digest= &thd->m_digest_state;
  thd->m_digest->reset(thd->m_token_array, max_digest_length);

  if (is_prepared)
  {
    parser_state.m_lip.stmt_prepare_mode= true;
    parser_state.m_lip.multi_statements= false;
    thd->lex->context_analysis_only|= CONTEXT_ANALYSIS_ONLY_PREPARE;
  }

  Plugin_error_handler
    error_handler(thd, handle_condition, condition_handler_state);

  int parse_status= parse_sql(thd, &parser_state, NULL);

  /*
    Handled conditions are thrown away at this point - they are supposedly
    handled by handle_condition. If there was no handler supplied, the
    diagnostics area is not touched. It will contain any errors thrown by the
    parser.
  */
  if (handle_condition != NULL)
  {
    thd->get_stmt_da()->reset_diagnostics_area();
    thd->get_stmt_da()->reset_condition_info(thd);
  }

  return parse_status;
}


extern "C"
int mysql_parser_get_statement_type(MYSQL_THD thd)
{
  LEX* lex= thd->lex;
  if (lex->sql_command == SQLCOM_SELECT)
    return STATEMENT_TYPE_SELECT;
  return STATEMENT_TYPE_OTHER;
}


extern "C"
int mysql_parser_get_statement_digest(MYSQL_THD thd, uchar *digest)
{
  if (thd->m_digest == NULL)
    return true;
  compute_digest_md5(&thd->m_digest->m_digest_storage, digest);
  return false;
}


extern "C"
int mysql_parser_get_number_params(MYSQL_THD thd)
{
  return thd->lex->param_list.elements;
}


extern "C"
int mysql_parser_extract_prepared_params(MYSQL_THD thd, int *positions)
{
  LEX* lex= thd->lex;
  List_iterator_fast<Item_param> it(lex->param_list);
  for (uint i= 0; i < lex->param_list.elements; i++)
    positions[i]= it++->pos_in_query;
  return lex->param_list.elements;
}


extern "C"
int mysql_parser_visit_tree(MYSQL_THD thd,
                            parse_node_visit_function processor,
                            unsigned char* arg)
{
  Service_visitor visitor(processor, arg);
  return thd->lex->accept(&visitor);
}


extern "C"
MYSQL_LEX_STRING mysql_parser_item_string(MYSQL_ITEM item)
{
  String str;
  static_cast<Item*>(item)->print(&str, QT_ORDINARY);
  MYSQL_LEX_STRING res= { new char[str.length()], 0 };
  if (res.str != NULL)
  {
    res.length= str.length();
    std::copy(str.ptr(), str.ptr() + str.length(), res.str);
  }
  return res;
}


extern "C"
void mysql_parser_free_string(MYSQL_LEX_STRING string)
{
  delete [] string.str;
}


extern "C"
MYSQL_LEX_STRING mysql_parser_get_query(MYSQL_THD thd)
{
  MYSQL_LEX_STRING str= {
    (char*)thd->query().str,
    thd->query().length
  };
  return str;
}


extern "C"
MYSQL_LEX_STRING mysql_parser_get_normalized_query(MYSQL_THD thd)
{
  String normalized_query= thd->normalized_query();

  MYSQL_LEX_STRING str= {
    const_cast<char*>(normalized_query.ptr()),
    normalized_query.length()
  };
  return str;
}