/* Copyright (c) 2022, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.

   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, version 2.0, 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 "sql/binlog/recovery.h"

#include "sql/binlog/decompressing_event_object_istream.h"  // binlog::Decompressing_event_object_istream
#include "sql/raii/sentry.h"                                // raii::Sentry<>
#include "sql/xa/xid_extract.h"                             // xa::XID_extractor

binlog::Binlog_recovery::Binlog_recovery(Binlog_file_reader &binlog_file_reader)
    : m_reader{binlog_file_reader},
      m_mem_root{key_memory_binlog_recover_exec,
                 static_cast<size_t>(my_getpagesize())},
      m_set_alloc{&m_mem_root},
      m_map_alloc{&m_mem_root},
      m_internal_xids{m_set_alloc},
      m_external_xids{m_map_alloc} {}

my_off_t binlog::Binlog_recovery::get_valid_pos() const {
  return this->m_valid_pos;
}

bool binlog::Binlog_recovery::has_failures() const {
  return this->m_is_malformed || this->m_no_engine_recovery;
}

bool binlog::Binlog_recovery::is_binlog_malformed() const {
  return this->m_is_malformed;
}

bool binlog::Binlog_recovery::has_engine_recovery_failed() const {
  return this->m_no_engine_recovery;
}

std::string const &binlog::Binlog_recovery::get_failure_message() const {
  return this->m_failure_message;
}

binlog::Binlog_recovery &binlog::Binlog_recovery::recover() {
  binlog::Decompressing_event_object_istream istream{this->m_reader};
  std::shared_ptr<Log_event> ev;
  this->m_valid_pos = this->m_reader.position();

  while (istream >> ev) {
    switch (ev->get_type_code()) {
      case binary_log::QUERY_EVENT: {
        this->process_query_event(dynamic_cast<Query_log_event &>(*ev));
        break;
      }
      case binary_log::XID_EVENT: {
        this->process_xid_event(dynamic_cast<Xid_log_event &>(*ev));
        break;
      }
      case binary_log::XA_PREPARE_LOG_EVENT: {
        this->process_xa_prepare_event(
            dynamic_cast<XA_prepare_log_event &>(*ev));
        break;
      }
      default: {
        break;
      }
    }

    // Whenever the current position is at a transaction boundary, save it
    // to m_valid_pos
    if (!this->m_is_malformed && !this->m_in_transaction &&
        !is_gtid_event(ev.get()) && !is_session_control_event(ev.get()))
      this->m_valid_pos = this->m_reader.position();

    if (this->m_is_malformed) break;
  }
  if (istream.has_error()) {
    using Status_t = binlog::Decompressing_event_object_istream::Status_t;
    switch (istream.get_status()) {
      case Status_t::corrupted:
      case Status_t::out_of_memory:
      case Status_t::exceeds_max_size:
        // @todo Uncomment this to fix BUG#34828252
        // this->m_is_malformed = true;
        // this->m_failure_message.assign(istream.get_error_str());
        // break;
      case Status_t::success:
      case Status_t::end:
      case Status_t::truncated:
        // not malformed, just truncated
        break;
    }
  }

  if (!this->m_is_malformed && total_ha_2pc > 1) {
    Xa_state_list xa_list{this->m_external_xids};
    this->m_no_engine_recovery = ha_recover(&this->m_internal_xids, &xa_list);
    if (this->m_no_engine_recovery) {
      this->m_failure_message.assign("Recovery failed in storage engines");
    }
  }

  return (*this);
}

void binlog::Binlog_recovery::process_query_event(Query_log_event const &ev) {
  std::string query{ev.query};

  if (query == "BEGIN" || query.find("XA START") == 0)
    this->process_start();

  else if (query == "COMMIT")
    this->process_commit();

  else if (query == "ROLLBACK")
    this->process_rollback();

  else if (is_atomic_ddl_event(&ev))
    this->process_atomic_ddl(ev);

  else if (query.find("XA COMMIT") == 0)
    this->process_xa_commit(query);

  else if (query.find("XA ROLLBACK") == 0)
    this->process_xa_rollback(query);
}

void binlog::Binlog_recovery::process_xid_event(Xid_log_event const &ev) {
  this->m_is_malformed = !this->m_in_transaction;
  if (this->m_is_malformed) {
    this->m_failure_message.assign(
        "Xid_log_event outside the boundary of a sequence of events "
        "representing an active transaction");
    return;
  }
  this->m_in_transaction = false;
  if (!this->m_internal_xids.insert(ev.xid).second) {
    this->m_is_malformed = true;
    this->m_failure_message.assign("Xid_log_event holds an invalid XID");
  }
}

void binlog::Binlog_recovery::process_xa_prepare_event(
    XA_prepare_log_event const &ev) {
  this->m_is_malformed = !this->m_in_transaction;
  if (this->m_is_malformed) {
    this->m_failure_message.assign(
        "XA_prepare_log_event outside the boundary of a sequence of events "
        "representing an active transaction");
    return;
  }

  this->m_in_transaction = false;

  XID xid;
  xid = ev.get_xid();
  auto found = this->m_external_xids.find(xid);
  if (found != this->m_external_xids.end()) {
    assert(found->second != enum_ha_recover_xa_state::PREPARED_IN_SE);
    if (found->second == enum_ha_recover_xa_state::PREPARED_IN_TC) {
      // If it was found already, must have been committed or rolled back, it
      // can't be in prepared state
      this->m_is_malformed = true;
      this->m_failure_message.assign(
          "XA_prepare_log_event holds an invalid XID");
      return;
    }
  }

  this->m_external_xids[xid] =
      ev.is_one_phase() ? enum_ha_recover_xa_state::COMMITTED_WITH_ONEPHASE
                        : enum_ha_recover_xa_state::PREPARED_IN_TC;
}

void binlog::Binlog_recovery::process_start() {
  this->m_is_malformed = this->m_in_transaction;
  if (this->m_is_malformed)
    this->m_failure_message.assign(
        "Query_log_event containing `BEGIN/XA START` inside the boundary of a "
        "sequence of events representing an active transaction");
  this->m_in_transaction = true;
}

void binlog::Binlog_recovery::process_commit() {
  this->m_is_malformed = !this->m_in_transaction;
  if (this->m_is_malformed)
    this->m_failure_message.assign(
        "Query_log_event containing `COMMIT` outside the boundary of a "
        "sequence of events representing an active transaction");
  this->m_in_transaction = false;
}

void binlog::Binlog_recovery::process_rollback() {
  this->m_is_malformed = !this->m_in_transaction;
  if (this->m_is_malformed)
    this->m_failure_message.assign(
        "Query_log_event containing `ROLLBACK` outside the boundary of a "
        "sequence of events representing an active transaction");
  this->m_in_transaction = false;
}

void binlog::Binlog_recovery::process_atomic_ddl(Query_log_event const &ev) {
  this->m_is_malformed = this->m_in_transaction;
  if (this->m_is_malformed) {
    this->m_failure_message.assign(
        "Query_log event containing a DDL inside the boundary of a sequence of "
        "events representing an active transaction");
    return;
  }
  if (!this->m_internal_xids.insert(ev.ddl_xid).second) {
    this->m_is_malformed = true;
    this->m_failure_message.assign(
        "Query_log_event containing a DDL holds an invalid XID");
  }
}

void binlog::Binlog_recovery::process_xa_commit(std::string const &query) {
  this->m_is_malformed = this->m_in_transaction;
  this->m_in_transaction = false;
  if (this->m_is_malformed) {
    this->m_failure_message.assign(
        "Query_log_event containing `XA COMMIT` inside the boundary of a "
        "sequence of events representing a transaction not yet in prepared "
        "state");
    return;
  }
  this->add_external_xid(query, enum_ha_recover_xa_state::COMMITTED);
  if (this->m_is_malformed)
    this->m_failure_message.assign(
        "Query_log_event containing `XA COMMIT` holds an invalid XID");
}

void binlog::Binlog_recovery::process_xa_rollback(std::string const &query) {
  this->m_is_malformed = this->m_in_transaction;
  this->m_in_transaction = false;
  if (this->m_is_malformed) {
    this->m_failure_message.assign(
        "Query_log_event containing `XA ROLLBACK` inside the boundary of a "
        "sequence of events representing a transaction not yet in prepared "
        "state");
    return;
  }
  this->add_external_xid(query, enum_ha_recover_xa_state::ROLLEDBACK);
  if (this->m_is_malformed)
    this->m_failure_message.assign(
        "Query_log_event containing `XA ROLLBACK` holds an invalid XID");
}

void binlog::Binlog_recovery::add_external_xid(std::string const &query,
                                               enum_ha_recover_xa_state state) {
  xa::XID_extractor tokenizer{query, 1};
  if (tokenizer.size() == 0) {
    this->m_is_malformed = true;
    return;
  }

  auto found = this->m_external_xids.find(tokenizer[0]);
  if (found != this->m_external_xids.end()) {
    assert(found->second != enum_ha_recover_xa_state::PREPARED_IN_SE);
    if (found->second != enum_ha_recover_xa_state::PREPARED_IN_TC) {
      // If it was found already, it needs to be in prepared in TC state
      this->m_is_malformed = true;
      return;
    }
  }

  this->m_external_xids[tokenizer[0]] = state;
}