/** Implementation of the pqxx::result class and support classes.
 *
 * pqxx::result represents the set of result rows from a database query
 *
 * Copyright (c) 2000-2021, Jeroen T. Vermeulen.
 *
 * See COPYING for copyright license.  If you did not receive a file called
 * COPYING with this source code, please notify the distributor of this
 * mistake, or contact the author.
 */
#include "pqxx-source.hxx"

#include <cstdlib>
#include <cstring>
#include <stdexcept>

extern "C"
{
#include <libpq-fe.h>
}

#include "pqxx/except"
#include "pqxx/result"

#include "pqxx/internal/concat.hxx"


namespace pqxx
{
PQXX_DECLARE_ENUM_CONVERSION(ExecStatusType);
}

std::string const pqxx::result::s_empty_string;


/// C++ wrapper for libpq's PQclear.
void pqxx::internal::clear_result(pq::PGresult const *data)
{
  PQclear(const_cast<pq::PGresult *>(data));
}


pqxx::result::result(
  pqxx::internal::pq::PGresult *rhs, std::shared_ptr<std::string> query,
  internal::encoding_group enc) :
        m_data{make_data_pointer(rhs)}, m_query{query}, m_encoding(enc)
{}


bool pqxx::result::operator==(result const &rhs) const noexcept
{
  if (&rhs == this)
    return true;
  auto const s{size()};
  if (std::size(rhs) != s)
    return false;
  for (size_type i{0}; i < s; ++i)
    if ((*this)[i] != rhs[i])
      return false;
  return true;
}


pqxx::result::const_reverse_iterator pqxx::result::rbegin() const
{
  return const_reverse_iterator{end()};
}


pqxx::result::const_reverse_iterator pqxx::result::crbegin() const
{
  return rbegin();
}


pqxx::result::const_reverse_iterator pqxx::result::rend() const
{
  return const_reverse_iterator{begin()};
}


pqxx::result::const_reverse_iterator pqxx::result::crend() const
{
  return rend();
}


pqxx::result::const_iterator pqxx::result::begin() const noexcept
{
  return const_iterator{this, 0};
}


pqxx::result::const_iterator pqxx::result::cbegin() const noexcept
{
  return begin();
}


pqxx::result::size_type pqxx::result::size() const noexcept
{
  return (m_data.get() == nullptr) ?
           0 :
           static_cast<size_type>(PQntuples(m_data.get()));
}


bool pqxx::result::empty() const noexcept
{
  return (m_data.get() == nullptr) or (PQntuples(m_data.get()) == 0);
}


pqxx::result::reference pqxx::result::front() const noexcept
{
  return row{*this, 0};
}


pqxx::result::reference pqxx::result::back() const noexcept
{
  return row{*this, size() - 1};
}


void pqxx::result::swap(result &rhs) noexcept
{
  m_data.swap(rhs.m_data);
  m_query.swap(rhs.m_query);
}


pqxx::row pqxx::result::operator[](result_size_type i) const noexcept
{
  return row{*this, i};
}


pqxx::row pqxx::result::at(pqxx::result::size_type i) const
{
  if (i >= size())
    throw range_error{"Row number out of range."};
  return operator[](i);
}


namespace
{
/// C string comparison.
inline bool equal(char const lhs[], char const rhs[])
{
  return strcmp(lhs, rhs) == 0;
}
} // namespace

void pqxx::result::throw_sql_error(
  std::string const &Err, std::string const &Query) const
{
  // Try to establish more precise error type, and throw corresponding
  // type of exception.
  char const *const code{PQresultErrorField(m_data.get(), PG_DIAG_SQLSTATE)};
  if (code == nullptr)
  {
    // No SQLSTATE at all.  Can this even happen?
    // Let's assume the connection is no longer usable.
    throw broken_connection{Err};
  }

  switch (code[0])
  {
  case '\0':
    // SQLSTATE is empty.  We may have seen this happen in one
    // circumstance: a client-side socket timeout (while using the
    // tcp_user_timeout connection option).  Unfortunately in that case the
    // connection was just fine, so we had no real way of detecting the
    // problem.  (Trying to continue to use the connection does break
    // though, so I feel justified in panicking.)
    throw broken_connection{Err};

  case '0':
    switch (code[1])
    {
    case 'A': throw feature_not_supported{Err, Query, code};
    case '8': throw broken_connection{Err};
    case 'L':
    case 'P': throw insufficient_privilege{Err, Query, code};
    }
    break;
  case '2':
    switch (code[1])
    {
    case '2': throw data_exception{Err, Query, code};
    case '3':
      if (equal(code, "23001"))
        throw restrict_violation{Err, Query, code};
      if (equal(code, "23502"))
        throw not_null_violation{Err, Query, code};
      if (equal(code, "23503"))
        throw foreign_key_violation{Err, Query, code};
      if (equal(code, "23505"))
        throw unique_violation{Err, Query, code};
      if (equal(code, "23514"))
        throw check_violation{Err, Query, code};
      throw integrity_constraint_violation{Err, Query, code};
    case '4': throw invalid_cursor_state{Err, Query, code};
    case '6': throw invalid_sql_statement_name{Err, Query, code};
    }
    break;
  case '3':
    switch (code[1])
    {
    case '4': throw invalid_cursor_name{Err, Query, code};
    }
    break;
  case '4':
    switch (code[1])
    {
    case '0':
      if (equal(code, "40000"))
        throw transaction_rollback{Err, Query, code};
      if (equal(code, "40001"))
        throw serialization_failure{Err, Query, code};
      if (equal(code, "40003"))
        throw statement_completion_unknown{Err, Query, code};
      if (equal(code, "40P01"))
        throw deadlock_detected{Err, Query, code};
      break;
    case '2':
      if (equal(code, "42501"))
        throw insufficient_privilege{Err, Query};
      if (equal(code, "42601"))
        throw syntax_error{Err, Query, code, errorposition()};
      if (equal(code, "42703"))
        throw undefined_column{Err, Query, code};
      if (equal(code, "42883"))
        throw undefined_function{Err, Query, code};
      if (equal(code, "42P01"))
        throw undefined_table{Err, Query, code};
    }
    break;
  case '5':
    switch (code[1])
    {
    case '3':
      if (equal(code, "53100"))
        throw disk_full{Err, Query, code};
      if (equal(code, "53200"))
        throw out_of_memory{Err, Query, code};
      if (equal(code, "53300"))
        throw too_many_connections{Err};
      throw insufficient_resources{Err, Query, code};
    }
    break;

  case 'P':
    if (equal(code, "P0001"))
      throw plpgsql_raise{Err, Query, code};
    if (equal(code, "P0002"))
      throw plpgsql_no_data_found{Err, Query, code};
    if (equal(code, "P0003"))
      throw plpgsql_too_many_rows{Err, Query, code};
    throw plpgsql_error{Err, Query, code};
  }

  // Unknown error code.
  throw sql_error{Err, Query, code};
}

void pqxx::result::check_status(std::string_view desc) const
{
  if (auto err{status_error()}; not std::empty(err))
  {
    if (not std::empty(desc))
      err = pqxx::internal::concat("Failure during '", desc, "': ", err);
    throw_sql_error(err, query());
  }
}


std::string pqxx::result::status_error() const
{
  if (m_data.get() == nullptr)
    throw failure{"No result set given."};

  std::string err;

  switch (PQresultStatus(m_data.get()))
  {
  case PGRES_EMPTY_QUERY: // The string sent to the backend was empty.
  case PGRES_COMMAND_OK:  // Successful completion, no result data.
  case PGRES_TUPLES_OK:   // The query successfully executed.
    break;

  case PGRES_COPY_OUT: // Copy Out (from server) data transfer started.
  case PGRES_COPY_IN:  // Copy In (to server) data transfer started.
    break;

  case PGRES_BAD_RESPONSE: // The server's response was not understood.
  case PGRES_NONFATAL_ERROR:
  case PGRES_FATAL_ERROR: err = PQresultErrorMessage(m_data.get()); break;

  default:
    throw internal_error{internal::concat(
      "pqxx::result: Unrecognized response code ",
      PQresultStatus(m_data.get()))};
  }
  return err;
}


char const *pqxx::result::cmd_status() const noexcept
{
  return PQcmdStatus(const_cast<internal::pq::PGresult *>(m_data.get()));
}


std::string const &pqxx::result::query() const noexcept
{
  return (m_query.get() == nullptr) ? s_empty_string : *m_query;
}


pqxx::oid pqxx::result::inserted_oid() const
{
  if (m_data.get() == nullptr)
    throw usage_error{
      "Attempt to read oid of inserted row without an INSERT result"};
  return PQoidValue(const_cast<internal::pq::PGresult *>(m_data.get()));
}


pqxx::result::size_type pqxx::result::affected_rows() const
{
  auto const rows_str{
    PQcmdTuples(const_cast<internal::pq::PGresult *>(m_data.get()))};
  return (rows_str[0] == '\0') ? 0 : size_type(atoi(rows_str));
}


char const *pqxx::result::get_value(
  pqxx::result::size_type row, pqxx::row::size_type col) const
{
  return PQgetvalue(m_data.get(), row, col);
}


bool pqxx::result::get_is_null(
  pqxx::result::size_type row, pqxx::row::size_type col) const
{
  return PQgetisnull(m_data.get(), row, col) != 0;
}

pqxx::field::size_type pqxx::result::get_length(
  pqxx::result::size_type row, pqxx::row::size_type col) const noexcept
{
  return static_cast<pqxx::field::size_type>(
    PQgetlength(m_data.get(), row, col));
}


pqxx::oid pqxx::result::column_type(row::size_type col_num) const
{
  oid const t{PQftype(m_data.get(), col_num)};
  if (t == oid_none)
    throw argument_error{internal::concat(
      "Attempt to retrieve type of nonexistent column ", col_num,
      " of query result.")};
  return t;
}


pqxx::row::size_type pqxx::result::column_number(zview col_name) const
{
  auto const n{PQfnumber(
    const_cast<internal::pq::PGresult *>(m_data.get()), col_name.c_str())};
  if (n == -1)
    throw argument_error{
      internal::concat("Unknown column name: '", col_name, "'.")};

  return static_cast<row::size_type>(n);
}


pqxx::oid pqxx::result::column_table(row::size_type col_num) const
{
  oid const t{PQftable(m_data.get(), col_num)};

  /* If we get oid_none, it may be because the column is computed, or because
   * we got an invalid row number.
   */
  if (t == oid_none and col_num >= columns())
    throw argument_error{internal::concat(
      "Attempt to retrieve table ID for column ", col_num, " out of ",
      columns())};

  return t;
}


pqxx::row::size_type pqxx::result::table_column(row::size_type col_num) const
{
  auto const n{row::size_type(PQftablecol(m_data.get(), col_num))};
  if (n != 0)
    return n - 1;

  // Failed.  Now find out why, so we can throw a sensible exception.
  auto const col_str{to_string(col_num)};
  if (col_num > columns())
    throw range_error{
      internal::concat("Invalid column index in table_column(): ", col_str)};

  if (m_data.get() == nullptr)
    throw usage_error{internal::concat(
      "Can't query origin of column ", col_str,
      ": result is not initialized.")};

  throw usage_error{internal::concat(
    "Can't query origin of column ", col_str,
    ": not derived from table column.")};
}

int pqxx::result::errorposition() const
{
  int pos{-1};
  if (m_data.get())
  {
    auto const p{PQresultErrorField(
      const_cast<internal::pq::PGresult *>(m_data.get()),
      PG_DIAG_STATEMENT_POSITION)};
    if (p)
      pos = from_string<decltype(pos)>(p);
  }
  return pos;
}


char const *pqxx::result::column_name(pqxx::row::size_type number) const
{
  auto const n{PQfname(m_data.get(), number)};
  if (n == nullptr)
  {
    if (m_data.get() == nullptr)
      throw usage_error{"Queried column name on null result."};
    throw range_error{internal::concat(
      "Invalid column number: ", number, " (maximum is ", (columns() - 1),
      ").")};
  }
  return n;
}


pqxx::row::size_type pqxx::result::columns() const noexcept
{
  auto ptr{const_cast<internal::pq::PGresult *>(m_data.get())};
  return (ptr == nullptr) ? 0 : row::size_type(PQnfields(ptr));
}


// const_result_iterator

pqxx::const_result_iterator pqxx::const_result_iterator::operator++(int)
{
  const_result_iterator old{*this};
  m_index++;
  return old;
}


pqxx::const_result_iterator pqxx::const_result_iterator::operator--(int)
{
  const_result_iterator old{*this};
  m_index--;
  return old;
}


pqxx::result::const_iterator
pqxx::result::const_reverse_iterator::base() const noexcept
{
  iterator_type tmp{*this};
  return ++tmp;
}


pqxx::const_reverse_result_iterator
pqxx::const_reverse_result_iterator::operator++(int)
{
  const_reverse_result_iterator tmp{*this};
  iterator_type::operator--();
  return tmp;
}


pqxx::const_reverse_result_iterator
pqxx::const_reverse_result_iterator::operator--(int)
{
  const_reverse_result_iterator tmp{*this};
  iterator_type::operator++();
  return tmp;
}


template<> std::string pqxx::to_string(field const &value)
{
  return std::string{value.c_str(), std::size(value)};
}
