module;

#include <sqlite3.h>

module routemon:sqlite3$impl;

import :sqlite3;

namespace routemon::sqlite3 {

mutex_guard::mutex_guard(::sqlite3_mutex* mut) noexcept : mut_{mut} {}

mutex_guard::~mutex_guard() { ::sqlite3_mutex_leave(mut_); }

auto do_guarded(::sqlite3_mutex* mut, std::invocable<mutex_guard const&> auto f)
    -> decltype(f(std::declval<mutex_guard const&>()))
{
  return f(mutex_guard{mut});
}

auto do_guarded(::sqlite3* dbc, std::invocable<mutex_guard const&> auto f)
    -> decltype(f(std::declval<mutex_guard const&>()))
{
  return do_guarded(::sqlite3_db_mutex(dbc), f);
}

error::error(mutex_guard const&, int code, ::sqlite3* dbc)
  : code_{code}, message_{::sqlite3_errmsg(dbc)}
{
}

error::error(int code) : code_{code}, message_{::sqlite3_errstr(code)} {}

[[nodiscard]] auto error::what() const noexcept -> char const*
{
  return message_.c_str();
}

[[nodiscard]] auto error::code() const noexcept -> int { return code_; }

statement::statement(::sqlite3_stmt* stmt) : stmt_{stmt} {}
statement::statement(statement&& s) noexcept
{
  stmt_ = s.stmt_;
  s.stmt_ = nullptr;
}
statement::~statement() { ::sqlite3_finalize(stmt_); }
auto statement::get() -> ::sqlite3_stmt* { return stmt_; }

row_reader::row_reader(statement stmt) : stmt_{std::move(stmt)} {}

auto row_reader::is_null(int col) -> bool
{
  return ::sqlite3_column_type(stmt_.get(), col) == SQLITE_NULL;
}

auto row_reader::ncols() -> std::size_t
{
  auto const mncols = util::size_from_int(::sqlite3_data_count(stmt_.get()));
  if (!mncols.has_value())
    throw std::logic_error{"got unexpected negative amount of columns"};
  return *mncols;
}

auto row_reader::scan(int col, std::string& s) -> void
{
  if (::sqlite3_column_type(stmt_.get(), col) != SQLITE_TEXT)
    throw std::invalid_argument{"invalid type for scan"};
  unsigned char const* chs = ::sqlite3_column_text(stmt_.get(), col);
  auto size = util::size_from_int(::sqlite3_column_bytes(stmt_.get(), col));
  if (!size.has_value())
    throw std::logic_error{"unexpected negative amount of bytes in column"};
  s = std::string{reinterpret_cast<char const*>(chs), *size};
}

auto row_reader::scan(int col, double& v) -> void
{
  if (::sqlite3_column_type(stmt_.get(), col) != SQLITE_FLOAT)
    throw std::invalid_argument{"invalid type for scan"};
  v = ::sqlite3_column_double(stmt_.get(), col);
}

auto row_reader::scan(int col, std::int64_t& v) -> void
{
  if (::sqlite3_column_type(stmt_.get(), col) != SQLITE_INTEGER)
    throw std::invalid_argument{"invalid type for scan"};
  v = ::sqlite3_column_int64(stmt_.get(), col);
}

auto row_reader::next() -> bool
{
  ::sqlite3* dbc = ::sqlite3_db_handle(stmt_.get());
  return do_guarded(
      dbc,
      [&](auto const& guard) -> bool
      {
        auto const s = ::sqlite3_step(stmt_.get());
        if (s == SQLITE_ROW)
          return true;
        if (s == SQLITE_DONE)
          return false;
        throw error{guard, s, dbc};
      });
}

binder::binder(statement& stmt) : stmt_{stmt} {}

auto binder::text(std::string const& param_name, std::string_view str) -> void
{
  int const i = ::sqlite3_bind_parameter_index(stmt_.get(), param_name.c_str());
  if (i == 0)
    throw std::invalid_argument{std::format(
        "bind: no parameter with name {} found", param_name)};
  auto str_size = util::int_from_size(str.size());
  if (!str_size.has_value())
    throw std::invalid_argument{"bind: provided text is too long"};
  if (auto s = ::sqlite3_bind_text(
          stmt_.get(), i, str.data(), *str_size, SQLITE_TRANSIENT);
      s != SQLITE_OK)
  {
    throw error{s};
  }
}

auto binder::noop(binder&) -> void {}

connection::connection(::sqlite3* dbc)
  : dbc_{dbc}, mut_{::sqlite3_db_mutex(dbc)}
{
}

connection::connection(connection const&) = delete;
connection::connection(connection&& c) noexcept
{
  dbc_ = c.dbc_;
  mut_ = c.mut_;
  c.dbc_ = nullptr;
  c.mut_ = nullptr;
}

auto connection::query(
    std::string const& sql, std::function<void(binder&)> const& bf)
    -> row_reader
{
  ::sqlite3_stmt* pstmt = nullptr;
  char const* sql_tail = nullptr;
  auto sql_size = util::int_from_size(sql.size());
  if (!sql_size.has_value() || *sql_size >= std::numeric_limits<int>::max() - 1)
    throw std::invalid_argument{"provided input text too large"};
  do_guarded(
      mut_,
      [&](auto const& guard) -> void
      {
        if (auto s = ::sqlite3_prepare_v2(
                dbc_, sql.data(), *sql_size + 1, &pstmt, &sql_tail);
            s != SQLITE_OK)
        {
          if (pstmt != nullptr)
          {
            // Use contract_assert when having a compiler with
            // contracts available
            ::sqlite3_finalize(pstmt);
            throw std::logic_error{
              "expected stmt to be null after failed preparation"
            };
          }
          throw error{guard, s, dbc_};
        }
      });
  if (!pstmt)
    throw std::invalid_argument{"provided input text contains no SQL"};
  auto stmt = statement{pstmt};
  if (sql_tail && std::strlen(sql_tail) > 0)
    throw std::invalid_argument{
      "provided input text contains more than one SQL statement"
    };
  auto b = binder{stmt};
  bf(b);
  return row_reader{std::move(stmt)};
}

auto connection::exec(
    std::string const& sql, std::function<void(binder&)> const& bf) -> void
{
  auto reader = query(sql, bf);
  while (reader.next())
    ;
}

connection::~connection()
{
  std::ignore = ::sqlite3_close(std::exchange(dbc_, nullptr));
}

auto open(std::string const& filename) -> connection
{
  ::sqlite3* dbc = nullptr;
  auto s = ::sqlite3_open_v2(
      filename.c_str(), &dbc,
      SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_FULLMUTEX
          | SQLITE_OPEN_EXRESCODE,
      nullptr);
  if (s != SQLITE_OK)
  {
    if (dbc)
    {
      do_guarded(
          dbc, [&](auto const& guard) -> void { throw error{guard, s, dbc}; });
    }
    else
    {
      throw error{s};
    }
  }
  return connection{dbc};
}

} // namespace routemon::sqlite3