#include "matador/sql/connection.hpp"

#include "matador/sql/backend_provider.hpp"
#include "matador/sql/dialect.hpp"
#include "matador/sql/dialect_token.hpp"
#include "matador/sql/error_code.hpp"
#include "matador/sql/interface/connection_impl.hpp"


#include <algorithm>
#include <stdexcept>
#include <utility>

namespace matador::sql {

namespace internal {
class connection_statement_proxy final : public statement_proxy {
public:
  explicit connection_statement_proxy(std::unique_ptr<statement_impl>&& stmt)
  : statement_proxy(std::move(stmt)) {}

  utils::result<size_t, utils::error> execute(interface::parameter_binder& bindings) override {
    return statement_->execute(bindings);
  }
  utils::result<std::unique_ptr<query_result_impl>, utils::error> fetch(interface::parameter_binder& bindings) override {
    return statement_->fetch(bindings);
  }
};

}
connection::connection(connection_info info, const std::shared_ptr<abstract_sql_logger> &sql_logger)
: connection_info_(std::move(info))
, logger_(sql_logger)
{
  connection_.reset(backend_provider::instance().create_connection(connection_info_.type, connection_info_));
}

connection::connection(const std::string& dns, const std::shared_ptr<abstract_sql_logger> &sql_logger)
: connection(connection_info::parse(dns), sql_logger)
{}

connection::connection(const connection &x)
: connection_info_(x.connection_info_)
{
  if (x.connection_) {
    throw std::runtime_error("couldn't copy connection with valid connection impl");
  }
}

connection &connection::operator=(const connection &x) {
  if (this == &x) {
    return *this;
  }

  connection_info_ = x.connection_info_;
  if (x.connection_) {
    throw std::runtime_error("couldn't copy connection with valid connection impl");
  }
  return *this;
}

connection::connection( connection&& x ) noexcept
: connection_info_(std::move(x.connection_info_))
, connection_(std::move(x.connection_))
, logger_(std::move(x.logger_)) {}

connection & connection::operator=(connection &&x) noexcept {
  connection_info_ = std::move(x.connection_info_);
  connection_  = std::move(x.connection_);
  logger_ = std::move(x.logger_);

  return *this;
}

connection::~connection() {
  if (!connection_) {
    return;
  }
  if (connection_->is_open()) {
    connection_->close();
  }
  backend_provider::instance().destroy_connection(connection_info_.type, connection_.release());
  connection_ = nullptr;
}

utils::result<void, utils::error> connection::open() const {
  const auto res = is_open();
  if (res.is_error()) {
    return utils::failure(res.err());
  }
  if (!*res) {
    logger_->on_connect();
    return connection_->open();
  }
  return utils::ok<void>();
}

utils::result<void, utils::error> connection::close() const {
  logger_->on_close();
  return connection_->close();
}

utils::result<bool, utils::error> connection::is_open() const
{
  return connection_->is_open();
}

const connection_info &connection::info() const
{
  return connection_info_;
}

std::string connection::type() const {
  return connection_info_.type;
}

utils::result<void, utils::error> connection::begin() const {
  const auto res = connection_->execute(dialect().token_at(dialect_token::BEGIN));
  if (res.is_error()) {
    return utils::failure(res.err());
  }

  return utils::ok<void>();
}

utils::result<void, utils::error> connection::commit() const {
  const auto res = connection_->execute(dialect().token_at(dialect_token::COMMIT));
  if (res.is_error()) {
    return utils::failure(res.err());
  }

  return utils::ok<void>();
}

utils::result<void, utils::error> connection::rollback() const {
  const auto res = connection_->execute(dialect().token_at(dialect_token::ROLLBACK));
  if (res.is_error()) {
    return utils::failure(res.err());
  }

  return utils::ok<void>();
}

utils::result<std::vector<object::attribute_definition>, utils::error> connection::describe(const std::string &table_name) const {
  return connection_->describe(table_name);
}

utils::result<bool, utils::error> connection::exists(const std::string &schema_name, const std::string &table_name) const {
  return connection_->exists(schema_name, table_name);
}

utils::result<bool, utils::error> connection::exists(const std::string &table_name) const {
  return connection_->exists(dialect().default_schema_name(), table_name);
}

utils::result<size_t, utils::error> connection::execute(const std::string &sql) const {
  logger_->on_execute(sql);
  return connection_->execute(sql);
}

bool has_unknown_columns(const std::vector<object::attribute_definition> &columns) {
  return std::any_of(std::begin(columns), std::end(columns), [](const auto &col) {
    return col.type() == utils::basic_type::type_null;
  });
}

// query_result<record> connection::fetch(const query_context &ctx) const
// {
//   if (ctx.prototype.empty() || is_unknown(ctx.prototype)) {
//     const auto table_prototype = describe(ctx.table.name);
//     for (auto &col : ctx.prototype) {
//       const auto rit = std::find_if(std::begin(table_prototype), std::end(table_prototype), [&col](const auto &value) {
//         return value.name() == col.name();
//       });
//       if (col.type() == data_type::type_unknown && rit != table_prototype.end()) {
//         const_cast<column_definition&>(col).type(rit->type());
//       }
//      }
//   }
// //  auto it = prototypes_.find(q.table_name);
// //  if (it == prototypes_.end()) {
// //    it = prototypes_.emplace(q.table_name, describe(q.table_name)).first;
// //  }
// //  // adjust columns from given query
// //  for (auto &col : q.prototype) {
// //    if (const auto rit = it->second.find(col.name()); col.type() == data_type_t::type_unknown && rit != it->second.end()) {
// //      const_cast<column&>(col).type(rit->type());
// //    }
// //  }
//   auto res = fetch(ctx.sql);
//   return query_result<record>{std::move(res), ctx.prototype};
// }

utils::result<std::unique_ptr<query_result_impl>, utils::error> connection::fetch(const query_context &ctx) const {
  logger_->on_fetch(ctx.sql);
  return connection_->fetch(ctx);
}

utils::result<size_t, utils::error> connection::execute(const query_context& ctx) const {
  return execute(ctx.sql);
}

utils::result<statement, utils::error> connection::prepare(const query_context &ctx) {
  auto result = perform_prepare(ctx);

  if (!result) {
    return utils::failure(result.err());
  }

  return utils::ok(statement(
    std::make_shared<internal::connection_statement_proxy>(result.release()),
    logger_)
  );
}

std::string connection::str( const query_context& ctx ) const
{
  return ctx.sql;
}

const class dialect &connection::dialect() const
{
  return connection_->dialect();
}

utils::result<std::unique_ptr<statement_impl>, utils::error> connection::perform_prepare(const query_context& ctx) const {
  if (ctx.command != sql_command::SQL_CREATE_TABLE && (ctx.prototype.empty() || has_unknown_columns(ctx.prototype))) {
    if (const auto result = describe(ctx.table.name); result.is_ok()) {
      for (auto &col: ctx.prototype) {
        const auto rit = std::find_if(
          std::begin(*result),
          std::end(*result),
          [&col](const auto &value) { return value.name() == col.name(); }
        );
        if (col.type() == utils::basic_type::type_null && rit != result->end()) {
          const_cast<object::attribute_definition&>(col).type(rit->type());
        }
      }
    }
  }

  auto result = connection_->prepare(ctx);
  if (!result) {
    return utils::failure(result.err());
  }

  return utils::ok(result.release());
}
}