1 files changed, 153 insertions, 0 deletions
diff --git a/src/database/select_query.hpp b/src/database/select_query.hpp
new file mode 100644
index 0000000..b41632e
--- /dev/null
+++ b/src/database/select_query.hpp
@@ -0,0 +1,153 @@
+#pragma once
+
+#include <database/query.hpp>
+#include <logger/logger.hpp>
+#include <database/row.hpp>
+
+#include <vector>
+#include <string>
+
+#include <sqlite3.h>
+
+using namespace std::string_literals;
+
+template <typename T>
+typename std::enable_if<std::is_integral<T>::value, sqlite3_int64>::type
+extract_row_value(sqlite3_stmt* statement, const int i)
+{
+  return sqlite3_column_int64(statement, i);
+}
+
+template <typename T>
+typename std::enable_if<std::is_same<std::string, T>::value, std::string>::type
+extract_row_value(sqlite3_stmt* statement, const int i)
+{
+  const auto size = sqlite3_column_bytes(statement, i);
+  const unsigned char* str = sqlite3_column_text(statement, i);
+  std::string result(reinterpret_cast<const char*>(str), size);
+  return result;
+}
+
+template <std::size_t N=0, typename... T>
+typename std::enable_if<N < sizeof...(T), void>::type
+extract_row_values(Row<T...>& row, sqlite3_stmt* statement)
+{
+  using ColumnType = typename std::remove_reference<decltype(std::get<N>(row.columns))>::type;
+
+  auto&& column = std::get<N>(row.columns);
+  column.value = static_cast<decltype(column.value)>(extract_row_value<typename ColumnType::real_type>(statement, N));
+
+  extract_row_values<N+1>(row, statement);
+}
+
+template <std::size_t N=0, typename... T>
+typename std::enable_if<N == sizeof...(T), void>::type
+extract_row_values(Row<T...>&, sqlite3_stmt*)
+{}
+
+template <typename... T>
+struct SelectQuery: public Query
+{
+    SelectQuery(std::string table_name):
+        Query("SELECT"),
+        table_name(table_name)
+    {
+      this->insert_col_name<0>();
+      this->body += " from " + this->table_name;
+    }
+
+    template <std::size_t N>
+    typename std::enable_if<N < sizeof...(T), void>::type
+    insert_col_name()
+    {
+      using ColumnsType = std::tuple<T...>;
+      ColumnsType tuple{};
+      auto value = std::get<N>(tuple);
+
+      this->body += " "s + value.name;
+
+      if (N < (sizeof...(T) - 1))
+        this->body += ", ";
+
+      this->insert_col_name<N+1>();
+    }
+    template <std::size_t N>
+    typename std::enable_if<N == sizeof...(T), void>::type
+    insert_col_name()
+    {}
+
+  SelectQuery& where()
+    {
+      this->body += " WHERE ";
+      return *this;
+    };
+
+    SelectQuery& order_by()
+    {
+      this->body += " ORDER BY ";
+      return *this;
+    }
+
+    SelectQuery& limit()
+    {
+      this->body += " LIMIT ";
+      return *this;
+    }
+
+    auto execute(sqlite3* db)
+    {
+      auto statement = this->prepare(db);
+      int i = 1;
+      for (const std::string& param: this->params)
+        {
+          if (sqlite3_bind_text(statement, i, param.data(), static_cast<int>(param.size()), SQLITE_TRANSIENT) != SQLITE_OK)
+            log_debug("Failed to bind ", param, " to param ", i);
+          else
+            log_debug("Bound ", param, " to ", i);
+
+          i++;
+        }
+      std::vector<Row<T...>> rows;
+      while (sqlite3_step(statement) == SQLITE_ROW)
+        {
+          Row<T...> row(this->table_name);
+          extract_row_values(row, statement);
+          rows.push_back(row);
+        }
+      return rows;
+    }
+
+    const std::string table_name;
+};
+
+template <typename T, typename... ColumnTypes>
+typename std::enable_if<!std::is_integral<T>::value, SelectQuery<ColumnTypes...>&>::type
+operator<<(SelectQuery<ColumnTypes...>& query, const T&)
+{
+  query.body += T::name;
+  return query;
+}
+
+template <typename... ColumnTypes>
+SelectQuery<ColumnTypes...>& operator<<(SelectQuery<ColumnTypes...>& query, const char* str)
+{
+  query.body += str;
+  return query;
+}
+
+template <typename... ColumnTypes>
+SelectQuery<ColumnTypes...>& operator<<(SelectQuery<ColumnTypes...>& query, const std::string& str)
+{
+  query.body += "?";
+  actual_add_param(query, str);
+  return query;
+}
+
+template <typename Integer, typename... ColumnTypes>
+typename std::enable_if<std::is_integral<Integer>::value, SelectQuery<ColumnTypes...>&>::type
+operator<<(SelectQuery<ColumnTypes...>& query, const Integer& i)
+{
+  query.body += "?";
+  actual_add_param(query, i);
+  return query;
+}