From 15c1e5566f7ad8448985ca6e52805ceb4ec389a8 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 24 May 2021 01:01:30 +0100
Subject: Basic support for queries with bound parameters

Bit of a reshuffle to make the types not DB specific, add some basic tests over query
execution, no selects yet and no validation anything is actually right.
---
 lib/input/mysqlConn.cpp | 78 +++++++++++++++++++++++++++++++++++++++++++++++++
 lib/input/mysqlConn.h   |  8 +++--
 2 files changed, 84 insertions(+), 2 deletions(-)

(limited to 'lib/input')

diff --git a/lib/input/mysqlConn.cpp b/lib/input/mysqlConn.cpp
index 3a2c9f4..179f9d5 100644
--- a/lib/input/mysqlConn.cpp
+++ b/lib/input/mysqlConn.cpp
@@ -1,9 +1,18 @@
 #include "mysqlConn.h"
 #include "helpers.h"
+#include <cstddef>
+#include <cstring>
+#include <dbTypes.h>
+#include <memory>
 #include <mysql.h>
+#include <mysql_types.h>
 #include <stdexcept>
+#include <variant>
+#include <vector>
 
 namespace MyGrate::Input {
+	using StmtPtr = std::unique_ptr<MYSQL_STMT, decltype(&mysql_stmt_close)>;
+
 	MySQLConn::MySQLConn(
 			const char * const host, const char * const user, const char * const pass, unsigned short port) :
 		st_mysql {}
@@ -26,4 +35,73 @@ namespace MyGrate::Input {
 	{
 		verify<std::runtime_error>(!mysql_query(this, q), q);
 	}
+
+	struct Bindings {
+		// NOLINTNEXTLINE(hicpp-explicit-conversions)
+		explicit Bindings(const std::initializer_list<DbValue> & vs)
+		{
+			binds.reserve(vs.size());
+			extras.reserve(vs.size());
+			for (const auto & v : vs) {
+				std::visit(*this, v);
+			}
+		}
+		template<std::integral T>
+		void
+		operator()(const T & v)
+		{
+			auto & b = binds.emplace_back();
+			b.buffer_type = MySQL::CType<T>::type;
+			b.buffer = const_cast<T *>(&v);
+			b.is_unsigned = std::unsigned_integral<T>;
+		}
+		template<std::floating_point T>
+		void
+		operator()(const T & v)
+		{
+			auto & b = binds.emplace_back();
+			b.buffer_type = MySQL::CType<T>::type;
+			b.buffer = const_cast<T *>(&v);
+		}
+		template<Viewable T>
+		void
+		operator()(const T & v)
+		{
+			auto & b = binds.emplace_back();
+			b.buffer_type = MySQL::CType<T>::type;
+			b.buffer = const_cast<typename T::value_type *>(v.data());
+			b.length = &extras.emplace_back(v.size(), 0).len;
+		}
+		void
+		operator()(const std::nullptr_t &)
+		{
+			auto & b = binds.emplace_back();
+			b.buffer = nullptr;
+			b.is_null = &extras.emplace_back(0, 1).null;
+		}
+		template<typename T>
+		void
+		operator()(const T &)
+		{
+			throw std::runtime_error("Not implemented");
+		}
+		struct extra {
+			explicit extra(unsigned long l, my_bool n = 0) : len {l}, null {n} { }
+			unsigned long len;
+			my_bool null;
+		};
+		std::vector<MYSQL_BIND> binds;
+		std::vector<extra> extras;
+	};
+
+	void
+	MySQLConn::query(const char * const q, const std::initializer_list<DbValue> & vs)
+	{
+		StmtPtr stmt {mysql_stmt_init(this), &mysql_stmt_close};
+		verify<std::runtime_error>(!mysql_stmt_prepare(stmt.get(), q, strlen(q)), q);
+		verify<std::logic_error>(mysql_stmt_param_count(stmt.get()) == vs.size(), "Param count mismatch");
+		Bindings b {vs};
+		verify<std::runtime_error>(!mysql_stmt_bind_param(stmt.get(), b.binds.data()), "Param count mismatch");
+		verify<std::runtime_error>(!mysql_stmt_execute(stmt.get()), q);
+	}
 }
diff --git a/lib/input/mysqlConn.h b/lib/input/mysqlConn.h
index 2f57f33..9e4ec25 100644
--- a/lib/input/mysqlConn.h
+++ b/lib/input/mysqlConn.h
@@ -1,15 +1,19 @@
 #ifndef MYGRATE_INPUT_MYSQLCONN_H
 #define MYGRATE_INPUT_MYSQLCONN_H
 
+#include <dbConn.h>
+#include <dbTypes.h>
+#include <initializer_list>
 #include <mysql.h>
 
 namespace MyGrate::Input {
-	class MySQLConn : public MYSQL {
+	class MySQLConn : public MYSQL, public DbConn {
 	public:
 		MySQLConn(const char * const host, const char * const user, const char * const pass, unsigned short port);
 		~MySQLConn();
 
-		void query(const char * const);
+		void query(const char * const) override;
+		void query(const char * const q, const std::initializer_list<DbValue> &) override;
 	};
 }
 
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