first thoughts about database

database/CMakeLists.txt

@@ -0,0 +1,11 @@
+set(HEADERS
+    dbinterface.h
+)
+
+set(SOURCES
+    dbinterface.cpp
+)
+
+target_sources(pica PRIVATE ${SOURCES})
+
+add_subdirectory(mysql)

database/dbinterface.cpp

@@ -0,0 +1,23 @@
+#include "dbinterface.h"
+
+#include "mysql/mysql.h"
+
+DBInterface::DBInterface(Type type):
+    type(type),
+    state(State::disconnected)
+{}
+
+DBInterface::~DBInterface() {}
+
+std::unique_ptr<DBInterface> DBInterface::create(Type type) {
+    switch (type) {
+        case Type::mysql:
+            return std::make_unique<MySQL>();
+    }
+
+    throw std::runtime_error("Unexpected database type: " + std::to_string((uint8_t)type));
+}
+
+DBInterface::State DBInterface::currentState() const {
+    return state;
+}

database/dbinterface.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <stdexcept>
+#include <string>
+#include <memory>
+
+class DBInterface {
+public:
+    enum class Type {
+        mysql
+    };
+    enum class State {
+        disconnected,
+        connecting,
+        connected
+    };
+    static std::unique_ptr<DBInterface> create(Type type);
+
+    virtual ~DBInterface();
+
+    State currentState() const;
+
+    const Type type;
+
+public:
+    virtual void connect(const std::string& path) = 0;
+    virtual void disconnect() = 0;
+    virtual void setDatabase(const std::string& newDatabase) = 0;
+    virtual void setCredentials(const std::string& login, const std::string& password) = 0;
+
+protected:
+    DBInterface(Type type);
+
+protected:
+    State state;
+};

database/mysql/CMakeLists.txt

@@ -0,0 +1,13 @@
+set(HEADERS
+    mysql.h
+)
+
+set(SOURCES
+    mysql.cpp
+)
+
+find_package(MariaDB REQUIRED)
+
+target_sources(pica PRIVATE ${SOURCES})
+
+target_link_libraries(pica PRIVATE MariaDB::client)

database/mysql/mysql.cpp

@@ -0,0 +1,85 @@
+#include "mysql.h"
+
+MySQL::MySQL():
+    DBInterface(Type::mysql),
+    connection(),
+    login(),
+    password(),
+    database()
+{
+    mysql_init(&connection);
+}
+
+MySQL::~MySQL() {
+    mysql_close(&connection);
+}
+
+
+void MySQL::connect(const std::string& path) {
+    if (state != State::disconnected)
+        return;
+
+    MYSQL* con = &connection;
+    MYSQL* res = mysql_real_connect(
+        con,
+        NULL,
+        login.c_str(),
+        password.c_str(),
+        database.empty() ? NULL : database.c_str(),
+        0,
+        path.c_str(),
+        0
+    );
+
+    if (res != con)
+        throw std::runtime_error(std::string("Error changing connecting: ") + mysql_error(con));
+
+    state = State::connected;
+}
+
+void MySQL::setCredentials(const std::string& login, const std::string& password) {
+    if (MySQL::login == login && MySQL::password == password)
+        return;
+
+    MySQL::login = login;
+    MySQL::password = password;
+
+    if (state == State::disconnected)
+        return;
+
+    MYSQL* con = &connection;
+    int result = mysql_change_user(
+        con,
+        login.c_str(),
+        password.c_str(),
+        database.empty() ? NULL : database.c_str()
+    );
+
+    if (result != 0)
+        throw std::runtime_error(std::string("Error changing credetials: ") + mysql_error(con));
+}
+
+void MySQL::setDatabase(const std::string& database) {
+    if (MySQL::database == database)
+        return;
+
+    MySQL::database = database;
+
+    if (state == State::disconnected)
+        return;
+
+    MYSQL* con = &connection;
+    int result = mysql_select_db(con, database.c_str());
+
+    if (result != 0)
+        throw std::runtime_error(std::string("Error changing db: ") + mysql_error(con));
+}
+
+void MySQL::disconnect() {
+    if (state == State::disconnected)
+        return;
+
+    MYSQL* con = &connection;
+    mysql_close(con);
+    mysql_init(con);            //this is ridiculous!
+}

database/mysql/mysql.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <stdexcept>
+
+#include <mysql.h>
+
+#include "database/dbinterface.h"
+
+class MySQL : public DBInterface {
+public:
+    MySQL();
+    ~MySQL() override;
+
+    void connect(const std::string& path) override;
+    void disconnect() override;
+    void setCredentials(const std::string& login, const std::string& password) override;
+    void setDatabase(const std::string& database) override;
+
+protected:
+    MYSQL connection;
+    std::string login;
+    std::string password;
+    std::string database;
+};