package net.mindoverflow.webmarker.utils.sql;

import net.mindoverflow.webmarker.utils.config.ConfigManager;
import net.mindoverflow.webmarker.utils.messaging.MessageLevel;
import net.mindoverflow.webmarker.utils.messaging.Messenger;
import net.mindoverflow.webmarker.utils.sql.primitives.SQLDataType;
import net.mindoverflow.webmarker.utils.sql.primitives.SQLTable;

import java.sql.*;
import java.util.List;

public class SQLiteManager {

    private final Messenger msg = new Messenger();
    private Connection connection;

    public void initialize()
    {
        msg.send(MessageLevel.INFO, "Connecting to SQLite database: ");

        String url = "jdbc:sqlite:" + ConfigManager.FileType.DATABASE_FILE.file.getAbsolutePath();
        try {
            connection = DriverManager.getConnection(url);
            if(connection != null && !connection.isClosed())
            {
                msg.sendLine(MessageLevel.NONE, "OK");
                doInitialSetup();
            }

        } catch (SQLException throwables) {
            msg.sendLine(MessageLevel.NONE, "FATAL");
            throwables.printStackTrace();
            msg.critical("Error connecting to SQLite database!");
            System.exit(1);
        }
    }

    private void doInitialSetup()
    {
        for(FDatabaseTable currentTable : FDatabaseTable.values())
        {
            if(!tableExists(currentTable))
            {
                msg.info("Creating SQLite table `" + currentTable.getTable().getTableSQLName() + "`");
                createTable(currentTable);
            }
        }
    }

    private boolean tableExists(FDatabaseTable tableEnum)
    {
        String name = tableEnum.getTable().getTableSQLName();

        try
        {
            DatabaseMetaData meta = connection.getMetaData();
            ResultSet result = meta.getTables(null, null, name, null);
            while(result.next())
            {
                String tableName = result.getString("TABLE_NAME");
                if(tableName != null && tableName.equals(name.toLowerCase())) return true;
            }

        } catch (SQLException e)
        {
            e.printStackTrace();
            msg.critical("Error checking SQLite table " + name + "!");
            System.exit(1);
        }
        return false;
    }

    private void createTable(FDatabaseTable tableEnum)
    {
        SQLTable table = tableEnum.getTable();
        List<FDatabaseColumn> columns = table.getColumns();
        List<SQLDataType> dataTypes = table.getDataTypes();

        StringBuilder query = new StringBuilder("CREATE TABLE IF NOT EXISTS ").append(table.getTableSQLName()).append(" (");

        int pos = 0;
        for(FDatabaseColumn column : columns)
        {
            query.append(column.getColumn().getColumnSQLName()).append(" ").append(dataTypes.get(pos).getSQLName());
            pos++;

            if(pos < columns.size()) // we don't want to append a colon to the last entry
            { query.append(", "); }
        }
        query.append(");");
        executeUpdate(query.toString());
    }

    private void executeUpdate(String query)
    {
        try
        {
            if(connection == null || connection.isClosed())
            {
                msg.critical("Lost connection to SQLite database!");
                System.exit(1);
            }

            Statement statement = connection.createStatement();
            statement.executeUpdate(query);
        } catch (SQLException e)
        {
            e.printStackTrace();
            msg.critical("Error executing SQLite update!");
            System.exit(1);
        }
    }
}