PandaLib/pandalib-db/src/main/java/fr/pandacube/lib/db/SQLFKField.java

package fr.pandacube.lib.db;

import fr.pandacube.lib.util.Log;

/**
 * A foreign key field in a SQL table.
 * @param <F> the table class of this current foreign key field
 * @param <T> the Java type of this field
 * @param <P> the table class of the targeted primary key
 */
public class SQLFKField<F extends SQLElement<F>, T, P extends SQLElement<P>> extends SQLField<F, T> {

    private SQLField<P, T> sqlPrimaryKeyField;
    private Class<P> sqlForeignKeyElemClass;

    /* package */ SQLFKField(SQLType<T> t, boolean nul, T deflt, Class<P> fkEl, SQLField<P, T> fkF) {
        super(t, nul, deflt);
        construct(fkEl, fkF);
    }

    /* package */ static <E extends SQLElement<E>, F extends SQLElement<F>> SQLFKField<E, Integer, F> idFK(boolean nul, Class<F> fkEl) {
        return idFK(nul, null, fkEl);
    }

    /* package */ static <E extends SQLElement<E>, F extends SQLElement<F>> SQLFKField<E, Integer, F> idFK(boolean nul, Integer deflt, Class<F> fkEl) {
        if (fkEl == null) throw new IllegalArgumentException("foreignKeyElement can't be null");
        try {
            SQLField<F, Integer> f = DB.getSQLIdField(fkEl);
            return new SQLFKField<>(f.type, nul, deflt, fkEl, f);
        } catch (DBInitTableException e) {
            Log.severe("Can't create Foreign key Field targeting id field of '"+fkEl+"'", e);
            return null;
        }
    }

    /* package */ static <E extends SQLElement<E>, T, F extends SQLElement<F>> SQLFKField<E, T, F> customFK(boolean nul, Class<F> fkEl, SQLField<F, T> fkF) {
        return customFK(nul, null, fkEl, fkF);
    }

    /* package */ static <E extends SQLElement<E>, T, F extends SQLElement<F>> SQLFKField<E, T, F> customFK(boolean nul, T deflt, Class<F> fkEl, SQLField<F, T> fkF) {
        if (fkEl == null) throw new IllegalArgumentException("foreignKeyElement can't be null");
        return new SQLFKField<>(fkF.type, nul, deflt, fkEl, fkF);
    }

    private void construct(Class<P> fkEl, SQLField<P, T> fkF) {
        if (fkF == null) throw new IllegalArgumentException("foreignKeyField can't be null");
        try {
            DB.initTable(fkEl);
        } catch (DBInitTableException e) {
            throw new RuntimeException(e);
        }

        if (fkF.getSQLElementType() == null)
            throw new RuntimeException("Can't initialize foreign key. The primary key in the table " + fkEl.getName() + " is not properly initialized and can't be targeted by a foreign key");
        sqlPrimaryKeyField = fkF;
        sqlForeignKeyElemClass = fkEl;
    }

    /**
     * Gets the targeted field of this foreign key.
     * @return the targeted field of this foreign key.
     */
    public SQLField<P, T> getPrimaryField() {
        return sqlPrimaryKeyField;
    }

    /**
     * Gets the type of the table containing the targeted field of this foreign key.
     * @return the type of the table containing the targeted field of this foreign key.
     */
    public Class<P> getForeignElementClass() {
        return sqlForeignKeyElemClass;
    }

}