package io.trygvis.persistence.generators;

import io.trygvis.container.compiler.SqlUnitModel;
import io.trygvis.container.compiler.model.ClassG;
import io.trygvis.container.compiler.model.Constructor;
import io.trygvis.container.compiler.model.FieldRef;
import io.trygvis.container.compiler.model.Imports;
import io.trygvis.container.compiler.model.MethodRef;
import io.trygvis.container.compiler.model.Parameters;
import io.trygvis.container.compiler.model.TypeRef;
import io.trygvis.persistence.EntityMirror;
import io.trygvis.persistence.sql.SqlEntityManagerFactory;
import io.trygvis.persistence.sql.SqlEntityMeta;
import io.trygvis.persistence.sql.SqlUnit;

import javax.persistence.EntityManager;
import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.util.ArrayList;
import java.util.List;

import static io.trygvis.container.compiler.Utils.toClassName;
import static java.lang.reflect.Modifier.*;
import static org.apache.commons.lang.StringUtils.join;

public class EntityManagerFactoryGenerator {
    public static ClassG generateEntityManagerFactory(SqlUnitModel unit) throws IOException {
        String prefix = unit.getPackageName() + "." + toClassName(unit.getName());
        TypeRef emfType = new TypeRef(prefix + "EntityManagerFactory");

        ClassG g = new ClassG(PUBLIC, emfType).
                extendsType(SqlEntityManagerFactory.class);

        List<String> s = new ArrayList<>();
        for (EntityMirror entity : unit.getEntities().values()) {
            s.add(entity.daoType.plainName + ".desc");
        }
        TypeRef sqlEntityMetaArrayType = new TypeRef(SqlEntityMeta[].class);
        FieldRef entities = g.addField(PUBLIC | STATIC, sqlEntityMetaArrayType, "entities").
                value("new " + sqlEntityMetaArrayType + "{" + join(s, ", ") + "}");

        g.add(constructor(entities, g.imports));
        g.add(createEntityManager(unit, g.imports));
        return g;
    }

    private static Constructor constructor(FieldRef entities, Imports imports) {
        TypeRef dataSourceType = imports.add(DataSource.class);
        TypeRef sqlUnitType = imports.add(SqlUnit.class);
        Parameters p = new Parameters();
        Parameters.ParameterRef ds = p.addParameter(dataSourceType, "ds");
        ArrayList<String> body = new ArrayList<>();
        body.add("super(new " + sqlUnitType.plainName + "(" + entities.name + "), " + ds.name + ");");
        return new Constructor(p, body);
    }

    private static MethodRef createEntityManager(SqlUnitModel unit, Imports imports) {
        String prefix = unit.getPackageName() + "." + toClassName(unit.getName());
        TypeRef entityManagerType = imports.add(EntityManager.class);
        TypeRef connectionType = imports.add(Connection.class);
        TypeRef emType = imports.add(new TypeRef(prefix + "EntityManager"));

        Parameters p = new Parameters();
        Parameters.ParameterRef c = p.addParameter(connectionType, "c");
        return new MethodRef(PROTECTED, entityManagerType, "createEntityManager", p,
                "return new " + emType + "(this, " + c.name + ");");
    }
}