package io.trygvis.container.compiler;

import io.trygvis.container.compiler.entity.EntityMirror;
import io.trygvis.container.compiler.model.ClassG;
import io.trygvis.container.compiler.model.Parameters;

import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;
import javax.tools.JavaFileObject;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import static io.trygvis.container.compiler.entity.EntityMirror.FieldMirror;
import static java.lang.Character.isUpperCase;
import static javax.lang.model.util.ElementFilter.fieldsIn;
import static org.springframework.util.StringUtils.collectionToDelimitedString;

public class EntityHandler extends AbstractHandler {
    public EntityHandler(ProcessingEnvironment processingEnv) {
        super(processingEnv);
    }

    public void processEntity(TypeElement element) throws Exception {
        EntityMirror entityMirror = new EntityMirror(sqlName(element.getSimpleName().toString()));

        for (VariableElement f : fieldsIn(elements.getAllMembers(element))) {
            entityMirror.add(fromElement(f));
        }

        String p = elements.getPackageOf(element).getQualifiedName().toString();
        String className = element.getSimpleName() + "_Sql";

        ClassG g = new ClassG(p, className, null);
        g.addPublicFinalField(String.class, "insertInto");
        String insertInto = insertInto(entityMirror);
        List<String> body = new ArrayList<>();
        body.add("this.insertInto = \"" + insertInto + "\";");
        g.addConstructor(new Parameters(), body);

        String fileName = (p.length() == 0 ? "" : p + ".") + className;
        JavaFileObject sourceFile = processingEnv.getFiler().createSourceFile(fileName, element);
        try (PrintWriter w = new PrintWriter(sourceFile.openWriter())) {
            g.write(w);
        }
    }

    public static String insertInto(EntityMirror entityMirror) {
        List<String> names = new ArrayList<>();
        List<String> placeholders = new ArrayList<>();
        for (FieldMirror field : entityMirror.fields) {
            names.add(field.sqlName);
            placeholders.add("?");
        }
        return "INSERT INTO " + entityMirror.tableName + "(" + collectionToDelimitedString(names, ", ") + ") " +
                "VALUES(" + collectionToDelimitedString(placeholders, ", ") + ");";
    }

    public FieldMirror fromElement(VariableElement var) {
        System.out.println("io.trygvis.container.compiler.entity.EntityMirror.FieldMirror.fromElement");
        System.out.print("element = ");
        elements.printElements(new PrintWriter(System.out), var);
        String javaName = var.getSimpleName().toString();
        String sqlName = sqlName(javaName);
        boolean notNull = false;
        FieldMirror field = new FieldMirror(javaName, sqlName, notNull);
        System.out.println("field = " + field);
        return field;
    }

    public static String sqlName(String javaName) {
        StringBuilder builder = new StringBuilder();
        for (char c : javaName.toCharArray()) {
            char lower = Character.toLowerCase(c);
            if(isUpperCase(c) && builder.length() > 0) {
                builder.append("_");
            }
            builder.append(lower);
        }
        return builder.toString();
    }
}