package com.fcannizzaro.jsoup.annotations;

import com.fcannizzaro.jsoup.annotations.interfaces.AfterBind;
import com.fcannizzaro.jsoup.annotations.interfaces.Attr;
import com.fcannizzaro.jsoup.annotations.interfaces.Child;
import com.fcannizzaro.jsoup.annotations.interfaces.ForEach;
import com.fcannizzaro.jsoup.annotations.interfaces.Html;
import com.fcannizzaro.jsoup.annotations.interfaces.Items;
import com.fcannizzaro.jsoup.annotations.interfaces.Selector;
import com.fcannizzaro.jsoup.annotations.interfaces.Text;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.List;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

/**
 * Created by Francesco Cannizzaro (fcannizzaro)
 */

public class JsoupProcessor {

  /**
   * Extract first element according to a query
   */
  private static Element element(Element container, String query) {

    Elements select = container.select(query);

    if (select.size() == 0) {
      return null;
    }

    return select.first();
  }

  private static Object valueOf(Element container, AnnotatedElement field) throws Exception{

    Selector selector = field.getAnnotation(Selector.class);
    Text text = field.getAnnotation(Text.class);
    Child child = field.getAnnotation(Child.class);
    Items items = field.getAnnotation(Items.class);
    Html html = field.getAnnotation(Html.class);
    Attr attr = field.getAnnotation(Attr.class);

    Object value = null;
    Element el;

    if (field instanceof Field) {

      Field f = (Field) field;

      if (items != null) {

        ParameterizedType type = (ParameterizedType) f.getGenericType();
        Class<?> cz = (Class<?>) type.getActualTypeArguments()[0];
        return fromList(container, cz);

      } else if (child != null) {

        Class cz = f.getType();
        Selector sel = (Selector) cz.getAnnotation(Selector.class);

        if (sel != null) {
          return from(element(container, sel.value()), cz);
        }

      }

    }

    if (selector != null) {

      return element(container, selector.value());

    } else if (text != null) {

      el = element(container, text.value());

      if (el != null) {
        return el.text();
      }

    } else if (html != null) {

      el = element(container, html.value());

      if (el != null) {
        return el.html();
      }

    } else if (attr != null) {

      el = element(container, attr.query());

      if (el != null) {

        value = el.attr(attr.attr());

        if (value == null) {
          return null;
        }

      }

    }

    return value;

  }

  /**
   * Bind a Jsoup element to a class
   *
   * @param container dom element
   * @param clazz object class
   * @return object instance
   */
  public static <T> T from(Element container, Class<T> clazz) throws Exception{

    T instance = clazz.newInstance();

    for (Field field : clazz.getDeclaredFields()) {

      Object value = valueOf(container, field);

      if (value != null) {
        field.setAccessible(true);
        field.set(instance, value);
      }

    }

    Method afterBindMethod = null;

    for (Method method : clazz.getDeclaredMethods()) {

      ForEach forEach = method.getAnnotation(ForEach.class);
      AfterBind afterBind = method.getAnnotation(AfterBind.class);

      method.setAccessible(true);

      Object value = valueOf(container, method);

      if (value != null) {

        method.invoke(instance, value);

      } else if (afterBind != null) {

        afterBindMethod = method;

      } else if (forEach != null) {

        Elements elements = container.select(forEach.value());

        for (int i = 0; i < elements.size(); i++) {

          Element element = elements.get(i);

          if (method.getParameterTypes().length > 1) {
            method.invoke(instance, element, i);
            continue;
          }

          method.invoke(instance, element);

        }

      }

    }

    if (afterBindMethod != null) {
      afterBindMethod.invoke(instance);
    }

    return instance;
  }

  /**
   * Bind multiple object. (Internally use from)
   */
  public static <T> List<T> fromList(Element container, Class<T> clazz) throws Exception{

    ArrayList<T> items = new ArrayList<>();

    Selector selector = clazz.getAnnotation(Selector.class);

    if (selector != null) {

      Elements elements = container.select(selector.value());

      for (Element element : elements) {
        items.add(from(element, clazz));
      }

    }

    return items;

  }

}
