package com.firefly.core.support.xml;

import com.firefly.core.support.AbstractBeanReader;
import com.firefly.core.support.BeanDefinition;
import com.firefly.core.support.xml.parse.XmlNodeStateMachine;
import com.firefly.utils.VerifyUtils;
import com.firefly.utils.dom.DefaultDom;
import com.firefly.utils.dom.Dom;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import static com.firefly.core.support.xml.parse.XmlNodeConstants.BEAN_ELEMENT;
import static com.firefly.core.support.xml.parse.XmlNodeConstants.IMPORT_ELEMENT;

/**
 * Reading XML configuration file
 *
 * @author JJ Xu, Alvin Qiu
 */
public class XmlBeanReader extends AbstractBeanReader {

    public XmlBeanReader() {
        this(null);
    }

    public XmlBeanReader(String file) {
        beanDefinitions = new ArrayList<>();
        Dom dom = new DefaultDom();
        Set<String> errorMemo = new HashSet<>(); // It's used for eliminating circular references

        // all bean elements
        List<Element> beansList = new ArrayList<>();

        parseXml(dom, file, beansList, errorMemo);

        for (Element ele : beansList) {
            beanDefinitions.add((BeanDefinition) XmlNodeStateMachine.stateProcessor(ele, dom));
        }
    }

    private void parseXml(Dom dom, String file, List<Element> beansList, Set<String> errorMemo) {
        Document doc = dom.getDocument(file == null ? "firefly.xml" : file);
        Element root = dom.getRoot(doc);
        // all bean nodes
        List<Element> list = dom.elements(root, BEAN_ELEMENT);
        // all import nodes
        List<Element> importList = dom.elements(root, IMPORT_ELEMENT);
        if (importList != null) {
            for (Element ele : importList) {
                if (ele.hasAttribute("resource")) {
                    String resource = ele.getAttribute("resource");
                    if (errorMemo.contains(resource)) {
                        error("disallow cyclic references between two XML files");
                        return;
                    } else {
                        if (VerifyUtils.isEmpty(resource)) {
                            error("resource cannot be null");
                            return;
                        } else {
                            errorMemo.add(resource);
                            parseXml(dom, resource, beansList, errorMemo);
                        }
                    }
                } else {
                    error("has no resource attribute");
                    return;
                }
            }
        }
        beansList.addAll(list);
    }
}