package eu.siacs.conversations.xml;

import android.util.Log;
import android.util.Xml;
import eu.siacs.conversations.Config;
import im.conversations.android.xmpp.ExtensionFactory;
import im.conversations.android.xmpp.model.StreamElement;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

public class XmlReader implements Closeable {
    private final XmlPullParser parser;
    private InputStream is;

    public XmlReader() {
        this.parser = Xml.newPullParser();
        try {
            this.parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
        } catch (XmlPullParserException e) {
            Log.d(Config.LOGTAG, "error setting namespace feature on parser");
        }
    }

    public void setInputStream(InputStream inputStream) throws IOException {
        if (inputStream == null) {
            throw new IOException();
        }
        this.is = inputStream;
        try {
            parser.setInput(new InputStreamReader(this.is));
        } catch (XmlPullParserException e) {
            throw new IOException("error resetting parser");
        }
    }

    public void reset() throws IOException {
        if (this.is == null) {
            throw new IOException();
        }
        try {
            parser.setInput(new InputStreamReader(this.is));
        } catch (XmlPullParserException e) {
            throw new IOException("error resetting parser");
        }
    }

    @Override
    public void close() {
        this.is = null;
    }

	public Tag readTag() throws IOException {
		try {
			while (this.is != null && parser.next() != XmlPullParser.END_DOCUMENT) {
				if (parser.getEventType() == XmlPullParser.START_TAG) {
					Tag tag = Tag.start(parser.getName());
					final String xmlns = parser.getNamespace();
					for (int i = 0; i < parser.getAttributeCount(); ++i) {
						final var prefix = parser.getAttributePrefix(i);
						final var ns = parser.getAttributeNamespace(i);
						String name;
						if ("xml".equals(prefix)) {
							name = "xml:" + parser.getAttributeName(i);
						} else if (ns != null && !ns.isEmpty()) {
							name = "{" + ns + "}" + parser.getAttributeName(i);
						} else {
							name = parser.getAttributeName(i);
						}
						tag.setAttribute(name,parser.getAttributeValue(i));
					}
					if (xmlns != null) {
						tag.setAttribute("xmlns", xmlns);
					}
					return tag;
				} else if (parser.getEventType() == XmlPullParser.END_TAG) {
					return Tag.end(parser.getName());
				} else if (parser.getEventType() == XmlPullParser.TEXT) {
					return Tag.no(parser.getText());
				}
			}

        } catch (Throwable throwable) {
            throw new IOException(
                    "xml parser mishandled "
                            + throwable.getClass().getSimpleName()
                            + "("
                            + throwable.getMessage()
                            + ")",
                    throwable);
        }
        return null;
    }

    public <T extends StreamElement> T readElement(final Tag current, final Class<T> clazz)
            throws IOException {
        final Element element = readElement(current);
        if (clazz.isInstance(element)) {
            return clazz.cast(element);
        }
        throw new IOException(
                String.format("Read unexpected {%s}%s", element.getNamespace(), element.getName()));
    }

	public Element readElement(final Tag currentTag) throws IOException {
		final var attributes = currentTag.getAttributes();
		final var namespace = attributes.get("xmlns");
		final var name = currentTag.getName();
		final Element element = ExtensionFactory.create(name, namespace);
		element.setAttributes(currentTag.getAttributes());
		Tag nextTag = this.readTag();
		if (nextTag == null) {
			throw new IOException("interrupted mid tag");
		}
		while (!nextTag.isEnd(element.getName())) {
			if (nextTag.isNo()) {
				if (nextTag.getName() != null) element.addChild(new TextNode(nextTag.getName()));
			} else {
				Element child = this.readElement(nextTag);
				element.addChild(child);
			}
			nextTag = this.readTag();
			if (nextTag == null) {
				throw new IOException("interrupted mid tag");
			}
		}
		return element;
	}
}