package eu.siacs.conversations.entities;

import android.content.ContentValues;
import android.database.Cursor;
import android.util.Base64;

import androidx.annotation.NonNull;

import com.google.common.base.Strings;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import eu.siacs.conversations.xml.Element;
import eu.siacs.conversations.xml.Namespace;
import eu.siacs.conversations.xmpp.forms.Data;
import eu.siacs.conversations.xmpp.forms.Field;
import eu.siacs.conversations.xmpp.stanzas.IqPacket;

public class ServiceDiscoveryResult {
	public static final String TABLENAME = "discovery_results";
	public static final String HASH = "hash";
	public static final String VER = "ver";
	public static final String RESULT = "result";
	protected final String hash;
	protected final byte[] ver;
	protected final List<String> features;
	protected final List<Data> forms;
	private final List<Identity> identities;
	public ServiceDiscoveryResult(final IqPacket packet) {
		this.identities = new ArrayList<>();
		this.features = new ArrayList<>();
		this.forms = new ArrayList<>();
		this.hash = "sha-1"; // We only support sha-1 for now

		final List<Element> elements = packet.query().getChildren();

		for (final Element element : elements) {
			if (element.getName().equals("identity")) {
				Identity id = new Identity(element);
				if (id.getType() != null && id.getCategory() != null) {
					identities.add(id);
				}
			} else if (element.getName().equals("feature")) {
				if (element.getAttribute("var") != null) {
					features.add(element.getAttribute("var"));
				}
			} else if (element.getName().equals("x") && element.getAttribute("xmlns").equals(Namespace.DATA)) {
				forms.add(Data.parse(element));
			}
		}
		this.ver = this.mkCapHash();
	}
	private ServiceDiscoveryResult(String hash, byte[] ver, JSONObject o) throws JSONException {
		this.identities = new ArrayList<>();
		this.features = new ArrayList<>();
		this.forms = new ArrayList<>();
		this.hash = hash;
		this.ver = ver;

		JSONArray identities = o.optJSONArray("identities");
		if (identities != null) {
			for (int i = 0; i < identities.length(); i++) {
				this.identities.add(new Identity(identities.getJSONObject(i)));
			}
		}
		JSONArray features = o.optJSONArray("features");
		if (features != null) {
			for (int i = 0; i < features.length(); i++) {
				this.features.add(features.getString(i));
			}
		}
		JSONArray forms = o.optJSONArray("forms");
		if (forms != null) {
			for (int i = 0; i < forms.length(); i++) {
				this.forms.add(createFormFromJSONObject(forms.getJSONObject(i)));
			}
		}
	}
	
	private ServiceDiscoveryResult() {
		this.hash = "sha-1";
		this.features = Collections.emptyList();
		this.identities = Collections.emptyList();
		this.ver = null;
		this.forms = Collections.emptyList();
	}

	public static ServiceDiscoveryResult empty() {
		return new ServiceDiscoveryResult();
	}

	public ServiceDiscoveryResult(Cursor cursor) throws JSONException {
		this(
				cursor.getString(cursor.getColumnIndexOrThrow(HASH)),
				Base64.decode(cursor.getString(cursor.getColumnIndexOrThrow(VER)), Base64.DEFAULT),
				new JSONObject(cursor.getString(cursor.getColumnIndexOrThrow(RESULT)))
		);
	}

	private static String clean(String s) {
		return s.replace("<","&lt;");
	}

	private static String blankNull(String s) {
		return s == null ? "" : clean(s);
	}

	private static Data createFormFromJSONObject(JSONObject o) {
		Data data = new Data();
		JSONArray names = o.names();
		for (int i = 0; i < names.length(); ++i) {
			try {
				String name = names.getString(i);
				JSONArray jsonValues = o.getJSONArray(name);
				ArrayList<String> values = new ArrayList<>(jsonValues.length());
				for (int j = 0; j < jsonValues.length(); ++j) {
					values.add(jsonValues.getString(j));
				}
				data.put(name, values);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return data;
	}

	private static JSONObject createJSONFromForm(Data data) {
		JSONObject object = new JSONObject();
		for (Field field : data.getFields()) {
			try {
				JSONArray jsonValues = new JSONArray();
				for (String value : field.getValues()) {
					jsonValues.put(value);
				}
				object.put(field.getFieldName(), jsonValues);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		try {
			JSONArray jsonValues = new JSONArray();
			jsonValues.put(data.getFormType());
			object.put(Data.FORM_TYPE, jsonValues);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return object;
	}

	public String getVer() {
		return Base64.encodeToString(this.ver, Base64.NO_WRAP);
	}

	public List<Identity> getIdentities() {
		return this.identities;
	}

	public List<String> getFeatures() {
		return this.features;
	}

	public Identity getIdentity(String category, String type) {
		for (Identity id : this.getIdentities()) {
			if ((category == null || id.getCategory().equals(category)) &&
					(type == null || id.getType().equals(type))) {
				return id;
			}
		}

		return null;
	}

	public boolean hasIdentity(String category, String type) {
		return getIdentity(category, type) != null;
	}

	public String getExtendedDiscoInformation(String formType, String name) {
		for (Data form : this.forms) {
			if (formType.equals(form.getFormType())) {
				for (Field field : form.getFields()) {
					if (name.equals(field.getFieldName())) {
						return field.getValue();
					}
				}
			}
		}
		return null;
	}

	private byte[] mkCapHash() {
		StringBuilder s = new StringBuilder();

		List<Identity> identities = this.getIdentities();
		Collections.sort(identities);

		for (Identity id : identities) {
			s.append(blankNull(id.getCategory()))
					.append("/")
					.append(blankNull(id.getType()))
					.append("/")
					.append(blankNull(id.getLang()))
					.append("/")
					.append(blankNull(id.getName()))
					.append("<");
		}

		final List<String> features = this.getFeatures();
		Collections.sort(features);
		for (final String feature : features) {
			s.append(clean(feature)).append("<");
		}

		Collections.sort(forms, Comparator.comparing(Data::getFormType));
		for (final Data form : forms) {
			s.append(clean(form.getFormType())).append("<");
			final List<Field> fields = form.getFields();
			Collections.sort(
                    fields, Comparator.comparing(lhs -> Strings.nullToEmpty(lhs.getFieldName())));
			for (final Field field : fields) {
				s.append(Strings.nullToEmpty(field.getFieldName())).append("<");
				final List<String> values = field.getValues();
				Collections.sort(values, Comparator.comparing(ServiceDiscoveryResult::blankNull));
				for (final String value : values) {
					s.append(blankNull(value)).append("<");
				}
			}
		}

		MessageDigest md;
		try {
			md = MessageDigest.getInstance("SHA-1");
		} catch (NoSuchAlgorithmException e) {
			return null;
		}

        return md.digest(s.toString().getBytes(StandardCharsets.UTF_8));
    }

	private JSONObject toJSON() {
		try {
			JSONObject o = new JSONObject();

			JSONArray ids = new JSONArray();
			for (Identity id : this.getIdentities()) {
				ids.put(id.toJSON());
			}
			o.put("identities", ids);

			o.put("features", new JSONArray(this.getFeatures()));

			JSONArray forms = new JSONArray();
			for (Data data : this.forms) {
				forms.put(createJSONFromForm(data));
			}
			o.put("forms", forms);

			return o;
		} catch (JSONException e) {
			return null;
		}
	}

	public ContentValues getContentValues() {
		final ContentValues values = new ContentValues();
		values.put(HASH, this.hash);
		values.put(VER, getVer());
		JSONObject jsonObject = toJSON();
		values.put(RESULT, jsonObject == null ? "" : jsonObject.toString());
		return values;
	}

	public static class Identity implements Comparable {
		protected final String type;
		protected final String lang;
		protected final String name;
		final String category;

		Identity(final String category, final String type, final String lang, final String name) {
			this.category = category;
			this.type = type;
			this.lang = lang;
			this.name = name;
		}

		Identity(final Element el) {
			this(
					el.getAttribute("category"),
					el.getAttribute("type"),
					el.getAttribute("xml:lang"),
					el.getAttribute("name")
			);
		}

		Identity(final JSONObject o) {

			this(
					o.optString("category", null),
					o.optString("type", null),
					o.optString("lang", null),
					o.optString("name", null)
			);
		}

		public String getCategory() {
			return this.category;
		}

		public String getType() {
			return this.type;
		}

		public String getLang() {
			return this.lang;
		}

		public String getName() {
			return this.name;
		}

		public int compareTo(@NonNull Object other) {
			Identity o = (Identity) other;
			int r = blankNull(this.getCategory()).compareTo(blankNull(o.getCategory()));
			if (r == 0) {
				r = blankNull(this.getType()).compareTo(blankNull(o.getType()));
			}
			if (r == 0) {
				r = blankNull(this.getLang()).compareTo(blankNull(o.getLang()));
			}
			if (r == 0) {
				r = blankNull(this.getName()).compareTo(blankNull(o.getName()));
			}

			return r;
		}

		JSONObject toJSON() {
			try {
				JSONObject o = new JSONObject();
				o.put("category", this.getCategory());
				o.put("type", this.getType());
				o.put("lang", this.getLang());
				o.put("name", this.getName());
				return o;
			} catch (JSONException e) {
				return null;
			}
		}
	}
}