package eu.siacs.conversations.ui.adapter;

import android.content.Context;
import android.widget.ArrayAdapter;
import android.widget.Filter;
import androidx.annotation.NonNull;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Ordering;
import eu.siacs.conversations.Config;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Locale;
import java.util.regex.Pattern;

public class KnownHostsAdapter extends ArrayAdapter<String> {

    private static final Pattern E164_PATTERN = Pattern.compile("^\\+[1-9]\\d{1,14}$");

    private List<String> domains;
    private final Filter domainFilter =
            new Filter() {

                @Override
                protected FilterResults performFiltering(final CharSequence constraint) {
                    final ImmutableList.Builder<String> builder = new ImmutableList.Builder<>();
                    final String[] split =
                            constraint == null ? new String[0] : constraint.toString().split("@");
                    if (split.length == 1) {
                        final String local = split[0].toLowerCase(Locale.ENGLISH);
                        if (Config.QUICKSY_DOMAIN != null
                                && E164_PATTERN.matcher(local).matches()) {
                            builder.add(local + '@' + Config.QUICKSY_DOMAIN);
                        } else {
                            for (String domain : domains) {
                                builder.add(local + '@' + domain);
                            }
                        }
                    } else if (split.length == 2) {
                        final String localPart = split[0].toLowerCase(Locale.ENGLISH);
                        final String domainPart = split[1].toLowerCase(Locale.ENGLISH);
                        if (domains.contains(domainPart)) {
                            return new FilterResults();
                        }
                        for (final String domain : domains) {
                            if (domain.contains(domainPart)) {
                                builder.add(localPart + "@" + domain);
                            }
                        }
                    } else {
                        return new FilterResults();
                    }
                    final var suggestions = builder.build();
                    final FilterResults filterResults = new FilterResults();
                    filterResults.values = suggestions;
                    filterResults.count = suggestions.size();
                    return filterResults;
                }

                @Override
                protected void publishResults(
                        final CharSequence constraint, final FilterResults results) {
                    final ImmutableList.Builder<String> suggestions = new ImmutableList.Builder<>();
                    if (results.values instanceof Collection<?> collection) {
                        for (final Object item : collection) {
                            if (item instanceof String string) {
                                suggestions.add(string);
                            }
                        }
                    }
                    clear();
                    addAll(suggestions.build());
                    notifyDataSetChanged();
                }
            };

    public KnownHostsAdapter(
            final Context context, final int viewResourceId, final Collection<String> knownHosts) {
        super(context, viewResourceId, new ArrayList<>());
        domains = Ordering.natural().sortedCopy(knownHosts);
    }

    public KnownHostsAdapter(final Context context, final int viewResourceId) {
        super(context, viewResourceId, new ArrayList<>());
        domains = ImmutableList.of();
    }

    public void refresh(final Collection<String> knownHosts) {
        this.domains = Ordering.natural().sortedCopy(knownHosts);
        notifyDataSetChanged();
    }

    @Override
    @NonNull
    public Filter getFilter() {
        return domainFilter;
    }
}