package org.thoughtcrime.securesms.search;

import android.content.Context;
import android.text.TextUtils;
import android.util.Log;
import androidx.annotation.NonNull;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;
import androidx.lifecycle.ViewModelProvider;
import com.b44t.messenger.DcChatlist;
import com.b44t.messenger.DcContext;
import com.b44t.messenger.DcLot;
import org.thoughtcrime.securesms.connect.DcHelper;
import org.thoughtcrime.securesms.search.model.SearchResult;
import org.thoughtcrime.securesms.util.Util;

class SearchViewModel extends ViewModel {
  private static final String TAG = "SearchViewModel";
  private final ObservingLiveData searchResult;
  private String lastQuery;
  private final Context appContext;
  private final DcContext dcContext;
  private boolean forwarding = false;
  private final Object bgSearchLock = new Object();
  private boolean inBgSearch;
  private boolean needsAnotherBgSearch;

  SearchViewModel(@NonNull Context context) {
    this.appContext = context.getApplicationContext();
    this.dcContext = DcHelper.getContext(appContext);
    this.searchResult = new ObservingLiveData();
  }

  LiveData<SearchResult> getSearchResult() {
    return searchResult;
  }

  public void setForwardingMode(boolean forwarding) {
    this.forwarding = forwarding;
  }

  void updateQuery(String query) {
    lastQuery = query;
    updateQuery();
  }

  public void updateQuery() {
    synchronized (bgSearchLock) {
      if (inBgSearch) {
        Log.i(TAG, "... search call debounced");
        needsAnotherBgSearch = true;
        return;
      }
      inBgSearch = true;
    }
    Util.runOnBackground(
        () -> {
          while (true) {
            Log.i(TAG, "... executing debounced search call");
            queryAndCallback(lastQuery, searchResult::postValue);
            synchronized (bgSearchLock) {
              if (!needsAnotherBgSearch) {
                inBgSearch = false;
                return;
              }
              needsAnotherBgSearch = false;
            }
            Util.sleep(100);
          }
        });
  }

  private void queryAndCallback(@NonNull String query, @NonNull SearchViewModel.Callback callback) {
    int overallCnt = 0;

    if (TextUtils.isEmpty(query)) {
      callback.onResult(SearchResult.EMPTY);
      return;
    }

    QrInviteData qrInviteData = null;
    if (!forwarding && query.contains(":")) {
      DcLot qrParsed = dcContext.checkQr(query);
      qrInviteData = QrInviteData.from(appContext, dcContext, qrParsed, query);
    }

    // #1 search for chats
    long startMs = System.currentTimeMillis();
    DcChatlist conversations =
        dcContext.getChatlist(forwarding ? DcContext.DC_GCL_FOR_FORWARDING : 0, query, 0);
    overallCnt += conversations.getCnt();
    Log.i(TAG, "⏰ getChatlist(" + query + "): " + (System.currentTimeMillis() - startMs) + "ms");

    // #2 search for contacts
    if (!query.equals(lastQuery) && overallCnt > 0) {
      Log.i(TAG, "... skipping getContacts() and searchMsgs(), more recent search pending");
      callback.onResult(
          new SearchResult(query, new int[0], conversations, new int[0], qrInviteData));
      return;
    }

    startMs = System.currentTimeMillis();
    int[] contacts = dcContext.getContacts(DcContext.DC_GCL_ADD_SELF, query);
    overallCnt += contacts.length;
    Log.i(TAG, "⏰ getContacts(" + query + "): " + (System.currentTimeMillis() - startMs) + "ms");

    // #3 search for messages
    if (forwarding) {
      Log.i(TAG, "... searchMsgs() disabled by caller");
      callback.onResult(new SearchResult(query, contacts, conversations, new int[0], qrInviteData));
      return;
    }

    if (query.length() <= 1) {
      Log.i(TAG, "... skipping searchMsgs(), string too short");
      callback.onResult(new SearchResult(query, contacts, conversations, new int[0], qrInviteData));
      return;
    }

    if (!query.equals(lastQuery) && overallCnt > 0) {
      Log.i(TAG, "... skipping searchMsgs(), more recent search pending");
      callback.onResult(new SearchResult(query, contacts, conversations, new int[0], qrInviteData));
      return;
    }

    startMs = System.currentTimeMillis();
    int[] messages = dcContext.searchMsgs(0, query);
    Log.i(TAG, "⏰ searchMsgs(" + query + "): " + (System.currentTimeMillis() - startMs) + "ms");

    callback.onResult(new SearchResult(query, contacts, conversations, messages, qrInviteData));
  }

  @NonNull
  String getLastQuery() {
    return lastQuery == null ? "" : lastQuery;
  }

  @Override
  protected void onCleared() {}

  private static class ObservingLiveData extends MutableLiveData<SearchResult> {}

  public static class Factory extends ViewModelProvider.NewInstanceFactory {

    private final Context context;

    public Factory(@NonNull Context context) {
      this.context = context;
    }

    @NonNull
    @Override
    public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
      return modelClass.cast(new SearchViewModel(context));
    }
  }

  public interface Callback {
    void onResult(@NonNull SearchResult result);
  }
}