Merge pull request 'Add trivia file source support' (#13) from dev into master

Reviewed-on: https://git.luca0N.com/luca0N/Pluck/pulls/13

app/src/main/java/com/luca0n/joguitos/pluck/activities/MainActivity.java

@@ -23,23 +23,33 @@ Contact us at <joguitos+pluck@luca0n.com>.
 
 package com.luca0n.joguitos.pluck.activities;
 
+import android.app.Activity;
 import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.Build;
 import android.os.Bundle;
+import android.preference.PreferenceManager;
 import android.widget.ArrayAdapter;
 import android.widget.Button;
 import android.widget.Spinner;
+import androidx.appcompat.app.AlertDialog;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
+
 import com.luca0n.joguitos.pluck.R;
+import com.luca0n.joguitos.pluck.trivia.TriviaSource;
 import com.luca0n.joguitos.pluck.trivia.TriviaCategory;
 import com.luca0n.joguitos.pluck.trivia.TriviaDifficulty;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuery;
+import com.luca0n.joguitos.pluck.trivia.TriviaFilters;
 
 public class MainActivity extends BaseActivity {
 
 	@BindView(R.id.button_play)
 	Button buttonPlay;
+	@BindView(R.id.spinner_source)
+	Spinner spinnerSource;
 	@BindView(R.id.spinner_number)
 	Spinner spinnerNumber;
 	@BindView(R.id.spinner_category)
@@ -47,6 +57,8 @@ public class MainActivity extends BaseActivity {
 	@BindView(R.id.spinner_difficulty)
 	Spinner spinnerDifficulty;
 
+	private static final int REQUEST_OPEN_DOCUMENT = 0;
+
 	@Override
 	protected void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -54,30 +66,88 @@ public class MainActivity extends BaseActivity {
 		ButterKnife.bind(this);
 
 		buttonPlay.setOnClickListener(v -> {
-            int amount = (int) spinnerNumber.getSelectedItem();
+			int sourcePos = spinnerSource.getSelectedItemPosition();
+			if (TriviaSource.values()[sourcePos] ==  TriviaSource.FILE){
+				// Check the Android version.
+				if (Build.VERSION.SDK_INT >= 19){
+					// TODO: Show the open document dialog and read the trivia file.
+					Intent i = new Intent(Intent.ACTION_OPEN_DOCUMENT);
+					i.setType("*/*");
+					startActivityForResult(i, REQUEST_OPEN_DOCUMENT);
+					return;
+				} else {
+					// Unsupported version.
+					new AlertDialog.Builder(this)
+					.setIcon(android.R.drawable.ic_dialog_alert)
+					.setTitle(R.string.error)
+					.setMessage(R.string.error_source_file_android_version_unsupported)
+					.setPositiveButton(android.R.string.ok, null)
+					.show();	
+				}
+				return;
+			}
+			String amount = (String) spinnerNumber.getSelectedItem();
 			TriviaCategory category = (TriviaCategory) spinnerCategory.getSelectedItem();
 			TriviaDifficulty difficulty = (TriviaDifficulty) spinnerDifficulty.getSelectedItem();
 
-            TriviaQuery query = new TriviaQuery.Builder(amount)
+			if (amount.equals(getString(R.string.ui_all))){
+				// The "All" option is only used for trivia files.
+				new AlertDialog.Builder(this)
+					.setIcon(android.R.drawable.ic_dialog_alert)
+					.setTitle(R.string.error)
+					.setMessage(R.string.error_option_all_unavailable)
+					.setPositiveButton(android.R.string.ok, null)
+					.show();
+				return;
+			}
+
+			// Put the server address in the TriviaQuery object.	
+			SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
+			String serverKey = getResources().getString(R.string.pref_network_server);
+			// Load default server URL in case the player did not specify a custom server URL.
+			String defaultServer = getResources().getString(R.string.pref_network_server_default);
+			String base = sp.getString(serverKey, defaultServer) + "?"; // append "?" to the end of the URL so we can specify GET parameters.
+
+			// Check if the custom server URL preference was empty. If it was, change it to the default URL.
+			if (base.equals("?")){
+				base = defaultServer + "?";
+				sp.edit().putString(serverKey, defaultServer).commit();
+			}
+
+			TriviaQuery query = new TriviaQuery.Builder(Integer.valueOf(amount))
 				.category(category)
 				.difficulty(difficulty)
+				.base(base)
 				.build();
 
+			// Launch the trivia game activity.
 			Intent intent = new Intent(getApplicationContext(), TriviaGameActivity.class);
+			intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_SOURCE, TriviaSource.SERVER.getName()); // Specify the trivia source.
 			intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_QUERY, query);
+			intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_FILTERS,
+				new TriviaFilters.Builder(Integer.valueOf(amount))
+					.category(category)
+					.difficulty(difficulty)
+					.build());
 			startActivity(intent);
 		});
 
-
+		// Create a String array that holds all options for spinnerNumber.
-        Integer[] numbers = new Integer[50];
+		String[] numbers = new String[51];
-        for (int i = 0; i < 50; ) {
+		for (int i = 0; i < 51; i++) {
-            numbers[i] = ++i;
+			// The first entry on the spinner should be the value "All", which is used with the
+			// file trivia source.
+			numbers[i] = i == 0 ? getString(R.string.ui_all) : String.valueOf(i);
 		}
+		spinnerSource.setAdapter(
+				new ArrayAdapter<>(
+					this, android.R.layout.simple_list_item_1, TriviaSource.values())
+				);
 		spinnerNumber.setAdapter(
 				new ArrayAdapter<>(
 					this, android.R.layout.simple_list_item_1, numbers)
 				);
-        spinnerNumber.setSelection(9);
+		spinnerNumber.setSelection(10);
 
 		spinnerCategory.setAdapter(
 				new ArrayAdapter<>(
@@ -87,4 +157,43 @@ public class MainActivity extends BaseActivity {
 				new ArrayAdapter<>(
 					this, android.R.layout.simple_list_item_1, TriviaDifficulty.values()));
 	}
+
+	@Override
+	public void onActivityResult(int requestCode, int resultCode, Intent extras){
+		switch (requestCode){
+			case REQUEST_OPEN_DOCUMENT:
+				// Was the request executed successfully?
+				if (resultCode == Activity.RESULT_OK){
+					// Check if the user canceled the operation.
+					if (extras == null)
+						break;
+	
+					String amount = (String) spinnerNumber.getSelectedItem();
+					TriviaCategory category = (TriviaCategory) spinnerCategory.getSelectedItem();
+					TriviaDifficulty difficulty = (TriviaDifficulty) spinnerDifficulty.getSelectedItem();
+
+					Intent intent = new Intent(getApplicationContext(), TriviaGameActivity.class);
+					// Put filters on the extras object.
+					intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_FILTERS,
+							new TriviaFilters.Builder(amount.equals(getString(R.string.ui_all)) ? -1 : Integer.valueOf(amount))
+								.category(category)
+								.difficulty(difficulty)
+								.build());
+					intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_SOURCE, TriviaSource.FILE.getName()); // Specify the trivia source.
+					intent.putExtra(TriviaGameActivity.EXTRA_TRIVIA_SOURCE_DATA, extras.getData()); // Specify the trivia source data. In this case, since the user chose the "File" source option, we should put the file Uri object here.
+					startActivity(intent);
+				} else {
+					new AlertDialog.Builder(this)
+						.setIcon(android.R.drawable.ic_dialog_alert)
+						.setTitle(R.string.error)
+						.setMessage(R.string.error_trivia_file_fetch_unknown)
+						.setPositiveButton(android.R.string.ok, null)
+						.show();
+				}
+				break;
+			default:
+				super.onActivityResult(requestCode, resultCode, extras);
+				break;
+		}
+	}
 }

app/src/main/java/com/luca0n/joguitos/pluck/activities/TriviaGameActivity.java

@@ -23,7 +23,6 @@ Contact us at <joguitos+pluck@luca0n.com>.
 
 package com.luca0n.joguitos.pluck.activities;
 
-import android.app.AlertDialog;
 import android.content.Intent;
 import android.content.res.ColorStateList;
 import android.graphics.PorterDuff;
@@ -32,6 +31,7 @@ import android.os.AsyncTask;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
+import android.net.Uri;
 import android.view.View;
 import android.view.MenuItem;
 import android.widget.Button;
@@ -40,30 +40,43 @@ import android.widget.ProgressBar;
 import android.widget.TextView;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.io.Reader;
+import java.io.InputStreamReader;
+import java.io.InputStream;
+import java.io.BufferedReader;
 
 import androidx.appcompat.app.ActionBar;
+import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentTransaction;
 import butterknife.BindView;
 import butterknife.ButterKnife;
 import com.luca0n.joguitos.pluck.R;
 import com.luca0n.joguitos.pluck.exceptions.NoTriviaResultsException;
-import com.luca0n.joguitos.pluck.exceptions.InvalidServerResponseException;
+import com.luca0n.joguitos.pluck.exceptions.InvalidTriviaFormatException;
 import com.luca0n.joguitos.pluck.fragments.TriviaGameErrorFragment;
 import com.luca0n.joguitos.pluck.fragments.TriviaQuestionFragment;
 import com.luca0n.joguitos.pluck.interfaces.IDownloadTriviaQuestionReceiver;
 import com.luca0n.joguitos.pluck.trivia.TriviaGame;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuery;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuestion;
+import com.luca0n.joguitos.pluck.trivia.TriviaSource;
+import com.luca0n.joguitos.pluck.trivia.TriviaFilters;
 import com.luca0n.joguitos.pluck.util.ApiUtil;
 import com.luca0n.joguitos.pluck.util.SoundUtil;
 
 public class TriviaGameActivity extends BaseActivity
 	implements IDownloadTriviaQuestionReceiver {
 	static final String EXTRA_TRIVIA_QUERY = "extra_trivia_query";
+	static final String EXTRA_TRIVIA_SOURCE = "extra_trivia_source";
+	static final String EXTRA_TRIVIA_SOURCE_DATA = "extra_trivia_source_data";
+	static final String EXTRA_TRIVIA_FILTERS = "extra_trivia_filters";
 	private final String STATE_TRIVIA_GAME = "state_trivia_game";
 
 	private TriviaGame game;
+	private TriviaSource source;
+	private TriviaFilters filters;
 
 	@BindView(R.id.progress_bar)
 	ProgressBar progressBar;
@@ -93,11 +106,39 @@ public class TriviaGameActivity extends BaseActivity
 			assert bundle != null;
 			TriviaQuery query = (TriviaQuery) bundle.get(EXTRA_TRIVIA_QUERY);
 		
+			filters = (TriviaFilters) bundle.get(EXTRA_TRIVIA_FILTERS);
+
 			progressBar.setVisibility(View.VISIBLE);
 
+			// Gather information about the trivia location.
+			String sourceData;
+			source = TriviaSource.get(bundle.getString(EXTRA_TRIVIA_SOURCE));
+			switch (source){
+				case SERVER:
 					DownloadTriviaQuestionsTask task = new DownloadTriviaQuestionsTask();
 					task.setReceiver(this);
 					task.execute(query);
+					break;
+				case FILE:
+					// Attempt to open the trivia file specified by the player.
+					// Read the file as a plain text JSON trivia file.
+					StringBuilder sb = new StringBuilder();
+					try {
+						InputStream is = getContentResolver().openInputStream((Uri) bundle.get(EXTRA_TRIVIA_SOURCE_DATA));
+						Reader in = new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8));
+						for (int c; (c = in.read()) >= 0;)
+							sb.append((char) c);
+					} catch (IOException e){
+						onException(e);
+						return;
+					}
+					onTriviaQuestionsDownloaded(sb.toString());
+					break;
+				default:
+					// Unknown trivia source.
+					// TODO: Show error message to the user about this internal error.
+					break;
+			}
 		}
 	}
 
@@ -142,9 +183,8 @@ public class TriviaGameActivity extends BaseActivity
 			return;
 		} else {
 			try {
-				this.game = new TriviaGame(ApiUtil.jsonToQuestionArray(json));
+				this.game = new TriviaGame(ApiUtil.jsonToQuestionArray(json, filters));
 			} catch (Exception e) {
-				//onNoTriviaResults();
 				onException(e);
 				return;
 			}
@@ -200,12 +240,23 @@ public class TriviaGameActivity extends BaseActivity
 		// Hide the progress bar.
 		progressBar.setVisibility(View.GONE);
 		String msg;
+		int id;
 		if (e instanceof NoTriviaResultsException)
-			msg = getResources().getString(R.string.error_no_trivia_results);
+			id = R.string.error_no_trivia_results;
-		else if (e instanceof InvalidServerResponseException)
+		else if (e instanceof InvalidTriviaFormatException)
-			msg = getResources().getString(R.string.error_server_response_invalid);
+			// Check the trivia source type.
+			if (source == TriviaSource.SERVER)
+				id = R.string.error_server_response_invalid;
 			else
-			msg = getResources().getString(R.string.error_unknown);
+				id = R.string.error_trivia_file_invalid;
+		else 
+			id = R.string.error_unknown;
+
+		new AlertDialog.Builder(this)
+			.setMessage(e.toString())
+			.show();
+
+		msg = getResources().getString(id);
 
 		Fragment errorFragment = TriviaGameErrorFragment.newInstance(msg);
 

app/src/main/java/com/luca0n/joguitos/pluck/exceptions/InvalidTriviaFormatException.java

@@ -0,0 +1,35 @@
+/*
+Pluck: an open source trivia game for Android
+
+Copyright (C) 2021 Joguitos do luca0N!
+
+This program is free software: you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <https://www.gnu.org/licenses/>.
+
+This game is a fork of LibreTrivia, and its source code is available at
+<https://github.com/tryton-vanmeer/LibreTrivia>.
+
+Contact us at <joguitos+pluck@luca0n.com>.
+*/
+
+package com.luca0n.joguitos.pluck.exceptions;
+
+import java.lang.Throwable;
+
+public class InvalidTriviaFormatException extends Exception {
+	public InvalidTriviaFormatException(){
+		super();
+	}
+	public InvalidTriviaFormatException(Throwable cause){
+		super(cause);
+	}
+}

app/src/main/java/com/luca0n/joguitos/pluck/trivia/TriviaCategory.java

@@ -110,7 +110,7 @@ public enum TriviaCategory {
         return this.ID;
     }
 
-    private String getName() {
+    public String getName() {
         return this.name;
     }
 

app/src/main/java/com/luca0n/joguitos/pluck/trivia/TriviaFilters.java

@@ -0,0 +1,128 @@
+/*
+Pluck: an open source trivia game for Android
+
+Copyright (C) 2021 Joguitos do luca0N!
+
+This program is free software: you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <https://www.gnu.org/licenses/>.
+
+This game is a fork of LibreTrivia, and its source code is available at
+<https://github.com/tryton-vanmeer/LibreTrivia>.
+
+Contact us at <joguitos+pluck@luca0n.com>.
+*/
+
+package com.luca0n.joguitos.pluck.trivia;
+
+import java.io.Serializable;
+
+public class TriviaFilters implements Serializable {
+	private static final int DEFAULT_AMOUNT = 10;
+
+	private final int amount;
+	private final TriviaCategory category;
+	private final TriviaDifficulty difficulty;
+	private final TriviaType type;
+
+	private TriviaFilters(Builder builder) {
+		this.amount = builder.amount;
+		this.category = builder.category;
+		this.difficulty = builder.difficulty;
+		this.type = builder.type;
+	}
+
+	/**
+	 * @return The desired amount of questions selected by the player.
+	 * @since 2021-03-16
+	 */
+	public int getAmount(){
+		return amount;
+	}
+	/**
+	 * @return The category selected by the player.
+	 * @since 2021-03-16
+	 */
+	public TriviaCategory getCategory(){
+		return category;
+	}
+	/**
+	 * @return The difficulty selected by the player.
+	 * @since 2021-03-16
+	 */
+	public TriviaDifficulty getDifficulty(){
+		return difficulty;
+	}
+	/**
+	 * @return The type selected by the player.
+	 * @since 2021-03-16
+	 */
+	public TriviaType getType(){
+		return type;
+	}
+
+	public static class Builder {
+		private final int amount;
+		private TriviaCategory category;
+		private TriviaDifficulty difficulty;
+		private TriviaType type;
+
+		public Builder() {
+			this.amount = DEFAULT_AMOUNT;
+		}
+
+		public Builder(int amount) {
+			if (amount > 50) {
+				this.amount = 50;
+			} else {
+				this.amount = amount;
+			}
+		}
+
+		public Builder category(TriviaCategory category) {
+			this.category = category;
+			return this;
+		}
+
+		public Builder difficulty(TriviaDifficulty difficulty) {
+			this.difficulty = difficulty;
+			return this;
+		}
+
+		public Builder type(TriviaType type) {
+			this.type = type;
+			return this;
+		}
+
+		public TriviaFilters build() {
+			return new TriviaFilters(this);
+		}
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder url = new StringBuilder();
+
+		url.append("amount=").append(this.amount);
+
+		if (this.category != null & this.category != TriviaCategory.ANY) {
+			url.append("&category=").append(this.category.getID());
+		}
+		if (this.difficulty != null & this.difficulty != TriviaDifficulty.ANY) {
+			url.append("&difficulty=").append(this.difficulty.getName());
+		}
+		if (this.type != null & this.type != TriviaType.ANY) {
+			url.append("&type=").append(this.type.getName());
+		}
+
+		return url.toString();
+	}
+}

app/src/main/java/com/luca0n/joguitos/pluck/trivia/TriviaQuery.java

@@ -23,15 +23,8 @@ Contact us at <joguitos+pluck@luca0n.com>.
 
 package com.luca0n.joguitos.pluck.trivia;
 
-import com.luca0n.joguitos.pluck.PluckApplication;
-import com.luca0n.joguitos.pluck.R;
-
 import java.io.Serializable;
 
-import android.content.Context;
-import android.content.SharedPreferences;
-import android.preference.PreferenceManager;
-
 public class TriviaQuery implements Serializable {
 	private static final int DEFAULT_AMOUNT = 10;
 
@@ -39,12 +32,14 @@ public class TriviaQuery implements Serializable {
 	private final TriviaCategory category;
 	private final TriviaDifficulty difficulty;
 	private final TriviaType type;
+	private final String base;
 
 	private TriviaQuery(Builder builder) {
 		this.amount = builder.amount;
 		this.category = builder.category;
 		this.difficulty = builder.difficulty;
 		this.type = builder.type;
+		this.base = builder.base;
 	}
 
 	public static class Builder {
@@ -52,6 +47,7 @@ public class TriviaQuery implements Serializable {
 		private TriviaCategory category;
 		private TriviaDifficulty difficulty;
 		private TriviaType type;
+		private String base;
 
 		public Builder() {
 			this.amount = DEFAULT_AMOUNT;
@@ -80,6 +76,11 @@ public class TriviaQuery implements Serializable {
 			return this;
 		}
 
+		public Builder base(String base){
+			this.base = base;
+			return this;
+		}
+
 		public TriviaQuery build() {
 			return new TriviaQuery(this);
 		}
@@ -89,20 +90,6 @@ public class TriviaQuery implements Serializable {
 	public String toString() {
 		StringBuilder url = new StringBuilder();
 
-		// Load custom server URL.
-		Context c = PluckApplication.getAppContext();
-		SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(c);
-		String serverKey = c.getResources().getString(R.string.pref_network_server);
-		// Load default server URL in case the player did not specify a custom server URL.
-		String defaultServer = c.getResources().getString(R.string.pref_network_server_default);
-		String base = sp.getString(serverKey, defaultServer) + "?"; // append "?" to the end of the URL so we can specify GET parameters.
-
-		// Check if the custom server URL preference was empty. If it was, change it to the default URL.
-		if (base.equals("?")){
-			base = defaultServer + "?";
-			sp.edit().putString(serverKey, defaultServer).commit();
-		}
-
 		url.append(base);
 		url.append("amount=").append(this.amount);
 

app/src/main/java/com/luca0n/joguitos/pluck/trivia/TriviaSource.java

@@ -0,0 +1,66 @@
+/*
+Pluck: an open source trivia game for Android
+
+Copyright (C) 2021 Joguitos do luca0N!
+
+This program is free software: you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <https://www.gnu.org/licenses/>.
+
+This game is a fork of LibreTrivia, and its source code is available at
+<https://github.com/tryton-vanmeer/LibreTrivia>.
+
+Contact us at <joguitos+pluck@luca0n.com>.
+*/
+
+package com.luca0n.joguitos.pluck.trivia;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.luca0n.joguitos.pluck.PluckApplication;
+import com.luca0n.joguitos.pluck.R;
+
+public enum TriviaSource {
+    SERVER("server", R.string.source_server),
+    FILE("file", R.string.source_file);
+
+    // Name of source
+    private final String name;
+    // Display name of the source
+    private final int displayName;
+
+    private static final Map<String, TriviaSource> lookup = new HashMap<>();
+
+    static {
+        for (TriviaSource source : TriviaSource.values()) {
+            lookup.put(source.getName(), source);
+        }
+    }
+
+    TriviaSource(String name, int displayName) {
+        this.name = name;
+        this.displayName = displayName;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public static TriviaSource get(String name) {
+        return lookup.get(name);
+    }
+
+    @Override
+    public String toString() {
+        return PluckApplication.getAppContext().getResources().getString(this.displayName);
+    }
+}

app/src/main/java/com/luca0n/joguitos/pluck/util/ApiUtil.java

@@ -43,16 +43,20 @@ import java.net.Proxy;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.util.ArrayList;
+import java.util.Collections;
 
 import com.luca0n.joguitos.pluck.R;
 import com.luca0n.joguitos.pluck.PluckApplication;
 import com.luca0n.joguitos.pluck.exceptions.NoTriviaResultsException;
-import com.luca0n.joguitos.pluck.exceptions.InvalidServerResponseException;
+import com.luca0n.joguitos.pluck.exceptions.InvalidTriviaFormatException;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuery;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuestion;
+import com.luca0n.joguitos.pluck.trivia.TriviaCategory;
+import com.luca0n.joguitos.pluck.trivia.TriviaDifficulty;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuestionBoolean;
 import com.luca0n.joguitos.pluck.trivia.TriviaQuestionMultiple;
 import com.luca0n.joguitos.pluck.trivia.TriviaType;
+import com.luca0n.joguitos.pluck.trivia.TriviaFilters;
 
 public class ApiUtil {
 
@@ -100,18 +104,20 @@ public class ApiUtil {
 		return response;
 	}
 
-	public static String GET(TriviaQuery query) throws IOException {
+	public static String GET(TriviaQuery query)
+			throws IOException {
 		return GET(query.toString());
 	}
 
-	public static ArrayList<TriviaQuestion> jsonToQuestionArray(String json)
+	public static ArrayList<TriviaQuestion> jsonToQuestionArray(String json,
-			throws NoTriviaResultsException, InvalidServerResponseException {
+			TriviaFilters filters) throws NoTriviaResultsException,
+			InvalidTriviaFormatException {
 		JsonObject jsonObject;
 		try{
 			jsonObject = new JsonParser().parse(json).getAsJsonObject();
 		} catch (JsonSyntaxException e){
 			// Unknown server response.
-			throw new InvalidServerResponseException();
+			throw new InvalidTriviaFormatException(e);
 		}
 
 		if (jsonObject.get("response_code").getAsInt() == 1) {
@@ -122,10 +128,25 @@ public class ApiUtil {
 
 		ArrayList<TriviaQuestion> questions = new ArrayList<>();
 
+		int elements = 0;
+
 		for (JsonElement element : jsonArray) {
+			int amount = filters.getAmount();
+			if (amount > 0 && elements++ == amount)
+				break;
 			JsonObject object = element.getAsJsonObject();
 			TriviaType type = TriviaType.get(object.get("type").getAsString());
 
+			TriviaCategory fc = filters.getCategory();
+
+			// Check if this question matches the user specified criteria.
+			if (fc != null &&
+				fc != TriviaCategory.ANY && !object.get("category").getAsString().equals(fc.getName()))
+					continue;
+
+			if (filters.getDifficulty() != TriviaDifficulty.ANY && !object.get("difficulty").getAsString().equals(filters.getDifficulty().getName()))
+				continue;
+
 			if (type == TriviaType.MULTIPLE) {
 				questions.add(TriviaQuestionMultiple.fromJson(object));
 			} else {
@@ -133,6 +154,13 @@ public class ApiUtil {
 			}
 		}
 
+		// Check if there are no questions that match the specified user criteria.
+		if (questions.size() == 0)
+			throw new NoTriviaResultsException();
+
+		// Shuffle the question array.
+		Collections.shuffle(questions);
+
 		return questions;
 	}
 }

app/src/main/res/layout/activity_main.xml

@@ -44,6 +44,16 @@ Contact us at <joguitos+pluck@luca0n.com>.
 			app:layout_constraintBottom_toBottomOf="parent"
 			app:layout_constraintTop_toTopOf="parent">
 
+			<!-- Trivia Source -->
+			<TextView
+				style="@style/TextLabel"
+				android:labelFor="@id/spinner_source"
+				android:text="@string/ui_source" />
+
+			<Spinner
+				android:id="@+id/spinner_source"
+				style="@style/Spinner" />
+
 			<!-- Select Amount -->
 			<TextView
 				style="@style/TextLabel"

app/src/main/res/values/strings.xml

@@ -61,12 +61,17 @@ Contact us at <joguitos+pluck@luca0n.com>.
     <string name="question_type_multiple">Multiple Choice</string>
     <string name="question_type_boolean">True / False</string>
 
+		<!-- Source Names -->
+		<string name="source_server">Server</string>
+		<string name="source_file">File</string>
+
     <!-- UI -->
     <string name="ui_settings">Settings</string>
     <string name="ui_about">About</string>
     <string name="ui_play">Play</string>
     <string name="ui_start_game">Start Game</string>
 		<string name="ui_any">Any</string>
+		<string name="ui_all">All</string>
     <string name="ui_true">True</string>
     <string name="ui_false">False</string>
     <string name="ui_correct">Correct</string>
@@ -81,12 +86,19 @@ Contact us at <joguitos+pluck@luca0n.com>.
     <string name="ui_results_wrong">Wrong Answers</string>
     <string name="ui_results_total">Total Questions</string>
 		<string name="ui_return_to_menu">Return To Menu</string>
+		<string name="ui_source">Source</string>
+		<string name="ui_source_about">This value specifies where the game should retrieve trivia data. By default, the game gathers trivia data from a server, but you can load trivia files with the "File" source option.</string>
 
 		<!-- Error Strings -->
+		<string name="error">Error</string>
 		<string name="error_network"><b>Network error!</b>\n\nCould not connect to a network. Check if your custom server address is correct. If Tor is enabled in the game settings, check if Orbot is running and then try again.</string>
 		<string name="error_no_trivia_results"><b>No trivia results!</b>\n\nWas not able to find trivia questions that satisfied all options.</string>
 		<string name="error_server_response_invalid"><b>Server response error!</b>\n\nCould not parse the server response. The server response may be in a unsupported version. If you are using a custom server, make sure the server address points to a valid address and then try again.</string>
 		<string name="error_unknown"><b>An unknown error occurred!</b></string>
+		<string name="error_source_file_android_version_unsupported">Trivia files are not supported in this version of Android.</string>
+		<string name="error_trivia_file_invalid"><b>Invalid trivia file!</b>\n\nTrivia files should be in a plain text JSON format.</string>
+		<string name="error_trivia_file_fetch_unknown">An unknown error occurred while attempting to read the opened file.</string>
+		<string name="error_option_all_unavailable">The selected question amount is only available for the "File" trivia game source.</string>
 
     <string name="title_activity_settings">Settings</string>
 
@@ -98,6 +110,6 @@ Contact us at <joguitos+pluck@luca0n.com>.
 		<string name="pref_category_network_title">Network</string>
 		<string name="pref_network_tor_title">Connect Using Tor</string>
 		<string name="pref_network_tor_summary">Retrieves trivia data via the Tor network. Requires Orbot (recommended) or a Tor daemon with a SOCKS5 proxy listening on port 9050.</string>
-		<string name="pref_network_server_title">Server address</string>
+		<string name="pref_network_server_title">Server Address</string>
-		<string name="pref_network_server_summary">Specifies the server location used by the game to fetch questions. Leave empty to use the default server.</string>
+		<string name="pref_network_server_summary">Specifies the server location used by the game to fetch questions when using a server as the trivia source. Leave this setting empty to use the default server.</string>
 </resources>