Guardar histórico e melhorar estabilidade do chat

app/src/main/java/com/example/api/MainActivity.java

@@ -1,5 +1,6 @@
 package com.example.api;
 
+import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.view.Gravity;
 import android.view.View;
@@ -16,6 +17,7 @@ import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
 
 import com.google.android.material.button.MaterialButton;
+import com.google.android.material.dialog.MaterialAlertDialogBuilder;
 
 import org.json.JSONArray;
 import org.json.JSONObject;
@@ -32,11 +34,20 @@ import java.nio.charset.StandardCharsets;
 public class MainActivity extends AppCompatActivity {
 
     private static final String API_URL = "https://text.pollinations.ai/openai";
+    private static final String PREFS_NAME = "chat_preferences";
+    private static final String HISTORY_KEY = "chat_history";
+    private static final int MAX_CONTEXT_MESSAGES = 24;
+    private static final int MAX_ATTEMPTS = 3;
+    private static final String WELCOME_MESSAGE =
+            "Olá! Sou uma IA ligada a uma API. Faz-me uma pergunta.";
 
     private LinearLayout messagesContainer;
     private ScrollView chatScroll;
     private EditText promptInput;
     private MaterialButton sendButton;
+    private MaterialButton newChatButton;
+    private SharedPreferences preferences;
+    private JSONArray conversation = new JSONArray();
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -54,10 +65,14 @@ public class MainActivity extends AppCompatActivity {
         chatScroll = findViewById(R.id.chatScroll);
         promptInput = findViewById(R.id.promptInput);
         sendButton = findViewById(R.id.sendButton);
+        newChatButton = findViewById(R.id.newChatButton);
+        preferences = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
 
-        addMessage("Olá! Sou uma IA ligada a uma API. Faz-me uma pergunta.", false);
+        loadConversation();
+        renderConversation();
 
         sendButton.setOnClickListener(v -> sendPrompt());
+        newChatButton.setOnClickListener(v -> confirmNewChat());
         promptInput.setOnEditorActionListener((v, actionId, event) -> {
             if (actionId == EditorInfo.IME_ACTION_SEND) {
                 sendPrompt();
@@ -74,17 +89,21 @@ public class MainActivity extends AppCompatActivity {
         }
 
         promptInput.setText("");
+        addConversationMessage("user", prompt);
         addMessage(prompt, true);
         TextView loadingMessage = addMessage("A pensar...", false);
         setSending(true);
 
         new Thread(() -> {
             try {
-                String answer = askAi(prompt);
-                runOnUiThread(() -> loadingMessage.setText(answer));
+                String answer = askAiWithRetry();
+                runOnUiThread(() -> {
+                    loadingMessage.setText(answer);
+                    addConversationMessage("assistant", answer);
+                });
             } catch (Exception exception) {
                 runOnUiThread(() -> loadingMessage.setText(
-                        "Não consegui ligar à API agora. Verifica a internet e tenta novamente."
+                        "A API está ocupada ou sem ligação. Tenta enviar novamente dentro de alguns segundos."
                 ));
             } finally {
                 runOnUiThread(() -> setSending(false));
@@ -92,11 +111,85 @@ public class MainActivity extends AppCompatActivity {
         }).start();
     }
 
+    private String askAiWithRetry() throws Exception {
+        Exception lastError = null;
+        for (int attempt = 1; attempt <= MAX_ATTEMPTS; attempt++) {
+            try {
+                return askAi();
+            } catch (Exception exception) {
+                lastError = exception;
+                if (attempt < MAX_ATTEMPTS) {
+                    Thread.sleep(attempt * 1200L);
+                }
+            }
+        }
+        throw lastError == null ? new IOException("API unavailable") : lastError;
+    }
+
     private void setSending(boolean sending) {
         sendButton.setEnabled(!sending);
+        newChatButton.setEnabled(!sending);
         sendButton.setText(sending ? "..." : "Enviar");
     }
 
+    private void loadConversation() {
+        String savedHistory = preferences.getString(HISTORY_KEY, "");
+        if (savedHistory != null && !savedHistory.isEmpty()) {
+            try {
+                conversation = new JSONArray(savedHistory);
+            } catch (Exception ignored) {
+                conversation = new JSONArray();
+            }
+        }
+
+        if (conversation.length() == 0) {
+            addConversationMessage("assistant", WELCOME_MESSAGE);
+        }
+    }
+
+    private void renderConversation() {
+        messagesContainer.removeAllViews();
+        for (int i = 0; i < conversation.length(); i++) {
+            JSONObject message = conversation.optJSONObject(i);
+            if (message == null) {
+                continue;
+            }
+            String role = message.optString("role", "");
+            String content = message.optString("content", "");
+            if (!content.isEmpty()) {
+                addMessage(content, "user".equals(role));
+            }
+        }
+    }
+
+    private void addConversationMessage(String role, String content) {
+        try {
+            JSONObject message = new JSONObject();
+            message.put("role", role);
+            message.put("content", content);
+            conversation.put(message);
+            preferences.edit().putString(HISTORY_KEY, conversation.toString()).apply();
+        } catch (Exception ignored) {
+            // The message is still visible even if local storage is unavailable.
+        }
+    }
+
+    private void confirmNewChat() {
+        new MaterialAlertDialogBuilder(this)
+                .setTitle("Começar um novo chat?")
+                .setMessage("A conversa guardada neste dispositivo será apagada.")
+                .setNegativeButton("Cancelar", null)
+                .setPositiveButton("Apagar", (dialog, which) -> resetConversation())
+                .show();
+    }
+
+    private void resetConversation() {
+        conversation = new JSONArray();
+        preferences.edit().remove(HISTORY_KEY).apply();
+        addConversationMessage("assistant", WELCOME_MESSAGE);
+        renderConversation();
+    }
+
     private TextView addMessage(String message, boolean fromUser) {
         LinearLayout row = new LinearLayout(this);
         row.setGravity(fromUser ? Gravity.END : Gravity.START);
@@ -117,50 +210,58 @@ public class MainActivity extends AppCompatActivity {
         return bubble;
     }
 
-    private String askAi(String userPrompt) throws Exception {
+    private String askAi() throws Exception {
         JSONObject systemMessage = new JSONObject();
         systemMessage.put("role", "system");
         systemMessage.put(
                 "content",
-                "Responde sempre em português europeu. "
-                        + "Sê natural, curto e claro, como uma IA de chat para um trabalho da escola."
+                "Responde sempre em português europeu. Sê natural, útil e claro. "
+                        + "Mantém o contexto da conversa e responde como uma IA de chat."
         );
 
-        JSONObject userMessage = new JSONObject();
-        userMessage.put("role", "user");
-        userMessage.put("content", userPrompt);
-
         JSONArray messages = new JSONArray();
         messages.put(systemMessage);
-        messages.put(userMessage);
+
+        int firstMessage = Math.max(0, conversation.length() - MAX_CONTEXT_MESSAGES);
+        for (int i = firstMessage; i < conversation.length(); i++) {
+            JSONObject message = conversation.optJSONObject(i);
+            if (message != null) {
+                messages.put(message);
+            }
+        }
 
         JSONObject requestBody = new JSONObject();
         requestBody.put("model", "openai");
         requestBody.put("messages", messages);
 
         HttpURLConnection connection = (HttpURLConnection) new URL(API_URL).openConnection();
-        connection.setRequestMethod("POST");
-        connection.setConnectTimeout(20000);
-        connection.setReadTimeout(60000);
-        connection.setDoOutput(true);
-        connection.setRequestProperty("Content-Type", "application/json");
+        try {
+            connection.setRequestMethod("POST");
+            connection.setConnectTimeout(20000);
+            connection.setReadTimeout(70000);
+            connection.setDoOutput(true);
+            connection.setRequestProperty("Content-Type", "application/json");
+            connection.setRequestProperty("Accept", "application/json");
 
-        byte[] body = requestBody.toString().getBytes(StandardCharsets.UTF_8);
-        try (OutputStream outputStream = connection.getOutputStream()) {
-            outputStream.write(body);
+            byte[] body = requestBody.toString().getBytes(StandardCharsets.UTF_8);
+            try (OutputStream outputStream = connection.getOutputStream()) {
+                outputStream.write(body);
+            }
+
+            int responseCode = connection.getResponseCode();
+            InputStream stream = responseCode >= 200 && responseCode < 300
+                    ? connection.getInputStream()
+                    : connection.getErrorStream();
+            String response = readStream(stream);
+
+            if (responseCode < 200 || responseCode >= 300) {
+                throw new IOException("API error: " + responseCode);
+            }
+
+            return readAiText(response);
+        } finally {
+            connection.disconnect();
         }
-
-        int responseCode = connection.getResponseCode();
-        InputStream stream = responseCode >= 200 && responseCode < 300
-                ? connection.getInputStream()
-                : connection.getErrorStream();
-        String response = readStream(stream);
-
-        if (responseCode < 200 || responseCode >= 300) {
-            throw new IOException("API error: " + responseCode);
-        }
-
-        return readAiText(response);
     }
 
     private String readStream(InputStream stream) throws IOException {
@@ -200,4 +301,3 @@ public class MainActivity extends AppCompatActivity {
         return Math.round(value * getResources().getDisplayMetrics().density);
     }
 }
-q

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

@@ -12,30 +12,52 @@
 
     <LinearLayout
         android:layout_width="match_parent"
-        android:layout_height="150dp"
+        android:layout_height="160dp"
         android:background="@drawable/bg_chat_header"
-        android:gravity="bottom"
-        android:orientation="vertical"
+        android:gravity="bottom|center_vertical"
+        android:orientation="horizontal"
         android:paddingStart="24dp"
         android:paddingEnd="24dp"
         android:paddingBottom="24dp">
 
-        <TextView
-            android:layout_width="match_parent"
+        <LinearLayout
+            android:layout_width="0dp"
             android:layout_height="wrap_content"
-            android:includeFontPadding="false"
-            android:text="Chat IA"
-            android:textColor="@color/white"
-            android:textSize="30sp"
-            android:textStyle="bold" />
+            android:layout_marginEnd="12dp"
+            android:layout_weight="1"
+            android:orientation="vertical">
 
-        <TextView
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="6dp"
-            android:text="Pergunta alguma coisa e recebe uma resposta da IA."
-            android:textColor="#EEF9F7"
-            android:textSize="15sp" />
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:includeFontPadding="false"
+                android:text="Chat IA"
+                android:textColor="@color/white"
+                android:textSize="30sp"
+                android:textStyle="bold" />
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="6dp"
+                android:text="A conversa fica guardada neste dispositivo."
+                android:textColor="#EEF9F7"
+                android:textSize="14sp" />
+        </LinearLayout>
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/newChatButton"
+            android:layout_width="104dp"
+            android:layout_height="46dp"
+            android:text="Novo chat"
+            android:textAllCaps="false"
+            android:textColor="@color/white"
+            android:textSize="13sp"
+            android:textStyle="bold"
+            app:backgroundTint="#26FFFFFF"
+            app:cornerRadius="18dp"
+            app:strokeColor="#70FFFFFF"
+            app:strokeWidth="1dp" />
     </LinearLayout>
 
     <ScrollView