Add AI chat feature

composeApp/src/commonMain/composeResources/values/strings.xml

@@ -17,6 +17,10 @@
     <string name="title_settings">Settings</string>
     <string name="title_profile">Profile</string>
     <string name="title_statistics">Statistics</string>
+    <string name="chat_title">AI Chat</string>
+    <string name="chat_message_hint">Enter message</string>
+    <string name="chat_api_key_hint">OpenAI API Key</string>
+    <string name="chat_send">Send</string>
 
     <string name="title_start_date">Start Date</string>
     <string name="title_end_date">End Date</string>

composeApp/src/commonMain/kotlin/feature/chat/presentation/ChatViewModel.kt

@@ -0,0 +1,39 @@
+package feature.chat.presentation
+
+import base.BaseViewModel
+import feature.chat.presentation.models.ChatAction
+import feature.chat.presentation.models.ChatEvent
+import feature.chat.presentation.models.ChatMessage
+import feature.chat.presentation.models.ChatViewState
+
+class ChatViewModel : BaseViewModel<ChatViewState, ChatAction, ChatEvent>(
+    initialState = ChatViewState()
+) {
+    override fun obtainEvent(viewEvent: ChatEvent) {
+        when (viewEvent) {
+            is ChatEvent.MessageChanged -> viewState = viewState.copy(currentMessage = viewEvent.text)
+            is ChatEvent.ApiKeyChanged -> viewState = viewState.copy(apiKey = viewEvent.key)
+            ChatEvent.SendClicked -> sendMessage()
+        }
+    }
+
+    private fun sendMessage() {
+        val text = viewState.currentMessage.trim()
+        if (text.isEmpty()) return
+        val updatedMessages = viewState.messages + ChatMessage(text, true)
+        val reply = generateReply(text)
+        viewState = viewState.copy(
+            messages = updatedMessages + ChatMessage(reply, false),
+            currentMessage = ""
+        )
+    }
+
+    private fun generateReply(message: String): String {
+        val calories = message.filter { it.isDigit() }.toIntOrNull()
+        return if (calories != null) {
+            "You logged $calories kcal. Consider adjusting your meal plan if this exceeds your goal."
+        } else {
+            "Thanks for the message!"
+        }
+    }
+}

composeApp/src/commonMain/kotlin/feature/chat/presentation/models/ChatAction.kt

@@ -0,0 +1,3 @@
+package feature.chat.presentation.models
+
+sealed class ChatAction

composeApp/src/commonMain/kotlin/feature/chat/presentation/models/ChatEvent.kt

@@ -0,0 +1,7 @@
+package feature.chat.presentation.models
+
+sealed class ChatEvent {
+    data class MessageChanged(val text: String) : ChatEvent()
+    data class ApiKeyChanged(val key: String) : ChatEvent()
+    data object SendClicked : ChatEvent()
+}

composeApp/src/commonMain/kotlin/feature/chat/presentation/models/ChatMessage.kt

@@ -0,0 +1,6 @@
+package feature.chat.presentation.models
+
+data class ChatMessage(
+    val text: String,
+    val isUser: Boolean
+)

composeApp/src/commonMain/kotlin/feature/chat/presentation/models/ChatViewState.kt

@@ -0,0 +1,7 @@
+package feature.chat.presentation.models
+
+data class ChatViewState(
+    val messages: List<ChatMessage> = emptyList(),
+    val currentMessage: String = "",
+    val apiKey: String = ""
+)

composeApp/src/commonMain/kotlin/feature/chat/ui/ChatScreen.kt

@@ -0,0 +1,114 @@
+package feature.chat.ui
+
+import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.*
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.navigation.NavController
+import feature.chat.presentation.ChatViewModel
+import feature.chat.presentation.models.ChatEvent
+import feature.chat.presentation.models.ChatMessage
+import org.jetbrains.compose.resources.stringResource
+import tech.mobiledeveloper.jethabit.resources.Res
+import tech.mobiledeveloper.jethabit.resources.chat_api_key_hint
+import tech.mobiledeveloper.jethabit.resources.chat_message_hint
+import tech.mobiledeveloper.jethabit.resources.chat_send
+import tech.mobiledeveloper.jethabit.resources.chat_title
+import ui.themes.JetHabitTheme
+import ui.themes.components.JetHabitButton
+
+@Composable
+fun ChatScreen(
+    navController: NavController,
+    viewModel: ChatViewModel = viewModel { ChatViewModel() }
+) {
+    val viewState by viewModel.viewStates().collectAsState()
+
+    ChatView(viewState = viewState) { viewModel.obtainEvent(it) }
+}
+
+@Composable
+private fun ChatView(viewState: feature.chat.presentation.models.ChatViewState, eventHandler: (ChatEvent) -> Unit) {
+    Surface(
+        modifier = Modifier.fillMaxSize(),
+        color = JetHabitTheme.colors.primaryBackground
+    ) {
+        Column(modifier = Modifier.fillMaxSize().padding(JetHabitTheme.shapes.padding)) {
+            OutlinedTextField(
+                value = viewState.apiKey,
+                onValueChange = { eventHandler(ChatEvent.ApiKeyChanged(it)) },
+                modifier = Modifier.fillMaxWidth(),
+                label = { Text(stringResource(Res.string.chat_api_key_hint)) },
+                colors = TextFieldDefaults.outlinedTextFieldColors(
+                    textColor = JetHabitTheme.colors.primaryText,
+                    focusedBorderColor = JetHabitTheme.colors.tintColor,
+                    unfocusedBorderColor = JetHabitTheme.colors.secondaryText,
+                    focusedLabelColor = JetHabitTheme.colors.tintColor,
+                    unfocusedLabelColor = JetHabitTheme.colors.secondaryText
+                )
+            )
+
+            Spacer(modifier = Modifier.height(16.dp))
+
+            LazyColumn(
+                modifier = Modifier.weight(1f).fillMaxWidth()
+            ) {
+                items(viewState.messages) { message ->
+                    ChatRow(message)
+                }
+            }
+
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                verticalAlignment = Alignment.CenterVertically
+            ) {
+                OutlinedTextField(
+                    value = viewState.currentMessage,
+                    onValueChange = { eventHandler(ChatEvent.MessageChanged(it)) },
+                    modifier = Modifier.weight(1f),
+                    label = { Text(stringResource(Res.string.chat_message_hint)) },
+                    colors = TextFieldDefaults.outlinedTextFieldColors(
+                        textColor = JetHabitTheme.colors.primaryText,
+                        focusedBorderColor = JetHabitTheme.colors.tintColor,
+                        unfocusedBorderColor = JetHabitTheme.colors.secondaryText,
+                        focusedLabelColor = JetHabitTheme.colors.tintColor,
+                        unfocusedLabelColor = JetHabitTheme.colors.secondaryText
+                    )
+                )
+
+                Spacer(modifier = Modifier.width(8.dp))
+
+                JetHabitButton(
+                    onClick = { eventHandler(ChatEvent.SendClicked) },
+                    text = stringResource(Res.string.chat_send)
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun ChatRow(message: ChatMessage) {
+    Row(
+        modifier = Modifier.fillMaxWidth().padding(vertical = 4.dp),
+        horizontalArrangement = if (message.isUser) Arrangement.End else Arrangement.Start
+    ) {
+        Surface(
+            shape = MaterialTheme.shapes.medium,
+            color = if (message.isUser) JetHabitTheme.colors.tintColor else JetHabitTheme.colors.secondaryBackground
+        ) {
+            Text(
+                text = message.text,
+                modifier = Modifier.padding(8.dp),
+                color = if (message.isUser) MaterialTheme.colors.onPrimary else JetHabitTheme.colors.primaryText
+            )
+        }
+    }
+}

composeApp/src/commonMain/kotlin/navigation/AppScreens.kt

@@ -4,6 +4,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Favorite
 import androidx.compose.material.icons.filled.Home
 import androidx.compose.material.icons.filled.Person
+import androidx.compose.material.icons.filled.Chat
 import androidx.compose.material.icons.outlined.Check
 import androidx.compose.ui.graphics.vector.ImageVector
 import org.jetbrains.compose.resources.StringResource
@@ -12,6 +13,7 @@ import tech.mobiledeveloper.jethabit.resources.health_tab
 import tech.mobiledeveloper.jethabit.resources.title_daily
 import tech.mobiledeveloper.jethabit.resources.title_profile
 import tech.mobiledeveloper.jethabit.resources.title_statistics
+import tech.mobiledeveloper.jethabit.resources.chat_title
 
 enum class AppScreens(
     val title: String,
@@ -21,5 +23,6 @@ enum class AppScreens(
     Daily("daily", Icons.Default.Home, Res.string.title_daily),
     Health("health", Icons.Default.Favorite, Res.string.health_tab),
     Statistics("statistics", Icons.Outlined.Check, Res.string.title_statistics),
+    Chat("chat", Icons.Default.Chat, Res.string.chat_title),
     Profile("profile", Icons.Default.Person, Res.string.title_profile)
 } 

composeApp/src/commonMain/kotlin/navigation/MainScreen.kt

@@ -17,6 +17,7 @@ import feature.daily.ui.DailyScreen
 import feature.detail.ui.DetailScreen
 import feature.health.list.ui.HealthScreen
 import feature.health.track.ui.TrackHabitScreen
+import feature.chat.ui.ChatScreen
 import screens.settings.SettingsScreen
 import feature.statistics.ui.StatisticsScreen
 import feature.create.ui.ComposeScreen
@@ -33,6 +34,10 @@ enum class HealthScreens {
     Start, Track, Create
 }
 
+enum class ChatScreens {
+    Start
+}
+
 @OptIn(ExperimentalFoundationApi::class, ExperimentalMaterialApi::class,
     ExperimentalComposeUiApi::class
 )
@@ -43,6 +48,7 @@ fun MainScreen() {
         AppScreens.Daily,
         AppScreens.Health,
         AppScreens.Statistics,
+        AppScreens.Chat,
         AppScreens.Profile
     )
 
@@ -73,9 +79,12 @@ fun MainScreen() {
                     ComposeScreen(type = type)
                 }
             }
-            composable(AppScreens.Statistics.title) { 
+            composable(AppScreens.Statistics.title) {
                 StatisticsScreen()
             }
+            composable(AppScreens.Chat.title) {
+                ChatScreen(navController)
+            }
             navigation(
                 startDestination = ProfileScreens.Start.name,
                 route = AppScreens.Profile.title