Écran pour ajouter un étudiant à une liste.

Sauvegarde d’une fiche de présence dans une session.

app/src/main/java/com/example/palto/NfcViewModel.kt

@@ -0,0 +1,22 @@
+package com.example.palto
+
+import android.nfc.Tag
+import android.util.Log
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import com.example.palto.domain.Card
+import com.example.palto.domain.Event
+import com.example.palto.domain.User
+
+class NfcViewModel: ViewModel() {
+
+    private var _tagId = MutableLiveData<Event<String>>()
+    val tagId: LiveData<Event<String>> = _tagId
+
+    @OptIn(ExperimentalStdlibApi::class)
+    fun setTag(tag: Tag) {
+        Log.d("Nfc", "A new tag has been set.")
+        _tagId.postValue(Event(tag.id.toHexString()))
+    }
+}

app/src/main/java/com/example/palto/PaltoActivity.kt

@@ -11,8 +11,7 @@ import androidx.navigation.fragment.NavHostFragment
 import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.setupWithNavController
 import com.example.palto.databinding.ActivityPaltoBinding
-import com.example.palto.ui.NfcViewModel
+import com.example.palto.ui.CardViewModel
-import com.example.palto.ui.UserViewModel
 
 
 class PaltoActivity : AppCompatActivity() {
@@ -21,8 +20,6 @@ class PaltoActivity : AppCompatActivity() {
 
     private val nfcViewModel: NfcViewModel by viewModels()
 
-    private val userViewModel: UserViewModel by viewModels() { UserViewModel.Factory }
-
     private lateinit var binding: ActivityPaltoBinding
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -81,7 +78,7 @@ class PaltoActivity : AppCompatActivity() {
         // Begin to read NFC Cards.
         nfcAdapter?.enableReaderMode(
             this,
-            nfcViewModel.tag::postValue,
+            nfcViewModel::setTag,
             NfcAdapter.FLAG_READER_NFC_A or NfcAdapter.FLAG_READER_SKIP_NDEF_CHECK,
             null
         )

app/src/main/java/com/example/palto/domain/Attendance.kt

@@ -1,10 +1,12 @@
 package com.example.palto.domain
 import java.io.Serializable
+import java.time.LocalTime
 
 /**
  * Data class that captures tokens for logged in users retrieved from LoginRepository
  */
 data class Attendance(
-    val date: String,
+    val id: Int,
-    val access: String
+    val student: User,
+    val date: LocalTime
 ) : Serializable

app/src/main/java/com/example/palto/domain/Card.kt

@@ -1,22 +1,7 @@
 package com.example.palto.domain
 
 data class Card(
-    val id: String,
+    val id: Int,
-    val uid: ByteArray,
+    val tagId: String,
-    val department: String,
+    val user: User,
-    val owner: String
+)
-) {
-    override fun equals(other: Any?): Boolean {
-        if (this === other) return true
-        if (javaClass != other?.javaClass) return false
-
-        other as Card
-
-        return uid.contentEquals(other.uid)
-    }
-
-    override fun hashCode(): Int {
-        return uid.contentHashCode()
-    }
-
-}

app/src/main/java/com/example/palto/domain/Event.kt

@@ -0,0 +1,18 @@
+package com.example.palto.domain
+
+class Event<out T>(private val content: T) {
+
+    var hasBeenHandled = false
+        private set
+
+    fun getContentIfNotHandled(): T? {
+        return if (hasBeenHandled) {
+            null
+        } else {
+            hasBeenHandled = true
+            content
+        }
+    }
+
+    fun peekContent(): T = content
+}

app/src/main/java/com/example/palto/domain/Session.kt

@@ -7,5 +7,6 @@ import java.io.Serializable
 data class Session(
     val id: Int,
     val name: String,
-    var attendances: List<User>
+    var attendances: List<Attendance>
+    // When the list is updated, it is replaced by a new one.
 )

app/src/main/java/com/example/palto/domain/User.kt

@@ -4,10 +4,9 @@ package com.example.palto.domain
  * Data class that captures user information for logged in users retrieved from LoginRepository
  */
 data class User(
-    //Not in the domain layer
+    val id: Int,
-    //val id: String,
     val username: String,
-    val first_name: String,
+    val firstName: String,
-    val last_name: String,
+    val lastName: String,
     val email: String
 )

app/src/main/java/com/example/palto/ui/CardViewModel.kt

@@ -0,0 +1,34 @@
+package com.example.palto.ui
+
+import android.nfc.Tag
+import android.util.Log
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import com.example.palto.domain.Card
+import com.example.palto.domain.User
+
+/**
+ * CardViewModel maintain a list of cards application wide.
+ * May be converted in a repository.
+ */
+class CardViewModel: ViewModel() {
+
+    private var _cards = MutableLiveData<List<Card>>()
+    private val cards: LiveData<List<Card>> = _cards
+
+    fun createCard(user: User, tagId: String): Card {
+        val list = _cards.value ?: emptyList()
+        val card = Card(list.size, tagId, user)
+        _cards.value = list + card
+        Log.d("Palto", "CardViewModel: a card has been added into the list.")
+        return card
+    }
+
+    fun getCard(tagId: String): Card? {
+        val card = _cards.value?.find() {
+            it.tagId == tagId
+        }
+        return card
+    }
+}

app/src/main/java/com/example/palto/ui/NfcViewModel.kt

@@ -1,14 +0,0 @@
-package com.example.palto.ui
-
-import android.nfc.Tag
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
-import androidx.lifecycle.ViewModel
-import com.example.palto.domain.User
-
-class NfcViewModel: ViewModel() {
-    val tag = MutableLiveData<Tag>()
-
-    private var _user : MutableLiveData<User> = MutableLiveData<User>()
-    val user : LiveData<User> = _user
-}

app/src/main/java/com/example/palto/ui/UserViewModel.kt

@@ -4,75 +4,28 @@ import android.util.Log
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
+import com.example.palto.domain.Card
-import androidx.lifecycle.viewModelScope
-import com.example.palto.R
-import com.example.palto.data.repository.TokenRepository
-import com.example.palto.data.repository.UserRepository
 import com.example.palto.domain.User
-import com.example.palto.ui.login.LoginResult
-import kotlinx.coroutines.launch
 
-class UserViewModel(
+/**
-    private val tokenRepository: TokenRepository,
+ * UserViewModel maintain a list of users application wide.
-    private val userRepository: UserRepository
+ * May be converted into a repository.
-): ViewModel() {
+ */
+class UserViewModel: ViewModel() {
 
-    private var _result = MutableLiveData<LoginResult>()
+    private var _users = MutableLiveData<List<User>>()
-    val result = _result as LiveData<LoginResult>
+    val users : LiveData<List<User>> = _users
 
-    // User is initially set to null to be disconnected.
+    fun createUser(username: String): User {
-    private var _user = MutableLiveData<User?>(null)
+        val list = _users.value ?: emptyList()
-    val user = _user as LiveData<User?>
+        val user = User(
-
+            id = list.size,
-    fun login(
+            username = username,
-        hostname: String,
+            firstName = "",
-        username: String,
+            lastName = "",
-        password: String) {
+            email = "")
-
+        _users.value = list + user
-        // Coroutine runs in background.
+        Log.d("Palto", "UserViewModel: a user has been added into the list.")
-        viewModelScope.launch {
+        return user
-            try {
-                tokenRepository.authenticate(hostname, username, password)
-                _user.value = User(
-                    username,
-                    "",
-                    "",
-                    ""
-                )
-                _result.value = LoginResult(success = true)
-            } catch (e: Exception) {
-                Log.e("Palto", "Connection error: " + e.message)
-                _result.value = LoginResult(
-                    success = false,
-                    error = R.string.login_failed,
-                    exception = e
-                )
-            }
-        }
-    }
-
-    fun loginAnonymous() {
-        _user.value = User(
-            "anonymous", "", "", ""
-        )
-        _result.value = LoginResult(success = true)
-    }
-
-    fun logout() {
-        _user.value = null
-        _result.value = LoginResult(success = false)
-    }
-
-    companion object {
-
-        val Factory: ViewModelProvider.Factory = object : ViewModelProvider.Factory {
-            override fun <T : ViewModel> create(modelClass: Class<T>): T {
-                return UserViewModel(
-                    tokenRepository = TokenRepository(),
-                    userRepository = UserRepository()
-                ) as T
-            }
-        }
     }
 }

app/src/main/java/com/example/palto/ui/login/LoginFragment.kt

@@ -8,22 +8,16 @@ import android.view.ViewGroup
 import android.widget.Toast
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
 import com.example.palto.databinding.FragmentLoginBinding
-import com.example.palto.ui.UserViewModel
 
 class LoginFragment : Fragment() {
 
-    // loginViewModel is used to update the login screen dynamically.
-    private val loginViewModel: LoginViewModel by viewModels()
-
     // userViewModel is where the user is logged in, at the activity level.
-    private val userViewModel: UserViewModel by activityViewModels() { UserViewModel.Factory }
+    private val loginViewModel: LoginViewModel by activityViewModels() { LoginViewModel.Factory }
 
     private lateinit var binding: FragmentLoginBinding
 
-    @SuppressLint("SetTextI18n")
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
@@ -36,7 +30,7 @@ class LoginFragment : Fragment() {
         // Bind the login button.
         binding.login.setOnClickListener {
             binding.loading.visibility = View.VISIBLE
-            userViewModel.login(
+            loginViewModel.login(
                 binding.hostname.text.toString(),
                 binding.username.text.toString(),
                 binding.password.text.toString()
@@ -45,16 +39,16 @@ class LoginFragment : Fragment() {
 
         // Bind anonymous login clickable text.
         binding.loginAnonymous.setOnClickListener {
-            userViewModel.loginAnonymous()
+            loginViewModel.loginAnonymous()
         }
 
         // On result of logging.
-        userViewModel.result.observe(viewLifecycleOwner) {
+        loginViewModel.result.observe(viewLifecycleOwner) {
             binding.loading.visibility = View.GONE
             if (it.success) {
                 navController.popBackStack()
             } else if (it.error != null) {
-                binding.loginError.text = "Exception : " + it.exception.toString()
+                binding.loginError.text = "Exception : ${it.exception.toString()}"
                 Toast.makeText(activity, it.error, Toast.LENGTH_LONG).show()
             }
         }

app/src/main/java/com/example/palto/ui/login/LoginViewModel.kt

@@ -1,41 +1,106 @@
 package com.example.palto.ui.login
 
+import android.util.Log
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import com.example.palto.R
+import com.example.palto.data.repository.TokenRepository
+import com.example.palto.data.repository.UserRepository
+import com.example.palto.domain.User
+import kotlinx.coroutines.launch
 
 /**
- * View Model to check dynamically the values of the form.
+ * LoginViewModel to access information about the logged in user and login form.
  */
-class LoginViewModel() : ViewModel() {
+class LoginViewModel(
+    private val tokenRepository: TokenRepository,
+    private val userRepository: UserRepository
+): ViewModel() {
+
+    private var _result = MutableLiveData<LoginResult>()
+    val result = _result as LiveData<LoginResult>
+
+    // User is initially set to null to be disconnected.
+    private var _user = MutableLiveData<User?>(null)
+    val user = _user as LiveData<User?>
+
     /*
     private val _loginFormState = MutableLiveData<LoginFormState>()
     val loginFormState: LiveData<LoginFormState> = _loginFormState
+    */
 
-    fun loginDataChanged(
+    fun login(
         hostname: String,
         username: String,
         password: String) {
-        if (!isHostNameValid(hostname)) {
+
-            _loginForm.value = LoginFormState(hostnameError = R.string.invalid_hostname)
+        // Coroutine runs in background.
-        } else if (!isUserNameValid(username)) {
+        viewModelScope.launch {
-            _loginForm.value = LoginFormState(usernameError = R.string.invalid_username)
+            try {
-        } else if (!isPasswordValid(password)) {
+                tokenRepository.authenticate(hostname, username, password)
-            _loginForm.value = LoginFormState(passwordError = R.string.invalid_password)
+                _user.value = User(-1, username, "", "", "")
-        } else {
+                _result.value = LoginResult(success = true)
-            _loginForm.value = LoginFormState(isDataValid = true)
+            } catch (e: Exception) {
+                Log.e("Palto", "Connection error: " + e.message)
+                _result.value = LoginResult(
+                    success = false,
+                    error = R.string.login_failed,
+                    exception = e
+                )
+            }
         }
     }
+
+    fun loginAnonymous() {
+        _user.value = User(-2, "anonymous", "", "", "")
+        _result.value = LoginResult(success = true)
+    }
+
+    fun logout() {
+        _user.value = null
+        _result.value = LoginResult(success = false)
+    }
+
+    /*
+    fun loginDataChanged(
+    hostname: String,
+    username: String,
+    password: String) {
+    if (!isHostNameValid(hostname)) {
+        _loginForm.value = LoginFormState(hostnameError = R.string.invalid_hostname)
+    } else if (!isUserNameValid(username)) {
+        _loginForm.value = LoginFormState(usernameError = R.string.invalid_username)
+    } else if (!isPasswordValid(password)) {
+        _loginForm.value = LoginFormState(passwordError = R.string.invalid_password)
+    } else {
+        _loginForm.value = LoginFormState(isDataValid = true)
+    }
+    }
     private fun isHostNameValid(hostname: String): Boolean {
-        return hostname.isNotBlank()
+    return hostname.isNotBlank()
     }
 
     private fun isUserNameValid(username: String): Boolean {
-        return username.isNotBlank()
+    return username.isNotBlank()
     }
 
     private fun isPasswordValid(password: String): Boolean {
-        return password.length > 5
+    return password.length > 5
+    }
+    */
+
+    companion object {
+
+        val Factory: ViewModelProvider.Factory = object : ViewModelProvider.Factory {
+            override fun <T : ViewModel> create(modelClass: Class<T>): T {
+                return LoginViewModel(
+                    tokenRepository = TokenRepository(),
+                    userRepository = UserRepository()
+                ) as T
+            }
+        }
     }
-     */
 }
-
-

app/src/main/java/com/example/palto/ui/menu/MenuFragment.kt

@@ -12,7 +12,7 @@ import androidx.navigation.navGraphViewModels
 import com.example.palto.R
 import com.example.palto.databinding.FragmentMenuListBinding
 import com.example.palto.domain.Session
-import com.example.palto.ui.UserViewModel
+import com.example.palto.ui.login.LoginViewModel
 
 /**
  * A fragment representing a list of Sessions.
@@ -22,8 +22,8 @@ class MenuFragment : Fragment() {
     private val menuViewModel: MenuViewModel by
         navGraphViewModels(R.id.nav_graph) { MenuViewModel.Factory }
 
-    private val userViewModel: UserViewModel by
+    private val loginViewModel: LoginViewModel by
-        activityViewModels() { UserViewModel.Factory }
+        activityViewModels() { LoginViewModel.Factory }
 
     // This property is only valid between onCreateView and onDestroyView
     private lateinit var binding: FragmentMenuListBinding
@@ -38,7 +38,7 @@ class MenuFragment : Fragment() {
         val navController = findNavController()
 
         // Connect the user.
-        userViewModel.user.observe(viewLifecycleOwner) {
+        loginViewModel.user.observe(viewLifecycleOwner) {
             if (it != null) {
                 // Get sessions of the user from remote.
             } else {

app/src/main/java/com/example/palto/ui/menu/MenuViewModel.kt

@@ -5,14 +5,16 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import com.example.palto.data.repository.TokenRepository
+import com.example.palto.domain.Attendance
-import com.example.palto.data.repository.UserRepository
 import com.example.palto.domain.Session
-import com.example.palto.ui.UserViewModel
 
+/**
+ * ViewModel for accessing all the sessions created.
+ */
 class MenuViewModel() : ViewModel() {
 
-    private var _sessions = MutableLiveData<List<Session>>(emptyList())
+    // A list of sessions.
+    private var _sessions = MutableLiveData<List<Session>>()
     val sessions: LiveData<List<Session>> = _sessions
 
     fun createSession(name: String) {
@@ -26,6 +28,14 @@ class MenuViewModel() : ViewModel() {
         Log.d("Palto", "MenuViewModel: A session has been added into the list.")
     }
 
+    fun getSession(id: Int): Session? {
+        return _sessions.value?.find { it.id == id }
+    }
+
+    fun setAttendanceListSession(id: Int, list: List<Attendance>) {
+        getSession(id)?.let { it.attendances = list }
+    }
+
     companion object {
 
         val Factory: ViewModelProvider.Factory = object : ViewModelProvider.Factory {

app/src/main/java/com/example/palto/ui/menu/new_session/NewSessionFragment.kt

@@ -0,0 +1,46 @@
+package com.example.palto.ui.menu.new_session
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.appcompat.view.menu.MenuView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.navGraphViewModels
+import com.example.palto.R
+import com.example.palto.databinding.FragmentNewSessionBinding
+import com.example.palto.ui.menu.MenuViewModel
+
+/**
+ *
+ */
+class NewSessionFragment : Fragment() {
+
+    private val newSessionViewModel: NewSessionViewModel by viewModels()
+
+    private val menuViewModel: MenuViewModel by
+        navGraphViewModels(R.id.nav_graph) { MenuViewModel.Factory }
+
+    // This property is only valid between onCreateView and onDestroyView
+    private lateinit var binding: FragmentNewSessionBinding
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        binding = FragmentNewSessionBinding.inflate(inflater, container, false)
+
+        // Bind the create button
+        binding.newSessionCreate.setOnClickListener {
+            menuViewModel.createSession(
+                name = binding.newSessionName.text.toString()
+            )
+            findNavController().popBackStack()
+        }
+
+        return binding.root
+    }
+}

app/src/main/java/com/example/palto/ui/menu/new_session/NewSessionViewModel.kt

@@ -0,0 +1,8 @@
+package com.example.palto.ui.menu.new_session
+
+import androidx.lifecycle.ViewModel
+
+/**
+ * ViewModel of the session creation form. Used for verification.
+ */
+class NewSessionViewModel() : ViewModel()

app/src/main/java/com/example/palto/ui/session/SessionAdapter.kt

@@ -7,47 +7,46 @@ import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
 import com.example.palto.databinding.FragmentSessionItemBinding
+import com.example.palto.domain.Attendance
 import com.example.palto.domain.Card
+import java.time.format.DateTimeFormatter
 
 /**
- * A [ListAdapter] that can display [Card] items.
+ * A [ListAdapter] that can display [Attendance] items.
  */
-class SessionAdapter :
+class SessionAdapter : ListAdapter<Attendance, SessionAdapter.ViewHolder>(AttendanceDiffCallback) {
-    ListAdapter<Card, SessionAdapter.ViewHolder>(CardDiffCallback) {
+
+
+    inner class ViewHolder(binding: FragmentSessionItemBinding) :
+            RecyclerView.ViewHolder(binding.root) {
+        private val attendanceUsernameText: TextView = binding.attendanceUsername
+        private val attendanceDate: TextView = binding.attendanceDate
+
+        fun bind(attendance: Attendance) {
+            attendanceUsernameText.text = attendance.student.username
+            attendanceDate.text = attendance.date.format(DateTimeFormatter.ofPattern("HH:mm:ss"))
+        }
+    }
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
-        return ViewHolder(
+        val binding = FragmentSessionItemBinding
-            FragmentSessionItemBinding.inflate(
+            .inflate(LayoutInflater.from(parent.context), parent, false)
-                LayoutInflater.from(parent.context),
+        return ViewHolder(binding)
-                parent,
-                false
-            )
-        )
     }
 
     @OptIn(ExperimentalStdlibApi::class)
     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
         val item = getItem(position)
-        holder.cardId.text = item.uid.toHexString()
+        holder.bind(item)
-    }
-
-    inner class ViewHolder(
-        binding: FragmentSessionItemBinding
-    ) : RecyclerView.ViewHolder(binding.root) {
-
-        val cardId: TextView = binding.cardId
-        override fun toString(): String {
-            return super.toString() + " '" + cardId.text + "'"
-        }
     }
 }
 
-object CardDiffCallback : DiffUtil.ItemCallback<Card>() {
+object AttendanceDiffCallback : DiffUtil.ItemCallback<Attendance>() {
-    override fun areItemsTheSame(oldItem: Card, newItem: Card): Boolean {
+    override fun areItemsTheSame(oldItem: Attendance, newItem: Attendance): Boolean {
         return oldItem == newItem
     }
 
-    override fun areContentsTheSame(oldItem: Card, newItem: Card): Boolean {
+    override fun areContentsTheSame(oldItem: Attendance, newItem: Attendance): Boolean {
         return oldItem.id == newItem.id
     }
 }

app/src/main/java/com/example/palto/ui/session/SessionFragment.kt

@@ -5,12 +5,18 @@ import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
+import androidx.core.os.bundleOf
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Lifecycle
+import androidx.navigation.fragment.findNavController
 import androidx.navigation.navGraphViewModels
-import com.example.palto.ui.NfcViewModel
+import com.example.palto.NfcViewModel
 import com.example.palto.R
 import com.example.palto.databinding.FragmentSessionListBinding
+import com.example.palto.ui.CardViewModel
+import com.example.palto.ui.menu.MenuViewModel
 
 /**
  * A fragment representing a list of attendances.
@@ -20,12 +26,16 @@ class SessionFragment : Fragment() {
     private val sessionViewModel: SessionViewModel by
         navGraphViewModels(R.id.nav_graph) { SessionViewModel.Factory }
 
-    private val nfcViewModel: NfcViewModel by
+    private val menuViewModel: MenuViewModel by
-        activityViewModels()
+        navGraphViewModels(R.id.nav_graph) { MenuViewModel.Factory }
+
+    private val cardViewModel: CardViewModel by
+        navGraphViewModels(R.id.nav_graph)
+
+    private val nfcViewModel: NfcViewModel by activityViewModels()
 
-    private var _binding: FragmentSessionListBinding? = null
     // This property is only valid between onCreateView and onDestroyView
-    private val binding get() = _binding!!
+    private lateinit var binding: FragmentSessionListBinding
 
     /**
      * Have the fragment instantiate the user interface.
@@ -35,25 +45,62 @@ class SessionFragment : Fragment() {
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        _binding = FragmentSessionListBinding.inflate(inflater, container, false)
+        binding = FragmentSessionListBinding.inflate(inflater, container, false)
+
+        // If the bundle value id of key "session" is not empty,
+        // set the attendance list to that of the selected session.
+        arguments?.getInt("session")?.let { id ->
+            val session = menuViewModel.getSession(id)
+            if (session != null) {
+                Log.d("Palto", "SessionFragment: Session id ${session.id} has been found.")
+                sessionViewModel.session = session
+                sessionViewModel.setAttendanceList(session.attendances)
+            }
+        }
 
         // Set the adapter of the view for managing automatically the list of items on the screen.
         val adapter = SessionAdapter()
         binding.sessionList.adapter = adapter
-        sessionViewModel.cards.observe(viewLifecycleOwner) {
+        sessionViewModel.attendances.observe(viewLifecycleOwner) {
             adapter.submitList(it)
         }
 
         // Set the listener for a new NFC tag.
-        nfcViewModel.tag.observe(viewLifecycleOwner) {
+        nfcViewModel.tagId.observe(viewLifecycleOwner) {
-            Log.d("NFC", "The tag observers has been notified.")
+
-            sessionViewModel.insertCard(it)
+            // If the NFC tag has not been handled.
+            it.getContentIfNotHandled()?.let { cardId ->
+                val card = cardViewModel.getCard(cardId)
+                // If a card with this tag exists, add this card.
+                if (card != null) {
+                    sessionViewModel.addAttendance(card.user)
+                // Else go to the NewStudentFragment to create a new card and student.
+                } else {
+                    val bundle = bundleOf("tagId" to cardId)
+                    findNavController()
+                        .navigate(R.id.action_sessionFragment_to_newStudentFragment, bundle)
+                }
+            }
         }
 
-        binding.createCard.setOnClickListener {
+        // Manual add student button
-            //sessionViewModel.
+        binding.addStudent.setOnClickListener {
+            findNavController().navigate(R.id.action_sessionFragment_to_newStudentFragment)
+        }
+
+        // Print the result of adding an attendance on the view.
+        sessionViewModel.result.observe(viewLifecycleOwner) {
+            // If the result has not been already shown
+            it.getContentIfNotHandled()?.let { result ->
+                Toast.makeText(
+                    activity,
+                    getString(result.message, result.username),
+                    Toast.LENGTH_LONG).show()
+            }
         }
 
         return binding.root
     }
+
+
 }

app/src/main/java/com/example/palto/ui/session/SessionResult.kt

@@ -0,0 +1,10 @@
+package com.example.palto.ui.session
+
+/**
+ * Authentication result : success is true if connected or error message with exception.
+ */
+data class SessionResult(
+    val success: Boolean,
+    val message: Int, // Id of the string resource to display to the user
+    val username: String
+)

app/src/main/java/com/example/palto/ui/session/SessionViewModel.kt

@@ -1,37 +1,74 @@
 package com.example.palto.ui.session
 
-import android.nfc.Tag
 import android.util.Log
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import com.example.palto.data.repository.AttendanceRepository
+import com.example.palto.R
-import com.example.palto.domain.Card
+import com.example.palto.domain.Attendance
+import com.example.palto.domain.Event
+import com.example.palto.domain.Session
+import com.example.palto.domain.User
+import java.time.LocalTime
 
 /**
  * ViewModel of a session which has a list of attendances.
  */
-class SessionViewModel(
+class SessionViewModel() : ViewModel() {
-    private val attendanceRepository: AttendanceRepository
-) : ViewModel() {
 
-    private val _cards = MutableLiveData<List<Card>>(emptyList())
+    private var _result = MutableLiveData<Event<SessionResult>>()
-    val cards = _cards as LiveData<List<Card>>
+    val result: LiveData<Event<SessionResult>> = _result
 
-    fun insertCard(tag: Tag) {
+    private var _attendances = MutableLiveData<List<Attendance>>()
-        val card = Card(
+    val attendances: LiveData<List<Attendance>> = _attendances
-            "0",
+
-            tag.id,
+    // The opened session which have been selected in the menu.
-            "tmp",
+    var session: Session? = null
-            "tmp"
+
-        )
+    /**
-        _cards.value = (_cards.value ?: emptyList()) + card
+     * Add the [student] in the attendance list [attendances].
-        Log.d("PALTO", "SessionViewModel: a card has been added into the list.")
+     * Return true if it has been added, else return false.
+     */
+    fun addAttendance(student: User) {
+        val list = _attendances.value ?: emptyList()
+
+        // If the list already contains the user, return false
+        if (list.any { it.student == student }) {
+            Log.d("Palto", "SessionViewModel: User already in the list.")
+            _result.value = Event(SessionResult(
+                false,
+                R.string.session_user_already_added,
+                student.username
+            ))
+
+        // Else create a new attendance and add it into the list.
+        } else {
+            val attendance = Attendance(
+                id = list.size,
+                student = student,
+                date = LocalTime.now()
+            )
+            // Add the attendance in the attendance list, and trigger the observers.
+            _attendances.value = list + attendance
+            // Saved the list in the session.
+            session?.attendances = list + attendance
+
+            _result.value = Event(SessionResult(
+                true,
+                R.string.session_user_added,
+                student.username
+            ))
+            Log.d("Palto", "SessionViewModel: An attendance has been added into the list.")
+        }
+    }
+
+    fun setAttendanceList(list: List<Attendance>) {
+        _attendances.value = list
     }
 
     /**
-     *  ViewModel Factory.
+     * ViewModel Factory.
      */
     companion object {
 
@@ -40,9 +77,7 @@ class SessionViewModel(
             override fun <T : ViewModel> create(
                 modelClass: Class<T>
             ): T {
-                return SessionViewModel(
+                return SessionViewModel() as T
-                    AttendanceRepository()
-                ) as T
             }
         }
     }

app/src/main/java/com/example/palto/ui/session/new_student/NewStudentFragment.kt

@@ -0,0 +1,69 @@
+package com.example.palto.ui.session.new_student
+
+import android.os.Bundle
+import android.util.Log
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.navGraphViewModels
+import com.example.palto.NfcViewModel
+import com.example.palto.R
+import com.example.palto.databinding.FragmentNewSessionBinding
+import com.example.palto.databinding.FragmentNewStudentBinding
+import com.example.palto.ui.CardViewModel
+import com.example.palto.ui.UserViewModel
+import com.example.palto.ui.menu.MenuViewModel
+import com.example.palto.ui.session.SessionViewModel
+
+/**
+ *
+ */
+class NewStudentFragment : Fragment() {
+
+    private val newStudentViewModel: NewStudentViewModel by viewModels()
+
+    private val sessionViewModel: SessionViewModel by navGraphViewModels(R.id.nav_graph)
+
+    private val userViewModel: UserViewModel by navGraphViewModels(R.id.nav_graph)
+
+    private val cardViewModel: CardViewModel by navGraphViewModels(R.id.nav_graph)
+
+    // This property is only valid between onCreateView and onDestroyView
+    private lateinit var binding: FragmentNewStudentBinding
+
+    @OptIn(ExperimentalStdlibApi::class)
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        binding = FragmentNewStudentBinding.inflate(inflater, container, false)
+
+        // If the bundle value tagId of key "tagId" exists,
+        // Set it on the screen.
+        val tagId = arguments?.getString("tagId")
+        if (tagId != null) {
+            binding.newStudentCardId.text = tagId
+        }
+
+        // Bind the create button.
+        binding.newStudentCreate.setOnClickListener {
+            val user = userViewModel.createUser(binding.newStudentName.text.toString())
+
+            // If a tag has been provided, create the card.
+            // The user would not need to create his account afterward.
+            if (tagId != null) {
+                cardViewModel.createCard(user, tagId)
+            }
+
+            sessionViewModel.addAttendance(user)
+            findNavController().popBackStack()
+        }
+
+        return binding.root
+    }
+}

app/src/main/java/com/example/palto/ui/session/new_student/NewStudentViewModel.kt

@@ -0,0 +1,8 @@
+package com.example.palto.ui.session.new_student
+
+import androidx.lifecycle.ViewModel
+
+/**
+ * ViewModel of the session creation form. Used for verifications.
+ */
+class NewStudentViewModel() : ViewModel()

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

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <EditText
+        android:id="@+id/new_student_name"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:ems="10"
+        android:hint="@string/new_student_name"
+        android:inputType="text"
+        android:textSize="20sp"
+        app:layout_constraintBottom_toTopOf="@+id/new_student_card_id"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <TextView
+        android:id="@+id/new_student_card_id"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/new_student_card_id_text"
+        app:layout_constraintBottom_toTopOf="@+id/new_student_create"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/new_student_name" />
+
+    <Button
+        android:id="@+id/new_student_create"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/new_student_button_create"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/new_student_card_id" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -5,7 +5,14 @@
     android:orientation="horizontal">
 
     <TextView
-        android:id="@+id/card_̤id"
+        android:id="@+id/attendance_username"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_margin="@dimen/text_margin"
+        android:textAppearance="?attr/textAppearanceListItem" />
+
+    <TextView
+        android:id="@+id/attendance_date"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_margin="@dimen/text_margin"

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

@@ -17,10 +17,11 @@
         tools:listitem="@layout/fragment_session_item" />
 
     <com.google.android.material.floatingactionbutton.FloatingActionButton
-        android:id="@+id/create_card"
+        android:id="@+id/add_student"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="bottom|end"
+        android:layout_margin="16dp"
         android:clickable="true"
         android:contentDescription="@string/create_card"
         app:srcCompat="@android:drawable/ic_input_add" />

app/src/main/res/menu/palto_menu.xml

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item
+    <!--<item
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:title="@string/menu_item_logout" />
+        android:title="@string/menu_item_logout" />-->
 </menu>

app/src/main/res/navigation/nav_graph.xml

@@ -34,7 +34,16 @@
         android:id="@+id/sessionFragment"
         android:name="com.example.palto.ui.session.SessionFragment"
         android:label="Fiche de présence"
-        tools:layout="@layout/fragment_session_list" />
+        tools:layout="@layout/fragment_session_list" >
+        <action
+            android:id="@+id/action_sessionFragment_to_newStudentFragment"
+            app:destination="@id/newStudentFragment" />
+    </fragment>
 
+    <fragment
+        android:id="@+id/newStudentFragment"
+        android:name="com.example.palto.ui.session.new_student.NewStudentFragment"
+        android:label="Nouvel étudiant"
+        tools:layout="@layout/fragment_new_student" />
 
 </navigation>

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

@@ -19,4 +19,9 @@
     <string name="new_session_name_hint">Nom de la fiche</string>
     <string name="new_session_button_create">Créer</string>
     <string name="menu_item_logout">Déconnexion</string>
+    <string name="new_student_button_create">Ajouter</string>
+    <string name="new_student_name">Nom de l’étudiant</string>
+    <string name="new_student_card_id_text">ID Carte : Pas de carte</string>
+    <string name="session_user_already_added">L’étudiant %1$s existe déjà dans la liste !\n</string>
+    <string name="session_user_added">L’étudiant %1$s a été ajouté</string>
 </resources>