From 8c11e18e0d3c2008c271042e65b6a08a3c53a6ee Mon Sep 17 00:00:00 2001
From: Faraphel <rc60650@hotmail.com>
Date: Wed, 8 May 2024 00:10:04 +0200
Subject: [PATCH] [WIP] implemented API class to connect the database and the
 HTTP server

---
 .idea/deploymentTargetDropDown.xml            | 12 ---
 .../connectivity/task/TaskServer.kt           | 32 +++-----
 .../tasks_valider/database/TaskDatabase.kt    | 41 +++-------
 .../tasks_valider/database/api/GroupApi.kt    | 10 +++
 .../database/api/GroupStudentApi.kt           | 10 +++
 .../tasks_valider/database/api/StudentApi.kt  | 10 +++
 .../tasks_valider/database/api/TaskApi.kt     | 10 +++
 .../database/api/TaskGroupApi.kt              | 10 +++
 .../tasks_valider/database/api/TeacherApi.kt  | 10 +++
 .../database/api/base/BaseApi.kt              | 33 ++++++++
 .../database/api/base/BaseJsonApi.kt          | 79 +++++++++++++++++++
 .../tasks_valider/database/dao/GroupDao.kt    | 11 ++-
 .../database/dao/GroupStudentDao.kt           | 11 +--
 .../tasks_valider/database/dao/StudentDao.kt  | 13 ++-
 .../tasks_valider/database/dao/TaskDao.kt     | 11 ++-
 .../database/dao/TaskGroupDao.kt              |  8 +-
 .../tasks_valider/database/dao/TeacherDao.kt  | 10 +--
 .../database/dao/base/BaseDao.kt              | 30 ++++++-
 .../entities/{Group.kt => GroupEntity.kt}     |  5 +-
 ...{GroupStudent.kt => GroupStudentEntity.kt} | 11 ++-
 .../entities/{Person.kt => PersonEntity.kt}   |  5 +-
 .../entities/{Student.kt => StudentEntity.kt} |  4 +-
 .../entities/{Task.kt => TaskEntity.kt}       |  5 +-
 .../{TaskGroup.kt => TaskGroupEntity.kt}      | 12 +--
 .../entities/{Teacher.kt => TeacherEntity.kt} |  4 +-
 .../database/entities/base/BaseEntity.kt      |  3 +
 .../tasks_valider/ui/widgets/task/Group.kt    |  4 +-
 .../tasks_valider/ui/widgets/task/Task.kt     |  4 +-
 .../ui/widgets/task/TaskGroup.kt              |  4 +-
 29 files changed, 280 insertions(+), 132 deletions(-)
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/GroupApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/GroupStudentApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/StudentApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/TaskApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/TaskGroupApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/TeacherApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseApi.kt
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseJsonApi.kt
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{Group.kt => GroupEntity.kt} (73%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{GroupStudent.kt => GroupStudentEntity.kt} (76%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{Person.kt => PersonEntity.kt} (75%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{Student.kt => StudentEntity.kt} (85%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{Task.kt => TaskEntity.kt} (76%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{TaskGroup.kt => TaskGroupEntity.kt} (81%)
 rename app/src/main/java/com/faraphel/tasks_valider/database/entities/{Teacher.kt => TeacherEntity.kt} (85%)
 create mode 100644 app/src/main/java/com/faraphel/tasks_valider/database/entities/base/BaseEntity.kt

diff --git a/.idea/deploymentTargetDropDown.xml b/.idea/deploymentTargetDropDown.xml
index f67f999..ad3ac93 100644
--- a/.idea/deploymentTargetDropDown.xml
+++ b/.idea/deploymentTargetDropDown.xml
@@ -4,18 +4,6 @@
     <value>
       <entry key="app">
         <State>
-          <runningDeviceTargetSelectedWithDropDown>
-            <Target>
-              <type value="RUNNING_DEVICE_TARGET" />
-              <deviceKey>
-                <Key>
-                  <type value="SERIAL_NUMBER" />
-                  <value value="2XJDU17923000406" />
-                </Key>
-              </deviceKey>
-            </Target>
-          </runningDeviceTargetSelectedWithDropDown>
-          <timeTargetWasSelectedWithDropDown value="2024-05-05T12:21:32.176293Z" />
           <runningDeviceTargetsSelectedWithDialog>
             <Target>
               <type value="RUNNING_DEVICE_TARGET" />
diff --git a/app/src/main/java/com/faraphel/tasks_valider/connectivity/task/TaskServer.kt b/app/src/main/java/com/faraphel/tasks_valider/connectivity/task/TaskServer.kt
index 211ba61..391e8e0 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/connectivity/task/TaskServer.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/connectivity/task/TaskServer.kt
@@ -1,8 +1,6 @@
 package com.faraphel.tasks_valider.connectivity.task
 
-import android.util.Log
 import com.faraphel.tasks_valider.database.TaskDatabase
-import com.faraphel.tasks_valider.database.entities.Task
 import com.google.gson.Gson
 import fi.iki.elonen.NanoHTTPD
 
@@ -24,31 +22,19 @@ class TaskServer(
 
         // remove the first slash
         val daoName: String = uri.substring(1)
+        // get the matching DAO in the database
+
+        TODO("Faraphel: get the correct DAO from the database")
+        TODO("Faraphel: pass more direct arguments to the API handler ?")
 
         // handle the request
         when (method) {
-            // get the data from the database
-            Method.GET -> {
-                return newFixedLengthResponse(
-                    Response.Status.OK,
-                    "application/json",
-                    jsonParser.toJson( database.taskDao().getAll() )
-                )
-            }
+            // check if the data is in the database
+            Method.HEAD -> { TODO() }
+            // get the data from the dao
+            Method.GET -> { TODO() }
             // insert the data into the database
-            Method.POST -> {
-                val task = jsonParser.fromJson(
-                    session.inputStream.bufferedReader(),
-                    Task::class.java
-                )
-                database.taskDao().insert(task)
-
-                return newFixedLengthResponse(
-                    Response.Status.CREATED,
-                    "application/json",
-                    jsonParser.toJson(task)
-                )
-            }
+            Method.POST -> { TODO() }
             // other methods are not allowed
             else -> {
                 return newFixedLengthResponse(
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/TaskDatabase.kt b/app/src/main/java/com/faraphel/tasks_valider/database/TaskDatabase.kt
index 718b6d1..2fa80a1 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/TaskDatabase.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/TaskDatabase.kt
@@ -10,13 +10,12 @@ import com.faraphel.tasks_valider.database.dao.StudentDao
 import com.faraphel.tasks_valider.database.dao.TaskDao
 import com.faraphel.tasks_valider.database.dao.TaskGroupDao
 import com.faraphel.tasks_valider.database.dao.TeacherDao
-import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.GroupStudent
-import com.faraphel.tasks_valider.database.entities.Student
-import com.faraphel.tasks_valider.database.entities.Task
-import com.faraphel.tasks_valider.database.entities.TaskGroup
-import com.faraphel.tasks_valider.database.entities.Teacher
+import com.faraphel.tasks_valider.database.entities.GroupEntity
+import com.faraphel.tasks_valider.database.entities.GroupStudentEntity
+import com.faraphel.tasks_valider.database.entities.StudentEntity
+import com.faraphel.tasks_valider.database.entities.TaskEntity
+import com.faraphel.tasks_valider.database.entities.TaskGroupEntity
+import com.faraphel.tasks_valider.database.entities.TeacherEntity
 
 
 /**
@@ -25,13 +24,13 @@ import com.faraphel.tasks_valider.database.entities.Teacher
  */
 @Database(
     entities = [
-        Group::class,
-        Student::class,
-        Teacher::class,
-        Task::class,
+        GroupEntity::class,
+        StudentEntity::class,
+        TeacherEntity::class,
+        TaskEntity::class,
 
-        GroupStudent::class,
-        TaskGroup::class,
+        GroupStudentEntity::class,
+        TaskGroupEntity::class,
     ],
     version = 1
 )
@@ -48,20 +47,4 @@ abstract class TaskDatabase : RoomDatabase() {
     // relations
     abstract fun groupStudentDao(): GroupStudentDao
     abstract fun taskGroupDao(): TaskGroupDao
-
-    /**
-     * Get the DAO from the name of the dao.
-     */
-    @Suppress("UNCHECKED_CAST")
-    fun <Entity> daoFromName(name: String): BaseDao<Entity>? {
-        return when (name) {
-            "group" -> groupDao()
-            "student" -> studentDao()
-            "teacher" -> teacherDao()
-            "task" -> taskDao()
-            "group_student" -> groupStudentDao()
-            "task_group" -> taskGroupDao()
-            else -> null
-        } as BaseDao<Entity>?
-    }
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupApi.kt
new file mode 100644
index 0000000..06f3668
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.GroupDao
+import com.faraphel.tasks_valider.database.entities.GroupEntity
+
+class GroupApi : BaseJsonApi<GroupEntity>() {
+    override fun getDao(database: TaskDatabase): GroupDao = database.groupDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupStudentApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupStudentApi.kt
new file mode 100644
index 0000000..d5760ad
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/GroupStudentApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.GroupStudentDao
+import com.faraphel.tasks_valider.database.entities.GroupStudentEntity
+
+class GroupStudentApi : BaseJsonApi<GroupStudentEntity>() {
+    override fun getDao(database: TaskDatabase): GroupStudentDao = database.groupStudentDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/StudentApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/StudentApi.kt
new file mode 100644
index 0000000..2e11f54
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/StudentApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.StudentDao
+import com.faraphel.tasks_valider.database.entities.StudentEntity
+
+class StudentApi : BaseJsonApi<StudentEntity>() {
+    override fun getDao(database: TaskDatabase): StudentDao = database.studentDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskApi.kt
new file mode 100644
index 0000000..402d2de
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.TaskDao
+import com.faraphel.tasks_valider.database.entities.TaskEntity
+
+class TaskApi : BaseJsonApi<TaskEntity>() {
+    override fun getDao(database: TaskDatabase): TaskDao = database.taskDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskGroupApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskGroupApi.kt
new file mode 100644
index 0000000..f48f7d6
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/TaskGroupApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.TaskGroupDao
+import com.faraphel.tasks_valider.database.entities.TaskGroupEntity
+
+class TaskGroupApi : BaseJsonApi<TaskGroupEntity>() {
+    override fun getDao(database: TaskDatabase): TaskGroupDao = database.taskGroupDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/TeacherApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/TeacherApi.kt
new file mode 100644
index 0000000..7a7169a
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/TeacherApi.kt
@@ -0,0 +1,10 @@
+package com.faraphel.tasks_valider.database.api
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.api.base.BaseJsonApi
+import com.faraphel.tasks_valider.database.dao.TeacherDao
+import com.faraphel.tasks_valider.database.entities.TeacherEntity
+
+class TeacherApi : BaseJsonApi<TeacherEntity>() {
+    override fun getDao(database: TaskDatabase): TeacherDao = database.teacherDao()
+}
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseApi.kt
new file mode 100644
index 0000000..e05e324
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseApi.kt
@@ -0,0 +1,33 @@
+package com.faraphel.tasks_valider.database.api.base
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import fi.iki.elonen.NanoHTTPD
+
+/**
+ * A base for the API to handle the database operations with an HTTP server.
+ */
+interface BaseApi {
+    /**
+     * Handle the HEAD request
+     * This is used to check if a data exists in the database
+     */
+    fun head(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response
+
+    /**
+     * Handle the GET request
+     * This is used to get data from the database
+     */
+    fun get(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response
+
+    /**
+     * Handle the POST request
+     * This is used to insert data into the database
+     */
+    fun post(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response
+
+    /**
+     * Handle the PUT request
+     * This is used to delete data from the database
+     */
+    fun delete(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseJsonApi.kt b/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseJsonApi.kt
new file mode 100644
index 0000000..aea579f
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/api/base/BaseJsonApi.kt
@@ -0,0 +1,79 @@
+package com.faraphel.tasks_valider.database.api.base
+
+import com.faraphel.tasks_valider.database.TaskDatabase
+import com.faraphel.tasks_valider.database.dao.base.BaseDao
+import com.faraphel.tasks_valider.database.entities.GroupEntity
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import fi.iki.elonen.NanoHTTPD
+
+/**
+ * A base for the API to handle the database operations.
+ * This is preconfigured to handle JSON data.
+ * @param Entity the entity type to handle
+ */
+abstract class BaseJsonApi<Entity: BaseEntity> : BaseApi {
+    companion object {
+        private val parser = Gson()  ///< The JSON parser
+    }
+
+    /**
+     * Get the DAO for the entity
+     * @param database the database to get the DAO from
+     * @return the DAO for the entity
+     */
+    abstract fun getDao(database: TaskDatabase): BaseDao<Entity>
+
+    /**
+     * Get the type token for the entity
+     * @return the type token for the entity
+     */
+    private fun getEntityTypeToken(): TypeToken<Entity> = object: TypeToken<Entity>() {}
+
+    // Requests
+
+    override fun head(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response {
+        val obj = parser.fromJson<Entity>(
+            session.inputStream.bufferedReader().readText(),
+            getEntityTypeToken().type
+        )
+        val exists = this.getDao(database).exists(obj)
+
+        return NanoHTTPD.newFixedLengthResponse(
+            if (exists) NanoHTTPD.Response.Status.OK else NanoHTTPD.Response.Status.NOT_FOUND,
+            "text/plain",
+            if (exists) "Exists" else "Not found"
+        )
+    }
+
+    override fun get(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response {
+        return NanoHTTPD.newFixedLengthResponse(
+            NanoHTTPD.Response.Status.OK,
+            "application/json",
+            parser.toJson(database.groupDao().getAll())
+        )
+    }
+
+    override fun post(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response {
+        val obj = parser.fromJson(session.inputStream.bufferedReader().readText(), GroupEntity::class.java)
+        val id = database.groupDao().insert(obj)
+
+        return NanoHTTPD.newFixedLengthResponse(
+            NanoHTTPD.Response.Status.CREATED,
+            "text/plain",
+            id.toString()
+        )
+    }
+
+    override fun delete(database: TaskDatabase, session: NanoHTTPD.IHTTPSession): NanoHTTPD.Response {
+        val obj = parser.fromJson(session.inputStream.bufferedReader().readText(), GroupEntity::class.java)
+        val count = database.groupDao().delete(obj)
+
+        return NanoHTTPD.newFixedLengthResponse(
+            if (count > 0) NanoHTTPD.Response.Status.OK else NanoHTTPD.Response.Status.NOT_FOUND,
+            "text/plain",
+            count.toString()
+        )
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupDao.kt
index 33511fd..e53764c 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupDao.kt
@@ -4,17 +4,16 @@ import androidx.room.Dao
 import androidx.room.Query
 import androidx.room.RewriteQueriesToDropUnusedColumns
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.Student
+import com.faraphel.tasks_valider.database.entities.GroupEntity
 
 
 @Dao
-interface GroupDao : BaseDao<Group> {
+interface GroupDao : BaseDao<GroupEntity> {
     @Query("SELECT * FROM `groups`")
-    override fun getAll(): List<Group>
+    override fun getAll(): List<GroupEntity>
 
     @Query("SELECT * FROM `groups` WHERE id = :id")
-    fun getById(id: Long): Group
+    fun getById(id: Long): GroupEntity
 
     /**
     Allow to get all groups with a specific student
@@ -25,5 +24,5 @@ interface GroupDao : BaseDao<Group> {
         "WHERE `group_student`.student_id = :studentId"
     )
     @RewriteQueriesToDropUnusedColumns
-    fun filterByStudentId(studentId: Long): List<Group>
+    fun filterByStudentId(studentId: Long): List<GroupEntity>
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupStudentDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupStudentDao.kt
index 2bd355e..6f86ea6 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupStudentDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/GroupStudentDao.kt
@@ -2,18 +2,15 @@ package com.faraphel.tasks_valider.database.dao
 
 import androidx.room.Dao
 import androidx.room.Query
-import androidx.room.RewriteQueriesToDropUnusedColumns
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.GroupStudent
-import com.faraphel.tasks_valider.database.entities.Student
+import com.faraphel.tasks_valider.database.entities.GroupStudentEntity
 
 
 @Dao
-interface GroupStudentDao : BaseDao<GroupStudent> {
+interface GroupStudentDao : BaseDao<GroupStudentEntity> {
     @Query("SELECT * FROM `group_student`")
-    override fun getAll(): List<GroupStudent>
+    override fun getAll(): List<GroupStudentEntity>
 
     @Query("SELECT * FROM `group_student` WHERE group_id = :groupId AND student_id = :studentId")
-    fun getById(groupId: Long, studentId: Long): GroupStudent
+    fun getById(groupId: Long, studentId: Long): GroupStudentEntity
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/StudentDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/StudentDao.kt
index e4b8dfb..d1451eb 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/StudentDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/StudentDao.kt
@@ -1,22 +1,19 @@
 package com.faraphel.tasks_valider.database.dao
 
-import androidx.lifecycle.LiveData
 import androidx.room.Dao
 import androidx.room.Query
 import androidx.room.RewriteQueriesToDropUnusedColumns
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.Person
-import com.faraphel.tasks_valider.database.entities.Student
+import com.faraphel.tasks_valider.database.entities.StudentEntity
 
 
 @Dao
-interface StudentDao : BaseDao<Student> {
+interface StudentDao : BaseDao<StudentEntity> {
     @Query("SELECT * FROM `students`")
-    override fun getAll(): List<Student>
+    override fun getAll(): List<StudentEntity>
 
     @Query("SELECT * FROM `students` WHERE id = :id")
-    fun getById(id: Long): Student
+    fun getById(id: Long): StudentEntity
 
 
     /**
@@ -28,5 +25,5 @@ interface StudentDao : BaseDao<Student> {
         "WHERE `group_student`.group_id = :groupId"
     )
     @RewriteQueriesToDropUnusedColumns
-    fun filterByGroupId(groupId: Long): List<Student>
+    fun filterByGroupId(groupId: Long): List<StudentEntity>
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskDao.kt
index 1e2cb8c..33df321 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskDao.kt
@@ -4,17 +4,16 @@ import androidx.room.Dao
 import androidx.room.Query
 import androidx.room.RewriteQueriesToDropUnusedColumns
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.Task
+import com.faraphel.tasks_valider.database.entities.TaskEntity
 
 
 @Dao
-interface TaskDao : BaseDao<Task> {
+interface TaskDao : BaseDao<TaskEntity> {
     @Query("SELECT * FROM `tasks`")
-    override fun getAll(): List<Task>
+    override fun getAll(): List<TaskEntity>
 
     @Query("SELECT * FROM `tasks` WHERE id = :id")
-    fun getById(id: Long): Task
+    fun getById(id: Long): TaskEntity
 
     /**
     Get all the tasks for a specific group
@@ -25,5 +24,5 @@ interface TaskDao : BaseDao<Task> {
         "WHERE `task_group`.group_id = :groupId"
     )
     @RewriteQueriesToDropUnusedColumns
-    fun filterByGroupId(groupId: Long): List<Task>
+    fun filterByGroupId(groupId: Long): List<TaskEntity>
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskGroupDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskGroupDao.kt
index 0caa673..8b2bea6 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskGroupDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TaskGroupDao.kt
@@ -3,14 +3,14 @@ package com.faraphel.tasks_valider.database.dao
 import androidx.room.Dao
 import androidx.room.Query
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.TaskGroup
+import com.faraphel.tasks_valider.database.entities.TaskGroupEntity
 
 
 @Dao
-interface TaskGroupDao : BaseDao<TaskGroup> {
+interface TaskGroupDao : BaseDao<TaskGroupEntity> {
     @Query("SELECT * FROM `task_group`")
-    override fun getAll(): List<TaskGroup>
+    override fun getAll(): List<TaskGroupEntity>
 
     @Query("SELECT * FROM `task_group` WHERE task_id = :taskId AND group_id = :groupId")
-    fun getById(taskId: Long, groupId: Long): TaskGroup
+    fun getById(taskId: Long, groupId: Long): TaskGroupEntity
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TeacherDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TeacherDao.kt
index f489725..3acba4d 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/TeacherDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/TeacherDao.kt
@@ -3,16 +3,14 @@ package com.faraphel.tasks_valider.database.dao
 import androidx.room.Dao
 import androidx.room.Query
 import com.faraphel.tasks_valider.database.dao.base.BaseDao
-import com.faraphel.tasks_valider.database.entities.Person
-import com.faraphel.tasks_valider.database.entities.Student
-import com.faraphel.tasks_valider.database.entities.Teacher
+import com.faraphel.tasks_valider.database.entities.TeacherEntity
 
 
 @Dao
-interface TeacherDao : BaseDao<Teacher> {
+interface TeacherDao : BaseDao<TeacherEntity> {
     @Query("SELECT * FROM `teachers`")
-    override fun getAll(): List<Teacher>
+    override fun getAll(): List<TeacherEntity>
 
     @Query("SELECT * FROM `teachers` WHERE id = :id")
-    fun getById(id: Long): Teacher
+    fun getById(id: Long): TeacherEntity
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/dao/base/BaseDao.kt b/app/src/main/java/com/faraphel/tasks_valider/database/dao/base/BaseDao.kt
index c9c4fe2..b06e62f 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/dao/base/BaseDao.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/dao/base/BaseDao.kt
@@ -2,18 +2,40 @@ package com.faraphel.tasks_valider.database.dao.base
 
 import androidx.room.Delete
 import androidx.room.Insert
+import androidx.room.OnConflictStrategy
 import androidx.room.Update
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
 
 
+
+/**
+ * A base DAO to handle the database operations.
+ * @param Entity the entity to handle
+ */
 interface BaseDao<Entity> {
-    @Insert
+    /**
+     * Check if the entities exists in the database.
+     */
+    fun exists(vararg entities: Entity): Boolean {
+        return this.getAll().containsAll(entities.toList())
+    }
+
+    /**
+     * Insert the entities into the database.
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
     fun insert(vararg entities: Entity): List<Long>
 
-    @Update
-    fun update(vararg entities: Entity): Int
-
+    /**
+     * Delete the entities from the database.
+     */
     @Delete
     fun delete(vararg entities: Entity): Int
 
+    /**
+     * Get all the entities from the database.
+     * TODO(Faraphel): support filters ?
+     */
     fun getAll(): List<Entity>
 }
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Group.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupEntity.kt
similarity index 73%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/Group.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupEntity.kt
index d0f3a09..d042662 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Group.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupEntity.kt
@@ -3,10 +3,11 @@ package com.faraphel.tasks_valider.database.entities
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
 
 
 @Entity(tableName = "groups")
-data class Group (
+data class GroupEntity (
     @ColumnInfo("id") @PrimaryKey(autoGenerate = true) val id: Long = 0,
     @ColumnInfo("name") val name: String? = null,
-)
+) : BaseEntity()
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudent.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudentEntity.kt
similarity index 76%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudent.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudentEntity.kt
index 2e830e3..ba003c8 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudent.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/GroupStudentEntity.kt
@@ -3,8 +3,7 @@ package com.faraphel.tasks_valider.database.entities
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.ForeignKey
-import com.faraphel.tasks_valider.database.entities.Group
-import com.faraphel.tasks_valider.database.entities.Student
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
 
 @Entity(
     tableName = "group_student",
@@ -14,20 +13,20 @@ import com.faraphel.tasks_valider.database.entities.Student
     ],
     foreignKeys = [
         ForeignKey(
-            entity = Group::class,
+            entity = GroupEntity::class,
             parentColumns = ["id"],
             childColumns = ["group_id"],
             onDelete = ForeignKey.CASCADE
         ),
         ForeignKey(
-            entity = Student::class,
+            entity = StudentEntity::class,
             parentColumns = ["id"],
             childColumns = ["student_id"],
             onDelete = ForeignKey.CASCADE
         )
     ]
 )
-data class GroupStudent(
+data class GroupStudentEntity(
     @ColumnInfo("group_id", index = true) val groupId: Long,
     @ColumnInfo("student_id", index = true) val studentId: Long,
-)
+) : BaseEntity()
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Person.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/PersonEntity.kt
similarity index 75%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/Person.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/PersonEntity.kt
index 347b05d..469c9d2 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Person.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/PersonEntity.kt
@@ -1,13 +1,14 @@
 package com.faraphel.tasks_valider.database.entities
 
 import java.util.Locale
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
 
 
-open class Person (
+open class PersonEntity (
     open val id: Long = 0,
     open val firstName: String,
     open val lastName: String,
-) {
+) : BaseEntity() {
     /**
     Get the full name of the person
      */
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Student.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/StudentEntity.kt
similarity index 85%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/Student.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/StudentEntity.kt
index 4cff4c6..fdfd648 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Student.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/StudentEntity.kt
@@ -5,8 +5,8 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 
 @Entity(tableName = "students")
-class Student(
+class StudentEntity(
     @ColumnInfo("id") @PrimaryKey(autoGenerate = true) override val id: Long = 0,
     @ColumnInfo("first_name") override val firstName: String,
     @ColumnInfo("last_name") override val lastName: String
-) : Person(id, firstName, lastName)
+) : PersonEntity(id, firstName, lastName)
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Task.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskEntity.kt
similarity index 76%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/Task.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskEntity.kt
index 15e1361..7d04402 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Task.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskEntity.kt
@@ -3,10 +3,11 @@ package com.faraphel.tasks_valider.database.entities
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.PrimaryKey
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
 
 @Entity(tableName = "tasks")
-data class Task (
+data class TaskEntity (
     @ColumnInfo("id") @PrimaryKey(autoGenerate = true) val id: Long = 0,
     @ColumnInfo("title") val title: String,
     @ColumnInfo("description") val description: String,
-)
+) : BaseEntity()
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroup.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroupEntity.kt
similarity index 81%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroup.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroupEntity.kt
index 07e9c57..006a6a0 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroup.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TaskGroupEntity.kt
@@ -3,6 +3,7 @@ package com.faraphel.tasks_valider.database.entities
 import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.ForeignKey
+import com.faraphel.tasks_valider.database.entities.base.BaseEntity
 import java.time.Instant
 
 
@@ -14,29 +15,30 @@ import java.time.Instant
     ],
     foreignKeys = [
         ForeignKey(
-            entity = Group::class,
+            entity = GroupEntity::class,
             parentColumns = ["id"],
             childColumns = ["group_id"],
             onDelete = ForeignKey.CASCADE
         ),
         ForeignKey(
-            entity = Task::class,
+            entity = TaskEntity::class,
             parentColumns = ["id"],
             childColumns = ["task_id"],
             onDelete = ForeignKey.CASCADE
         ),
         ForeignKey(
-            entity = Teacher::class,
+            entity = TeacherEntity::class,
             parentColumns = ["id"],
             childColumns = ["approval_teacher_id"],
             onDelete = ForeignKey.CASCADE
         ),
     ]
 )
-data class TaskGroup (
+data class TaskGroupEntity (
     @ColumnInfo("task_id") val taskId: Long,
     @ColumnInfo("group_id") val groupId: Long,
     @ColumnInfo("approval_status") var approvalStatus: Boolean = false,
     @ColumnInfo("approval_teacher_id") val approvalTeacherId: Long? = null,
     @ColumnInfo("approval_time") val approvalTime: Instant? = null
-)
+) : BaseEntity()
+
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Teacher.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TeacherEntity.kt
similarity index 85%
rename from app/src/main/java/com/faraphel/tasks_valider/database/entities/Teacher.kt
rename to app/src/main/java/com/faraphel/tasks_valider/database/entities/TeacherEntity.kt
index b499973..c244edc 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/database/entities/Teacher.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/TeacherEntity.kt
@@ -5,8 +5,8 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 
 @Entity(tableName = "teachers")
-class Teacher(
+class TeacherEntity(
     @ColumnInfo("id") @PrimaryKey(autoGenerate = true) override val id: Long = 0,
     @ColumnInfo("first_name") override val firstName: String,
     @ColumnInfo("last_name") override val lastName: String
-) : Person(id, firstName, lastName)
+) : PersonEntity(id, firstName, lastName)
diff --git a/app/src/main/java/com/faraphel/tasks_valider/database/entities/base/BaseEntity.kt b/app/src/main/java/com/faraphel/tasks_valider/database/entities/base/BaseEntity.kt
new file mode 100644
index 0000000..44654b2
--- /dev/null
+++ b/app/src/main/java/com/faraphel/tasks_valider/database/entities/base/BaseEntity.kt
@@ -0,0 +1,3 @@
+package com.faraphel.tasks_valider.database.entities.base
+
+open class BaseEntity
diff --git a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Group.kt b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Group.kt
index 95520a7..fb35f98 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Group.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Group.kt
@@ -3,10 +3,10 @@ package com.faraphel.tasks_valider.ui.widgets.task
 import androidx.compose.foundation.layout.Column
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import com.faraphel.tasks_valider.database.entities.Group
+import com.faraphel.tasks_valider.database.entities.GroupEntity
 
 @Composable
-fun WidgetGroup(group: Group) {
+fun WidgetGroup(group: GroupEntity) {
     // TODO
     Column {
         Text(text = group.name!!)
diff --git a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Task.kt b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Task.kt
index fc604fb..6ed1293 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Task.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/Task.kt
@@ -3,10 +3,10 @@ package com.faraphel.tasks_valider.ui.widgets.task
 import androidx.compose.foundation.layout.Column
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import com.faraphel.tasks_valider.database.entities.Task
+import com.faraphel.tasks_valider.database.entities.TaskEntity
 
 @Composable
-fun WidgetTask(task: Task) {
+fun WidgetTask(task: TaskEntity) {
     // task information
     Column {
         Text(text = task.title)
diff --git a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/TaskGroup.kt b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/TaskGroup.kt
index 75e0353..d14bb27 100644
--- a/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/TaskGroup.kt
+++ b/app/src/main/java/com/faraphel/tasks_valider/ui/widgets/task/TaskGroup.kt
@@ -12,11 +12,11 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import com.faraphel.tasks_valider.database.TaskDatabase
-import com.faraphel.tasks_valider.database.entities.TaskGroup
+import com.faraphel.tasks_valider.database.entities.TaskGroupEntity
 
 
 @Composable
-fun WidgetTaskStudent(database: TaskDatabase, taskStudent: TaskGroup) {
+fun WidgetTaskStudent(database: TaskDatabase, taskStudent: TaskGroupEntity) {
     val teacherDao = database.teacherDao()
 
     Column {