DB: setup Room database

examples/llama.android/app/src/main/java/com/example/llama/revamp/data/local/AppDatabase.kt

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+package com.example.llama.revamp.data.local
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+
+/**
+ * Main database for the application.
+ */
+@Database(entities = [SystemPromptEntity::class], version = 1, exportSchema = false)
+abstract class AppDatabase : RoomDatabase() {
+
+    abstract fun systemPromptDao(): SystemPromptDao
+
+    companion object {
+        @Volatile
+        private var INSTANCE: AppDatabase? = null
+
+        fun getDatabase(context: Context): AppDatabase {
+            return INSTANCE ?: synchronized(this) {
+                val instance = Room.databaseBuilder(
+                    context.applicationContext,
+                    AppDatabase::class.java,
+                    "llama_app_database"
+                )
+                    .fallbackToDestructiveMigration()
+                    .build()
+                INSTANCE = instance
+                instance
+            }
+        }
+    }
+}

examples/llama.android/app/src/main/java/com/example/llama/revamp/data/local/SystemPromptDao.kt

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+package com.example.llama.revamp.data.local
+
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * Data Access Object for System Prompts.
+ */
+@Dao
+interface SystemPromptDao {
+
+    @Query("SELECT * FROM system_prompts ORDER BY timestamp DESC")
+    fun getAllPrompts(): Flow<List<SystemPromptEntity>>
+
+    @Query("SELECT * FROM system_prompts WHERE id = :id")
+    suspend fun getPromptById(id: String): SystemPromptEntity?
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertPrompt(prompt: SystemPromptEntity)
+
+    @Delete
+    suspend fun deletePrompt(prompt: SystemPromptEntity)
+
+    @Query("DELETE FROM system_prompts WHERE id = :id")
+    suspend fun deletePromptById(id: String)
+
+    @Query("DELETE FROM system_prompts")
+    suspend fun deleteAllPrompts()
+
+    @Query("SELECT COUNT(*) FROM system_prompts")
+    suspend fun getPromptCount(): Int
+
+    // Get the most recent prompts, limited by count
+    @Query("SELECT * FROM system_prompts ORDER BY timestamp DESC LIMIT :count")
+    fun getRecentPrompts(count: Int): Flow<List<SystemPromptEntity>>
+
+    // Update the timestamp of an existing prompt to make it the most recent
+    @Query("UPDATE system_prompts SET timestamp = :timestamp WHERE id = :id")
+    suspend fun updatePromptTimestamp(id: String, timestamp: Long)
+}

examples/llama.android/app/src/main/java/com/example/llama/revamp/data/local/SystemPromptEntity.kt

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+package com.example.llama.revamp.data.local
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import com.example.llama.revamp.data.model.SystemPrompt
+
+/**
+ * Database entity for storing system prompts.
+ */
+@Entity(tableName = "system_prompts")
+data class SystemPromptEntity(
+    @PrimaryKey
+    val id: String,
+    val content: String,
+    val name: String?,
+    val timestamp: Long,
+    val isPreset: Boolean
+) {
+    /**
+     * Convert to domain model.
+     */
+    fun toDomainModel(): SystemPrompt {
+        return if (isPreset) {
+            SystemPrompt.Preset(
+                id = id,
+                content = content,
+                name = name ?: "Unnamed Preset",
+                timestamp = timestamp
+            )
+        } else {
+            SystemPrompt.Custom(
+                id = id,
+                content = content,
+                timestamp = timestamp
+            )
+        }
+    }
+
+    companion object {
+        /**
+         * Create an entity from a domain model.
+         */
+        fun fromDomainModel(prompt: SystemPrompt): SystemPromptEntity {
+            return when (prompt) {
+                is SystemPrompt.Preset -> SystemPromptEntity(
+                    id = prompt.id,
+                    content = prompt.content,
+                    name = prompt.name,
+                    timestamp = prompt.timestamp ?: System.currentTimeMillis(),
+                    isPreset = true
+                )
+                is SystemPrompt.Custom -> SystemPromptEntity(
+                    id = prompt.id,
+                    content = prompt.content,
+                    name = null,
+                    timestamp = prompt.timestamp,
+                    isPreset = false
+                )
+            }
+        }
+    }
+}