init

app/src/main/java/cc/n0th1ng/tripmoney/data/TripDatabase.kt

@@ -8,9 +8,11 @@ import androidx.room.Room
 import androidx.room.RoomDatabase
 import androidx.sqlite.db.SupportSQLiteDatabase
 import cc.n0th1ng.tripmoney.data.dao.CategoryDao
+import cc.n0th1ng.tripmoney.data.dao.ExchangeRateDao
 import cc.n0th1ng.tripmoney.data.dao.ExpenseDao
 import cc.n0th1ng.tripmoney.data.dao.TripDao
 import cc.n0th1ng.tripmoney.data.entity.Category
+import cc.n0th1ng.tripmoney.data.entity.ExchangeRate
 import cc.n0th1ng.tripmoney.data.entity.Expense
 import cc.n0th1ng.tripmoney.data.entity.Trip
 import cc.n0th1ng.tripmoney.utils.Icons
@@ -26,11 +28,12 @@ import java.time.LocalDateTime
 import javax.inject.Inject
 import javax.inject.Singleton
 
-@Database(entities = [Trip::class, Expense::class, Category::class], version = 1)
+@Database(entities = [Trip::class, Expense::class, Category::class, ExchangeRate::class], version = 1)
 abstract class TripDatabase : RoomDatabase() {
     abstract fun tripDao(): TripDao
     abstract fun expenseDao(): ExpenseDao
     abstract fun categoryDao(): CategoryDao
+    abstract fun exchangeRateDao(): ExchangeRateDao
 }
 
 
@@ -74,6 +77,12 @@ object DatabaseModule {
     fun provideCategoryDao(database: TripDatabase): CategoryDao {
         return database.categoryDao()
     }
+
+    @Provides
+    @Singleton
+    fun provideExchangeRateDao(database: TripDatabase): ExchangeRateDao {
+        return database.exchangeRateDao()
+    }
 }
 
 

app/src/main/java/cc/n0th1ng/tripmoney/data/dao/ExchangeRateDao.kt

@@ -0,0 +1,22 @@
+package cc.n0th1ng.tripmoney.data.dao
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Transaction
+import androidx.room.Upsert
+import cc.n0th1ng.tripmoney.data.entity.Category
+import cc.n0th1ng.tripmoney.data.entity.ExchangeRate
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface ExchangeRateDao {
+    @Upsert
+    suspend fun insert(exchangeRate: ExchangeRate)
+
+    @Query("SELECT * FROM exchange_rate WHERE id = :id")
+    suspend fun getById(id: String): ExchangeRate?
+
+    @Query("DELETE FROM exchange_rate WHERE DATE(date) < :cutoffDate")
+    suspend fun deleteOldRates(cutoffDate: String)
+}

app/src/main/java/cc/n0th1ng/tripmoney/data/dao/TripDao.kt

@@ -16,6 +16,7 @@ interface TripDao {
     @Query(
         """
         SELECT * FROM trip
+        ORDER BY DATE(trip.start_date) DESC
     """
     )
     fun tripsPaged(): PagingSource<Int, Trip>

app/src/main/java/cc/n0th1ng/tripmoney/data/entity/ExchangeRate.kt

@@ -0,0 +1,20 @@
+package cc.n0th1ng.tripmoney.data.entity
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity("exchange_rate")
+data class ExchangeRate(
+    @PrimaryKey
+    val id: String,
+    val base: String,
+    val target: String,
+    val rate: Double,
+    val date: String
+) {
+    companion object {
+        fun buildKey(base: String, target: String, date: String): String {
+            return "${base}_${target}_${date}"
+        }
+    }
+}

app/src/main/java/cc/n0th1ng/tripmoney/data/repository/ExchangeRateRepository.kt

@@ -0,0 +1,54 @@
+package cc.n0th1ng.tripmoney.data.repository
+
+import android.os.Build
+import androidx.annotation.RequiresApi
+import androidx.annotation.WorkerThread
+import cc.n0th1ng.tripmoney.data.dao.CategoryDao
+import cc.n0th1ng.tripmoney.data.dao.ExchangeRateDao
+import cc.n0th1ng.tripmoney.data.entity.Category
+import cc.n0th1ng.tripmoney.data.entity.ExchangeRate
+import cc.n0th1ng.tripmoney.service.ExchangeService
+import cc.n0th1ng.tripmoney.utils.Currencies
+import kotlinx.coroutines.flow.Flow
+import java.time.LocalDate
+import javax.inject.Inject
+
+class ExchangeRateRepository @Inject constructor(
+    private val exchangeRateDao: ExchangeRateDao,
+    private val exchangeService: ExchangeService
+) {
+
+    @WorkerThread
+    suspend fun save(exchangeRate: ExchangeRate) {
+        exchangeRateDao.insert(exchangeRate)
+    }
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    suspend fun getRate(base: Currencies, target: Currencies, date: LocalDate): Double {
+        val id = ExchangeRate.buildKey(base.name, target.name, date.toString())
+        val cachedRate = exchangeRateDao.getById(id)
+        return if (cachedRate != null) {
+            cachedRate.rate
+        } else {
+            val rate = exchangeService.getRate(base, target, date)
+            exchangeRateDao.insert(
+                ExchangeRate(
+                    id = id,
+                    base = base.name,
+                    target = target.name,
+                    rate = rate,
+                    date = date.toString()
+                )
+            )
+            clearOldRates()
+            rate
+        }
+    }
+
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    private suspend fun clearOldRates(daysToKeep: Int = 180) {
+        val cutoffDate = LocalDate.now().minusDays(daysToKeep.toLong()).toString()
+        exchangeRateDao.deleteOldRates(cutoffDate)
+    }
+}