package org.terst.feedreader.data

import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
import androidx.sqlite.db.SupportSQLiteDatabase
import androidx.room.migration.Migration

@Database(
    entities = [FeedEntity::class, ArticleEntity::class, FilterRuleEntity::class],
    version = 2,
    exportSchema = false
)
abstract class AppDatabase : RoomDatabase() {
    abstract fun feedDao(): FeedDao
    abstract fun articleDao(): ArticleDao
    abstract fun filterRuleDao(): FilterRuleDao

    companion object {
        @Volatile private var instance: AppDatabase? = null

        // v2: added ArticleEntity.imageUrl (thumbnail support). Real migrations,
        // not fallbackToDestructiveMigration, since this app already has real
        // subscriptions/read-state on-device during active development --
        // wiping the DB on every schema tweak would mean re-importing OPML
        // and losing read history each time.
        private val MIGRATION_1_2 = object : Migration(1, 2) {
            override fun migrate(db: SupportSQLiteDatabase) {
                db.execSQL("ALTER TABLE articles ADD COLUMN imageUrl TEXT")
            }
        }

        fun get(context: Context): AppDatabase = instance ?: synchronized(this) {
            instance ?: Room.databaseBuilder(
                context.applicationContext,
                AppDatabase::class.java,
                "feedreader.db"
            ).addMigrations(MIGRATION_1_2).build().also { instance = it }
        }
    }
}