package com.example.shiftalarm

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

@Database(entities = [ShiftOverride::class, DailyMemo::class, CustomAlarm::class, AnnualLeave::class], version = 4, exportSchema = false)
abstract class AppDatabase : RoomDatabase() {
    abstract fun shiftDao(): ShiftDao

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

        // Migration from version 3 to 4: Add AnnualLeave table
        private val MIGRATION_3_4 = object : Migration(3, 4) {
            override fun migrate(database: SupportSQLiteDatabase) {
                // Create AnnualLeave table
                database.execSQL(
                    """
                    CREATE TABLE IF NOT EXISTS annual_leave (
                        id INTEGER PRIMARY KEY NOT NULL,
                        totalDays REAL NOT NULL,
                        remainingDays REAL NOT NULL,
                        updatedAt INTEGER NOT NULL
                    )
                    """.trimIndent()
                )
            }
        }

        fun getDatabase(context: Context): AppDatabase {
            return INSTANCE ?: synchronized(this) {
                val instance = Room.databaseBuilder(
                    context.applicationContext,
                    AppDatabase::class.java,
                    "shift_database"
                )
                .addMigrations(MIGRATION_3_4)
                .build()
                INSTANCE = instance
                instance
            }
        }
    }
}