package com.doumee.keyCabinet.dao;

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 = {CabinetGridDo.class}, version = 1,exportSchema = false)
public abstract class CabinetGridDB extends RoomDatabase {
    public abstract CabinetGridDao cabinetGridDao();
    private static CabinetGridDB INSTANCE;
    private static final Object sLock = new Object();
    //数据库迁移 1-->2
    static final Migration MIGRATION_1_2 = new Migration(1, 2) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            database.execSQL("ALTER TABLE department ADD COLUMN phone_num TEXT");
            //database.execSQL("ALTER TABLE department ADD COLUMN phone_num INTEGER NOT NULL DEFAULT 0");
        }
    };
    //跳跃式迁移
    static final Migration MIGRATION_2_4 = new Migration(2, 4) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            //创建表
            database.execSQL(
                    "CREATE TABLE student_new (student_id TEXT, student_name TEXT, phone_num INTEGER, PRIMARY KEY(student_id))");
            //复制表
            database.execSQL(
                    "INSERT INTO student_new (student_id, student_name, phone_num) SELECT student_id, student_name, phone_num FROM student");
            //删除表
            database.execSQL("DROP TABLE student");
            //修改表名称
            database.execSQL("ALTER TABLE student_new RENAME TO students");
        }
    };
    //跳跃式迁移
    static final Migration MIGRATION_1_4 = new Migration(1, 4) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            //创建表
            database.execSQL(
                    "CREATE TABLE student_new (student_id TEXT, student_name TEXT, phone_num INTEGER, PRIMARY KEY(student_id))");
            //复制表
            database.execSQL(
                    "INSERT INTO student_new (student_id, student_name, phone_num) SELECT student_id, student_name, phone_num FROM student");
            //删除表
            database.execSQL("DROP TABLE student");
            //修改表名称
            database.execSQL("ALTER TABLE student_new RENAME TO students");
        }
    };

    public static CabinetGridDB getInstance(Context context) {
        synchronized (sLock) {
            if (INSTANCE == null) {
                INSTANCE =
                        Room.databaseBuilder(context.getApplicationContext(), CabinetGridDB.class, "CabinetGrid.db")
                                .allowMainThreadQueries()//Room不允许在主线程中访问数据库
                                //.addMigrations(MIGRATION_1_2)//数据库迁移
                                //.addMigrations(MIGRATION_1_2,MIGRATION_2_4,MIGRATION_1_4)//数据库迁移 ,可以用1_4,快速迁移
                                .build();
            }
            return INSTANCE;
        }
    }
}