DDM 2021-12-07

package com.joythis.android.simplestsqlite;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import androidx.annotation.Nullable;

public class MyContactDB extends SQLiteOpenHelper {

    public final static String DB_NAME = "my_contacts.DB";
    //increases in DB_VERSION should cause "onUpgrade"
    public final static int DB_VERSION = 1;

    public final static String TABLE_CONTACTS = "tContacts";
    public final static String COL_NAME = "cName";
    public final static String COL_PHONE = "cPhone";

    /*
    create table if not exists tContacts(
        _id INTEGER PRIMARY KEY NOT NULL,
        cName TEXT NOT NULL,
        cPhone TEXT NOT NULL
    );
     */
    public final static String CREATE_TABLE_CONTACTS =
        "create table if not exists "+TABLE_CONTACTS+"(\n"+
        "_id INTEGER PRIMARY KEY NOT NULL,\n"+
        COL_NAME+" TEXT NOT NULL,\n"+
        COL_PHONE+" TEXT NOT NULL\n);";

    public final static String DROP_TABLE_CONTACTS =
        "drop table if exists "+TABLE_CONTACTS+";";

    public MyContactDB(
        @Nullable Context context, //context
        @Nullable String name, //DB_NAME
        @Nullable SQLiteDatabase.CursorFactory factory, //
        int version //DB_VERSION
    ) {
        super(context, name, factory, version);
    }//MyContactDB

    public MyContactDB(
        @Nullable Context context //context
    ){
        super(
            context,
            DB_NAME,
            null,
            DB_VERSION
        );
    }//MyContact


    @Override
    public void onCreate(SQLiteDatabase db) {
        //automatically called by the framework
        //when the need to work with still non-existing
        //tables
        installDB(db);
    }//onCreate

    void installDB(SQLiteDatabase pDB){
        if (pDB!=null){
            try {
                pDB.execSQL(CREATE_TABLE_CONTACTS);
            }
            catch (Exception e){
                Log.e(
                    "@MyContactDB",
                    e.toString()
                );
            }
        }
    }//installDB

    @Override
    public void onUpgrade(
        SQLiteDatabase db,
        int oldVersion, //1
        int newVersion //2
    )
    {
        //automatically called when
        //the database changes
        //that is signaled by the database "version"
        if (newVersion>oldVersion){
            try{
                //destroy
                db.execSQL(
                    DROP_TABLE_CONTACTS
                );
                //reconstruct
                installDB(db);
            }//try
            catch (Exception e){
                Log.e(
                   "@MyContactsDB",
                   e.toString()
                );
            }//catch
        }//if
    }//onUpgrade

    public final int DOES_NOT_EXIST = -1;
    /*
    receives a MyContact
    returns the _id in TABLE_CONTACTS
    where that MyContact already exists
    or
    -1, if it does not exist
     */
    public long getIdForContact(MyContact pC){
        SQLiteDatabase db = this.getReadableDatabase();
        if (db!=null){
            //select * from tContacts where (cName='Rita' and cPhone='123')
            String strQ = String.format(
                "select %s from %s where (%s='%s' and %s='%s')",
                //COL_NAME+","+COL_PHONE
                "*",
                TABLE_CONTACTS,
                COL_NAME,
                pC.mName,
                COL_PHONE,
                pC.mPhone
            );
            Cursor cursorResults =
                db.rawQuery(
                    strQ,
                    null
                );

            if (cursorResults!=null){
                int iHowMany = cursorResults.getCount();
                if (iHowMany>0){
                    //a contact with that name and phone
                    //already exists
                    cursorResults.moveToFirst();
                    int indexOfIdColumn =
                        cursorResults.getColumnIndex(
                            "_id"
                        );
                    long idOfAlreadyExistingContact =
                        cursorResults.getLong(
                            //0
                            indexOfIdColumn
                        );
                    return idOfAlreadyExistingContact;
                }//if
            }
        }
        return DOES_NOT_EXIST;
    }//getIdForContact

    long insertNewContact(MyContact pC){
        long iCurrentIdForContact =
            getIdForContact(pC);

        boolean bWillBeNew =
            iCurrentIdForContact == DOES_NOT_EXIST;

        if (bWillBeNew){
            SQLiteDatabase db =
                this.getWritableDatabase();
            if (db!=null){
                ContentValues cvs = new ContentValues();
                cvs.put(COL_NAME, pC.mName);
                cvs.put(COL_PHONE, pC.mPhone);

                long lWhereInserted =
                    db.insert(
                        TABLE_CONTACTS,
                        null,//we have no columns allowing null
                        cvs
                    );

                return lWhereInserted;
            }
        }

        return iCurrentIdForContact;
    }//insertNewContact
}//MyContactDB