DDM 20201124

package com.joythis.android.myphonecaller;

/*
a "natural" representation of what we understand
by "contact"
 */
public class Contact {
    protected String mContactName;
    protected String mContactNumber;

    public Contact(
        String pName,
        String pNumber
    ){
        this.mContactName = pName;
        this.mContactNumber = pNumber;
    }//Contact

    @Override
    public String toString(){
        String strRet = String.format(
            "%s : %s",
            this.mContactName,
            this.mContactNumber
        );
        return strRet;
    }//toString

    public String getName(){
        return this.mContactName;
    }//getName

    public String getNumber(){
        return this.mContactNumber;
    }//getNumber
}//Contact

//*

package com.joythis.android.myphonecaller;

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;

import java.util.ArrayList;

/*
for the non-volatile representation of "contacts"
following the framework, regarding inheritance from
SQLiteOpenHelper
 */
public class ContactDB extends SQLiteOpenHelper{

    public final static String DB_NAME = "contacts.db";
    public final static int DB_VERSION = 1;

    //create constants for all table and column names
    public final static String TABLE_CONTACTS = "tContacts";
    public final static String COL_ID = "_id";
    public final static String COL_NAME = "cName";
    public final static String COL_NUMBER = "cNumber";

    /*
    CREATE TABLE IF NOT EXISTS tContacts(
    _id INTEGER PRIMARY KEY AUTOINCREMENT,
    cName TEXT NOT NULL,
    cNumber TEXT NOT NULL
    );
     */
    public final static String CREATE_TABLE_CONTACTS =
    "CREATE TABLE IF NOT EXISTS "+TABLE_CONTACTS+"(\n"+
    COL_ID+" INTEGER PRIMARY KEY NOT NULL, \n"+
    COL_NAME+" TEXT NOT NULL, \n"+
    COL_NUMBER+" TEXT NOT NULL\n"+
    ");";

    /*
    DROP TABLE IF EXISTS tContacts;
     */
    public final static String DROP_TABLE_CONTACTS =
    "DROP TABLE IF EXISTS "+TABLE_CONTACTS+";";

    public ContactDB(
        Context pContext
    ){
        super(
            pContext,
            DB_NAME,
            null,
            DB_VERSION
        );
    }//ContactDB

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

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

    /*
    will be AUTOMATICALLY called upon the first need to
    use the database; e.g. upon the first "insert", or the
    first "select".
    The developer will NEVER, EVER, call this method directly.
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
        //perform database installation here
        installDB(db);
    }//onCreate

    /*
    will be AUTOMATICALLY called
     */
    @Override
    public void onUpgrade(
        SQLiteDatabase db,
        int oldVersion,
        int newVersion
    )
    {
        if (db!=null){
            //upgrade/change the database infrastructure here
            if (newVersion > oldVersion){
                //destroy the current infrastructure7
                //TODO: backup of the previous data
                try {
                    db.execSQL(DROP_TABLE_CONTACTS);
                }//try
                catch(Exception e){
                    Log.e(
                        getClass().getName(),
                        e.toString()
                    );
                }//catch
                installDB(db);
            }//if
        }//if
    }//onUpgrade

    //insertContact
    /*
    will return the "line" where the record is inserted
     */
    public final static String KEY_NAME = "KEY_NAME";
    public final static String KEY_NUMBER = "KEY_NUMBER";
    public long insertContact (Contact pC)
    {
        SQLiteDatabase db = this.getWritableDatabase();
        if (db!=null){
            ContentValues pairsKeyValue = new ContentValues();

            pairsKeyValue.put(
                KEY_NAME,
                pC.getName()
            ); //contact name
            pairsKeyValue.put(
                KEY_NUMBER,
                pC.getNumber()
            ); //contact number

            //-1 on failure
            long iRecordNumber =
                db.insert(
                    TABLE_CONTACTS,
                    null,
                    pairsKeyValue
                );

            return iRecordNumber;
        }//if

        return -1;
    }//insertContact

    /*
    public long insertContact(
        String pStrName, String pStrNumber
    ){

    }//insertContact

     */

    public final static String SELECT_ALL_CONTACTS_BY_NAME_ASC =
        "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_NAME+" ASC;";
    public final static String SELECT_ALL_CONTACTS_BY_NAME_DESC =
            "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_NAME+" DESC;";

    public final static String SELECT_ALL_CONTACTS_BY_NUMBER_ASC =
        "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_NUMBER+" ASC;";
    public final static String SELECT_ALL_CONTACTS_BY_NUMBER_DESC =
            "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_NUMBER+" DESC;";

    public final static String SELECT_ALL_CONTACTS_BY_INSERT_DATE_ASC =
        "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_ID+" ASC;";
    public final static String SELECT_ALL_CONTACTS_BY_INSERT_DATE_DESC =
        "SELECT * FROM "+TABLE_CONTACTS+" ORDER BY "+COL_ID+" DESC;";

    public ArrayList<Contact> selectAllContactsByNameASC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_NAME_ASC);
    }//selectAllContactsByNameASC

    public ArrayList<Contact> selectAllContactsByNameDESC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_NAME_DESC);
    }//selectAllContactsByNameASC

    public ArrayList<Contact> selectAllContactsByNumberASC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_NUMBER_ASC);
    }//selectAllContactsByNumberASC

    public ArrayList<Contact> selectAllContactsByNumberDESC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_NUMBER_DESC);
    }//selectAllContactsByNumberASC

    public ArrayList<Contact> selectAllContactsByInsertDateASC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_INSERT_DATE_ASC);
    }//selectAllContactsByNameASC

    public ArrayList<Contact> selectAllContactsByInsertDateDESC(){
        return selectAllByQuery(SELECT_ALL_CONTACTS_BY_INSERT_DATE_DESC);
    }//selectAllContactsByNameASC

    private ArrayList<Contact> selectAllByQuery(
        String pSelectQuery
    ){
        ArrayList<Contact> aRet = new ArrayList<>();

        boolean bCheck = pSelectQuery.length()>0;
        if (bCheck){
            SQLiteDatabase db = getReadableDatabase();
            if (db!=null){
                Cursor cursor =
                    db.rawQuery(
                        pSelectQuery,
                        null
                    );

                if (cursor!=null){
                    cursor.moveToFirst();
                    while(!cursor.isAfterLast()){
                        String strName =
                            cursor.getString(
                                cursor.getColumnIndex(COL_NAME)
                               //which column INDEX?
                            );
                        String strNumber =
                            cursor.getString(
                                cursor.getColumnIndex(COL_NUMBER)
                                //which column INDEX?
                            );

                        Contact c = new Contact(strName, strNumber);
                        aRet.add(c);

                        cursor.moveToNext();
                    }//while
                }//if
            }//if can read the database
        }//if got a non empty query

        return aRet;
    }//selectAll
}//ContactDB

//**

package com.joythis.android.myphonecaller;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    Context mContext;
    ContactDB mDB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        init();
    }//onCreate

    void init(){
        mContext = this;

        //TODO:
        /*
        layout
        op layout
         */

        mDB = new ContactDB(this);
        Contact c = new Contact("Artur", "123");
        mDB.insertContact(c);

        ArrayList<Contact> all = mDB.selectAllContactsByNumberDESC();
    }
}