package com.programmingninja.coeus.helper

import android.content.ContentValues
import android.content.Context
import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteException
import android.database.sqlite.SQLiteOpenHelper
import com.programmingninja.coeus.model.PersonModel
import java.time.LocalDateTime

import kotlin.collections.ArrayList

class HandlerDB (context: Context): SQLiteOpenHelper(context, DATABASE_NAME,null,DATABASE_VERSION) {
    companion object {
        private val DATABASE_VERSION = 1
        private val DATABASE_NAME = "ProjectTitan"
        private val TABLE_NAME = "Person"
        private val KEY_ID = "userid"
        private val KEY_USERNAME = "username"
        private val KEY_FIRST_NAME = "firstname"
        private val KEY_LAST_NAME = "lastname"
    }

    override fun onCreate(db: SQLiteDatabase?) {
        //creating the table and columns
        val CREATE_PERSON_TABLE = ("CREATE TABLE $TABLE_NAME (" +
                "$KEY_ID TEXT PRIMARY KEY," +
                "$KEY_USERNAME TEXT," +
                "$KEY_FIRST_NAME TEXT," +
                "$KEY_LAST_NAME TEXT," +
                "timestamp DEFAULT CURRENT_TIMESTAMP)")
        db?.execSQL(CREATE_PERSON_TABLE)
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        db!!.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
    }

    //method to read data
    fun ViewPerson(): List<PersonModel> {
        val personList:ArrayList<PersonModel> = ArrayList()
        val personCandidates = "SELECT * FROM $TABLE_NAME"
        val db = this.readableDatabase

        val cursor: Cursor?
        try {
            cursor = db.rawQuery(personCandidates, null)
        } catch (e: SQLiteException) {
            db.execSQL(personCandidates)
            return ArrayList()
        }

        var userId: String
        var userName: String
        var fName: String
        var lName: String

        if (cursor.moveToFirst()) {
            do {
                userId = cursor.getString(cursor.getColumnIndex("userid"))
                userName = cursor.getString(cursor.getColumnIndex("username"))
                fName = cursor.getString(cursor.getColumnIndex("firstname"))
                lName = cursor.getString(cursor.getColumnIndex("lastname"))

                val person = PersonModel(userId = userId, userName = userName, fName = fName, lName = lName)
                personList.add(person)
            } while (cursor.moveToNext())
        }
        return personList
    }

    //method to create data
    fun CreatePerson(person: PersonModel): Long {
        val db = this.writableDatabase
        val cv = ContentValues()
        cv.put(KEY_ID, person.userId)
        cv.put(KEY_USERNAME, person.userName)
        cv.put(KEY_FIRST_NAME, person.fName)
        cv.put(KEY_LAST_NAME, person.lName)

        //now insert into the db
        val successfulInsert = db.insert(TABLE_NAME, null, cv)
        db.close()
        return successfulInsert
    }

    //method to update data

    fun UpdatePerson(person: PersonModel): Int {
        val db = this.writableDatabase
        val cv = ContentValues()

        cv.put(KEY_USERNAME, person.userName)
        cv.put(KEY_FIRST_NAME, person.fName)
        cv.put(KEY_LAST_NAME, person.lName)

        val whereClause = "${KEY_ID} = ?"
        val whereArgs = arrayOf(person.userId.toString())

        //attempt to update the record
        val successfulUpdate = db.update(TABLE_NAME, cv, whereClause, whereArgs)
        db.close()
        return successfulUpdate
    }

    //method to delete data
    fun DeletePerson(person: PersonModel): Int {
        val db = this.writableDatabase
        val cv = ContentValues()
        cv.put(KEY_ID, person.userId)

        val whereClause = "${KEY_ID} = ?"
        val whereArg = arrayOf(person.userId.toString())
        //delete candidate
        val successfulDelete = db.delete(TABLE_NAME, whereClause, whereArg)
        db.close()
        return successfulDelete
    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.appcompat.widget.LinearLayoutCompat
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:orientation="vertical">

        <TableLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <TableRow>
                <androidx.appcompat.widget.AppCompatTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="User ID"
                    android:layout_column="1"/>
                <androidx.appcompat.widget.AppCompatTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:id="@+id/tv_userId"
                    android:layout_marginLeft="20dp"
                    android:layout_marginStart="20dp"
                    android:width="150dp"/>
            </TableRow>
            <TableRow>
                <androidx.appcompat.widget.AppCompatTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="Username"
                    android:layout_column="1"/>
                <androidx.appcompat.widget.AppCompatEditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/et_userName"
                    android:layout_marginLeft="20dp"
                    android:layout_marginStart="20dp"
                    android:width="150dp"/>
            </TableRow>
            <TableRow>
                <androidx.appcompat.widget.AppCompatTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="First Name"
                    android:layout_column="1"/>
                <androidx.appcompat.widget.AppCompatEditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/et_fName"
                    android:layout_marginLeft="20dp"
                    android:layout_marginStart="20dp"
                    android:width="150dp"/>
            </TableRow>
            <TableRow>
                <androidx.appcompat.widget.AppCompatTextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:hint="Last Name"
                    android:layout_column="1"/>
                <androidx.appcompat.widget.AppCompatEditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/et_lName"
                    android:layout_marginLeft="20dp"
                    android:layout_marginStart="20dp"
                    android:width="150dp"/>
            </TableRow>

        </TableLayout>
        <androidx.appcompat.widget.LinearLayoutCompat
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp">

            <ListView
                android:id="@+id/listView"
                android:layout_width="wrap_content"
                android:layout_height="350sp"
                android:longClickable="false" />
        </androidx.appcompat.widget.LinearLayoutCompat>

        <androidx.appcompat.widget.LinearLayoutCompat
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="40dp"
            android:orientation="horizontal"
            android:layout_gravity="center">
            <androidx.appcompat.widget.AppCompatButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="View"
                android:id="@+id/pressMe"
                android:onClick="ViewRecord" />
            <androidx.appcompat.widget.AppCompatButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Save"
                android:onClick="SaveRecord" />
            <androidx.appcompat.widget.AppCompatButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Update"
                android:onClick="UpdateRecord" />
            <androidx.appcompat.widget.AppCompatButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Delete"
                android:onClick="DeleteRecord" />
        </androidx.appcompat.widget.LinearLayoutCompat>
    </androidx.appcompat.widget.LinearLayoutCompat>
</androidx.constraintlayout.widget.ConstraintLayout>

//creat the layout to display an alertdialog to update request item
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp"
    android:orientation="vertical">

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_userId_update"
        android:ems="10"
        android:text="User Id"/>

    <androidx.appcompat.widget.AppCompatEditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/et_nameUser_update"
        android:ems="10"
        android:hint="username"/>

    <androidx.appcompat.widget.AppCompatEditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/et_firstname_update"
        android:ems="10"
        android:hint="first name"/>

    <androidx.appcompat.widget.AppCompatEditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/et_lastname_update"
        android:ems="10"
        android:hint="Last Name"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp">

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_userId_delete"
        android:textSize="20dp"
        android:text="userid" />

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_Name_delete"
        android:textSize="20dp"
        android:text="Name"/>

</LinearLayout>

package com.programmingninja.coeus

import android.content.DialogInterface
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.AdapterView
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.widget.AppCompatButton
import androidx.appcompat.widget.AppCompatEditText
import androidx.appcompat.widget.AppCompatTextView
import com.programmingninja.coeus.helper.HandlerDB
import com.programmingninja.coeus.helper.MyListadapter
import com.programmingninja.coeus.model.PersonModel
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.activity_main.view.*
import kotlinx.android.synthetic.main.update_person.*
import java.util.*

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    //method for reviewing records
    fun ViewRecord (view:View) {
        //creating the instance of the db handler
        val dbHandler = HandlerDB(this)
        //calling the person view
        val person: List<PersonModel> = dbHandler.ViewPerson()
        val personArrayId = Array<String>(person.size){"0"}
        val personArrayUsername = Array<String>(person.size){""}
        val personArrayFirst = Array<String>(person.size){""}
        val personArrayLast = Array<String>(person.size){""}

        for ((index, p) in person.withIndex()) {
            personArrayId[index] = p.userId
            personArrayUsername[index] = p.userName
            personArrayFirst[index] = p.fName
            personArrayLast[index] = p.lName
        }
        //creating custom adapter
        val listAdapter = MyListadapter(this, personArrayId, personArrayUsername, personArrayFirst, personArrayLast)
        listView.adapter = listAdapter
        listView.onItemClickListener = AdapterView.OnItemClickListener {
                adapterView, view, position, id -> 
            //Toast.makeText(applicationContext, "${person[position].userId}",Toast.LENGTH_LONG).show()
            UpdateRecord(person[position].userId)
        }
        listView.onItemLongClickListener = AdapterView.OnItemLongClickListener {
            adapterView, view, position, l ->
            DeleteRecord(person[position].userId, person[position].fName + " " +  person[position].lName)
        }
    }
    //method for deleting a record
     fun DeleteRecord(deleteUserId: String, deleteUserName: String): Boolean {
        //create AlertDisplay
        val alertDialog = AlertDialog.Builder(this)
        val inflater = this.layoutInflater
        val dv = inflater.inflate(R.layout.delete_person, null)

        alertDialog.setView(dv)

        val delete_id = dv.findViewById<AppCompatTextView>(R.id.tv_userId_delete)
        val delete_name = dv.findViewById<AppCompatTextView>(R.id.tv_Name_delete)
        delete_id.text = deleteUserId
        delete_name.text = deleteUserName
        val deletePersonId = delete_id.text

        alertDialog.setTitle("Delete User")
        alertDialog.setMessage("Are you sure you want to delete the user")
        alertDialog.setPositiveButton("Yes, Delete", DialogInterface.OnClickListener { _,_->
            //creating the instance of the handler
            val db = HandlerDB(this)

            //calling the delete method within the handler
            val status = db.DeletePerson(PersonModel(deletePersonId.toString(),"","",""))
            if (status > -1) {
                Toast.makeText(applicationContext, "User has been deleted", Toast.LENGTH_LONG).show()
                val buttonPress = findViewById<AppCompatButton>(R.id.pressMe)
                buttonPress.performClick()
            }
        })

        alertDialog.setNegativeButton("Cancel", DialogInterface.OnClickListener { _, _->

        })
        val b = alertDialog.create()
        b.show()
        return false
    }

    //method for updating a record
     fun UpdateRecord(updatingUser: String) {
        val alertBuilder = AlertDialog.Builder(this)
        val inflater = this.layoutInflater
        val dv = inflater.inflate(R.layout.update_person, null)
        val uPersonUserId = dv.findViewById(R.id.tv_userId_update) as AppCompatTextView
        val uPersonUsername = dv.findViewById(R.id.et_nameUser_update) as AppCompatEditText
        val uPersonFirstName = dv.findViewById<AppCompatEditText>(R.id.et_firstname_update)
        val uPersonLastName = dv.findViewById(R.id.et_lastname_update) as AppCompatEditText
        uPersonUserId.text = updatingUser
        val updatePersonId = uPersonUserId.text
        val updatePersonUsername = uPersonUsername.text
        val updatePersonFirst = uPersonFirstName.text
        val updatePersonLast = uPersonLastName.text

        alertBuilder.setTitle("Update Person")
        alertBuilder.setMessage("Update person data")
        alertBuilder.setPositiveButton("Update", DialogInterface.OnClickListener { _, _->
            //creating an instance of the handler class
            val db = HandlerDB(this)
            if (!updatePersonUsername.isNullOrEmpty() && !updatePersonFirst.isNullOrEmpty() && !updatePersonLast.isNullOrEmpty()) {
                val status = db.UpdatePerson(PersonModel(updatePersonId.toString(), updatePersonUsername.toString(), updatePersonFirst.toString(), updatePersonLast.toString()))

                if (status>-1) {
                    Toast.makeText(applicationContext,"Record Update", Toast.LENGTH_LONG).show()
                    val buttonPress = findViewById<AppCompatButton>(R.id.pressMe)
                    buttonPress.performClick()
                }
            } else {
                Toast.makeText(applicationContext, "username, first and last name required", Toast.LENGTH_LONG).show()
            }
        })

        alertBuilder.setNegativeButton("Cancel", DialogInterface.OnClickListener { di, which ->  })
        alertBuilder.setView(dv)
        val b = alertBuilder.create()
        b.show()
    }

    //method for saving the records
    fun SaveRecord (view: View) {
        val id = UUID.randomUUID()
        val uName = et_userName.text.toString()
        val fName = et_fName.text.toString()
        val lName = et_lName.text.toString()
        val db_handler: HandlerDB = HandlerDB(this)

        if (uName.trim().isNotEmpty() || fName.trim().isNotEmpty() || lName.trim().isNotEmpty()) {
            val status = db_handler.CreatePerson(PersonModel(id.toString(), uName, fName, lName))
            if (status > -1) {
                Toast.makeText(applicationContext, "Person saved", Toast.LENGTH_LONG).show()
                et_userName.setText("")
                et_fName.setText("")
                et_lName.setText("")
            }
        } else {
            Toast.makeText(applicationContext, "Username, First Name and Last Name is required", Toast.LENGTH_LONG).show()
        }
    }
}

package com.programmingninja.coeus.model

class PersonModel (var userId: String, val userName: String, val fName: String, val lName: String) {
}

//create a custom row layout for displauong the list items in the ListView
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:id="@+id/lLayout">
    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_userId"
        android:text="User Id"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_nameU"
        android:text="Username"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_nameF"
        android:text="First Name"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />

    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tv_nameL"
        android:text="Last Name"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />

</LinearLayout>

//Now, we create the adapter that will populate the data model within the listview
package com.programmingninja.coeus.helper

import android.app.Activity
import android.content.Context
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import androidx.appcompat.widget.AppCompatTextView
import com.programmingninja.coeus.R

class MyListadapter (private val context: Activity, private val idUser: Array<String>, private val nameUser: Array<String>, private val userFirst: Array<String>, private val userLast: Array<String>)
    : ArrayAdapter<String>(context, R.layout.custom_list, nameUser)
{
    override fun getView(position: Int, view: View?, parent: ViewGroup): View {
        val inflater = context.layoutInflater
        val rowView = inflater.inflate(R.layout.custom_list, null, true)

        val idUserTxt =  rowView.findViewById(R.id.tv_userId) as AppCompatTextView
        val nameUserTxt =  rowView.findViewById(R.id.tv_nameU) as AppCompatTextView
        val nameFTxt =  rowView.findViewById(R.id.tv_nameF) as AppCompatTextView
        val nameLTxt =  rowView.findViewById(R.id.tv_nameL) as AppCompatTextView

        idUserTxt.text = "User Id: ${idUser[position]}"
        nameUserTxt.text = "Username: ${nameUser[position]}"
        nameFTxt.text = "First Name: ${userFirst[position]}"
        nameLTxt.text = "Last Name: ${userLast[position]}"
        return rowView
    }
}