Imports System.IO 'imports the system io library in order to use the stream reader/writer commands

Public Class Books

    Dim BookData As String 'creates a new string variable for the textfile data to be stored in
    Dim LineCount As Integer 'creates a new integer variabe that will store the number of lines in the textfile
    Dim RowIndex As Integer = 0 'creates a new integer variable that will store the index of the current row, and it is set to 0 to begin


    Private Sub DataGridRefresh() 'creates a new sub that can be called when the data grid needs to be refreshed

        BookData = Application.StartupPath & "\books.txt" 'sets the bookData variable equal to the file path of the books text file
        If Dir(BookData) = "" Then 'checks if the book text file directory has no data

            'Opening a streamwriter creates a new textfile if there isn't a textfile to be written in
            Dim sw As New StreamWriter(BookData, True) 'false will overwrite text, so use true unless you need to remove text
            sw.Close() 'closes the streamwriter to avoid data loss
            MsgBox("File has been created") 'shows message to the user to make them aware that a new file has been created

        End If

        Dim NewRecord As String 'creates a new string variable that will store the data in a record in the texfile
        Dim Fields() As String 'creates a new string array to store each record with comma splits to identify each field

        dgv_Books.Rows.Clear() 'clears the data grid

        LineCount = File.ReadAllLines(BookData).Length 'makes the linecount equal to the number of lines in the textfile

        Dim sr As New StreamReader(BookData) 'opens a new streamwreader to read the data in the textfile

        While sr.Peek >= 0 'creates a loop for each line until the end of the file

            NewRecord = sr.ReadLine 'the newrecord variable stores the data on the currently viewed line (record) in the text file
            Fields = NewRecord.Split(",") 'the fields array stores each field in the record, by splitting the data at each comma

            Dim index = dgv_Books.Rows.Add 'creates a new variable that adds data to the data grid

            dgv_Books.Rows(index).SetValues(Decryption(Fields(0)), Decryption(Fields(1)), Decryption(Fields(2)), Decryption(Fields(3)), Decryption(Fields(4)))
            'adds values to the datagrid for each field in the record, and also decrypts them so that they can be viewed

        End While
        sr.Close() 'closes streamreader to avoid data loss

        dgv_Books.RowHeadersVisible = False 'turns off the row headers
        dgv_Books.ClearSelection() 'unselects any highlighted rows in the datagrid

    End Sub

    Private Sub Books_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        'when the books form loads, the data grid will be refreshed by calling the subroutine
        DataGridRefresh()

    End Sub

    Private Sub pbx_ExitButton_Click(sender As Object, e As EventArgs) Handles pbx_ExitButton.Click

        If MsgBox("Are you sure you want to exit to the menu form?", vbYesNo) = vbYes Then 'shows the user a message box that asks if they want to exit to the menu form

            'when the exit button is clicked, exit the form if yes is selected
            Dim menu As New LibraryMenu 'creates new instance of the menu form
            menu.Show() 'shows the menu form
            Me.Close() 'closes the currrent form

        End If

    End Sub

    Private Sub btn_Add_Click(sender As Object, e As EventArgs) Handles btn_Add.Click

        Dim validation As New Validation

        'if every textbox has no data inputed / presence check
        If txt_BookID.Text = "" Or txt_Name.Text = "" Or txt_ISBN.Text = "" Or txt_Genre.Text = "" Or txt_AuthorID.Text = "" Then


            MsgBox("Please input data into all textboxes") 'shows message to ask user to input data into texboxes
            txt_BookID.Clear() 'clears textboxes
            txt_Name.Clear()
            txt_ISBN.Clear()
            txt_Genre.Clear()
            txt_AuthorID.Clear()

        ElseIf validation.lengthCheck(txt_ISBN.Text, 13, "ISBN", "Limit") = False Then

            txt_ISBN.Clear()

        Else 'if there is data

            Dim sw As New StreamWriter(BookData, True) 'opens new streamwriter

            'adds the information in the textboxes to the textfile using streamwrite, with commas to split it up
            sw.WriteLine(Encryption(txt_BookID.Text) & "," & Encryption(txt_Name.Text) & "," & Encryption(txt_ISBN.Text) & "," & Encryption(txt_Genre.Text) & "," & Encryption(txt_AuthorID.Text))
            sw.Close()

            MsgBox("New file added") 'shows the user that the file has been added to database

            'clear all data in the textboxes
            txt_BookID.Text = ""
            txt_Name.Text = ""
            txt_ISBN.Text = ""
            txt_Genre.Text = ""
            txt_AuthorID.Text = ""

            DataGridRefresh() 'refreshes data grid

        End If

    End Sub

    Private Sub btn_Search_Click(sender As Object, e As EventArgs) Handles btn_Search.Click

        Dim i As Integer 'creates new integer variable to be used in a loop


        If txt_BookID.Text = "" Then 'if there is no data inputted into the bookid textbox

            MsgBox("Please input a memberID to search in the textbox and try again.") 'prompts the user to enter data

        Else 'when there is data in the bookid textbox

            For i = 0 To LineCount - 1 'starts loop to read every line in the textfile

                If txt_BookID.Text = dgv_Books.Rows(i).Cells(0).Value Then 'if the data in the bookid textbox matches the first field of the currently selected record, then:

                    dgv_Books.Rows(i).Selected = True 'highlight the currrently selected row

                    'make each textbox show the corresponding field from the data grid:
                    txt_BookID.Text = dgv_Books.Rows(i).Cells(0).Value
                    txt_Name.Text = dgv_Books.Rows(i).Cells(1).Value
                    txt_ISBN.Text = dgv_Books.Rows(i).Cells(2).Value
                    txt_Genre.Text = dgv_Books.Rows(i).Cells(3).Value
                    txt_AuthorID.Text = dgv_Books.Rows(i).Cells(4).Value


                End If

            Next
            DataGridRefresh() 'refreshes data grid

            dgv_Books.Rows(txt_BookID.Text - 1).Selected = True 'highlights the row of the data grid view that matches the bookID
            'bookid.text - 1 because the data grid starts with 0



        End If

    End Sub

    Private Sub btn_Edit_Click(sender As Object, e As EventArgs) Handles btn_Edit.Click

        'shows the selected record in the textboxes to be edited
        txt_BookID.Text = dgv_Books.Rows(RowIndex).Cells(0).Value 'each textbox shows the data from the corresponding field in the record currently selected
        txt_Name.Text = dgv_Books.Rows(RowIndex).Cells(1).Value
        txt_ISBN.Text = dgv_Books.Rows(RowIndex).Cells(2).Value
        txt_Genre.Text = dgv_Books.Rows(RowIndex).Cells(3).Value
        txt_AuthorID.Text = dgv_Books.Rows(RowIndex).Cells(4).Value


        MsgBox("Edit the data in the textboxes, then click the save edited data button when finished") 'shows a message box to tell the user what to do

    End Sub

    Private Sub btn_Delete_Click(sender As Object, e As EventArgs) Handles btn_Delete.Click

        Dim fileLines() As String 'creates a new string array to store each line in the text file
        Dim i As Integer 'creates new integer variable to be used in a loop
        Dim fieldSplit() As String 'creates an array to store the data in each field of a record


        fileLines = File.ReadAllLines(BookData) 'saves all of the data in the textfile to the constant

        If MsgBox("Are you sure you want to delete?", vbYesNo) = vbYes Then 'shows message box to ask the user if they are sure they want to delete the record

            'if yes was clicked in the messsage box:

            If txt_BookID.Text = "" Then 'if the memberid textbox is empty then:

                MsgBox("Please input a bookID to delete in the textbox and try again.") 'shows the user a message box prompt to tell them to input data

            Else

                Dim sw As New StreamWriter(BookData, False) 'opens new streamwriter using false instead of true in order to delete data
                For i = 0 To fileLines.Length - 1 'starts new loop for every line in the textfile

                    fieldSplit = fileLines(i).Split(",") 'makes the fieldsplit array store each field in the current record by splitting the record at each comma

                    If txt_BookID.Text <> dgv_Books.Rows(i).Cells(0).Value AndAlso fieldSplit(i).Length > 0 Then

                        'if the data in the bookID textbox doesn't match the currently seleted record, and if the length of the field is more than 0, then:
                        'the data will be written back to the textfile
                        sw.WriteLine(Encryption(dgv_Books.Rows(i).Cells(0).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(1).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(2).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(3).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(4).Value))

                    End If

                    'if the bookid in the textbox does match the currently selected record, it will be skipped from being re-written to the textfile

                Next
                sw.Close() 'closes the streamwriter to avoid data loss
                DataGridRefresh() 'refreshes the data grid

            End If

        Else 'if the user choose "no" to continuing to delete the file, then:

            MsgBox("Data will not be deleted") 'shows a message box to confirm that the data will not be deleted

        End If

    End Sub

    Private Sub btn_up_Click(sender As Object, e As EventArgs) Handles btn_up.Click

        If RowIndex > 0 Then 'if the current row selected is more than the first row

            RowIndex = RowIndex - 1 'decrease the row index by 1 which moves to the previous row

        Else

            MsgBox("The first record is selected") 'gives the user a message that tells them that the first row is already selected

        End If

        dgv_Books.ClearSelection() 'this clears which row is highlighted
        dgv_Books.Rows(RowIndex).Selected = True 'this highlights the currently selected row

    End Sub

    Private Sub btn_Down_Click(sender As Object, e As EventArgs) Handles btn_Down.Click

        If RowIndex < LineCount - 1 Then 'if the current row selected is less than the number of rows then:

            RowIndex = RowIndex + 1 'increase index of the row by 1, which moves to the next row

        Else

            MsgBox("The last record is selected") 'this gives a message to the user that they alrady have the last record selected

        End If



        dgv_Books.ClearSelection() 'this clears which row is highlighted
        dgv_Books.Rows(RowIndex).Selected = True 'this highlights the currently selected row

    End Sub

    Private Sub btn_save_Click(sender As Object, e As EventArgs) Handles btn_save.Click

        Dim fileLines() As String 'creates a new string array to store each line in the text file
        Dim i As Integer 'creates new integer variable to be used in a loop
        Dim fieldSplit() As String 'creates an array to store the data in each field of a record

        fileLines = File.ReadAllLines(BookData)  'saves all of the data in the textfile to the variable

        For i = 0 To fileLines.Length - 1 'starts loop to read all of the lines

            fieldSplit = fileLines(i).Split(",") 'splits each record into each field using the commas

            If fieldSplit.Length > 0 AndAlso Decryption(fieldSplit(0)) = txt_BookID.Text Then 'when there is data in the textfile, and the bookID matches:

                'changes each field to match the new data in the textboxes
                'The data is also encrypted as the data in the datagrid view is decrypted, so it must be encrypted to be written
                fieldSplit(0) = Encryption(txt_BookID.Text)
                fieldSplit(1) = Encryption(txt_Name.Text)
                fieldSplit(2) = Encryption(txt_ISBN.Text)
                fieldSplit(3) = Encryption(txt_Genre.Text)
                fieldSplit(4) = Encryption(txt_AuthorID.Text)

                fileLines(i) = String.Join(",", fieldSplit) 'joins all data in each line back together with commas to split it

            End If
        Next

        File.WriteAllLines(BookData, fileLines) 'writes all the data back to the textfile
        DataGridRefresh() 'refreshes datgrid

    End Sub

    Private Sub btn_clear_Click(sender As Object, e As EventArgs) Handles btn_clear.Click

        'clears all textboxes
        txt_BookID.Clear()
        txt_Name.Clear()
        txt_ISBN.Clear()
        txt_Genre.Clear()
        txt_AuthorID.Clear()

        DataGridRefresh() 'refreshes data grid

    End Sub

    Private Sub btn_checkout_Click(sender As Object, e As EventArgs) Handles btn_checkout.Click

        Dim checkout As New Checkout 'creates new instance of the checkout form
        checkout.Show() 'shows the checkout form
        Me.Close() 'closes the currrent form

    End Sub

    Private Sub btn_author_Click(sender As Object, e As EventArgs) Handles btn_author.Click

        Dim author As New Author 'creates new instance of the author form
        author.Show() 'shows the author form
        Me.Close() 'closes the currrent form

    End Sub

    Private Sub btn_Sort_Click(sender As Object, e As EventArgs) Handles btn_Sort.Click

        Dim i As Integer 'creates an integer variable to be used as a counter
        Dim sortingArray(4) As String 'creates an array to store temporary data in order to swap the data in other arrays
        Dim currentRecord(4) As String 'creates an array to store the data in the currently viewed record in the loop
        Dim nextRecord(4) As String 'creates an array to store the data in the next record after the current record in the loop

        Dim sw1 As New StreamWriter(BookData, False) 'deletes the data in the textfile
        sw1.Close() 'closes streamwriter

        For i = 0 To LineCount - 1 'starts a loop to view every line in the textfile

            For counter = 0 To LineCount - 2 'creates another loop with linecount - 2 so that it gets to the second last row in the textfile (won't need to swap if it gets to the last row)

                'makes the currentrecord array store every field of the current record
                currentRecord(0) = dgv_Books.Rows(counter).Cells(0).Value
                currentRecord(1) = dgv_Books.Rows(counter).Cells(1).Value
                currentRecord(2) = dgv_Books.Rows(counter).Cells(2).Value
                currentRecord(3) = dgv_Books.Rows(counter).Cells(3).Value
                currentRecord(4) = dgv_Books.Rows(counter).Cells(4).Value

                'makes the nextrecord array store every field in the next record
                nextRecord(0) = dgv_Books.Rows(counter + 1).Cells(0).Value
                nextRecord(1) = dgv_Books.Rows(counter + 1).Cells(1).Value
                nextRecord(2) = dgv_Books.Rows(counter + 1).Cells(2).Value
                nextRecord(3) = dgv_Books.Rows(counter + 1).Cells(3).Value
                nextRecord(4) = dgv_Books.Rows(counter + 1).Cells(4).Value

                If currentRecord(0) > nextRecord(0) Then 'if the first field in the current record is larger than the first field in the next array:

                    sortingArray = currentRecord 'makes the temporary sorting array store the data in the current record
                    currentRecord = nextRecord 'the current record will then store the data from the next record
                    nextRecord = sortingArray 'the next record will store the data from the current record

                    'this is essentially a swap of the data in the two arrays

                End If

                dgv_Books.Rows(counter).SetValues(currentRecord) 'sets the currently viewed row in the datagrid to the data in the currentrecord array
                dgv_Books.Rows(counter + 1).SetValues(nextRecord) 'sets the next row in the datagrid to the data in the nextrecord array



            Next


            Dim sw As New StreamWriter(BookData, True) 'opens new streamwriter to write data to the textfi;e

            'adds each sorted line in the datagrid to the textfile using the loop
            sw.WriteLine(Encryption(dgv_Books.Rows(i).Cells(0).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(1).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(2).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(3).Value) & "," & Encryption(dgv_Books.Rows(i).Cells(4).Value))
            sw.Close() 'closes streamwriter to avoid data loss

        Next

    End Sub

    Private Sub btn_Help_Click(sender As Object, e As EventArgs) Handles btn_Help.Click

        Help.txt_help.Text = "This is the book form. On the right of the form is a data grid viewm, which displays the book database. " _
            & "You can navigate this by using either the arrow buttons underneath, or by searching for a specific bookID. " _
            & "To search, you need to input a bookID into the bookID textbox, then click the search button. To add data to the database, " _
            & "You will need to input all of the correct data into the corresponding textboxes on the left side of the form, then click the add button. " _
            & "If you wish to delete data from the database, you can input the bookID of the record you wish to delete into the bookID textbox, then click the delete button. " _
            & "If you wish to edit data that is already in the database, navigate to the record you wish to edit, then click the edit button. " _
            & "The existing data in that record will be displayed in the textboxes, and you can edit the data, then click the 'save edited data' button to save your edit. " _
            & "If you want to clear the textboxes of unnecessary data, you can click the clear textboxes button to do this. " _
            & "If the data is in an incorrect order (it should be chronological by bookID), click the sort button to sort the data. " _
            & "To view either the author form or the checkout form, click the respective buttons. " _
            & "Finally, to exit back to the menu form, you can click the cross button in the top right of the form."

        Help.Show()

    End Sub
End Class