PM Task 1 2021

ReadOnly maxNumberBooks As Integer = 10
ReadOnly bookByteSize As Integer = 80 + 2
' 80 for chars in (random) bookString, 2 for metadata
Structure book
    Public code As Integer
    Public title As String
    Public author As String
    Public publicationYear As Integer
End Structure
Sub Main()
    Console.ReadLine()
End Sub
Function inputBooks(n)
    Dim books(n - 1) As book
    For i = 0 To n - 1
        Dim bookCode As Integer
        Do
            Console.Write("Enter book code (100-999): ")
            bookCode = Convert.ToInt32(Console.ReadLine())
        Loop Until 100 <= bookCode And bookCode <= 999
        books(i).code = bookCode

        Console.Write("Enter title: ")
        books(i).title = Console.ReadLine()
        Console.Write("Enter author: ")
        books(i).author = Console.ReadLine()
        Console.Write("Enter publication year: ")
        books(i).publicationYear = Convert.ToInt32(Console.ReadLine())

        Console.WriteLine("==============================")
        Console.WriteLine("Book code: " & books(i).code)
        Console.WriteLine("Title: " & books(i).title)
        Console.WriteLine("Main author: " & books(i).author)
        Console.WriteLine("Year of publication: " & books(i).publicationYear)
        Console.WriteLine("==============================")
    Next
    Return books
End Function

Sub storeBooksSerial(books() As book)
    FileOpen(1, "C:\Users\tfqsy\OneDrive\Documents\BooksSerial.txt", OpenMode.Append)
    Dim bookString As String
    For i = 0 To books.Length - 1
        bookString = books(i).code & "," &
            books(i).title & "," &
            books(i).author & "," &
            books(i).publicationYear
        PrintLine(1, bookString)
    Next
    FileClose(1)
End Sub

Sub readBooksSerial()
    FileOpen(1, "C:\Users\tfqsy\OneDrive\Documents\BooksSerial.txt", OpenMode.Input)
    Dim bookArr() As String
    While Not EOF(1)
        bookArr = LineInput(1).Split(",")
        Console.WriteLine("==============================")
        Console.WriteLine("Book code: " & bookArr(0))
        Console.WriteLine("Title: " & bookArr(1))
        Console.WriteLine("Main author: " & bookArr(2))
        Console.WriteLine("Year of publication: " & bookArr(3))
        Console.WriteLine("==============================")
    End While
    FileClose(1)
End Sub

Function hash(key)
    Return key Mod maxNumberBooks
End Function

Sub storeBookRandom(book As book)
    Dim collision As String
    Dim bookString As String = Convert.ToString(book.code) & "," &
        book.title.PadRight(45, " ") & "," &
        book.author.PadRight(25, " ") & "," &
        Convert.ToString(book.publicationYear).PadLeft(4, "0")

    Dim address As Integer = hash(book.code)
    Dim initialAddress As Integer = hash(book.code)
    FileOpen(1, "C:\Users\tfqsy\OneDrive\Documents\BooksRandom.txt", OpenMode.Random, OpenAccess.ReadWrite, , bookByteSize)
    Seek(1, address)
    FileGet(1, collision)
    While collision <> ""
        address += 1
        If address >= maxNumberBooks Then
            address = 0
        End If
        If address = initialAddress Then
            Console.WriteLine("Error: File is full")
            FileClose(1)
            Exit Sub
        End If
        Seek(1, address)
        FileGet(1, collision)
    End While
    FilePut(1, bookString)
    FileClose(1)
End Sub
Sub readBookRandom(bookCode As Integer)
    Dim bookString As String
    Dim address As Integer = hash(bookCode)
    Dim initialAddress As Integer = address
    FileOpen(1, "C:\Users\tfqsy\OneDrive\Documents\BooksRandom.txt", OpenMode.Random, OpenAccess.Read, , bookByteSize)
    Seek(1, address)
    FileGet(1, bookString)

    While Convert.ToInt32(bookString.Substring(0, 3)) <> bookCode
        address += 1
        If address >= maxNumberBooks Then
            address = 0
        End If
        If address = initialAddress Then
            Console.WriteLine("Book code not found!")
            FileClose(1)
            Exit Sub
        End If
        Seek(1, address)
        FileGet(1, bookString)
    End While

    FileClose(1)
    outputBook(bookString.Substring(0, 3),
                bookString.Substring(4, 45).TrimEnd(" "),
                bookString.Substring(50, 25).TrimEnd(" "),
                bookString.Substring(76, 4))
    Console.ReadLine()
End Sub
Sub outputBook(code As String, title As String, author As String, publicationYear As String)
    Console.WriteLine("==============================")
    Console.WriteLine("Book code: " & code)
    Console.WriteLine("Title: " & title)
    Console.WriteLine("Main author: " & author)
    Console.WriteLine("Year of publication: " & publicationYear)
    Console.WriteLine("==============================")
End Sub