VB.Net Search for text and replace with file content - vb.net

Question

This is a follow on question to a post I made. Append one file into another file
I need to search the master document for entities "&CH1.sgm" to "&CH33.sgm",
mark where they are in the master document and replace the entity call with the matching file "Chapter1.sgm" found in "fnFiles". I can change the file names and entities to anything if that will help.
My code copies the text of a file and appends it to the bottom of the master_document.sgm. But now I need it to be more intelligent. Search the Master document for entity markers, then replace that entity marker with that file contents match. The file number and entity number match up. e.g.(&CH1; and Bld1_Ch1.sgm)
Private Sub btnImport_Click(sender As Object, e As EventArgs) Handles btnImport.Click
Dim searchDir As String = txtSGMFile.Text 'Input field from form
Dim masterFile = "Bld1_Master_Document.sgm"
Dim existingFileMaster = Path.Combine(searchDir, masterFile)
'Read all lines of the Master Document
Dim strMasterDoc = File.ReadAllText(existingFileMaster) '// add each line as String Array.
'?search strMasterDoc for entities &Ch1.sgm
'?replace entity name "&Ch1.sgm" with content of file "Bld1_Ch1.sgm" this content if found below
'? do I use a book mark? Replace function?
'Get all the sgm files in the directory specified
Dim fndFiles = Directory.GetFiles(searchDir, "*.sgm")
'Set up the regular expression you will make as the condition for the file
Dim rx = New Regex(".*_Ch\d\.sgm")
Dim ch1 = New Regex(".*_Ch[1]\.sgm")
'Use path.combine for concatenatin directory together
'Loop through each file found by the REGEX
For Each fileNo In fndFiles
If rx.IsMatch(fileNo) Then
If ch1.IsMatch(fileNo) Then
Dim result = Path.GetFileName(fileNo)
'Use path.combine for concatenatin directory together
Dim fileToCopy = Path.Combine(searchDir, result)
'This is the file we want to copy into MasterBuild but at specific location.
'match &ch1.sgm inside strMasterDoc
Dim fileContent = File.ReadAllText(fileToCopy)
'Search master file for entity match then append all content of fileContent
File.AppendAllText(existingFileMaster, fileContent)
MessageBox.Show("File Copied")
End If
End If
Next
Close()
End Sub

Answer 1

If I understand correctly (big if), you want to replace the the text of the abbreviated chapter name in the master file with the contents of the file it refers to at the spot where the abbreviation is found.
I made a class to handle the details.
Private Sub btnImport_Click(sender As Object, e As EventArgs) Handles btnImport.Click
'Add a FolderBrowseDialog to your form designer
FolderBrowserDialog1.ShowDialog()
Dim searchDir As String = FolderBrowserDialog1.SelectedPath
Dim existingFileMaster = Path.Combine(searchDir, "Bld1_Master_Document.sgm")
Dim lstFileChanges = CreateList(searchDir)
'The following method does NOT return an array of lines
Dim strMasterDoc = File.ReadAllText(existingFileMaster)
For Each fc In lstFileChanges
strMasterDoc = strMasterDoc.Replace(fc.OldString, fc.NewString)
Next
File.WriteAllText(existingFileMaster, strMasterDoc)
End Sub
Private Function CreateList(selectedPath As String) As List(Of FileChanges)
Dim lstFC As New List(Of FileChanges)
For i = 1 To lstFC.Count
Dim fc As New FileChanges
fc.OldString = $"&CH{i}.sgm"
fc.FileName = $"Chapter{i}.sgm"
fc.NewString = File.ReadAllText(Path.Combine(selectedPath, fc.FileName))
lstFC.Add(fc)
Next
Return lstFC
End Function
Public Class FileChanges
Public Property OldString As String '&CH1.sgm
Public Property FileName As String 'Chapter1.sgm
Public Property NewString As String 'Contents of Chapter1.sgm, the string to insert
End Class
Testing .Replace
Dim s As String = "The quick brown fox jumped over the lazy dogs."
s = s.Replace("fox", "foxes")
MessageBox.Show(s)