VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
END
Attribute VB_Name = "API_Logger"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
' ================ Log functionality =============
' Shared module version: 20210413
' Tested in: TestCommons
' Depends on: ex_VBA
' Required reference: Scripting
' Note: log is saved as UTF-16 encoded text file
Option Explicit

Private fileName_ As String

Public Function Init(sName$)
  If sName = vbNullString Then _
    Exit Function
  fileName_ = sName
  Call EnsureOutputExists
End Function

Public Property Get LogFileName() As String
  LogFileName = fileName_
End Property

Public Function Log(sMsg$)
  If fileName_ <> vbNullString Then
    Call LogIntoFile(StampTime(sMsg))
  Else
    Call LogDefault(StampTime(sMsg))
  End If
End Function

Public Function Report(sMsg$, Optional nFlags& = 0)
  ' TODO: indicate flags
  Call Log(sMsg)
End Function

Public Function Clear()
  If fileName_ <> vbNullString Then _
    Call CreateLogFile
End Function

' ==========
Private Function LogIntoFile(sMsg$)
  Const UTF16_MODE = TristateTrue
  
  Dim fso As New Scripting.FileSystemObject
  If Not fso.FileExists(fileName_) Then _
    GoTo CANNOT_ACCESS
    
  Dim fs As Scripting.TextStream: Set fs = fso.OpenTextFile(fileName_, ForAppending, Format:=UTF16_MODE)
  If fs Is Nothing Then _
    GoTo CANNOT_ACCESS
  
  Call fs.WriteLine(sMsg)
  Call fs.Close
  Exit Function
  
CANNOT_ACCESS:
  Call LogDefault(StampTime("Cannot access log"))
  Call LogDefault(sMsg)
End Function

Private Function LogDefault(sMsg$)
  Debug.Print sMsg
End Function

Private Function EnsureOutputExists()
  Dim fso As New Scripting.FileSystemObject
  If fso.FileExists(fileName_) Then _
    Exit Function
    
  Call CreateLogFile
End Function

Private Function StampTime(sMsg$) As String
  StampTime = Format(Now(), "yyyy-mm-dd hh:mm:ss") & ": " & sMsg
End Function

Private Function CreateLogFile()
  Dim fso As New Scripting.FileSystemObject
  Call EnsureFolderExists(fso.GetParentFolderName(fileName_))
  Dim fs As Scripting.TextStream: Set fs = fso.CreateTextFile(fileName_, Unicode:=True)
  If fs Is Nothing Then
    Call LogDefault(StampTime("Cannot create log: " & fileName_))
  Else
    Call fs.Close
    Call Log("Log file created")
  End If
End Function