'**************************************************
' FILE      : BBCodeParser.vb
' AUTHOR    : Paulo Santos
' CREATION  : 4/29/2009 11:03:53 AM
' COPYRIGHT : Copyright © 2009
'             PJ on Development
'             All Rights Reserved.
'
' Description:
'       TODO: Add file description
'
' Change log:
' 0.1   4/29/2009 11:03:53 AM
'       Paulo Santos
'       Created.
'***************************************************

Imports System.Text.RegularExpressions
Imports System.Diagnostics.CodeAnalysis

''' <summary>
''' The parser of 
''' </summary>
Public NotInheritable Class BBCodeParser(Of TContext As Class)

	Private __Factory As BBCodeElementFactory(Of TContext)
	Private __Configuration As BBCodeConfiguration(Of TContext)

	Private Shared ReadOnly __ConfigSerializer As New System.Xml.Serialization.XmlSerializer(GetType(BBCodeConfiguration(Of TContext)))
	Private Shared ReadOnly __Tokenizer As Tokenization.Tokenizer = PrepareTokenizer()

	''' <summary>Initializes an instance of the <see cref="BBCodeParser" /> class.
	''' This is the default constructor for this class.</summary>
	Public Sub New()
	End Sub

	''' <summary>
	''' Gets the dictionary of elements to be replaced by the <see cref="BBCodeParser"/>.
	''' </summary>
	Public ReadOnly Property Dictionary() As BBCodeElementDictionary
		Get
			If (__Configuration Is Nothing) Then
				__Configuration = New BBCodeConfiguration(Of TContext)()
			End If
			Return __Configuration.Dictionary
		End Get
	End Property

	''' <summary>
	''' Gets the dictionary of types created by the parser.
	''' </summary>
	Public ReadOnly Property ElementTypes() As BBCodeElementTypeDictionary(Of TContext)
		Get
			If (__Configuration Is Nothing) Then
				__Configuration = New BBCodeConfiguration(Of TContext)()
			End If
			Return __Configuration.ElementTypes
		End Get
	End Property

#Region " LoadConfiguration Methods "

	''' <summary>
	''' Loads the configuration from the specified filename.
	''' </summary>
	''' <param name="fileName">The name of the file to read the dictionary from.</param>
	Public Sub LoadConfiguration(ByVal fileName As String)
		If (String.IsNullOrEmpty(fileName)) Then
			Throw New ArgumentNullException("fileName")
		End If
		Using fileStream As New IO.FileStream(fileName, IO.FileMode.Open)
			LoadConfiguration(fileStream)
		End Using
	End Sub

	''' <summary>
	''' Loads the configuration from the specified <see cref="IO.Stream"/>.
	''' </summary>
	''' <param name="stream">A <see cref="IO.Stream"/> to read the dictionary from.</param>
	Public Sub LoadConfiguration(ByVal stream As IO.Stream)
		LoadConfiguration(New IO.StreamReader(stream, Text.Encoding.UTF8, True))
	End Sub

	''' <summary>
	''' Loads the configuration from the specified <see cref="IO.TextReader"/>.
	''' </summary>
	''' <param name="reader">The <see cref="IO.TextReader"/> to read the dictionary from.</param>
	Public Sub LoadConfiguration(ByVal reader As IO.TextReader)
		Dim dic = __ConfigSerializer.Deserialize(reader)
		If (dic IsNot Nothing) Then
			__Configuration = dic
		End If
	End Sub

#End Region

#Region " SaveConfiguration Methods "

	''' <summary>
	''' Saves the conficuration to the specified file.
	''' </summary>
	''' <param name="fileName">The name of the file to save the dictionary.</param>
	Public Sub SaveConfiguration(ByVal fileName As String)
		If (String.IsNullOrEmpty(fileName)) Then
			Throw New ArgumentNullException("fileName")
		End If
		Using fileStream As New IO.FileStream(fileName, IO.FileMode.Create)
			SaveConfiguration(fileStream)
		End Using
	End Sub

	''' <summary>
	''' Saves the conficuration to the specified <see cref="IO.Stream"/>.
	''' </summary>
	''' <param name="stream">The <see cref="IO.Stream"/> to save the dictionary.</param>
	Public Sub SaveConfiguration(ByVal stream As IO.Stream)
		SaveConfiguration(New IO.StreamWriter(stream, Text.Encoding.UTF8))
	End Sub

	''' <summary>
	''' Saves the conficuration to the specified <see cref="IO.TextWriter"/>.
	''' </summary>
	''' <param name="writer">The <see cref="IO.TextWriter"/> to save the dictionary.</param>
	Public Sub SaveConfiguration(ByVal writer As IO.TextWriter)
		__ConfigSerializer.Serialize(writer, __Configuration)
	End Sub

#End Region

#Region " Parse Methods "

	''' <summary>
	''' Parses the specified text, returning a collection of <see cref="BBCodeNode"/>.
	''' </summary>
	''' <param name="text">The text to be parsed.</param>
	''' <returns>A <see cref="BBCodeNodeCollection"/> containing the parsed text.</returns>
	Public Function Parse(ByVal text As String) As BBCodeDocument(Of TContext)
		Using reader As New IO.StringReader(text)
			Return Parse(reader)
		End Using
	End Function

	''' <summary>
	''' Parses the specified stream, returning a collection of <see cref="BBCodeNode"/>.
	''' </summary>
	''' <param name="stream">The <see cref="IO.Stream"/> to be parsed.</param>
	''' <returns>A <see cref="BBCodeNodeCollection"/> containing the parsed <see cref="IO.Stream"/>.</returns>
	Public Function Parse(ByVal stream As IO.Stream) As BBCodeDocument(Of TContext)
		Return Parse(stream, Text.Encoding.UTF8)
	End Function

	''' <summary>
	''' Parses the specified stream, returning a collection of <see cref="BBCodeNode"/>.
	''' </summary>
	''' <param name="stream">The <see cref="IO.Stream"/> to be parsed.</param>
	''' <param name="encoding">The encoding of the stream.</param>
	''' <returns>A <see cref="BBCodeNodeCollection"/> containing the parsed <see cref="IO.Stream"/>.</returns>
	Public Function Parse(ByVal stream As IO.Stream, ByVal encoding As Text.Encoding) As BBCodeDocument(Of TContext)
		Return Parse(New IO.StreamReader(stream, encoding))
	End Function

	''' <summary>
	''' Parses the specified <see cref="IO.TextReader"/>, returning a collection of <see cref="BBCodeNode"/>.
	''' </summary>
	''' <param name="reader">The <see cref="IO.TextReader"/> to be parsed.</param>
	''' <returns>A <see cref="BBCodeNodeCollection"/> containing the parsed <see cref="IO.TextReader"/>.</returns>
	Public Function Parse(ByVal reader As IO.TextReader) As BBCodeDocument(Of TContext)

		Dim doc = New BBCodeDocument(Of TContext)(Me)
		Dim rootElement As New BBCodeElement(Of TContext)(Me)
		Dim currentElement As BBCodeElement(Of TContext) = rootElement

		Dim tk As Tokenization.Token
		Dim sb As New Text.StringBuilder()
		Dim sbText As New Text.StringBuilder()
		Do While (reader.Peek() <> -1)
			Dim line As String = reader.ReadLine() & vbCrLf
			sbText.AppendLine(line)
			Do
				'*
				'* Get the next token
				'*
				tk = Tokenizer.GetToken(line)
				If (tk Is Nothing) Then
					Exit Do
				End If

				Dim tag = New BBCodeTag(tk.Value)

				ParseElement(rootElement, currentElement, tk, sb, tag)
			Loop
		Loop

		'*
		'* Add the text node
		'*
		If (sb.Length > 0) Then
			currentElement.Nodes.Add(New BBCodeText(Of TContext)(sb.ToString()))
		End If

		'*
		'* Add the nodes to the document
		'*
		doc.Nodes.AddRange(rootElement.Nodes)

		'*
		'* Sets the source text
		'*
		doc.SetText(sbText.ToString())

		Return doc

	End Function

#End Region

	''' <summary>
	''' Gets the <see cref="Tokenization.Tokenizer"/>.
	''' </summary>
	Private Shared ReadOnly Property Tokenizer() As Tokenization.Tokenizer
		Get
			Return __Tokenizer
		End Get
	End Property

	''' <summary>
	''' Gets the <see cref="BBCodeElementFactory"/>.
	''' </summary>
	Private ReadOnly Property Factory() As BBCodeElementFactory(Of TContext)
		Get
			If (__Factory Is Nothing) Then
				__Factory = New BBCodeElementFactory(Of TContext)(Me)
			End If
			Return __Factory
		End Get
	End Property

	Private Sub ParseElement(ByVal rootElement As BBCodeElement(Of TContext), ByRef currentElement As BBCodeElement(Of TContext), ByVal token As Tokenization.Token, ByVal sb As Text.StringBuilder, ByVal tag As BBCodeTag)

		'*
		'* Check the token Type
		'*
		Select Case token.RuleType
			Case 0, -1
				'*
				'* Empty tag or char
				'*
				sb.Append(token.Value)
			Case 1
				'*
				'* Closing tag
				'*

				ParseClosingTag(rootElement, currentElement, token, sb, tag)
			Case 2, 3, 4
				'*
				'* Value Tag, Parametrized Tag, Generic Tag
				'*
				ParseTag(currentElement, sb, tag)
		End Select

	End Sub

	Private Sub ParseTag(ByRef currentElement As BBCodeElement(Of TContext), ByVal sb As Text.StringBuilder, ByVal tag As BBCodeTag)

		'*
		'* Add the text previous to the current element
		'*
		If (sb.Length > 0) Then
			currentElement.Nodes.Add(New BBCodeText(Of TContext)(sb.ToString()))
			sb.Remove(0, sb.Length)
		End If

		'*
		'* Add the new element to the list of nodes
		'*
		Dim el = Factory.CreateElement(tag.Name, tag.Paramters)
		currentElement.Nodes.Add(el)

		'*
		'* Change the current element, if it requires an closing tag
		'*
		If (el.RequireClosingTag) Then
			currentElement = el
		End If

	End Sub

	Private Shared Sub ParseClosingTag(ByVal rootElement As BBCodeElement(Of TContext), ByRef currentElement As BBCodeElement(Of TContext), ByVal token As Tokenization.Token, ByVal sb As Text.StringBuilder, ByVal tag As BBCodeTag)

		'*
		'* Check if the closing tag is closing a previously open tag
		'*
		If currentElement.RequireClosingTag AndAlso (String.CompareOrdinal(currentElement.Name, tag.Name) = 0) Then
			'*
			'* Add the inner text
			'*
			If (sb.Length > 0) Then
				currentElement.Nodes.Add(New BBCodeText(Of TContext)(sb.ToString()))
				sb.Remove(0, sb.Length)
			End If

			'*
			'* Move up a level
			'*
			currentElement = If(currentElement.Parent, rootElement)
		Else
			'*
			'* Adds to the text
			'*
			sb.Append(token.Value)
		End If

	End Sub

	Private Shared Function PrepareTokenizer() As Tokenization.Tokenizer
		Dim tk As New Tokenization.Tokenizer
		'*
		'* Prepares the BBCode Grammar
		'*
		With tk
			'*
			'* Define the grammar macros
			'*
			AddTokenizerBaseMacros(tk)

			'*
			'* Define the grammar rules
			'*
			.AddRule("EmptyTag", 0, "\[{w}\]")
			.AddRule("ClosingTag", 1, "\[/{name}\]")
			.AddRule("ValueTag", 2, "\[{param}\]")
			.AddRule("ParamsTag", 3, "\[{name}{params}\]")
			.AddRule("Tag", 4, "\[[^ \t\r\n\f\]]+?\]")
			.AddRule("Char", -1, ".")
		End With
		Return tk
	End Function

End Class