Imports System.Runtime.InteropServices.ComTypes

Imports Newtonsoft.Json

Imports Pilz.Cryptography

Namespace SimpleSorting

    ''' <summary>
    ''' Provides some management methods for sorting a list without changing the list itself.
    ''' Useful if the host list can not be changed or the sorting is indipendent from the required sorting.
    ''' </summary>
    ''' <typeparam name="T">The content of the host list to sort.</typeparam>
    Public Class SimpleSortingList(Of T As IUniquieIDHost)

        Private ReadOnly host As ISimpleSortingHost

        <JsonProperty("SortingInfo")>
        Private ReadOnly sortingList As New List(Of SimpleSortingEntry)

        Public Sub New(parentList As ISimpleSortingHost)
            host = parentList
            AddHandler host.OnInsert, AddressOf Host_OnInsert
            AddHandler host.OnRemove, AddressOf Host_OnRemove
        End Sub

        Protected Overrides Sub Finalize()
            RemoveHandler host.OnInsert, AddressOf Host_OnInsert
            RemoveHandler host.OnRemove, AddressOf Host_OnRemove
        End Sub

        Private Sub Host_OnInsert(sender As Object, e As SimpleSortingHostEventArgs)
            '...
        End Sub

        Private Sub Host_OnRemove(sender As Object, e As SimpleSortingHostEventArgs)
            '...
        End Sub

        ''' <summary>
        ''' Stores positioning infos for the given element.
        ''' </summary>
        ''' <param name="elementID"></param>
        ''' <param name="position"></param>
        ''' <param name="referenceElementID"></param>
        Public Sub SetElementPosition(elementID As UniquieID, position As ElementSortingPosition, referenceElementID As UniquieID)
            '...
        End Sub

        ''' <summary>
        ''' Removes the positioning infos for the given element if available.
        ''' </summary>
        ''' <param name="elementID"></param>
        Public Sub RemoveElementPosition(elementID As UniquieID)
            Dim infoToRemove = FindSortInfoByID(elementID)

            If infoToRemove IsNot Nothing Then
                sortingList.Remove(infoToRemove)

                For Each info In sortingList
                    If info.ReferenceElement = elementID Then
                        info.ReferenceElement = infoToRemove.ReferenceElement
                    End If
                Next
            End If
        End Sub

        ''' <summary>
        ''' Completely removes an element from all positioning infos. If possible, elements will be assigned to nearby reference or removed completely.
        ''' </summary>
        ''' <param name="elementID"></param>
        Public Sub InvalidateElement(elementID As UniquieID)
            '...
        End Sub

        ''' <summary>
        ''' Creates a sorted list with all elements from the host list.
        ''' </summary>
        ''' <returns></returns>
        Public Function GetSortedList() As List(Of T)
            Dim list As New List(Of T)
            list.AddRange(host)

            For Each info In sortingList
                Dim element As T = list.FirstOrDefault(Function(n) n.ID = info.Element)
                Dim referenceElement As T = list.FirstOrDefault(Function(n) n.ID = info.ReferenceElement)

                If element IsNot Nothing AndAlso referenceElement IsNot Nothing Then
                    list.Remove(element)
                    Dim referenceElementIndex As Integer = list.IndexOf(referenceElement)

                    If info.Position = ElementSortingPosition.After Then
                        referenceElementIndex += 1
                    End If

                    list.Insert(referenceElementIndex, element)
                End If
            Next

            Return list
        End Function

        ''' <summary>
        ''' Creates a sorted list with all elements from the host list.
        ''' </summary>
        ''' <returns></returns>
        Public Function GetSortedArray() As T()
            Return GetSortedList.ToArray
        End Function

        Private Function FindSortInfoByID(id As UniquieID) As SimpleSortingEntry
            Return sortingList.FirstOrDefault(Function(n) n.Element = id)
        End Function

        Private Function FindSortInfoByReferenceID(id As UniquieID) As SimpleSortingEntry
            Return sortingList.FirstOrDefault(Function(n) n.ReferenceElement = id)
        End Function

    End Class

End Namespace