=============================================================================================
-- ************Purpose		: AMIN for Devanagari
-- ************Developed by	: Technical Team Election, Commission of India, New Delhi.

--==============================================================================================

'***************************************
    'Algorithm for Devanagari Names
    '***************************************
    Function AMIN_Devanagari(ByVal str1 As String, ByVal str2 As String)
        Dim d(Len(str1), Len(str2)) As Decimal
        Dim i As Integer
        Dim j As Integer
        ReDim Preserve source(str1.Length + 1)
        ReDim Preserve target(str2.Length + 1)

        'Building source array  
        source(0) = "#"
        For i = 1 To str1.Length
            source(i) = str1.Substring(i - 1, 1)
        Next
        source(str1.Length + 1) = "!"
        '##########################

        'Building Target array
        target(0) = "#"
        For i = 1 To str2.Length
            target(i) = str2.Substring(i - 1, 1)
        Next
        target(str2.Length + 1) = "!"
        '##########################

        Dim cost As Integer
        Dim len1 As Integer = str1.Length
        Dim len2 As Integer = str2.Length
        Dim SimplificationCost As Decimal
        For i = 0 To len1
            d(i, 0) = i
        Next
        For j = 0 To len2
            d(0, j) = j
        Next
        For i = 1 To len1
            For j = 1 To len2
                Dim values(2) As Decimal
                values(0) = d(i - 1, j) + costInsertDelete_Devanagari(source(i), source(i - 1), source(i + 1)) 'cost deletion
                values(1) = d(i, j - 1) + costInsertDelete_Devanagari(target(j), target(j - 1), target(j + 1)) 'cost insertion
                values(2) = d(i - 1, j - 1) + costsubstitution_Devanagari(source(i), target(j)) 'cost substitution
                d(i, j) = Min(values)
            Next
        Next
        Dim intdist As Decimal
        intdist = d(len1, len2)
        source.Clear(source, 0, source.Length)
        target.Clear(target, 0, target.Length)
        Return intdist
    End Function
    Private Function costInsertDelete_Devanagari(ByVal thischar As Char, ByVal prevchar As Char, ByVal nextchar As Char)
        'Cost Insertion for the Target Character or deletion of source character
        If AscW(thischar) < 2305 Or AscW(thischar) > 2416 Then
            Return 0.0
        ElseIf (thischar = prevchar) Then
            Return 0.25
        ElseIf Regex.IsMatch(thischar, "[्]") Then
            If prevchar = "र" Then
                Return 0.05
            End If
            Return 0.1
        ElseIf Regex.IsMatch(thischar, "[ँं]") Then
            Return 0.1
        End If
        If IsDependentVowel(thischar) Then
            Return 0.25
        ElseIf IsHindiConsonant(thischar) Then
            Return 1.0
        Else ' MATRA etc.
            Return 0.75
        End If
    End Function
    Private Function costsubstitution_Devanagari(ByVal chr1 As Char, ByVal chr2 As Char) As Decimal
        If chr1 = chr2 Then
            Return 0.0
        End If
        Select Case chr1 & chr2
            Case "ँं", "ंँ"
                Return 0.05
            Case "िी", "ीि", "ूु", "ुू", "ोौ", "ौो", "ेै", "ैे", "लळ", "ळल", "ज" & ChrW(2395), ChrW(2395) & "ज"
                Return 0.1
            Case "सश", "शस", "सष", "षस", "शष", "षश", "ओऔ", "औओ", "अआ", "आअ", "इई", "ईइ", "उऊ", "ऊउ", "एऐ", "ऐए"
                Return 0.15
            Case "नण", "णन", "नं", "ंन", "नँ", "ँन", "ंण", "णं", "ँण", "णँ", "नञ", "ञन", "णञ", "ञण", "ंञ", "ञं", "ँञ", "ञँ"
                Return 0.15
            Case "यइ", "इय"
                Return 0.25
            Case "बव", "वब", "वभ", "भव", "बभ", "भब"
                Return 0.3
            Case "रड", "डर", "पफ", "फप", "शछ", "छश"
                Return 0.4
            Case "जय", "यज", "तट", "टत"
                Return 0.5
            Case Else
                Return 1.0
        End Select
    End Function
    Private Function IsDependentVowel(ByVal chr As Char) As Boolean
        IsDependentVowel = False
        If AscW(chr) > 2365 And AscW(chr) < 2381 Then Return True
    End Function
    Private Function IsIndependentVowel(ByVal chr As Char) As Boolean
        IsIndependentVowel = False
        If AscW(chr) > 2308 And AscW(chr) < 2325 Then Return True
    End Function
    Private Function IsHindiConsonant(ByVal chr As Char) As Boolean
        IsHindiConsonant = False
        If AscW(chr) > 2324 And AscW(chr) < 2362 Then Return True
    End Function