Can someone explain me how the script given below is working ?

Especially the CASE Statement

DECLARE @Text NVARCHAR(2000)

DECLARE @StringDelimiter CHAR(1)

SELECT @Text = 'This T-sql will split senteneces into rows.'+

'How many rows will be returned?.'+

'M.a.y.b.e..n.n.o.e.?',

@StringDelimiter = '.';

With Tally (Number)

AS

(

SELECT ROW_NUMBER() OVER( ORDER BY (SELECT NULL) )AS Number

UNION ALL

SELECT Number + 1 AS Number

FROM Tally WHERE Number <= LEN(@Text)

)

SELECT CASE WHEN RIGHT(LEFT(@Text,Number),

CASE WHEN CHARINDEX(@StringDelimiter,REVERSE(LEFT(@Text,Number -1)),0) > 0

THEN CHARINDEX(@StringDelimiter,REVERSE(LEFT(@Text,Number -1)),0) - 1

ELSE CHARINDEX(@StringDelimiter,Reverse(LEFT(@Text,Number -1)),0) END) = ''

AND

CHARINDEX(@StringDelimiter,REVERSE(LEFT(@Text,Number -1))) = 0

THEN LEFT(@Text,Number -1)

ELSE RIGHT(LEFT(@Text,Number - 1),

CASE WHEN CHARINDEX(@StringDelimiter,Reverse(LEFT(@Text,Number -1)),0) >0

THEN CHARINDEX(@StringDelimiter,REVERSE(LEFT(@Text,Number -1)),0) -1

ELSE CHARINDEX(@StringDelimiter,REVERSE(LEFT(@Text,Number -1)),0) END)

END AS SPLIT FROM TALLY

WHERE(NCHAR(UNICODE(SUBSTRING(@Text,Number,1))) = @StringDelimiter

ORNumber - 1 = LEN(@Text))

OPTION (MAXRECURSION 32767)