Group by Start Date and End Date using a condition

Hi data_SWVO, check this:

Edited

Output

let
    fn_ShiftRows = 
        (tbl as table, col as text, shift as nullable number, optional newColName as text, optional _type as type) as table =>
        //v 3. parametri zadaj zaporne cislo ak chces posunut riadky hore, kladne ak dole, 4. je nepovinny (novy nazov stlpca), 5. je nepovinny typ
        let
            a = Table.Column(tbl, col),
            b = if shift = 0 or shift = null then a else if shift > 0
                then List.Repeat({null}, shift) & List.RemoveLastN(a, shift)
                else List.RemoveFirstN(a, shift * -1) & List.Repeat({null}, shift * -1),    
            c = Table.FromColumns(Table.ToColumns(tbl) & {b}, Table.ColumnNames(tbl) &
                ( if newColName <> null then {newColName} else
                    if shift = 0 then {col & "_Duplicate"} else
                    if shift > 0 then {col & "_PrevValue"} 
                    else              {col & "_NextValue"} )),
            d = Table.TransformColumnTypes(c, {List.Last(Table.ColumnNames(c)), if _type <> null then _type else type any})
        in
            d,
            
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc3BCoAgEATQXxHPLjirVv5F9/DYtaD+H0o3SchuA/tmdln0vB7nvikobTRoJLaMOzpLQ86sk+kizggE/lPl4ERNOfsWsaBYpzhKoYecHN6l0CJXUBCV/8HXxkdRaKZg+yoQ0DJ+XqYL", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Person = _t, #"Start Date" = _t, #"End Date" = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"Start Date", type date}, {"End Date", type date}}, "sk-SK"),
    GroupedRows = Table.Group(ChangedType, {"Person"}, {{"All", each
            [ //_tbl = GroupedRows{[Person="Person 1 "]}[All],
              _tbl = _,
              SortedRows = Table.Sort(_tbl,{{"Start Date", Order.Ascending}}),
              Ad_EndDatePrevValue = fn_ShiftRows(SortedRows, "End Date", 1, null, type date),
              Ad_Index = Table.AddIndexColumn(Ad_EndDatePrevValue, "Index", 0, 1, Int64.Type),
              Ad_GroupHelper = Table.AddColumn(Ad_Index, "GroupHelper", each try if Duration.Days([Start Date] - [End Date_PrevValue]) <= 30 then [Index] else [Index] + 1000000 otherwise 0, Int64.Type),
              GroupedRows1 = Table.Group(Ad_GroupHelper, {"Person", "GroupHelper"}, {{"All", each _, type table}, {"Start Date", each List.Min([Start Date]), type date}, {"End Date", each List.Max([End Date]), type date}}, GroupKind.Local,
                                   (x,y)=> try Number.From( y[GroupHelper] - x[GroupHelper] > 1)  otherwise false ),
              RemovedColumns = Table.RemoveColumns(GroupedRows1,{"GroupHelper", "All"})
            ][RemovedColumns], type table}}),
    Combined = Table.Combine(GroupedRows[All])
in
    Combined