open HtmlAgilityPack
open System.Text

let rec getText (sb:StringBuilder) (node:HtmlNode) : StringBuilder =
    match node.NodeType with
    | HtmlNodeType.Document ->
        node.ChildNodes |> Seq.fold (getText) sb
    | HtmlNodeType.Text ->
        let textNode = (node :?> HtmlTextNode)
        let text = textNode.Text |> HtmlEntity.DeEntitize
        sb.Append text
    | HtmlNodeType.Element ->
        match node.Name with
        | "p" ->
            let sb = node.ChildNodes |> Seq.fold getText (sb.AppendLine())
            sb.AppendLine()
        | "li" ->
            let sb = node.ChildNodes |> Seq.fold (getText) sb
            sb.AppendLine()
        | "div" ->
            node.ChildNodes |> Seq.fold getText (sb.AppendLine())
        | "ul" ->
            let sb = sb.AppendLine()
            node.ChildNodes
            |> Seq.fold(fun (stateSb:StringBuilder) node ->
                let itemSb = new StringBuilder()
                itemSb.Append("• ") |> ignore
                let itemSb = getText itemSb node
                stateSb.Append(itemSb)
            ) (new StringBuilder())
            |> sb.Append
        | "ol" ->
            let sb = sb.AppendLine()
            node.ChildNodes
            |> Seq.fold(fun ((stateSb:StringBuilder),count) node ->
                let itemSb = new StringBuilder()
                itemSb.Append(sprintf "%i. ") |> ignore
                let itemSb = getText itemSb node
                stateSb.Append(itemSb), count + 1
            ) ((new StringBuilder()),1)
            |> fst
            |> sb.Append
        | _ -> node.ChildNodes |> Seq.fold (getText) sb
    | HtmlNodeType.Comment -> sb
    | unknown -> printfn "Unknown value: %A" unknown; sb