module internal DataProcessing

    open System.Text.RegularExpressions
    open DataCleaning
    open System
    open System.IO

    let MatchText pattern text = Regex.IsMatch(text, pattern)

    let ConcatToString words = String.concat " " words

    let GibberishLevelIsValid gibberishLevel =
        match gibberishLevel with
        | gibberishLevel when gibberishLevel < 2 || gibberishLevel > 20 ->
            invalidArg "gibberishLevel" "Invalid argument. Must be between 2 and 20 (inclusive)."
        | _ -> ignore

    let SentencesIsValid sentences =
        match sentences with
        | sentences when sentences < 1 ->
            invalidArg "sentences" "Invalid argument. Must be greater than 0."
        | _ -> ignore

    let FilePathIsValid filePath =
        match filePath with
        | filePath when Path.GetExtension filePath <> ".txt" ->
            invalidArg "filePath" "Invalid argument. File must be a .txt file."
        | filePath when not (File.Exists filePath) ->
            raise (FileNotFoundException("Unable to find the file at the location specified."))
        | _ -> ignore

    let TextContainsValidEndToken (text: string) =
        match text with
        | text when text.Contains "." -> true
        | text when text.Contains "!" -> true
        | text when text.Contains "?" -> true
        | _ -> false

    let SortIntoGroups groupSize text =
        SplitText @"\s+" text // Splits text where there is a space.
        |> Seq.windowed groupSize

    let BisectWords words =
        let length = Array.length words
        let start =
            words
            |> Seq.take (length - 1)
            |> ConcatToString
        (start, words.[length - 1])

    let CombineWords prev next =
        [prev; next]
        |> List.filter(fun s -> not (String.IsNullOrWhiteSpace s))
        |> ConcatToString

    let ApplyStandardSetup text =
        text
        |> ReplaceArtifact "\""
        |> ReplaceArtifact "\n\nIn"
        |> ReplaceArtifact "\r"
        |> ReplaceArtifact "\n"
        |> SplitText @"\s+"
        |> ConcatToString