module Task6

open System

type BinaryTree =
    | Empty
    | Node of string * BinaryTree * BinaryTree

let empty = Empty

let rec insert value tree =
    match tree with
    | Empty -> Node(value, Empty, Empty)
    | Node(v, left, right) ->
        if value < v then
            Node(v, insert value left, right)
        elif value > v then
            Node(v, left, insert value right)
        else
            tree

let rec contains value tree =
    match tree with
    | Empty -> false
    | Node(v, left, right) ->
        if value = v then true
        elif value < v then contains value left
        else contains value right

let rec findMin tree =
    match tree with
    | Empty -> None
    | Node(v, Empty, _) -> Some v
    | Node(_, left, _) -> findMin left

let rec findMax tree =
    match tree with
    | Empty -> None
    | Node(v, _, Empty) -> Some v
    | Node(_, _, right) -> findMax right

let rec remove value tree =
    match tree with
    | Empty -> Empty
    | Node(v, left, right) ->
        if value < v then
            Node(v, remove value left, right)
        elif value > v then
            Node(v, left, remove value right)
        else
            match left, right with
            | Empty, Empty -> Empty
            | Empty, right -> right
            | left, Empty -> left
            | left, right ->
                match findMin right with
                | Some minValue ->
                    Node(minValue, left, remove minValue right)
                | None -> left

let rec inOrder tree =
    match tree with
    | Empty -> []
    | Node(v, left, right) ->
        (inOrder left) @ [v] @ (inOrder right)

let rec preOrder tree =
    match tree with
    | Empty -> []
    | Node(v, left, right) ->
        [v] @ (preOrder left) @ (preOrder right)

let rec postOrder tree =
    match tree with
    | Empty -> []
    | Node(v, left, right) ->
        (postOrder left) @ (postOrder right) @ [v]

let rec height tree =
    match tree with
    | Empty -> 0
    | Node(_, left, right) ->
        1 + max (height left) (height right)

let rec size tree =
    match tree with
    | Empty -> 0
    | Node(_, left, right) ->
        1 + (size left) + (size right)

let rec map f tree =
    match tree with
    | Empty -> Empty
    | Node(v, left, right) ->
        Node(f v, map f left, map f right)

let rec fold f acc tree =
    match tree with
    | Empty -> acc
    | Node(v, left, right) ->
        let leftAcc = fold f acc left
        let nodeAcc = f leftAcc v
        fold f nodeAcc right

let rec filter predicate tree =
    match tree with
    | Empty -> Empty
    | Node(v, left, right) ->
        let filteredLeft = filter predicate left
        let filteredRight = filter predicate right
        if predicate v then
            Node(v, filteredLeft, filteredRight)
        else
            let leftList = inOrder filteredLeft
            let rightList = inOrder filteredRight
            let combinedList = leftList @ rightList
            List.fold (fun acc x -> insert x acc) Empty combinedList

let fromList lst =
    List.fold (fun acc x -> insert x acc) Empty lst

let toList tree = inOrder tree

[<EntryPoint>]
let main argv =
    let tree1 = empty
                |> insert "dog"
                |> insert "cat"
                |> insert "elephant"
                |> insert "bird"
                |> insert "fish"
    
    printfn "Tree contents (in-order): %A" (inOrder tree1)
    printfn "Tree contents (pre-order): %A" (preOrder tree1)
    printfn "Tree contents (post-order): %A" (postOrder tree1)
    
    printfn "Contains 'cat': %b" (contains "cat" tree1)
    printfn "Contains 'zebra': %b" (contains "zebra" tree1)
    
    printfn "Min value: %A" (findMin tree1)
    printfn "Max value: %A" (findMax tree1)
    
    printfn "Tree height: %d" (height tree1)
    printfn "Tree size: %d" (size tree1)
    
    let tree2 = remove "cat" tree1
    printfn "After removing 'cat': %A" (inOrder tree2)
    
    let upperTree = map (fun s -> s.ToUpper()) tree1
    printfn "Uppercase tree: %A" (inOrder upperTree)
    
    let longWords = filter (fun s -> s.Length > 3) tree1
    printfn "Words longer than 3 chars: %A" (inOrder longWords)
    
    let wordCount = fold (fun acc _ -> acc + 1) 0 tree1
    printfn "Word count using fold: %d" wordCount
    
    let listTree = fromList ["apple"; "banana"; "cherry"; "date"]
    printfn "Tree from list: %A" (toList listTree)
    
    0