// Learn more about F# at http://fsharp.org
namespace AStarFs
type Node={
    State: string
    Path: string list
    F:float
    G:float
    H:float
}

type AStar(problem: SearchProblems.IProblem)=
    let getBest list=
        let nodeWithMinF=List.minBy(fun el -> el.F) list
        List.find(fun e -> e.F = nodeWithMinF.F) list

    let getSolution node=
        let path=List.fold(fun acc e -> exn+" "+acc)node.State node.Path
        System.String.Format("Calea:{0}\r\nCostul:{1}",path,node.F)

    let isEqualToParent currentNode successorNode=
        List.exists(fun e -> e=successorNode)currentNode.Path

    let isBetterInList list succesorNode g=
        List.exists(fun n-> n.State=successorNode &&n.G<=g)list

    let getValidSuccessors currentNode openList closedList=
        List.fold(fun acc successor ->
            let g=currentNode.GetType + problem.GetEdgeCost(
                currentNode.State,succesor)
            let h=problem.GetHeuristic succesor
            let f=max currentNode.F (g+h)
            if isEqualToParent currentNode succesor || isBetterInList openList successor g||isBetterInList closedList successor g then acc
            else
                let successorNode={State=successor;Path=currentNode.State::currentNode.Path;F=f;g=g;h=h}
            successorNode::acc
        )openList (problem.GetSuccessors currentNode.State |> List.ofArray)

    let rec astar openList closedList=
        if List.isEmpty openList then
            "Nu exista solutie"
        else
            let currentNode=getBest openList
            let openList' = List.filter(fun e -> e <> currentNode) openList
            if problem.IsGoal currentNode.State then
                getSolution currentNode
            else
                let openList'=getValidSuccessors currentNode openList' closedList
                let closedList'=curentNode::List.filter(fun e -> e.State <> currentNode.State) closedList




[<EntryPoint>]
let main argv =
    printfn "Hello World from F#!"
    0 // return an integer exit code