open System 

let RPS plr npc : int8 =

    match plr, npc with 
        | 0 , 0 | 2 , 2 | 5 , 5 ->  0y // Draw
        | 0 , 2 | 2 , 5 | 5 , 0 ->  1y // Player wins
        | 0 , 5 | 5 , 2 | 2 , 0 ->  2y // NPC wins
        | 6 , _                 -> -6y // Valid input from the player
        |           _           ->  9y // Default case

let Game : unit =
    
    let mutable local = 0
    let mutable total = 0

    let mutable again = ConsoleKey.Y
    while again = ConsoleKey.Y do

        local <- 0

        printf  "\n\n\t\t\tPLAYER\t\tNPC\t\tRESULT\n\n"

        for i in 1 .. 5 do
            
            printf "  ROUND %d / 5 :\t\t" i
            let plr = match System.Console.ReadKey(true).Key with

                        | ConsoleKey.NumPad0 | ConsoleKey.D0
                        | ConsoleKey.R  ->  Console.ForegroundColor <- ConsoleColor.Green
                                            printf "ROCK\t\t"
                                            0

                        | ConsoleKey.NumPad2 | ConsoleKey.D2
                        | ConsoleKey.S  ->  Console.ForegroundColor <- ConsoleColor.Yellow
                                            printf "SCISSORS\t"
                                            2

                        | ConsoleKey.NumPad5 | ConsoleKey.D5
                        | ConsoleKey.P  ->  Console.ForegroundColor <- ConsoleColor.Cyan
                                            printf "PAPER\t\t"
                                            5

                        | _             ->  Console.ForegroundColor <- ConsoleColor.DarkRed
                                            printf "???\t\t"
                                            6

            let npc = match (System.Random()).Next(0,3) with
                        | 0     ->  Console.ForegroundColor <- ConsoleColor.Green
                                    printf "ROCK\t\t"
                                    0
                        | 1     ->  Console.ForegroundColor <- ConsoleColor.Yellow
                                    printf "SCISSORS\t"
                                    2
                        | _     ->  Console.ForegroundColor <- ConsoleColor.Cyan
                                    printf "PAPER\t\t"
                                    5

            let dxs = match RPS plr npc with
                        |  0y   ->  Console.ForegroundColor <- ConsoleColor.Cyan
                                    printf "TIE\n" 
                                    +0
                        |  1y   ->  Console.ForegroundColor <- ConsoleColor.Green
                                    printf "WON\n" 
                                    +1
                        |  2y   ->  Console.ForegroundColor <- ConsoleColor.Red
                                    printf "LOST\n" 
                                    -1
                        | -6y   ->  Console.ForegroundColor <- ConsoleColor.DarkRed
                                    printf "???\n" 
                                    -2
                        |  _  ->    -0
            
            local <- local + dxs

            Console.ResetColor ()

        match local with
            | _ when local > 0 -> total <- total + 1
            | _ when local < 0 -> total <- total - 1   
            | _                -> ()

        printf "\n      >>  YOUR TOTAL SCORE: %d\n" total
        printf "\n      >>  Do you want to play again ? (Y/N) "
        again <- Console.ReadKey(true).Key

        printf "\n\n  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  "

    printf "\n\n      >>  YOUR FINAL SCORE: %d " total

    ()

Console.ReadKey(true).Key |> ignore