module PC.Helpers   exposing (..)

import Array        exposing (Array)
import Http         exposing (..)

-- Convert a number from  42 to 0042
-- number : (Prefered positive) whole number
-- length : positive whole number
-- Please note that only 0 are added. The number will not be shortend!
addLeadingZero : Int -> Int -> String
addLeadingZero number length =
    let
        num_str = String.fromInt number
    in
    (String.fromList <| List.repeat (length - String.length num_str) '0'
    ) 
    ++ num_str


-- Get the value at a given position in a List.
-- For performance reasons it might be better
-- to use an Array instead.
valueAt : Int -> List a -> Maybe a
valueAt pos list = List.head <| List.drop pos list


-- Change the value at a given position in a List.
-- If your pos is greater than the length of
-- the list, then the rest is filled with the
-- default element.
overwriteAt : a -> Int -> a ->List a -> List a
overwriteAt default pos newVal list =
    let
        len = List.length list
    in
    if pos > len then
        list ++ 
        (List.repeat (pos-len) default) ++
        [newVal]
    else
        let
            before  = List.take pos     list
            after   = List.drop (pos+1) list
        in
        before ++ [newVal] ++ after

overwriteAt_Arr : a -> Int -> a -> Array a -> Array a
overwriteAt_Arr default pos newVal list =
    let
        len = Array.length list
    in
    if pos > len then
        Array.append list 
        <| Array.append (Array.repeat (pos-len) default) 
        <| Array.fromList [newVal]
    else
        Array.set pos newVal list


-- Prints Http Errors into something readable
printHttpError : Http.Error -> String
printHttpError err =
    case err of
        Http.BadUrl str     -> "Bad Url: " ++ str
        Http.Timeout        -> "Timeout"
        Http.NetworkError   -> "Network Error"
        Http.BadStatus num  -> "Bad Status: " ++ String.fromInt num
        Http.BadBody str    -> "Bad Body: " ++ str


seperateInstructionsEntry : Int -> (Int, Int)
seperateInstructionsEntry i =
    let
        instruction = i // 100000
        address = i - instruction*100000
    in
    (instruction, address)


valueAtRam : Int -> Array (Int, String) -> (Int, String)
valueAtRam pos arr =
    case Array.get pos arr of
        Just a  -> a
        Nothing -> (0, "")


changeAtRam : Int -> Int -> Array (Int, String) -> Array (Int,String)
changeAtRam pos newVal list =
    let
        (_,comment) = valueAtRam pos list
    in
    overwriteAt_Arr (0, "") pos (newVal, comment) list