Quilt.elm

module Quilt exposing (..)

import Array.Hamt as Array exposing (Array)


{-| A quilt is a datastructure for maintaining a Pinterest-like
grid of images. Each image is wrapped with a Cell which calculates
its width/height from the image, but scales the dimensions to
something that fits.

Example:

type alias Item = 
    { id : String 
    , height : Int
    , width : Int
    -- Extra fields for my use
    , name : String
    , color : String
    }

-- Error: The annotation says `Quilt Item` but the actual type is `Quilt {}`
myQuilt : Quilt Item
myQuilt = Quilt.empty 800 600 3
    |> Quilt.insert (Item "a" 100 200 "item1" "yellow")
    |> Quilt.insert (Item "b" 800 180 "item2" "red")
    |> Quilt.insert (Item "c" 450 350 "item3" "purple")
-}

{-| Holds whatever the user wants to store in the Quilt.
Its properties are derived from the entry that it holds.
-}
type alias Cell a =
    { contents : a
    , id : Int
    , width : Int
    , height : Int
    , pruned : Bool
    }


{-| Something with an id, width, and height can be sewn in to the quilt.
-}
type alias Quiltable a =
    { a
        | id : String
        , width : Int
        , height : Int
    }


type alias Quilt a =
    { columns : Array (Array (Cell (Quiltable a)))
    , width : Int
    , height : Int
    }


empty : Int -> Int -> Int -> Quilt a
empty width height columns =
    let
        columns_ =
            Basics.max 1 columns
    in
        { width = width
        , height = height
        , columns = (Array.initialize columns (\_ -> Array.empty))
        }


insert : Quiltable a -> Quilt a -> Quilt a
insert entry quilt =
    let
        cell =
            { id = entry.id
            , contents = entry
            , width = entry.width
            , height = entry.height
            , prune = False
            }
    in
        -- Unimplemented
        quilt