/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Defines a layout that's used to lay out the `Dream` that's shown in

                the detail view.

*/

import CoreGraphics

/** 

    The layout used for the `Dream` preview functionality in `DreamPreviewHeaderReusableView`.

    This type composes multiple smaller layouts together to form its layout.

*/

struct DreamEffectLayout<ChildContent: Layout, Decoration: Layout, Effect: Layout>: Layout where

ChildContent.Content == Decoration.Content, ChildContent.Content == Effect.Content {

    typealias Content = ChildContent.Content

    private var content: ChildContent

    private var decoration: Decoration

    private var effects: [Effect]

    init(content: ChildContent, decoration: Decoration, effects: [Effect]) {

        self.content = content

        self.decoration = decoration

        self.effects = effects

    }

    mutating func layout(in rect: CGRect) {

        // Here we're composing many different layouts to achieve the desired layout.

        let stack = ZStackLayout(children: effects)

        /*

            Note the simple way to create a `BackgroundLayout` using the 

            `withBackground(...)` method.

        */

        let combinedDecoration = stack.withBackground(decoration)

        var decoratingLayout = DecoratingLayout(content: content, decoration: combinedDecoration)

        decoratingLayout.layout(in: rect)

    }

    var contents: [Content] {

        return content.contents + decoration.contents + effects.flatMap { $0.contents }

    }

}