/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Provides the `makeImages(from:completion:)` function that turns dreams

                into images. Note that we're using the `MultiPaneLayout` type to lay

                out the text and images.

*/

import UIKit

/// Makes a single image from a dream.

private func makeImage(from dream: Dream) -> UIImage {

    let size = CGSize(width: 500, height: 200)

    UIGraphicsBeginImageContext(size)

    defer { UIGraphicsEndImageContext() }

    let context = UIGraphicsGetCurrentContext()!

    let content = TextDrawable(text: dream.description, frame: .zero)

    let decoration = ImageDrawable(image: dream.creature.image, frame: .zero)

    let accessories = Array(repeatElement(decoration, count: dream.numberOfCreatures))

    /*

        Here we're re-using one of our layouts to render an image that looks like

        the view layout we have in the app.

    */

    var multiPaneLayout = MultiPaneLayout(content: content, accessories: accessories)

    multiPaneLayout.layout(in: CGRect(origin: .zero, size: size))

    let drawables = multiPaneLayout.contents

    for drawable in drawables {

        drawable.draw(in: context)

    }

    return UIGraphicsGetImageFromCurrentImageContext()!

}

/**

    Creates an array of images from an array of dreams. This is called when the

    user shares dreams in the `DreamListViewController`.

*/

func makeImages(from dreams: [Dream], completion: @escaping ([UIImage]) -> Void) {

    let backgroundQueue = DispatchQueue(label: "com.example.apple-samplecode.LucidDreams.renderer.background")

    backgroundQueue.async {

        let images = dreams.map { makeImage(from: $0) }

        DispatchQueue.main.async {

            completion(images)

        }

    }

}