/*

    Copyright (C) 2017 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A class that conforms to the `TVTopShelfProvider` protocol. The Top Shelf extension uses this class to query for items to show.

*/

import TVServices

class ServiceProvider: NSObject, TVTopShelfProvider {

    // MARK: TVTopShelfProvider

    /**

        The style of Top Shelf items to show.

        Modify this property to view different styles.

    */

    let topShelfStyle: TVTopShelfContentStyle = .sectioned

    var topShelfItems: [TVContentItem] {

        switch topShelfStyle {

            case .inset:

                return insetTopShelfItems

            case .sectioned:

                return sectionedTopShelfItems

        }

    }

    // MARK: Convenience

    /// An array of `TVContentItem`s to show when `topShelfStyle` returns `.Inset`.

    fileprivate var insetTopShelfItems: [TVContentItem] {

        // Get an array of `DataItem`s to show on the Top Shelf.

        let itemsToDisplay = DataItem.sampleItemsForInsetTopShelfItems

        // Map the array of `DataItem`s to an array of `TVContentItem`s.

        let contentItems: [TVContentItem] = itemsToDisplay.map { dataItem in

            return contentItemWithDataItem(dataItem, imageShape: .extraWide)

        }

        return contentItems

    }

    /**

        An array of `TVContentItem`s to show when `topShelfStyle` returns `.Sectioned`.

        Each `TVContentItem` in the returned array represents a section of

        `TVContentItem`s on the Top Shelf. e.g.

            - TVContentItem, "Iceland"

                - TVContentItem, "Iceland one"

                - TVContentItem, "Iceland two"

            - TVContentItem, "Lola"

                - TVContentItem, "Lola one"

                - TVContentItem, "Lola two"

    */

    fileprivate var sectionedTopShelfItems: [TVContentItem] {

        // Get an array of `DataItem` arrays to show on the Top Shelf.

        let groupedItemsToDisplay = DataItem.sampleItemsForSectionedTopShelfItems

        /*

            Map the array of `DataItem` arrays to an array of `TVContentItem`s.

            Each `TVContentItem` will represent a section of `TVContentItem`s on

            the Top Shelf.

        */

        let sectionContentItems: [TVContentItem] = groupedItemsToDisplay.map { dataItems in

            // Determine the title of the `DataItem.Group` that the array of `DataItem`s belong to.

            let sectionTitle = dataItems.first!.group.rawValue

            /*

                Create a `TVContentItem` that will represent a section of `TVContentItem`s

                on the Top Shelf.

            */

            guard let sectionIdentifier = TVContentIdentifier(identifier: sectionTitle, container: nil) else { fatalError("Error creating content identifier for section item.") }

            guard let sectionItem = TVContentItem(contentIdentifier: sectionIdentifier) else { fatalError("Error creating section content item.") }

            sectionItem.title = sectionTitle

            /*

                Map the array of `DataItem`s to an array of `TVContentItem`s and

                assign it to the `TVContentItem` that represents the section of

                Top Shelf items.

            */

            sectionItem.topShelfItems = dataItems.map { dataItem in

                return contentItemWithDataItem(dataItem, imageShape: .square)

            }

            return sectionItem

        }

        return sectionContentItems

    }

    /// Returns a `TVContentItem` for a `DataItem`.

    fileprivate func contentItemWithDataItem(_ dataItem: DataItem, imageShape: TVContentItemImageShape) -> TVContentItem {

        guard let contentIdentifier = TVContentIdentifier(identifier: dataItem.identifier, container: nil) else { fatalError("Error creating content identifier.") }

        guard let contentItem = TVContentItem(contentIdentifier: contentIdentifier) else { fatalError("Error creating content item.") }

        contentItem.title = dataItem.title

        contentItem.displayURL = dataItem.displayURL

        contentItem.imageURL = dataItem.imageURL

        contentItem.imageShape = imageShape

        return contentItem

    }

}