import UIKit

extension RDEpubReaderView {

    public func register(contentView: UIView.Type, contentViewWithReuseIdentifier identifier: String) {
        contentViews[identifier] = contentView
        collectionView.register(RDEpubReaderContentCell.self, forCellWithReuseIdentifier: identifier)
    }

    public func dequeueReusableContentView(withReuseIdentifier identifier: String, for pageNum: Int) -> UIView {
        if self.currentDisplayType != .pageCurl, let cell = self.collectionView.cellForItem(at: IndexPath(row: pageNum, section: 0)) as? RDEpubReaderContentCell, let containerView = cell.containerView {
            return containerView
        }
        let contentViewClass = contentViews[identifier]
        assert(contentViewClass != nil, "请调用register(contentView：contentViewWithReuseIdentifier：）")
        let contentView = contentViewClass!.init()
        return contentView
    }

    public func pageContentView(pageNum: Int) -> UIView? {
        if currentDisplayType == .pageCurl {
            return (self.pageViewController.viewControllers?.first as? RDEpubReaderPageChildViewController)?.contentView
        } else {
            let cell = collectionView.cellForItem(at: IndexPath(item: pageNum, section: 0)) as? RDEpubReaderContentCell
            return cell?.containerView
        }
    }

    public func resolvedSinglePageSize(pageNum: Int? = nil) -> CGSize {
        let targetPage = pageNum ?? (currentPage >= 0 ? currentPage : nil)
        if let targetPage,
           let contentView = pageContentView(pageNum: targetPage),
           contentView.bounds.width > 0,
           contentView.bounds.height > 0 {
            return contentView.bounds.size
        }

        if currentDisplayType == .pageCurl {
            if let childViewController = pageViewController.viewControllers?.first as? RDEpubReaderPageChildViewController,
               childViewController.view.bounds.width > 0,
               childViewController.view.bounds.height > 0 {
                return childViewController.view.bounds.size
            }
            if pageViewController.view.bounds.width > 0, pageViewController.view.bounds.height > 0 {
                return pageViewController.view.bounds.size
            }
            return bounds.size
        }

        let containerBounds = collectionView.bounds.size == .zero ? bounds.size : collectionView.bounds.size
        guard containerBounds.width > 0, containerBounds.height > 0 else {
            return bounds.size
        }

        switch currentDisplayType {
        case .horizontalScroll:
            return CGSize(
                width: containerBounds.width / CGFloat(max(pagesPerScreen, 1)),
                height: containerBounds.height
            )
        case .verticalScroll:
            return containerBounds
        case .pageCurl:
            return bounds.size
        }
    }
}