import UIKit

extension RDEPUBReaderController {

    func currentLayoutContext() -> RDEPUBNavigatorLayoutContext {
        readerContext.currentLayoutContext()
    }

    func currentPreferences() -> RDEPUBPreferences {
        readerContext.currentPreferences()
    }

    func currentTextPageSize() -> CGSize {
        readerContext.currentTextPageSize()
    }

    func currentTextRenderStyle() -> RDEPUBTextRenderStyle {
        readerContext.currentTextRenderStyle()
    }

    func currentTextLayoutConfig(pageSize: CGSize) -> RDEPUBTextLayoutConfig {
        readerContext.currentTextLayoutConfig(pageSize: pageSize)
    }

    func resolvedTextRenderer() -> RDEPUBTextRenderer {
        readerContext.resolvedTextRenderer()
    }

    func ensurePaginationHostView() -> UIView {
        let viewportSize = currentLayoutContext().viewportSize
        let hostFrame = CGRect(x: -viewportSize.width - 32, y: 0, width: viewportSize.width, height: viewportSize.height)
        if paginationHostView.superview == nil {
            view.addSubview(paginationHostView)
            view.sendSubviewToBack(paginationHostView)
        }
        paginationHostView.frame = hostFrame
        return paginationHostView
    }

    func request(for pageIndex: Int) -> RDEPUBRenderRequest? {
        guard let publication, activePages.indices.contains(pageIndex) else {
            return nil
        }
        let page = activePages[pageIndex]
        let pendingLocation = readingSession?.pendingLocation(forPageNumber: pageIndex + 1, spineIndex: page.spineIndex)
        let pendingHighlightRangeInfo = readingSession?.pendingHighlightRangeInfo(
            forPageNumber: pageIndex + 1,
            spineIndex: page.spineIndex
        )
        return currentPreferences().renderRequest(
            for: page,
            publication: publication,
            viewportSize: currentLayoutContext().viewportSize,
            targetLocation: pendingLocation,
            targetHighlightRangeInfo: pendingHighlightRangeInfo,
            highlights: highlights(for: page),
            searchPresentation: searchPresentation(for: page)
        )
    }

    func fallbackLocation(for pageIndex: Int) -> RDEPUBLocation? {
        guard activePages.indices.contains(pageIndex) else { return nil }
        return readingSession?.fallbackLocation(for: activePages[pageIndex], bookIdentifier: currentBookIdentifier)
    }

    private func highlights(for page: EPUBPage) -> [RDEPUBHighlight] {
        guard let publication else { return [] }
        if let spread = page.fixedSpread {
            let hrefs = Set(spread.resources.compactMap { publication.resourceResolver.normalizedHref($0.href) })
            return activeHighlights.filter { highlight in
                guard let normalizedHref = publication.resourceResolver.normalizedHref(highlight.location.href) else {
                    return false
                }
                return hrefs.contains(normalizedHref)
            }
        }

        guard publication.spine.indices.contains(page.spineIndex) else { return [] }
        let href = publication.spine[page.spineIndex].href
        let normalizedHref = publication.resourceResolver.normalizedHref(href)
        return activeHighlights.filter { highlight in
            publication.resourceResolver.normalizedHref(highlight.location.href) == normalizedHref
        }
    }
}