import UIKit
import WebKit

extension RDEPUBWebView {

    public func loadFixedSpread(
        parser: RDEPUBParser,
        spread: EPUBFixedSpread,
        viewportSize: CGSize,
        contentInset: UIEdgeInsets,
        backgroundColor: UIColor?
    ) {
        let request = RDEPUBRenderRequest.fixed(
            RDEPUBFixedRenderRequest(
                spread: spread,
                viewportSize: viewportSize,
                contentInset: contentInset,
                backgroundColorCSS: backgroundColor?.rd_hexString,
                fit: .page,
                searchPresentation: nil
            )
        )
        load(publication: parser.makePublication(), request: request)
    }

    func handleFixedLayoutLoad(
        publication: RDEPUBPublication,
        request: RDEPUBFixedRenderRequest,
        loadSignature: String,
        in webView: WKWebView
    ) {
        currentPageIndex = 0
        currentTotalPagesInChapter = 1
        viewportSize = request.viewportSize
        currentPadding = request.contentInset
        currentFontSize = 16
        currentLineHeightMultiple = 1.5
        currentThemeBackgroundColor = request.backgroundColorCSS
        currentThemeTextColor = nil
        targetLocation = nil
        pendingHighlights = []
        fixedSpread = request.spread
        isFixedLayout = true
        pendingProgressionRequest = false
        currentLoadSignature = loadSignature
        scheduleFixedLayoutReadyFallback()

        let html = RDEPUBFixedLayoutTemplate.html(for: request, publication: publication)
        RDEPUBWebViewDebug.log(debugScope, message: "load fixed spread resources=\(request.spread.resources.map(\.href).joined(separator: ",")) fit=\(request.fit.rawValue)")
        webView.loadHTMLString(
            html,
            baseURL: URL(string: "\(RDEPUBResourceURLSchemeHandler.scheme)://\(RDEPUBResourceURLSchemeHandler.host)/")
        )
    }

    func fixedLayoutLoadSignature(publicationKey: String, request: RDEPUBFixedRenderRequest) -> String {
        let searchSignature = [
            request.searchPresentation?.keyword ?? "",
            request.searchPresentation?.resources.map {
                [
                    $0.href,
                    String($0.matchCount),
                    String($0.activeLocalMatchIndex ?? -1)
                ].joined(separator: "|")
            }.joined(separator: ",") ?? ""
        ].joined(separator: "#")
        return [
            publicationKey,
            "fixed",
            request.spread.resources.map(\.href).joined(separator: "|"),
            String(format: "%.2f", request.viewportSize.width),
            String(format: "%.2f", request.viewportSize.height),
            String(format: "%.2f", request.contentInset.top),
            String(format: "%.2f", request.contentInset.left),
            String(format: "%.2f", request.contentInset.bottom),
            String(format: "%.2f", request.contentInset.right),
            request.backgroundColorCSS ?? "",
            request.fit.rawValue,
            searchSignature
        ].joined(separator: "#")
    }

    func scheduleFixedLayoutReadyFallback() {
        let workItem = DispatchWorkItem { [weak self] in
            RDEPUBWebViewDebug.log(self?.debugScope ?? "ReaderWebView", message: "fixed ready fallback fired")
            self?.applyFixedPresentationIfNeeded {
                self?.refreshNativeDecorationsIfNeeded {
                    self?.rendered()
                }
            }
        }
        fixedLayoutReadyWorkItem = workItem
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0, execute: workItem)
    }

    func cancelFixedLayoutReadyFallback() {
        fixedLayoutReadyWorkItem?.cancel()
        fixedLayoutReadyWorkItem = nil
    }

    func applyFixedPresentationIfNeeded(completion: (() -> Void)? = nil) {
        guard let webView,
              let currentRenderRequest,
              case .fixed(let request) = currentRenderRequest else {
            completion?()
            return
        }

        let script = RDEPUBJavaScriptBridge.applyFixedPresentationScript(for: request)
        webView.evaluateJavaScript(script) { [weak self] _, error in
            guard let self else {
                completion?()
                return
            }
            if let error {
                self.delegate?.epubWebView(self, didLogJavaScriptError: error.localizedDescription)
            }
            self.applySearchDecorationsIfNeeded(completion: completion)
        }
    }
}