import Models
import SwiftUI
import Utils
import Views
import WebKit

#if os(iOS)
  struct WebReader: UIViewRepresentable {
    let articleContent: ArticleContentDep
    let item: FeedItem
    let openLinkAction: (URL) -> Void
    let webViewActionHandler: (WKScriptMessage, WKScriptMessageReplyHandler?) -> Void
    let navBarVisibilityRatioUpdater: (Double) -> Void

    @Binding var increaseFontActionID: UUID?
    @Binding var decreaseFontActionID: UUID?
    @Binding var annotationSaveTransactionID: UUID?
    @Binding var annotation: String

    func makeCoordinator() -> WebReaderCoordinator {
      WebReaderCoordinator()
    }

    func fontSize() -> Int {
      let storedSize = UserDefaults.standard.integer(forKey: UserDefaultKey.preferredWebFontSize.rawValue)
      return storedSize <= 1 ? UITraitCollection.current.preferredWebFontSize : storedSize
    }

    func makeUIView(context: Context) -> WKWebView {
      let webView = WebViewManager.shared()
      let contentController = WKUserContentController()

      webView.navigationDelegate = context.coordinator
      webView.isOpaque = false
      webView.backgroundColor = .clear
      webView.configuration.userContentController = contentController
      webView.scrollView.delegate = context.coordinator
      webView.scrollView.contentInset.top = readerViewNavBarHeight
      webView.scrollView.verticalScrollIndicatorInsets.top = readerViewNavBarHeight

      webView.configuration.userContentController.removeAllScriptMessageHandlers()

      for action in WebViewAction.allCases {
        webView.configuration.userContentController.add(context.coordinator, name: action.rawValue)
      }

      webView.configuration.userContentController.add(webView, name: "viewerAction")

      webView.configuration.userContentController.addScriptMessageHandler(
        context.coordinator, contentWorld: .page, name: "articleAction"
      )

      context.coordinator.linkHandler = openLinkAction
      context.coordinator.webViewActionHandler = webViewActionHandler
      context.coordinator.updateNavBarVisibilityRatio = navBarVisibilityRatioUpdater
      loadContent(webView: webView)

      return webView
    }

    func updateUIView(_ webView: WKWebView, context: Context) {
      if annotationSaveTransactionID != context.coordinator.lastSavedAnnotationID {
        context.coordinator.lastSavedAnnotationID = annotationSaveTransactionID
        (webView as? WebView)?.saveAnnotation(annotation: annotation)
      }

      if increaseFontActionID != context.coordinator.previousIncreaseFontActionID {
        context.coordinator.previousIncreaseFontActionID = increaseFontActionID
        (webView as? WebView)?.increaseFontSize()
      }

      if decreaseFontActionID != context.coordinator.previousDecreaseFontActionID {
        context.coordinator.previousDecreaseFontActionID = decreaseFontActionID
        (webView as? WebView)?.decreaseFontSize()
      }

      // If the webview had been terminated `needsReload` will have been set to true
      if context.coordinator.needsReload {
        loadContent(webView: webView)
        context.coordinator.needsReload = false
        return
      }

      if webView.isLoading { return }

      // If the root element is not detected then `WKWebView` may have unloaded the content
      // so we need to load it again.
      webView.evaluateJavaScript("document.getElementById('root') ? true : false") { hasRootElement, _ in
        guard let hasRootElement = hasRootElement as? Bool else { return }

        if !hasRootElement {
          DispatchQueue.main.async {
            loadContent(webView: webView)
          }
        }
      }
    }

    func loadContent(webView: WKWebView) {
      webView.loadHTMLString(
        WebReaderContent(
          articleContent: articleContent,
          item: item,
          isDark: UITraitCollection.current.userInterfaceStyle == .dark,
          fontSize: fontSize()
        )
        .styledContent,
        baseURL: ViewsPackage.bundleURL
      )
    }
  }
#endif