import Foundation
import WebKit

extension RDEPUBWebView {

    func internalLocation(from url: URL) -> RDEPUBLocation? {
        let href = url.path.removingPercentEncoding?.trimmingCharacters(in: CharacterSet(charactersIn: "/")) ?? ""
        let fragment = url.fragment
        guard !href.isEmpty || fragment != nil else { return nil }
        return RDEPUBLocation(href: href, progression: 0, fragment: fragment)
    }

    func currentLocation(from body: [String: Any]) -> RDEPUBLocation {
        let progression = (body["progression"] as? NSNumber)?.doubleValue ?? 0
        let lastProgression = (body["lastProgression"] as? NSNumber)?.doubleValue
        let fragment = body["fragment"] as? String
        let href = body["href"] as? String ?? currentHref
        return RDEPUBLocation(href: href, progression: progression, lastProgression: lastProgression, fragment: fragment)
    }
}

extension RDEPUBWebView: WKNavigationDelegate {
    public func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didStart", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didCommit navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didCommit", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFinish", url: webView.url)
        applyPresentation()
    }

    public func webViewWebContentProcessDidTerminate(_ webView: WKWebView) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "processTerminated", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFail", url: webView.url, error: error)
    }

    public func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFailProvisional", url: webView.url, error: error)
    }

    public func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "decidePolicy", url: navigationAction.request.url)
        guard navigationAction.navigationType == .linkActivated,
              let url = navigationAction.request.url else {
            decisionHandler(.allow)
            return
        }

        if url.scheme == RDEPUBResourceURLSchemeHandler.scheme,
           let location = internalLocation(from: url) {
            delegate?.epubWebView(self, didActivateInternalLink: location, fromSpineIndex: currentSpineIndex)
            decisionHandler(.cancel)
            return
        }

        if let scheme = url.scheme?.lowercased(), ["http", "https", "mailto", "tel"].contains(scheme) {
            delegate?.epubWebView(self, didActivateExternalLink: url)
            decisionHandler(.cancel)
            return
        }

        decisionHandler(.allow)
    }
}

extension RDEPUBWebView: WKScriptMessageHandler {

    public func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        RDEPUBWebViewDebug.logMessage(debugScope, webView: message.webView, name: message.name, body: message.body)
        switch message.name {
        case RDEPUBJavaScriptBridgeMessage.progressionChanged.rawValue:
            guard let body = message.body as? [String: Any] else { return }
            delegate?.epubWebView(self, didUpdateLocation: currentLocation(from: body), spineIndex: currentSpineIndex)
        case RDEPUBJavaScriptBridgeMessage.selectionChanged.rawValue:
            if let body = message.body as? [String: Any],
               let text = body["text"] as? String,
               let rangeInfo = body["rangeInfo"] as? String {
                let location = currentLocation(from: body)
                let selection = RDEPUBSelection(location: location, text: text, rangeInfo: rangeInfo)
                delegate?.epubWebView(self, didChangeSelection: selection, spineIndex: currentSpineIndex)
            } else {
                delegate?.epubWebView(self, didChangeSelection: nil, spineIndex: currentSpineIndex)
            }
        case RDEPUBJavaScriptBridgeMessage.internalLink.rawValue:
            guard let body = message.body as? [String: Any],
                  let href = body["href"] as? String else { return }
            let location = RDEPUBLocation(href: href, progression: 0)
            delegate?.epubWebView(self, didActivateInternalLink: location, fromSpineIndex: currentSpineIndex)
        case RDEPUBJavaScriptBridgeMessage.externalLink.rawValue:
            guard let body = message.body as? [String: Any],
                  let urlString = body["url"] as? String,
                  let url = URL(string: urlString) else { return }
            delegate?.epubWebView(self, didActivateExternalLink: url)
        case RDEPUBJavaScriptBridgeMessage.javaScriptError.rawValue:
            delegate?.epubWebView(self, didLogJavaScriptError: "\(message.body)")
        case RDEPUBJavaScriptBridgeMessage.fixedLayoutReady.rawValue:
            applyFixedPresentationIfNeeded {
                self.refreshNativeDecorationsIfNeeded {
                    self.rendered()
                }
            }
        case RDEPUBJavaScriptBridgeMessage.imageDidTap.rawValue:
            guard let body = message.body as? [String: Any],
                  let src = body["src"] as? String else { return }
            let sourceRect = sourceRect(from: body["rect"])
            delegate?.epubWebView(self, didTapImageWithSource: src, sourceRect: sourceRect)
        case RDEPUBJavaScriptBridgeMessage.footnoteDidTap.rawValue:
            guard let body = message.body as? [String: Any],
                  let altText = body["alt"] as? String else { return }
            let sourceRect = sourceRect(from: body["rect"])
            delegate?.epubWebView(self, didTapFootnoteWithAltText: altText, sourceRect: sourceRect)
        default:
            break
        }
    }

    private func sourceRect(from value: Any?) -> CGRect? {
        guard let rectDict = value as? [String: Any] else { return nil }
        return CGRect(
            x: cgFloatValue(rectDict["x"]),
            y: cgFloatValue(rectDict["y"]),
            width: cgFloatValue(rectDict["width"]),
            height: cgFloatValue(rectDict["height"])
        )
    }

    private func cgFloatValue(_ value: Any?) -> CGFloat {
        switch value {
        case let number as NSNumber:
            return CGFloat(truncating: number)
        case let double as Double:
            return CGFloat(double)
        case let int as Int:
            return CGFloat(int)
        case let string as String:
            return CGFloat(Double(string) ?? 0)
        default:
            return 0
        }
    }
}