add webview inspection diagnostics

Dreamio/DreamioWebViewController.swift

@@ -4,6 +4,7 @@ import WebKit
 final class DreamioWebViewController: UIViewController {
     private enum Constants {
         static let stremioWebURL = URL(string: "https://web.stremio.com/")!
+        static let diagnosticsMessageHandler = "dreamioDiagnostics"
     }
 
     private lazy var webView: WKWebView = {
@@ -12,6 +13,13 @@ final class DreamioWebViewController: UIViewController {
         configuration.allowsInlineMediaPlayback = true
         configuration.mediaTypesRequiringUserActionForPlayback = []
         configuration.preferences.javaScriptCanOpenWindowsAutomatically = true
+#if DEBUG
+        configuration.userContentController.add(
+            WeakScriptMessageHandler(delegate: self),
+            name: Constants.diagnosticsMessageHandler
+        )
+        configuration.userContentController.addUserScript(Self.playbackDiagnosticsScript)
+#endif
 
         let webView = WKWebView(frame: .zero, configuration: configuration)
         webView.translatesAutoresizingMaskIntoConstraints = false
@@ -20,6 +28,11 @@ final class DreamioWebViewController: UIViewController {
         webView.navigationDelegate = self
         webView.uiDelegate = self
         webView.scrollView.contentInsetAdjustmentBehavior = .never
+#if DEBUG
+        if #available(iOS 16.4, *) {
+            webView.isInspectable = true
+        }
+#endif
         return webView
     }()
 
@@ -32,6 +45,96 @@ final class DreamioWebViewController: UIViewController {
 
     private var progressObservation: NSKeyValueObservation?
 
+#if DEBUG
+    private static let playbackDiagnosticsScript = WKUserScript(
+        source: """
+        (() => {
+          if (window.__dreamioPlaybackDiagnosticsInstalled) {
+            return;
+          }
+          window.__dreamioPlaybackDiagnosticsInstalled = true;
+
+          const post = (type, payload = {}) => {
+            try {
+              window.webkit.messageHandlers.dreamioDiagnostics.postMessage({
+                type,
+                payload,
+                href: window.location.href
+              });
+            } catch (_) {}
+          };
+
+          const describeValue = (value) => {
+            if (value instanceof Error) {
+              return {
+                name: value.name,
+                message: value.message,
+                stack: value.stack
+              };
+            }
+            if (typeof value === "string") {
+              return value;
+            }
+            try {
+              return JSON.stringify(value);
+            } catch (_) {
+              return String(value);
+            }
+          };
+
+          ["error", "warn"].forEach((level) => {
+            const original = console[level];
+            console[level] = (...args) => {
+              post(`console.${level}`, { args: args.map(describeValue) });
+              original.apply(console, args);
+            };
+          });
+
+          window.addEventListener("unhandledrejection", (event) => {
+            post("unhandledrejection", {
+              reason: describeValue(event.reason)
+            });
+          });
+
+          const videoState = (video) => ({
+            currentSrc: video.currentSrc || video.src || "",
+            networkState: video.networkState,
+            readyState: video.readyState,
+            errorCode: video.error ? video.error.code : null,
+            errorMessage: video.error ? video.error.message : null
+          });
+
+          const attachVideoDiagnostics = (video) => {
+            if (!video || video.__dreamioDiagnosticsAttached) {
+              return;
+            }
+            video.__dreamioDiagnosticsAttached = true;
+            video.addEventListener("error", () => {
+              post("video.error", videoState(video));
+            }, true);
+          };
+
+          document.querySelectorAll("video").forEach(attachVideoDiagnostics);
+
+          new MutationObserver((mutations) => {
+            mutations.forEach((mutation) => {
+              mutation.addedNodes.forEach((node) => {
+                if (node instanceof HTMLVideoElement) {
+                  attachVideoDiagnostics(node);
+                }
+                if (node.querySelectorAll) {
+                  node.querySelectorAll("video").forEach(attachVideoDiagnostics);
+                }
+              });
+            });
+          }).observe(document.documentElement, { childList: true, subtree: true });
+        })();
+        """,
+        injectionTime: .atDocumentStart,
+        forMainFrameOnly: false
+    )
+#endif
+
     override func viewDidLoad() {
         super.viewDidLoad()
 
@@ -77,6 +180,70 @@ final class DreamioWebViewController: UIViewController {
         })
         present(alert, animated: true)
     }
+
+#if DEBUG
+    private func logDiagnostic(type: String, payload: Any, pageURL: String?) {
+        let redactedPageURL = pageURL.map(redactedURLString) ?? "unknown"
+        let redactedPayload = redactDiagnosticValue(payload)
+        print("[DreamioDiagnostics] \(type) page=\(redactedPageURL) payload=\(redactedPayload)")
+    }
+
+    private func redactDiagnosticValue(_ value: Any) -> Any {
+        switch value {
+        case let string as String:
+            return redactedURLString(string)
+        case let array as [Any]:
+            return array.map(redactDiagnosticValue)
+        case let dictionary as [String: Any]:
+            return dictionary.reduce(into: [String: Any]()) { result, entry in
+                result[entry.key] = redactDiagnosticValue(entry.value)
+            }
+        default:
+            return value
+        }
+    }
+
+    private func redactedURLString(_ value: String) -> String {
+        guard var components = URLComponents(string: value), components.scheme != nil else {
+            return redactTokenLikeFragments(in: value)
+        }
+
+        components.query = nil
+        components.fragment = nil
+        if let path = components.percentEncodedPath.nilIfEmpty {
+            components.percentEncodedPath = redactTokenLikePathSegments(in: path)
+        }
+        return redactTokenLikeFragments(in: components.string ?? value)
+    }
+
+    private func redactTokenLikePathSegments(in path: String) -> String {
+        path
+            .split(separator: "/", omittingEmptySubsequences: false)
+            .map { segment -> String in
+                let text = String(segment)
+                if text.range(of: #"^[A-Za-z0-9_-]{24,}$"#, options: .regularExpression) != nil {
+                    return "[redacted]"
+                }
+                return text
+            }
+            .joined(separator: "/")
+    }
+
+    private func redactTokenLikeFragments(in value: String) -> String {
+        let patterns = [
+            #"(?i)((?:token|access_token|auth|signature|sig|key|apikey|api_key|jwt|session|password)=)([^&\s]+)"#,
+            #"(?i)(bearer\s+)[A-Za-z0-9._~+/=-]+"#
+        ]
+
+        return patterns.reduce(value) { redacted, pattern in
+            redacted.replacingOccurrences(
+                of: pattern,
+                with: "$1[redacted]",
+                options: .regularExpression
+            )
+        }
+    }
+#endif
 }
 
 extension DreamioWebViewController: WKNavigationDelegate {
@@ -99,11 +266,31 @@ extension DreamioWebViewController: WKNavigationDelegate {
         decisionHandler(.allow)
     }
 
+    func webView(
+        _ webView: WKWebView,
+        decidePolicyFor navigationResponse: WKNavigationResponse,
+        decisionHandler: @escaping (WKNavigationResponsePolicy) -> Void
+    ) {
+#if DEBUG
+        if let response = navigationResponse.response as? HTTPURLResponse {
+            let url = response.url?.absoluteString ?? "unknown"
+            print("[DreamioNavigation] status=\(response.statusCode) url=\(redactedURLString(url))")
+        }
+#endif
+        decisionHandler(.allow)
+    }
+
     func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
+#if DEBUG
+        print("[DreamioNavigation] didFail url=\(redactedURLString(webView.url?.absoluteString ?? "unknown")) error=\(redactedURLString(error.localizedDescription))")
+#endif
         showLoadFailure(error)
     }
 
     func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
+#if DEBUG
+        print("[DreamioNavigation] didFailProvisional url=\(redactedURLString(webView.url?.absoluteString ?? "unknown")) error=\(redactedURLString(error.localizedDescription))")
+#endif
         showLoadFailure(error)
     }
 
@@ -124,6 +311,44 @@ extension DreamioWebViewController: WKNavigationDelegate {
     }
 }
 
+#if DEBUG
+extension DreamioWebViewController: WKScriptMessageHandler {
+    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
+        guard message.name == Constants.diagnosticsMessageHandler,
+              let body = message.body as? [String: Any],
+              let type = body["type"] as? String
+        else {
+            return
+        }
+
+        logDiagnostic(
+            type: type,
+            payload: body["payload"] ?? [:],
+            pageURL: body["href"] as? String
+        )
+    }
+}
+
+private final class WeakScriptMessageHandler: NSObject, WKScriptMessageHandler {
+    weak var delegate: WKScriptMessageHandler?
+
+    init(delegate: WKScriptMessageHandler) {
+        self.delegate = delegate
+        super.init()
+    }
+
+    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
+        delegate?.userContentController(userContentController, didReceive: message)
+    }
+}
+
+private extension String {
+    var nilIfEmpty: String? {
+        isEmpty ? nil : self
+    }
+}
+#endif
+
 extension DreamioWebViewController: WKUIDelegate {
     func webView(
         _ webView: WKWebView,