Improve/Fix CDP navigation event order

These changes all better align with chrome's event ordering/timing.

There are two big changes. The first is that our internal page_navigated event,
which is kind of our heavy hitter, is sent once the header is received as
opposed to (much later) on document load. The main goal of this internal event
is to trigger the "Page.frameNavigated" CDP event which is meant to happen
once the URL is committed, which _is_ on header response.

To accommodate this earlier trigger, new explicit events for DOMContentLoaded
and load have be added.

This drastically changes the flow of events as things go from:
Start Page Navigation
Response Received
  Start Frame Navigation
  Response Received
  End Frame Navigation
End Page Navigation
context clear + reset
DOMContentLoaded
Loaded

TO:
Start Page Navigation
Response Received
End Page Navigation
context clear + reset
Start Frame Navigation
Response Received
End Frame Navigation
DOMContentLoaded
Loaded

So not only does it remove the nesting, but it ensures that the context are
cleared and reset once the main page's navigation is locked in, and before any
frame is created.

src/Notification.zig

@@ -74,6 +74,8 @@ const EventListeners = struct {
     page_network_idle: List = .{},
     page_network_almost_idle: List = .{},
     page_frame_created: List = .{},
+    page_dom_content_loaded: List = .{},
+    page_loaded: List = .{},
     http_request_fail: List = .{},
     http_request_start: List = .{},
     http_request_intercept: List = .{},
@@ -91,6 +93,8 @@ const Events = union(enum) {
     page_network_idle: *const PageNetworkIdle,
     page_network_almost_idle: *const PageNetworkAlmostIdle,
     page_frame_created: *const PageFrameCreated,
+    page_dom_content_loaded: *const PageDOMContentLoaded,
+    page_loaded: *const PageLoaded,
     http_request_fail: *const RequestFail,
     http_request_start: *const RequestStart,
     http_request_intercept: *const RequestIntercept,
@@ -137,6 +141,18 @@ pub const PageFrameCreated = struct {
     timestamp: u64,
 };
 
+pub const PageDOMContentLoaded = struct {
+    req_id: u32,
+    frame_id: u32,
+    timestamp: u64,
+};
+
+pub const PageLoaded = struct {
+    req_id: u32,
+    frame_id: u32,
+    timestamp: u64,
+};
+
 pub const RequestStart = struct {
     transfer: *Transfer,
 };

src/browser/HttpClient.zig

@@ -1325,15 +1325,15 @@ pub const Transfer = struct {
             }
         }
 
+        transfer.req.notification.dispatch(.http_response_header_done, &.{
+            .transfer = transfer,
+        });
+
         const proceed = transfer.req.header_callback(transfer) catch |err| {
             log.err(.http, "header_callback", .{ .err = err, .req = transfer });
             return err;
         };
 
-        transfer.req.notification.dispatch(.http_response_header_done, &.{
-            .transfer = transfer,
-        });
-
         return proceed and transfer.aborted == false;
     }
 

src/browser/Page.zig

@@ -487,7 +487,6 @@ pub fn navigate(self: *Page, request_url: [:0]const u8, opts: NavigateOpts) !voi
                 return error.InjectBlankFailed;
             };
         }
-        self.documentIsComplete();
 
         session.notification.dispatch(.page_navigate, &.{
             .frame_id = self._frame_id,
@@ -519,6 +518,8 @@ pub fn navigate(self: *Page, request_url: [:0]const u8, opts: NavigateOpts) !voi
 
         // force next request id manually b/c we won't create a real req.
         _ = session.browser.http_client.incrReqId();
+
+        self.documentIsComplete();
         return;
     }
 
@@ -738,6 +739,12 @@ pub fn _documentIsLoaded(self: *Page) !void {
         self.document.asEventTarget(),
         event,
     );
+
+    self._session.notification.dispatch(.page_dom_content_loaded, &.{
+        .frame_id = self._frame_id,
+        .req_id = self._req_id,
+        .timestamp = timestamp(.monotonic),
+    });
 }
 
 pub fn scriptsCompletedLoading(self: *Page) void {
@@ -796,19 +803,6 @@ pub fn documentIsComplete(self: *Page) void {
     self._documentIsComplete() catch |err| {
         log.err(.page, "document is complete", .{ .err = err, .type = self._type, .url = self.url });
     };
-
-    if (self._navigated_options) |no| {
-        // _navigated_options will be null in special short-circuit cases, like
-        // "navigating" to about:blank, in which case this notification has
-        // already been sent
-        self._session.notification.dispatch(.page_navigated, &.{
-            .frame_id = self._frame_id,
-            .req_id = self._req_id,
-            .opts = no,
-            .url = self.url,
-            .timestamp = timestamp(.monotonic),
-        });
-    }
 }
 
 fn _documentIsComplete(self: *Page) !void {
@@ -827,6 +821,12 @@ fn _documentIsComplete(self: *Page) !void {
         try self._event_manager.dispatchDirect(window_target, event, self.window._on_load, .{ .inject_target = false, .context = "page load" });
     }
 
+    self._session.notification.dispatch(.page_loaded, &.{
+        .frame_id = self._frame_id,
+        .req_id = self._req_id,
+        .timestamp = timestamp(.monotonic),
+    });
+
     if (self._event_manager.hasDirectListeners(window_target, "pageshow", self.window._on_pageshow)) {
         const pageshow_event = (try PageTransitionEvent.initTrusted(comptime .wrap("pageshow"), .{}, self)).asEvent();
         try self._event_manager.dispatchDirect(window_target, pageshow_event, self.window._on_pageshow, .{ .context = "page show" });
@@ -879,6 +879,19 @@ fn pageHeaderDoneCallback(transfer: *HttpClient.Transfer) !bool {
         });
     }
 
+    if (self._navigated_options) |no| {
+        // _navigated_options will be null in special short-circuit cases, like
+        // "navigating" to about:blank, in which case this notification has
+        // already been sent
+        self._session.notification.dispatch(.page_navigated, &.{
+            .frame_id = self._frame_id,
+            .req_id = self._req_id,
+            .opts = no,
+            .url = self.url,
+            .timestamp = timestamp(.monotonic),
+        });
+    }
+
     return true;
 }
 

src/cdp/CDP.zig

@@ -427,6 +427,8 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             try notification.register(.page_navigate, self, onPageNavigate);
             try notification.register(.page_navigated, self, onPageNavigated);
             try notification.register(.page_frame_created, self, onPageFrameCreated);
+            try notification.register(.page_dom_content_loaded, self, onPageDOMContentLoaded);
+            try notification.register(.page_loaded, self, onPageLoaded);
         }
 
         pub fn deinit(self: *Self) void {
@@ -602,6 +604,16 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             return @import("domains/page.zig").pageFrameCreated(self, msg);
         }
 
+        pub fn onPageDOMContentLoaded(ctx: *anyopaque, msg: *const Notification.PageDOMContentLoaded) !void {
+            const self: *Self = @ptrCast(@alignCast(ctx));
+            return @import("domains/page.zig").pageDOMContentLoaded(self, msg);
+        }
+
+        pub fn onPageLoaded(ctx: *anyopaque, msg: *const Notification.PageLoaded) !void {
+            const self: *Self = @ptrCast(@alignCast(ctx));
+            return @import("domains/page.zig").pageLoaded(self, msg);
+        }
+
         pub fn onPageNetworkIdle(ctx: *anyopaque, msg: *const Notification.PageNetworkIdle) !void {
             const self: *Self = @ptrCast(@alignCast(ctx));
             return @import("domains/page.zig").pageNetworkIdle(self, msg);

src/cdp/domains/page.zig

@@ -437,9 +437,9 @@ pub fn pageNavigated(arena: Allocator, bc: anytype, event: *const Notification.P
     const page = bc.session.currentPage() orelse return error.PageNotLoaded;
 
     // When we actually recreated the context we should have the inspector send
-    // this event, see: resetContextGroup Sending this event will tell the
-    // client that the context ids they had are invalid and the context shouls
-    // be dropped The client will expect us to send new contextCreated events,
+    // this event, see: resetContextGroup. Sending this event will tell the
+    // client that the context ids they had are invalid and the context should
+    // be dropped. The client will expect us to send new contextCreated events,
     // such that the client has new id's for the active contexts.
     // Only send executionContextsCleared for main frame navigations. For child
     // frames (iframes), clearing all contexts would destroy the main frame's
@@ -449,6 +449,18 @@ pub fn pageNavigated(arena: Allocator, bc: anytype, event: *const Notification.P
         try cdp.sendEvent("Runtime.executionContextsCleared", null, .{ .session_id = session_id });
     }
 
+    // frameNavigated event
+    try cdp.sendEvent("Page.frameNavigated", .{
+        .type = "Navigation",
+        .frame = Frame{
+            .id = frame_id,
+            .url = event.url,
+            .loaderId = loader_id,
+            .securityOrigin = bc.security_origin,
+            .secureContextType = bc.secure_context_type,
+        },
+    }, .{ .session_id = session_id });
+
     {
         const aux_data = try std.fmt.allocPrint(arena, "{{\"isDefault\":true,\"type\":\"default\",\"frameId\":\"{s}\",\"loaderId\":\"{s}\"}}", .{ frame_id, loader_id });
 
@@ -541,6 +553,57 @@ pub fn pageNavigated(arena: Allocator, bc: anytype, event: *const Notification.P
     }, .{ .session_id = session_id });
 }
 
+pub fn pageDOMContentLoaded(bc: anytype, event: *const Notification.PageDOMContentLoaded) !void {
+    const session_id = bc.session_id orelse return;
+    const timestamp = event.timestamp;
+    var cdp = bc.cdp;
+
+    try cdp.sendEvent(
+        "Page.domContentEventFired",
+        .{ .timestamp = timestamp },
+        .{ .session_id = session_id },
+    );
+
+    if (bc.page_life_cycle_events) {
+        const frame_id = &id.toFrameId(event.frame_id);
+        const loader_id = &id.toLoaderId(event.req_id);
+        try cdp.sendEvent("Page.lifecycleEvent", LifecycleEvent{
+            .timestamp = timestamp,
+            .name = "DOMContentLoaded",
+            .frameId = frame_id,
+            .loaderId = loader_id,
+        }, .{ .session_id = session_id });
+    }
+}
+
+pub fn pageLoaded(bc: anytype, event: *const Notification.PageLoaded) !void {
+    const session_id = bc.session_id orelse return;
+    const timestamp = event.timestamp;
+    var cdp = bc.cdp;
+
+    const frame_id = &id.toFrameId(event.frame_id);
+
+    try cdp.sendEvent(
+        "Page.loadEventFired",
+        .{ .timestamp = timestamp },
+        .{ .session_id = session_id },
+    );
+
+    if (bc.page_life_cycle_events) {
+        const loader_id = &id.toLoaderId(event.req_id);
+        try cdp.sendEvent("Page.lifecycleEvent", LifecycleEvent{
+            .timestamp = timestamp,
+            .name = "load",
+            .frameId = frame_id,
+            .loaderId = loader_id,
+        }, .{ .session_id = session_id });
+    }
+
+    return cdp.sendEvent("Page.frameStoppedLoading", .{
+        .frameId = frame_id,
+    }, .{ .session_id = session_id });
+}
+
 pub fn pageNetworkIdle(bc: anytype, event: *const Notification.PageNetworkIdle) !void {
     return sendPageLifecycle(bc, "networkIdle", event.timestamp, &id.toFrameId(event.frame_id), &id.toLoaderId(event.req_id));
 }