Emit networkIdle and networkAlmostIdle Page.lifecycleEvent

Most CDP drivers have a mechanism to wait for idle network, or an almost idle
network (sometimes called networkIdle2). These are events the browser must emit.

The page will now emit `networkIdle` when we are reasonably sure there's no more
network activity (this requires some slight changes to request interception,
since, I believe, intercepted requests should be considered).

`networkAlmostIdle` is currently _always_ emitted prior to emitting
`networkIdle`. We should tweak this but I can't, at a glance, think of a great
heuristic for when this should be emitted.

src/cdp/cdp.zig

@@ -487,6 +487,18 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             self.cdp.browser.notification.unregister(.http_request_auth_required, self);
         }
 
+        pub fn lifecycleEventsEnable(self: *Self) !void {
+            self.page_life_cycle_events = true;
+            try self.cdp.browser.notification.register(.page_network_idle, self, onPageNetworkIdle);
+            try self.cdp.browser.notification.register(.page_network_almost_idle, self, onPageNetworkAlmostIdle);
+        }
+
+        pub fn lifecycleEventsDisable(self: *Self) void {
+            self.page_life_cycle_events = false;
+            self.cdp.browser.notification.unregister(.page_network_idle, self);
+            self.cdp.browser.notification.unregister(.page_network_almost_idle, self);
+        }
+
         pub fn onPageRemove(ctx: *anyopaque, _: Notification.PageRemove) !void {
             const self: *Self = @ptrCast(@alignCast(ctx));
             try @import("domains/page.zig").pageRemove(self);
@@ -508,6 +520,16 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             return @import("domains/page.zig").pageNavigated(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);
+        }
+
+        pub fn onPageNetworkAlmostIdle(ctx: *anyopaque, msg: *const Notification.PageNetworkAlmostIdle) !void {
+            const self: *Self = @ptrCast(@alignCast(ctx));
+            return @import("domains/page.zig").pageNetworkAlmostIdle(self, msg);
+        }
+
         pub fn onHttpRequestStart(ctx: *anyopaque, msg: *const Notification.RequestStart) !void {
             const self: *Self = @ptrCast(@alignCast(ctx));
             defer self.resetNotificationArena();

src/cdp/domains/fetch.zig

@@ -261,7 +261,7 @@ fn continueRequest(cmd: anytype) !void {
         transfer.req.body = body;
     }
 
-    try bc.cdp.browser.http_client.process(transfer);
+    try bc.cdp.browser.http_client.continueTransfer(transfer);
     return cmd.sendResult(null, .{});
 }
 
@@ -311,7 +311,7 @@ fn continueWithAuth(cmd: anytype) !void {
     );
 
     transfer.reset();
-    try bc.cdp.browser.http_client.process(transfer);
+    try bc.cdp.browser.http_client.continueTransfer(transfer);
     return cmd.sendResult(null, .{});
 }
 
@@ -352,7 +352,7 @@ fn fulfillRequest(cmd: anytype) !void {
         body = buf;
     }
 
-    try transfer.fulfill(params.responseCode, params.responseHeaders orelse &.{}, body);
+    try bc.cdp.browser.http_client.fulfillTransfer(transfer, params.responseCode, params.responseHeaders orelse &.{}, body);
 
     return cmd.sendResult(null, .{});
 }
@@ -368,7 +368,7 @@ fn failRequest(cmd: anytype) !void {
     const request_id = try idFromRequestId(params.requestId);
 
     const transfer = intercept_state.remove(request_id) orelse return error.RequestNotFound;
-    defer transfer.abort();
+    defer bc.cdp.browser.http_client.abortTransfer(transfer);
 
     log.info(.cdp, "request intercept", .{
         .state = "fail",

src/cdp/domains/page.zig

@@ -78,12 +78,16 @@ fn getFrameTree(cmd: anytype) !void {
 }
 
 fn setLifecycleEventsEnabled(cmd: anytype) !void {
-    // const params = (try cmd.params(struct {
-    //     enabled: bool,
-    // })) orelse return error.InvalidParams;
+    const params = (try cmd.params(struct {
+        enabled: bool,
+    })) orelse return error.InvalidParams;
 
     const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
-    bc.page_life_cycle_events = true;
+    if (params.enabled) {
+        try bc.lifecycleEventsEnable();
+    } else {
+        bc.lifecycleEventsDisable();
+    }
     return cmd.sendResult(null, .{});
 }
 
@@ -357,6 +361,27 @@ pub fn pageNavigated(bc: anytype, event: *const Notification.PageNavigated) !voi
     }, .{ .session_id = session_id });
 }
 
+pub fn pageNetworkIdle(bc: anytype, event: *const Notification.PageNetworkIdle) !void {
+    return sendPageLifecycle(bc, "networkIdle", event.timestamp);
+}
+
+pub fn pageNetworkAlmostIdle(bc: anytype, event: *const Notification.PageNetworkAlmostIdle) !void {
+    return sendPageLifecycle(bc, "networkAlmostIdle", event.timestamp);
+}
+
+fn sendPageLifecycle(bc: anytype, name: []const u8, timestamp: u32) !void {
+    const loader_id = bc.loader_id;
+    const target_id = bc.target_id orelse unreachable;
+    const session_id = bc.session_id orelse unreachable;
+
+    return bc.cdp.sendEvent("Page.lifecycleEvent", LifecycleEvent{
+        .name = name,
+        .frameId = target_id,
+        .loaderId = loader_id,
+        .timestamp = timestamp,
+    }, .{ .session_id = session_id });
+}
+
 const LifecycleEvent = struct {
     frameId: []const u8,
     loaderId: ?[]const u8,