LibWebView: Implement a JavaScript console tab in the Inspector

This adds a JS console to the bottom section of the Inspector WebView.
Much of this code is based on the existing WebView::ConsoleClient, but
ported to fit the inspector model. That is, much of the code from that
class is now handled in the Inspector's JS.

Base/res/html/inspector/inspector.css

@@ -138,6 +138,58 @@ details > :not(:first-child) {
     }
 }
 
+.console {
+    font-family: Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
+    width: 100%;
+    height: 100%;
+}
+
+.console-output {
+    height: calc(100% - 75px);
+    overflow: scroll;
+}
+
+.console-input {
+    width: 100%;
+    height: 24px;
+    padding: 4px;
+    position: absolute;
+    bottom: 0;
+    left: 0;
+}
+
+.console-input input {
+    width: calc(100% - 60px);
+}
+
+@media (prefers-color-scheme: dark) {
+    .console-prompt {
+        color: cyan;
+    }
+
+    .console-input {
+        background-color: rgb(57, 57, 57);
+    }
+
+    .console-input input:focus {
+        outline: 1px dashed cyan;
+    }
+}
+
+@media (prefers-color-scheme: light) {
+    .console-prompt {
+        color: blue;
+    }
+
+    .console-input {
+        background-color: rgb(229, 229, 229);
+    }
+
+    .console-input input:focus {
+        outline: 1px dashed blue;
+    }
+}
+
 .property-table {
     width: 100%;
 

Base/res/html/inspector/inspector.js

@@ -6,6 +6,12 @@ let selectedBottomTabButton = null;
 
 let selectedDOMNode = null;
 
+let consoleGroupStack = [];
+let consoleGroupNextID = 0;
+
+let consoleHistory = [];
+let consoleHistoryIndex = 0;
+
 const selectTab = (tabButton, tabID, selectedTab, selectedTabButton) => {
     let tab = document.getElementById(tabID);
 
@@ -36,8 +42,8 @@ const selectBottomTab = (tabButton, tabID) => {
 let initialTopTabButton = document.getElementById("dom-tree-button");
 selectTopTab(initialTopTabButton, "dom-tree");
 
-let initialBottomTabButton = document.getElementById("computed-style-button");
+let initialBottomTabButton = document.getElementById("console-button");
-selectBottomTab(initialBottomTabButton, "computed-style");
+selectBottomTab(initialBottomTabButton, "console");
 
 const scrollToElement = element => {
     // Include an offset to prevent the element being placed behind the fixed `tab-controls` header.
@@ -131,6 +137,140 @@ const inspectDOMNode = domNode => {
     inspector.inspectDOMNode(domNode.dataset.id, domNode.dataset.pseudoElement);
 };
 
+const executeConsoleScript = consoleInput => {
+    const script = consoleInput.value;
+
+    if (!/\S/.test(script)) {
+        return;
+    }
+
+    if (consoleHistory.length === 0 || consoleHistory[consoleHistory.length - 1] !== script) {
+        consoleHistory.push(script);
+    }
+
+    consoleHistoryIndex = consoleHistory.length;
+
+    inspector.executeConsoleScript(script);
+    consoleInput.value = "";
+};
+
+const setConsoleInputToPreviousHistoryItem = consoleInput => {
+    if (consoleHistoryIndex === 0) {
+        return;
+    }
+
+    --consoleHistoryIndex;
+
+    const script = consoleHistory[consoleHistoryIndex];
+    consoleInput.value = script;
+};
+
+const setConsoleInputToNextHistoryItem = consoleInput => {
+    if (consoleHistory.length === 0) {
+        return;
+    }
+
+    const lastIndex = consoleHistory.length - 1;
+
+    if (consoleHistoryIndex < lastIndex) {
+        ++consoleHistoryIndex;
+
+        consoleInput.value = consoleHistory[consoleHistoryIndex];
+        return;
+    }
+
+    if (consoleHistoryIndex === lastIndex) {
+        ++consoleHistoryIndex;
+
+        consoleInput.value = "";
+        return;
+    }
+};
+
+const consoleParentGroup = () => {
+    if (consoleGroupStack.length === 0) {
+        return document.getElementById("console-output");
+    }
+
+    const lastConsoleGroup = consoleGroupStack[consoleGroupStack.length - 1];
+    return document.getElementById(`console-group-${lastConsoleGroup.id}`);
+};
+
+const scrollConsoleToBottom = () => {
+    let consoleOutput = document.getElementById("console-output");
+
+    // FIXME: It should be sufficient to scrollTo a y value of document.documentElement.offsetHeight,
+    //        but due to an unknown bug offsetHeight seems to not be properly updated after spamming
+    //        a lot of document changes.
+    //
+    // The setTimeout makes the scrollTo async and allows the DOM to be updated.
+    setTimeout(function () {
+        consoleOutput.scrollTo(0, 1_000_000_000);
+    }, 0);
+};
+
+inspector.appendConsoleOutput = output => {
+    let parent = consoleParentGroup();
+
+    let element = document.createElement("p");
+    element.innerHTML = atob(output);
+
+    parent.appendChild(element);
+    scrollConsoleToBottom();
+};
+
+inspector.clearConsoleOutput = () => {
+    let consoleOutput = document.getElementById("console-output");
+    consoleOutput.innerHTML = "";
+
+    consoleGroupStack = [];
+};
+
+inspector.beginConsoleGroup = (label, startExpanded) => {
+    let parent = consoleParentGroup();
+
+    const group = {
+        id: ++consoleGroupNextID,
+        label: label,
+    };
+    consoleGroupStack.push(group);
+
+    let details = document.createElement("details");
+    details.id = `console-group-${group.id}`;
+    details.open = startExpanded;
+
+    let summary = document.createElement("summary");
+    summary.innerHTML = atob(label);
+
+    details.appendChild(summary);
+    parent.appendChild(details);
+    scrollConsoleToBottom();
+};
+
+inspector.endConsoleGroup = () => {
+    consoleGroupStack.pop();
+};
+
 document.addEventListener("DOMContentLoaded", () => {
+    let consoleInput = document.getElementById("console-input");
+    consoleInput.focus();
+
+    consoleInput.addEventListener("keydown", event => {
+        const UP_ARROW_KEYCODE = 38;
+        const DOWN_ARROW_KEYCODE = 40;
+        const RETURN_KEYCODE = 13;
+
+        if (event.keyCode === UP_ARROW_KEYCODE) {
+            setConsoleInputToPreviousHistoryItem(consoleInput);
+            event.preventDefault();
+        } else if (event.keyCode === DOWN_ARROW_KEYCODE) {
+            setConsoleInputToNextHistoryItem(consoleInput);
+            event.preventDefault();
+        } else if (event.keyCode === RETURN_KEYCODE) {
+            executeConsoleScript(consoleInput);
+            event.preventDefault();
+        }
+    });
+
     inspector.inspectorLoaded();
 });

Userland/Libraries/LibWebView/InspectorClient.cpp

@@ -9,6 +9,7 @@
 #include <AK/JsonObject.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/Resource.h>
+#include <LibJS/MarkupGenerator.h>
 #include <LibWeb/Infra/Strings.h>
 #include <LibWebView/InspectorClient.h>
 #include <LibWebView/SourceHighlighter.h>
@@ -63,11 +64,21 @@ InspectorClient::InspectorClient(ViewImplementation& content_web_view, ViewImple
         m_inspector_web_view.run_javascript(script);
     };
 
+    m_content_web_view.on_received_console_message = [this](auto message_index) {
+        handle_console_message(message_index);
+    };
+
+    m_content_web_view.on_received_console_messages = [this](auto start_index, auto const& message_types, auto const& messages) {
+        handle_console_messages(start_index, message_types, messages);
+    };
+
     m_inspector_web_view.enable_inspector_prototype();
     m_inspector_web_view.use_native_user_style_sheet();
 
     m_inspector_web_view.on_inspector_loaded = [this]() {
         inspect();
+
+        m_content_web_view.js_console_request_messages(0);
     };
 
     m_inspector_web_view.on_inspector_selected_dom_node = [this](auto node_id, auto const& pseudo_element) {
@@ -98,6 +109,12 @@ InspectorClient::InspectorClient(ViewImplementation& content_web_view, ViewImple
         m_inspector_web_view.run_javascript(builder.string_view());
     };
 
+    m_inspector_web_view.on_inspector_executed_console_script = [this](auto const& script) {
+        append_console_source(script);
+
+        m_content_web_view.js_console_input(script.to_deprecated_string());
+    };
+
     load_inspector();
 }
 
@@ -105,6 +122,8 @@ InspectorClient::~InspectorClient()
 {
     m_content_web_view.on_received_dom_tree = nullptr;
     m_content_web_view.on_received_accessibility_tree = nullptr;
+    m_content_web_view.on_received_console_message = nullptr;
+    m_content_web_view.on_received_console_messages = nullptr;
 }
 
 void InspectorClient::inspect()
@@ -119,6 +138,11 @@ void InspectorClient::reset()
     m_pending_selection.clear();
 
     m_dom_tree_loaded = false;
+
+    clear_console_output();
+    m_highest_notified_message_index = -1;
+    m_highest_received_message_index = -1;
+    m_waiting_for_messages = false;
 }
 
 void InspectorClient::select_hovered_node()
@@ -189,11 +213,22 @@ void InspectorClient::load_inspector()
         <div id="inspector-bottom" class="split-view-container" style="height: 40%">
             <div class="tab-controls-container">
                 <div class="tab-controls">
+                    <button id="console-button" onclick="selectBottomTab(this, 'console')">Console</button>
                     <button id="computed-style-button" onclick="selectBottomTab(this, 'computed-style')">Computed Style</button>
                     <button id="resolved-style-button" onclick="selectBottomTab(this, 'resolved-style')">Resolved Style</button>
                     <button id="custom-properties-button" onclick="selectBottomTab(this, 'custom-properties')">Custom Properties</button>
                 </div>
             </div>
+            <div id="console" class="tab-content">
+                <div class="console">
+                    <div id="console-output" class="console-output"></div>
+                    <div class="console-input">
+                        <label for="console-input" class="console-prompt">&gt;&gt;</label>
+                        <input id="console-input" type="text" placeholder="Enter statement to execute">
+                        <button id="console-clear" title="Clear the console output" onclick="inspector.clearConsoleOutput()">X</button>
+                    </div>
+                </div>
+            </div>
 )~~~"sv);
 
     auto generate_property_table = [&](auto name) {
@@ -384,4 +419,100 @@ String InspectorClient::generate_accessibility_tree(JsonObject const& accessibil
     return MUST(builder.to_string());
 }
 
+void InspectorClient::request_console_messages()
+{
+    VERIFY(!m_waiting_for_messages);
+
+    m_content_web_view.js_console_request_messages(m_highest_received_message_index + 1);
+    m_waiting_for_messages = true;
+}
+
+void InspectorClient::handle_console_message(i32 message_index)
+{
+    if (message_index <= m_highest_received_message_index) {
+        dbgln("Notified about console message we already have");
+        return;
+    }
+    if (message_index <= m_highest_notified_message_index) {
+        dbgln("Notified about console message we're already aware of");
+        return;
+    }
+
+    m_highest_notified_message_index = message_index;
+
+    if (!m_waiting_for_messages)
+        request_console_messages();
+}
+
+void InspectorClient::handle_console_messages(i32 start_index, ReadonlySpan<DeprecatedString> message_types, ReadonlySpan<DeprecatedString> messages)
+{
+    auto end_index = start_index + static_cast<i32>(message_types.size()) - 1;
+    if (end_index <= m_highest_received_message_index) {
+        dbgln("Received old console messages");
+        return;
+    }
+
+    for (size_t i = 0; i < message_types.size(); ++i) {
+        auto const& type = message_types[i];
+        auto const& message = messages[i];
+
+        if (type == "html"sv)
+            append_console_output(message);
+        else if (type == "clear"sv)
+            clear_console_output();
+        else if (type == "group"sv)
+            begin_console_group(message, true);
+        else if (type == "groupCollapsed"sv)
+            begin_console_group(message, false);
+        else if (type == "groupEnd"sv)
+            end_console_group();
+        else
+            VERIFY_NOT_REACHED();
+    }
+
+    m_highest_received_message_index = end_index;
+    m_waiting_for_messages = false;
+
+    if (m_highest_received_message_index < m_highest_notified_message_index)
+        request_console_messages();
+}
+
+void InspectorClient::append_console_source(StringView source)
+{
+    StringBuilder builder;
+
+    builder.append("<span class=\"console-prompt\">&gt;&nbsp;</span>"sv);
+    builder.append(MUST(JS::MarkupGenerator::html_from_source(source)));
+
+    append_console_output(builder.string_view());
+}
+
+void InspectorClient::append_console_output(StringView html)
+{
+    auto html_base64 = MUST(encode_base64(html.bytes()));
+
+    auto script = MUST(String::formatted("inspector.appendConsoleOutput(\"{}\");", html_base64));
+    m_inspector_web_view.run_javascript(script);
+}
+
+void InspectorClient::clear_console_output()
+{
+    static constexpr auto script = "inspector.clearConsoleOutput();"sv;
+    m_inspector_web_view.run_javascript(script);
+}
+
+void InspectorClient::begin_console_group(StringView label, bool start_expanded)
+{
+    auto label_base64 = MUST(encode_base64(label.bytes()));
+
+    auto script = MUST(String::formatted("inspector.beginConsoleGroup(\"{}\", {});", label_base64, start_expanded));
+    m_inspector_web_view.run_javascript(script);
+}
+
+void InspectorClient::end_console_group()
+{
+    static constexpr auto script = "inspector.endConsoleGroup();"sv;
+    m_inspector_web_view.run_javascript(script);
+}
+
 }

Userland/Libraries/LibWebView/InspectorClient.h

@@ -26,11 +26,22 @@ public:
 
 private:
     void load_inspector();
+
     String generate_dom_tree(JsonObject const&);
     String generate_accessibility_tree(JsonObject const&);
-
     void select_node(i32 node_id);
 
+    void request_console_messages();
+    void handle_console_message(i32 message_index);
+    void handle_console_messages(i32 start_index, ReadonlySpan<DeprecatedString> message_types, ReadonlySpan<DeprecatedString> messages);
+
+    void append_console_source(StringView);
+    void append_console_output(StringView);
+    void clear_console_output();
+
+    void begin_console_group(StringView label, bool start_expanded);
+    void end_console_group();
+
     ViewImplementation& m_content_web_view;
     ViewImplementation& m_inspector_web_view;
 
@@ -38,6 +49,10 @@ private:
     Optional<i32> m_pending_selection;
 
     bool m_dom_tree_loaded { false };
+
+    i32 m_highest_notified_message_index { -1 };
+    i32 m_highest_received_message_index { -1 };
+    bool m_waiting_for_messages { false };
 };
 
 }