// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/webui/examples/browser/devtools/devtools_frontend.h"

#include <map>
#include <memory>
#include <string_view>

#include "base/memory/raw_ptr.h"
#include "base/memory/ref_counted.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/uuid.h"
#include "base/values.h"
#include "content/public/browser/devtools_agent_host.h"
#include "content/public/browser/devtools_frontend_host.h"
#include "content/public/browser/navigation_handle.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/browser/web_contents_user_data.h"
#include "ipc/constants.mojom.h"
#include "ui/webui/examples/browser/devtools/devtools_server.h"
#include "url/gurl.h"

namespace webui_examples {

namespace {

static GURL GetFrontendURL() {
  return GURL(
      base::StringPrintf("http://127.0.0.1:%d/devtools/devtools_app.html",
                         devtools::GetHttpHandlerPort()));
}

// This constant should be in sync with
// the constant
// kMaxMessageChunkSize in chrome/browser/devtools/devtools_ui_bindings.cc.
constexpr size_t kMaxMessageChunkSize =
    IPC::mojom::kChannelMaximumMessageSize / 4;

}  // namespace

class DevToolsFrontend::AgentHostClient
    : public content::WebContentsObserver,
      public content::DevToolsAgentHostClient {
 public:
  AgentHostClient(content::WebContents* devtools_contents,
                  content::WebContents* inspected_contents)
      : content::WebContentsObserver(devtools_contents),
        devtools_contents_(devtools_contents),
        inspected_contents_(inspected_contents) {}
  AgentHostClient(const AgentHostClient&) = delete;
  AgentHostClient& operator=(const AgentHostClient&) = delete;
  ~AgentHostClient() override = default;

  // content::DevToolsAgentHostClient
  void DispatchProtocolMessage(content::DevToolsAgentHost* agent_host,
                               base::span<const uint8_t> message) override {
    std::string_view str_message(reinterpret_cast<const char*>(message.data()),
                                 message.size());
    if (str_message.length() < kMaxMessageChunkSize) {
      CallClientFunction("DevToolsAPI", "dispatchMessage",
                         base::Value(std::string(str_message)));
    } else {
      size_t total_size = str_message.length();
      for (size_t pos = 0; pos < str_message.length();
           pos += kMaxMessageChunkSize) {
        std::string_view str_message_chunk =
            str_message.substr(pos, kMaxMessageChunkSize);

        CallClientFunction(
            "DevToolsAPI", "dispatchMessageChunk",
            base::Value(std::string(str_message_chunk)),
            base::Value(base::NumberToString(pos ? 0 : total_size)));
      }
    }
  }

  void AgentHostClosed(content::DevToolsAgentHost* agent_host) override {}

  void FrameDeleted(content::FrameTreeNodeId frame_tree_node_id) override {
    if (agent_host_) {
      agent_host_->DetachClient(this);
      agent_host_.reset();
    }
  }

  void Attach() {
    if (agent_host_)
      agent_host_->DetachClient(this);

    agent_host_ =
        content::DevToolsAgentHost::GetOrCreateFor(inspected_contents_);
    agent_host_->AttachClient(this);
  }

  void CallClientFunction(
      const std::string& object_name,
      const std::string& method_name,
      base::Value arg1 = {},
      base::Value arg2 = {},
      base::Value arg3 = {},
      base::OnceCallback<void(base::Value)> cb = base::NullCallback()) {
    content::RenderFrameHost* host = devtools_contents_->GetPrimaryMainFrame();
    host->AllowInjectingJavaScript();

    base::Value::List arguments;
    if (!arg1.is_none()) {
      arguments.Append(std::move(arg1));
      if (!arg2.is_none()) {
        arguments.Append(std::move(arg2));
        if (!arg3.is_none()) {
          arguments.Append(std::move(arg3));
        }
      }
    }

    host->ExecuteJavaScriptMethod(base::ASCIIToUTF16(object_name),
                                  base::ASCIIToUTF16(method_name),
                                  std::move(arguments), std::move(cb));
  }

 private:
  // content::WebContentsObserver:
  void ReadyToCommitNavigation(
      content::NavigationHandle* navigation_handle) override {
    content::RenderFrameHost* frame = navigation_handle->GetRenderFrameHost();
    // TODO(crbug.com/40185886): With MPArch there may be multiple main
    // frames. This caller was converted automatically to the primary main frame
    // to preserve its semantics. Follow up to confirm correctness.
    if (navigation_handle->IsInPrimaryMainFrame()) {
      frontend_host_ = content::DevToolsFrontendHost::Create(
          frame, base::BindRepeating(
                     &AgentHostClient::HandleMessageFromDevToolsFrontend,
                     base::Unretained(this)));
      return;
    }
    std::string origin =
        navigation_handle->GetURL().DeprecatedGetOriginAsURL().spec();
    auto it = extensions_api_.find(origin);
    if (it == extensions_api_.end())
      return;
    std::string script = base::StringPrintf(
        "%s(\"%s\")", it->second.c_str(),
        base::Uuid::GenerateRandomV4().AsLowercaseString().c_str());
    content::DevToolsFrontendHost::SetupExtensionsAPI(frame, script);
  }

  void HandleMessageFromDevToolsFrontend(base::Value::Dict message) {
    const std::string* method = message.FindString("method");
    if (!method)
      return;

    int request_id = message.FindInt("id").value_or(0);
    base::Value::List* params_value = message.FindList("params");

    // Since we've received message by value, we can take the list.
    base::Value::List params;
    if (params_value) {
      params = std::move(*params_value);
    }

    if (*method == "dispatchProtocolMessage" && params.size() == 1) {
      const std::string* protocol_message = params[0].GetIfString();
      if (!agent_host_ || !protocol_message)
        return;
      agent_host_->DispatchProtocolMessage(
          this, base::as_byte_span(*protocol_message));
    } else if (*method == "loadCompleted") {
      CallClientFunction("DevToolsAPI", "setUseSoftMenu", base::Value(true));
    } else if (*method == "loadNetworkResource" && params.size() == 3) {
      // TODO(robliao): Add support for this if necessary.
      NOTREACHED();
    } else if (*method == "getPreferences") {
      SendMessageAck(request_id, base::Value(std::move(preferences_)));
      return;
    } else if (*method == "getHostConfig") {
      base::Value::Dict response_dict;

      // Chrome's DevToolsUIBindings sets feature flag values to this
      // devToolsVeLogging dictionary, but they're not accessible from //ui.
      // Just set the default values instead.
      base::Value::Dict ve_logging_dict;
      ve_logging_dict.Set("enabled", true);
      ve_logging_dict.Set("testing", false);
      response_dict.Set("devToolsVeLogging", std::move(ve_logging_dict));

      SendMessageAck(request_id, base::Value(std::move(response_dict)));
      return;
    } else if (*method == "setPreference") {
      if (params.size() < 2)
        return;
      const std::string* name = params[0].GetIfString();

      // We're just setting params[1] as a value anyways, so just make sure it's
      // the type we want, but don't worry about getting it.
      if (!name || !params[1].is_string())
        return;

      preferences_.Set(*name, std::move(params[1]));
    } else if (*method == "removePreference") {
      const std::string* name = params[0].GetIfString();
      if (!name)
        return;
      preferences_.Remove(*name);
    } else if (*method == "requestFileSystems") {
      CallClientFunction("DevToolsAPI", "fileSystemsLoaded",
                         base::Value(base::Value::Type::LIST));
    } else if (*method == "reattach") {
      if (!agent_host_)
        return;
      agent_host_->DetachClient(this);
      agent_host_->AttachClient(this);
    } else if (*method == "registerExtensionsAPI") {
      if (params.size() < 2)
        return;
      const std::string* origin = params[0].GetIfString();
      const std::string* script = params[1].GetIfString();
      if (!origin || !script)
        return;
      extensions_api_[*origin + "/"] = *script;
    } else {
      return;
    }

    if (request_id)
      SendMessageAck(request_id, {});
  }

  void SendMessageAck(int request_id, base::Value arg) {
    CallClientFunction("DevToolsAPI", "embedderMessageAck",
                       base::Value(request_id), std::move(arg));
  }

  const raw_ptr<content::WebContents> devtools_contents_;
  const raw_ptr<content::WebContents> inspected_contents_;

  scoped_refptr<content::DevToolsAgentHost> agent_host_;
  std::unique_ptr<content::DevToolsFrontendHost> frontend_host_;

  std::map<std::string, std::string> extensions_api_;

  base::Value::Dict preferences_;
};

class DevToolsFrontend::Pointer : public content::WebContentsUserData<Pointer> {
 public:
  ~Pointer() override = default;

  static DevToolsFrontend* Create(content::WebContents* web_contents) {
    CreateForWebContents(web_contents);
    Pointer* ptr = FromWebContents(web_contents);
    return ptr->Get();
  }

  DevToolsFrontend* Get() { return ptr_.get(); }

 private:
  friend class content::WebContentsUserData<Pointer>;
  Pointer(content::WebContents* web_contents)
      : content::WebContentsUserData<Pointer>(*web_contents),
        ptr_(new DevToolsFrontend(web_contents)) {}
  Pointer(const Pointer*) = delete;
  Pointer& operator=(const Pointer&) = delete;

  WEB_CONTENTS_USER_DATA_KEY_DECL();

  std::unique_ptr<DevToolsFrontend> ptr_;
};

WEB_CONTENTS_USER_DATA_KEY_IMPL(DevToolsFrontend::Pointer);

DevToolsFrontend::DevToolsFrontend(content::WebContents* inspected_contents)
    : frontend_url_(GetFrontendURL()),
      inspected_contents_(inspected_contents) {}
DevToolsFrontend::~DevToolsFrontend() = default;

// static
DevToolsFrontend* DevToolsFrontend::CreateAndGet(
    content::WebContents* inspected_contents) {
  return DevToolsFrontend::Pointer::Create(inspected_contents);
}

void DevToolsFrontend::SetDevtoolsWebContents(
    content::WebContents* devtools_contents) {
  devtools_contents_ = devtools_contents;
  agent_host_client_ = std::make_unique<AgentHostClient>(devtools_contents_,
                                                         inspected_contents_);
  agent_host_client_->Attach();
}

}  // namespace webui_examples