/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include "PageTarget.h"
#include "InspectorInterfaces.h"
#include "InspectorUtilities.h"
#include "InstanceTarget.h"
#include "PageAgent.h"
#include "Parsing.h"
#include "SessionState.h"

#include <folly/dynamic.h>
#include <folly/json.h>

#include <memory>

namespace facebook::react::jsinspector_modern {

/**
 * A Session connected to a PageTarget, passing CDP messages to and from a
 * PageAgent which it owns.
 */
class PageTargetSession {
 public:
  explicit PageTargetSession(
      std::unique_ptr<IRemoteConnection> remote,
      PageTargetController& targetController,
      PageTarget::SessionMetadata sessionMetadata)
      : remote_(std::make_shared<RAIIRemoteConnection>(std::move(remote))),
        frontendChannel_(
            [remoteWeak = std::weak_ptr(remote_)](std::string_view message) {
              if (auto remote = remoteWeak.lock()) {
                remote->onMessage(std::string(message));
              }
            }),
        pageAgent_(
            frontendChannel_,
            targetController,
            std::move(sessionMetadata),
            state_) {}

  /**
   * Called by CallbackLocalConnection to send a message to this Session's
   * Agent.
   */
  void operator()(std::string message) {
    cdp::PreparsedRequest request;
    // Messages may be invalid JSON, or have unexpected types.
    try {
      request = cdp::preparse(message);
    } catch (const cdp::ParseError& e) {
      frontendChannel_(folly::toJson(folly::dynamic::object("id", nullptr)(
          "error",
          folly::dynamic::object("code", -32700)("message", e.what()))));
      return;
    } catch (const cdp::TypeError& e) {
      frontendChannel_(folly::toJson(folly::dynamic::object("id", nullptr)(
          "error",
          folly::dynamic::object("code", -32600)("message", e.what()))));
      return;
    }

    // Catch exceptions that may arise from accessing dynamic params during
    // request handling.
    try {
      pageAgent_.handleRequest(request);
    } catch (const cdp::TypeError& e) {
      frontendChannel_(folly::toJson(folly::dynamic::object("id", request.id)(
          "error",
          folly::dynamic::object("code", -32600)("message", e.what()))));
      return;
    }
  }

  /**
   * Replace the current instance agent inside pageAgent_ with a new one
   * connected to the new InstanceTarget.
   * \param instance The new instance target. May be nullptr to indicate
   * there's no current instance.
   */
  void setCurrentInstance(InstanceTarget* instance) {
    if (instance) {
      pageAgent_.setCurrentInstanceAgent(
          instance->createAgent(frontendChannel_, state_));
    } else {
      pageAgent_.setCurrentInstanceAgent(nullptr);
    }
  }

 private:
  // Owned by this instance, but shared (weakly) with the frontend channel
  std::shared_ptr<RAIIRemoteConnection> remote_;
  FrontendChannel frontendChannel_;
  PageAgent pageAgent_;
  SessionState state_;
};

std::shared_ptr<PageTarget> PageTarget::create(
    PageTargetDelegate& delegate,
    VoidExecutor executor) {
  std::shared_ptr<PageTarget> pageTarget{new PageTarget(delegate)};
  pageTarget->setExecutor(executor);
  return pageTarget;
}

PageTarget::PageTarget(PageTargetDelegate& delegate)
    : delegate_(delegate),
      executionContextManager_{std::make_shared<ExecutionContextManager>()} {}

std::unique_ptr<ILocalConnection> PageTarget::connect(
    std::unique_ptr<IRemoteConnection> connectionToFrontend,
    SessionMetadata sessionMetadata) {
  auto session = std::make_shared<PageTargetSession>(
      std::move(connectionToFrontend), controller_, std::move(sessionMetadata));
  session->setCurrentInstance(currentInstance_.get());
  sessions_.insert(std::weak_ptr(session));
  return std::make_unique<CallbackLocalConnection>(
      [session](std::string message) { (*session)(message); });
}

PageTarget::~PageTarget() {
  // Sessions are owned by InspectorPackagerConnection, not by PageTarget, but
  // they hold a PageTarget& that we must guarantee is valid.
  assert(
      sessions_.empty() &&
      "PageTargetSession objects must be destroyed before their PageTarget. Did you call getInspectorInstance().removePage()?");
}

PageTargetDelegate::~PageTargetDelegate() {}

InstanceTarget& PageTarget::registerInstance(InstanceTargetDelegate& delegate) {
  assert(!currentInstance_ && "Only one instance allowed");
  currentInstance_ = InstanceTarget::create(
      executionContextManager_, delegate, makeVoidExecutor(executorFromThis()));
  sessions_.forEach(
      [currentInstance = &*currentInstance_](PageTargetSession& session) {
        session.setCurrentInstance(currentInstance);
      });
  return *currentInstance_;
}

void PageTarget::unregisterInstance(InstanceTarget& instance) {
  assert(
      currentInstance_ && currentInstance_.get() == &instance &&
      "Invalid unregistration");
  sessions_.forEach(
      [](PageTargetSession& session) { session.setCurrentInstance(nullptr); });
  currentInstance_.reset();
}

PageTargetController::PageTargetController(PageTarget& target)
    : target_(target) {}

PageTargetDelegate& PageTargetController::getDelegate() {
  return target_.getDelegate();
}

bool PageTargetController::hasInstance() const {
  return target_.hasInstance();
}

} // namespace facebook::react::jsinspector_modern