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

#include "JSDeltaBundleClient.h"

#include <memory>
#include <sstream>

namespace facebook {
namespace react {

namespace {
std::string startupCode(const folly::dynamic *pre, const folly::dynamic *post) {
  std::ostringstream startupCode;

  for (auto section : {pre, post}) {
    if (section != nullptr) {
      startupCode << section->getString() << '\n';
    }
  }

  return startupCode.str();
}
} // namespace

void JSDeltaBundleClient::patchModules(const folly::dynamic *modules) {
  for (const folly::dynamic &pair : *modules) {
    auto id = pair[0].getInt();
    auto module = pair[1];
    modules_[id] = std::move(module.getString());
  }
}

void JSDeltaBundleClient::patch(const folly::dynamic &delta) {
  auto const base = delta.get_ptr("base");

  if (base != nullptr && base->asBool()) {
    clear();

    auto const pre = delta.get_ptr("pre");
    auto const post = delta.get_ptr("post");

    startupCode_ = startupCode(pre, post);

    const folly::dynamic *modules = delta.get_ptr("modules");
    if (modules != nullptr) {
      patchModules(modules);
    }
  } else {
    const folly::dynamic *deleted = delta.get_ptr("deleted");
    if (deleted != nullptr) {
      for (const folly::dynamic &id : *deleted) {
        modules_.erase(id.getInt());
      }
    }

    // TODO T37123645 This is deprecated but necessary in order to support older
    // versions of the Metro server.
    const folly::dynamic *modules = delta.get_ptr("modules");
    if (modules != nullptr) {
      patchModules(modules);
    }

    const folly::dynamic *added = delta.get_ptr("added");
    if (added != nullptr) {
      patchModules(added);
    }

    const folly::dynamic *modified = delta.get_ptr("modified");
    if (modified != nullptr) {
      patchModules(modified);
    }
  }
}

JSModulesUnbundle::Module JSDeltaBundleClient::getModule(
    uint32_t moduleId) const {
  auto search = modules_.find(moduleId);
  if (search != modules_.end()) {
    return {folly::to<std::string>(search->first, ".js"), search->second};
  }

  throw JSModulesUnbundle::ModuleNotFound(moduleId);
}

std::unique_ptr<const JSBigString> JSDeltaBundleClient::getStartupCode() const {
  return std::make_unique<JSBigStdString>(startupCode_);
}

void JSDeltaBundleClient::clear() {
  modules_.clear();
  startupCode_.clear();
}

} // namespace react
} // namespace facebook