// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/extensions/shared_module_service.h"

#include <vector>

#include "base/version.h"
#include "chrome/browser/extensions/extension_service.h"
#include "chrome/browser/extensions/install_tracker.h"
#include "chrome/browser/extensions/pending_extension_manager.h"
#include "chrome/common/extensions/extension_constants.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/browser/extension_system.h"
#include "extensions/common/extension.h"

namespace extensions {

namespace {

typedef std::vector<SharedModuleInfo::ImportInfo> ImportInfoVector;
typedef std::list<SharedModuleInfo::ImportInfo> ImportInfoList;

}  // namespace

SharedModuleService::SharedModuleService(content::BrowserContext* context)
    : context_(context), observing_(false) {
  InstallTracker::Get(context_)->AddObserver(this);
}

SharedModuleService::~SharedModuleService() {
  if (observing_)
    InstallTracker::Get(context_)->RemoveObserver(this);
}

SharedModuleService::ImportStatus SharedModuleService::CheckImports(
    const extensions::Extension* extension,
    ImportInfoList* missing_modules,
    ImportInfoList* outdated_modules) {
  DCHECK(extension);
  DCHECK(missing_modules && missing_modules->empty());
  DCHECK(outdated_modules && outdated_modules->empty());

  ImportStatus status = IMPORT_STATUS_OK;

  ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
  const ImportInfoVector& imports = SharedModuleInfo::GetImports(extension);
  for (ImportInfoVector::const_iterator iter = imports.begin();
       iter != imports.end();
       ++iter) {
    base::Version version_required(iter->minimum_version);
    const Extension* imported_module =
        registry->GetExtensionById(iter->extension_id,
                                   ExtensionRegistry::EVERYTHING);
    if (!imported_module) {
      if (extension->from_webstore()) {
        status = IMPORT_STATUS_UNSATISFIED;
        missing_modules->push_back(*iter);
      } else {
        return IMPORT_STATUS_UNRECOVERABLE;
      }
    } else if (!SharedModuleInfo::IsSharedModule(imported_module)) {
      return IMPORT_STATUS_UNRECOVERABLE;
    } else if (!SharedModuleInfo::IsExportAllowedByWhitelist(imported_module,
                                                             extension->id())) {
      return IMPORT_STATUS_UNRECOVERABLE;
    } else if (version_required.IsValid() &&
               imported_module->version()->CompareTo(version_required) < 0) {
      if (imported_module->from_webstore()) {
        outdated_modules->push_back(*iter);
        status = IMPORT_STATUS_UNSATISFIED;
      } else {
        return IMPORT_STATUS_UNRECOVERABLE;
      }
    }
  }

  return status;
}

SharedModuleService::ImportStatus SharedModuleService::SatisfyImports(
    const Extension* extension) {
  ImportInfoList missing_modules;
  ImportInfoList outdated_modules;
  ImportStatus status =
      CheckImports(extension, &missing_modules, &outdated_modules);

  ExtensionService* service =
      ExtensionSystem::Get(context_)->extension_service();

  PendingExtensionManager* pending_extension_manager =
      service->pending_extension_manager();
  DCHECK(pending_extension_manager);

  if (status == IMPORT_STATUS_UNSATISFIED) {
    for (ImportInfoList::const_iterator iter = missing_modules.begin();
         iter != missing_modules.end();
         ++iter) {
      pending_extension_manager->AddFromExtensionImport(
          iter->extension_id,
          extension_urls::GetWebstoreUpdateUrl(),
          SharedModuleInfo::IsSharedModule);
    }
    service->CheckForUpdatesSoon();
  }
  return status;
}

scoped_ptr<const ExtensionSet> SharedModuleService::GetDependentExtensions(
    const Extension* extension) {
  scoped_ptr<ExtensionSet> dependents(new ExtensionSet());

  if (SharedModuleInfo::IsSharedModule(extension)) {
    ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
    ExtensionService* service =
        ExtensionSystem::Get(context_)->extension_service();

    ExtensionSet set_to_check;
    set_to_check.InsertAll(registry->enabled_extensions());
    set_to_check.InsertAll(registry->disabled_extensions());
    set_to_check.InsertAll(*service->delayed_installs());

    for (ExtensionSet::const_iterator iter = set_to_check.begin();
         iter != set_to_check.end();
         ++iter) {
      if (SharedModuleInfo::ImportsExtensionById(iter->get(),
                                                 extension->id())) {
        dependents->Insert(*iter);
      }
    }
  }
  return dependents.PassAs<const ExtensionSet>();
}

void SharedModuleService::PruneSharedModulesOnUninstall(
    const Extension* extension) {
  if (!SharedModuleInfo::ImportsModules(extension))
    return;

  ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
  ExtensionService* service =
      ExtensionSystem::Get(context_)->extension_service();

  const ImportInfoVector& imports = SharedModuleInfo::GetImports(extension);
  for (ImportInfoVector::const_iterator iter = imports.begin();
       iter != imports.end();
       ++iter) {
    const Extension* imported_module =
        registry->GetExtensionById(iter->extension_id,
                                   ExtensionRegistry::EVERYTHING);
    if (imported_module && imported_module->from_webstore()) {
      scoped_ptr<const ExtensionSet> dependents =
          GetDependentExtensions(imported_module);
      if (dependents->is_empty()) {
        service->UninstallExtension(iter->extension_id,
                                    true,  // External uninstall.
                                    NULL);  // Ignore error.
      }
    }
  }
}

void SharedModuleService::OnExtensionUninstalled(const Extension* extension) {
  PruneSharedModulesOnUninstall(extension);
}

void SharedModuleService::OnShutdown() {
  InstallTracker::Get(context_)->RemoveObserver(this);
  observing_ = false;
}

}  // namespace extensions