package software.amazon.ssm.maintenancewindow;

import com.amazonaws.util.StringUtils;
import software.amazon.awssdk.services.ssm.SsmClient;
import software.amazon.awssdk.services.ssm.model.UpdateMaintenanceWindowRequest;
import software.amazon.awssdk.services.ssm.model.UpdateMaintenanceWindowResponse;
import software.amazon.awssdk.utils.CollectionUtils;
import software.amazon.cloudformation.exceptions.BaseHandlerException;
import software.amazon.cloudformation.proxy.ProgressEvent;
import software.amazon.cloudformation.proxy.Logger;
import software.amazon.cloudformation.proxy.AmazonWebServicesClientProxy;
import software.amazon.cloudformation.proxy.ResourceHandlerRequest;
import software.amazon.cloudformation.proxy.OperationStatus;
import software.amazon.cloudformation.proxy.HandlerErrorCode;
import software.amazon.ssm.maintenancewindow.translator.ExceptionTranslator;
import software.amazon.ssm.maintenancewindow.translator.resourcemodel.UpdateMaintenanceWindowToResourceModelTranslator;
import software.amazon.ssm.maintenancewindow.translator.request.UpdateMaintenanceWindowTranslator;
import software.amazon.ssm.maintenancewindow.util.ClientBuilder;
import software.amazon.ssm.maintenancewindow.translator.resourcemodel.ResourceModelPropertyTranslator;
import software.amazon.ssm.maintenancewindow.util.TagUtil;

import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;

public class UpdateHandler extends BaseHandler<CallbackContext> {

    private static final SsmClient SSM_CLIENT = ClientBuilder.getClient();

    private final UpdateMaintenanceWindowTranslator updateMaintenanceWindowTranslator;
    private final UpdateMaintenanceWindowToResourceModelTranslator updateMaintenanceWindowToResourceModelTranslator;
    private final ExceptionTranslator exceptionTranslator;

    UpdateHandler() {
        this.updateMaintenanceWindowTranslator = new UpdateMaintenanceWindowTranslator();
        this.updateMaintenanceWindowToResourceModelTranslator = new UpdateMaintenanceWindowToResourceModelTranslator();
        this.exceptionTranslator = new ExceptionTranslator();
    }

    /**
     * Used for unit tests.
     *
     * @param updateMaintenanceWindowTranslator Generate UpdateMaintenanceWindowRequest from the ResourceModel.
     * @param updateMaintenanceWindowTranslator Translates UpdateMaintenanceWindowResponse into ResourceModel objects.
     * @param exceptionTranslator               Translates service model exceptions.
     */
    UpdateHandler(final UpdateMaintenanceWindowTranslator updateMaintenanceWindowTranslator,
                  final UpdateMaintenanceWindowToResourceModelTranslator updateMaintenanceWindowToResourceModelTranslator,
                  final ExceptionTranslator exceptionTranslator) {
        this.updateMaintenanceWindowTranslator = updateMaintenanceWindowTranslator;
        this.updateMaintenanceWindowToResourceModelTranslator = updateMaintenanceWindowToResourceModelTranslator;
        this.exceptionTranslator = exceptionTranslator;
    }

    @Override
    public ProgressEvent<ResourceModel, CallbackContext> handleRequest(
            final AmazonWebServicesClientProxy proxy,
            final ResourceHandlerRequest<ResourceModel> request,
            final CallbackContext callbackContext,
            final Logger logger) {

        logger.log(String.format("Processing UpdateHandler request %s", request));

        final ResourceModel model = request.getDesiredResourceState();

        final ProgressEvent<ResourceModel, CallbackContext> progressEvent = new ProgressEvent<>();
        progressEvent.setResourceModel(request.getPreviousResourceState());
        progressEvent.setStatus(OperationStatus.FAILED);

        final String windowId = model.getWindowId();

        if (StringUtils.isNullOrEmpty(windowId)) {
            progressEvent.setErrorCode(HandlerErrorCode.InvalidRequest);
            progressEvent.setMessage("WindowId must be present to update the existing maintenance window.");
            return progressEvent;
        }

        final UpdateMaintenanceWindowRequest updateMaintenanceWindowRequest =
                updateMaintenanceWindowTranslator.resourceModelToRequest(model);

        try {
            final UpdateMaintenanceWindowResponse response =
                    proxy.injectCredentialsAndInvokeV2(updateMaintenanceWindowRequest, SSM_CLIENT::updateMaintenanceWindow);

            final ResourceModel updatedModel =
                    updateMaintenanceWindowToResourceModelTranslator.updateMaintenanceWindowResponseToResourceModel(response);

            updateTags(request.getDesiredResourceTags(), request.getSystemTags(), windowId, proxy);
            progressEvent.setResourceModel(updatedModel);

            progressEvent.setStatus(OperationStatus.SUCCESS);

        } catch (final Exception e) {
            final BaseHandlerException cfnException = exceptionTranslator
                    .translateFromServiceException(e, updateMaintenanceWindowRequest);

            logger.log(cfnException.getCause().getMessage());

            throw cfnException;
        }

        return progressEvent;
    }

    private void updateTags(final Map<String, String> resourceModelTags,
                            final Map<String, String> systemTags,
                            final String windowId,
                            final AmazonWebServicesClientProxy proxy) {
        final List<Tag> consolidatedTags = TagUtil.consolidateTags(resourceModelTags, systemTags);
        final Set<software.amazon.awssdk.services.ssm.model.Tag> newTags =
                TagUtil.translateTagsToSdk(consolidatedTags)
                        == null ? Collections.emptySet() : new HashSet<>(TagUtil.translateTagsToSdk(consolidatedTags));
        final Set<software.amazon.awssdk.services.ssm.model.Tag> existingTags =
                new HashSet<software.amazon.awssdk.services.ssm.model.Tag>(proxy.injectCredentialsAndInvokeV2(
                        TagUtil.buildListTagsForResourceRequest(windowId),
                        SSM_CLIENT::listTagsForResource).tagList());

        final List<String> tagsToRemove = existingTags.stream()
                .filter(tag -> !newTags.contains(tag))
                .map(tag -> tag.key())
                .collect(Collectors.toList());
        // request.getSystemTag() is null
        tagsToRemove.removeIf(tagKey -> tagKey.toLowerCase().startsWith("aws:"));

        final List<software.amazon.awssdk.services.ssm.model.Tag> tagsToAdd = newTags.stream()
                .filter(tag -> !existingTags.contains(tag))
                .collect(Collectors.toList());

        if (!CollectionUtils.isNullOrEmpty(tagsToRemove))
            proxy.injectCredentialsAndInvokeV2(TagUtil.buildRemoveTagsFromResourceRequest(windowId, tagsToRemove), SSM_CLIENT::removeTagsFromResource);
        if (!CollectionUtils.isNullOrEmpty(tagsToAdd))
            proxy.injectCredentialsAndInvokeV2(TagUtil.buildAddTagsToResourceRequest(windowId, tagsToAdd), SSM_CLIENT::addTagsToResource);
    }
}