@task
def deploy():
    """
    Deploy the project.
    """

    # check stage
    require('stage', provided_by=(stage_api, stage_admin,
                                  production_api, production_admin))

    repo = env.docker_repo
    latest_tag = env.docker_tag
    prev_latest_tag = 'prev-{0}'.format(latest_tag)
    service = env.docker_compose_service

    with aws_credential():
        ecr_login = local('aws ecr get-login', capture=True)

        # check tags from current commit_id image
        commit_id = local('git rev-parse HEAD', capture=True)
        with settings(warn_only=True):
            image = local('aws ecr describe-images '
                          '--repository-name {0} '
                          '--image-ids '
                          '--query imageDetails[0] '
                          'imageTag={1}'.format(repo, commit_id), capture=True)

        if image.return_code != 0:
            return abort("<ECR {0}:{1}> doesn't exist.".format(repo, commit_id))

        image = json.loads(image)
        image_tags = image['imageTags']

        if latest_tag not in image_tags:
            # "latest" image tagged "prev_latest"
            manifest = local('aws ecr batch-get-image '
                             '--repository-name {0} '
                             '--image-ids imageTag={1} '
                             '--query images[].imageManifest '
                             '--output text'.format(repo, latest_tag), capture=True)
            if manifest:
                with settings(warn_only=True):
                    local('aws ecr put-image '
                          '--repository-name {0} '
                          '--image-tag {1} '
                          '--image-manifest \'{2}\''.format(repo, prev_latest_tag, manifest))

            # last image tagged "latest"
            commit_id = local('git rev-parse HEAD', capture=True)
            manifest = local('aws ecr batch-get-image '
                             '--repository-name {0} '
                             '--image-ids imageTag={1} '
                             '--query images[].imageManifest '
                             '--output text'.format(repo, commit_id), capture=True)
            local('aws ecr put-image '
                  '--repository-name {0} '
                  '--image-tag {1} '
                  '--image-manifest \'{2}\''.format(repo, latest_tag, manifest))

    migrated = False
    for host in env.docker_hosts:
        with shell_env(DOCKER_HOST='tcp://{0}'.format(host)):
            # docker login to ecr
            local(ecr_login)

            # pull image
            local('docker-compose -f {0} pull {1}'.format(env.docker_compose_file, service))

            # db migration
            if env.db_migration and not migrated:
                migration_container = '{0}-{1}'.format(repo, env.docker_compose_migration_service)
                with settings(warn_only=True):
                    result = local(
                        'docker-compose -f {0} run --name {1} {2} '
                        '/bin/bash -c "cd {3}; python manage.py db upgrade"'.format(
                            env.docker_compose_file,
                            migration_container,
                            env.docker_compose_migration_service,
                            env.code_path)
                    )
                local('docker rm {0}'.format(migration_container))
                if result.return_code != 0:
                    return abort("Database migration failed.")
                migrated = True

            # check blue-green
            blue_name = '{0}-blue'.format(repo)
            green_name = '{0}-green'.format(repo)
            with settings(warn_only=True):
                exist_blue = local('docker-compose '
                                   '-f {0} '
                                   'ps | grep {1}.*Up'.format(env.docker_compose_file, blue_name),
                                   capture=True)
            if exist_blue:
                current_container = blue_name
                deploy_container = green_name
            else:
                current_container = green_name
                deploy_container = blue_name

            # run deploy container
            local('docker-compose -f {0} run -d --name {1} {2}'.format(env.docker_compose_file,
                                                                       deploy_container,
                                                                       service))

            # stop & remove current container
            with settings(warn_only=True):
                local('docker stop {0}'.format(current_container))
                local('docker rm {0}'.format(current_container))