from typing import Any, Mapping, Optional, Tuple

from zerver.lib.exceptions import UnexpectedWebhookEventType

SUPPORTED_BOARD_ACTIONS = [
    'removeMemberFromBoard',
    'addMemberToBoard',
    'createList',
    'updateBoard',
]

REMOVE_MEMBER = 'removeMemberFromBoard'
ADD_MEMBER = 'addMemberToBoard'
CREATE_LIST = 'createList'
CHANGE_NAME = 'changeName'

TRELLO_BOARD_URL_TEMPLATE = '[{board_name}]({board_url})'

ACTIONS_TO_MESSAGE_MAPPER = {
    REMOVE_MEMBER: 'removed {member_name} from {board_url_template}.',
    ADD_MEMBER: 'added {member_name} to {board_url_template}.',
    CREATE_LIST: 'added {list_name} list to {board_url_template}.',
    CHANGE_NAME: 'renamed the board from {old_name} to {board_url_template}.',
}

def process_board_action(payload: Mapping[str, Any],
                         action_type: Optional[str]) -> Optional[Tuple[str, str]]:
    action_type = get_proper_action(payload, action_type)
    if action_type is not None:
        return get_subject(payload), get_body(payload, action_type)
    return None

def get_proper_action(payload: Mapping[str, Any], action_type: Optional[str]) -> Optional[str]:
    if action_type == 'updateBoard':
        data = get_action_data(payload)
        # we don't support events for when a board's background
        # is changed
        if data['old'].get('prefs', {}).get('background') is not None:
            return None
        elif data['old']['name']:
            return CHANGE_NAME
        raise UnexpectedWebhookEventType("Trello", action_type)
    return action_type

def get_subject(payload: Mapping[str, Any]) -> str:
    return get_action_data(payload)['board']['name']

def get_body(payload: Mapping[str, Any], action_type: str) -> str:
    message_body = ACTIONS_TO_FILL_BODY_MAPPER[action_type](payload, action_type)
    creator = payload['action']['memberCreator']['fullName']
    return f'{creator} {message_body}'

def get_managed_member_body(payload: Mapping[str, Any], action_type: str) -> str:
    data = {
        'member_name': payload['action']['member']['fullName'],
    }
    return fill_appropriate_message_content(payload, action_type, data)

def get_create_list_body(payload: Mapping[str, Any], action_type: str) -> str:
    data = {
        'list_name': get_action_data(payload)['list']['name'],
    }
    return fill_appropriate_message_content(payload, action_type, data)

def get_change_name_body(payload: Mapping[str, Any], action_type: str) -> str:
    data = {
        'old_name': get_action_data(payload)['old']['name'],
    }
    return fill_appropriate_message_content(payload, action_type, data)


def fill_appropriate_message_content(payload: Mapping[str, Any],
                                     action_type: str,
                                     data: Mapping[str, Any] = {}) -> str:
    data = dict(data)
    if 'board_url_template' not in data:
        data['board_url_template'] = get_filled_board_url_template(payload)
    message_body = get_message_body(action_type)
    return message_body.format(**data)

def get_filled_board_url_template(payload: Mapping[str, Any]) -> str:
    return TRELLO_BOARD_URL_TEMPLATE.format(board_name=get_board_name(payload),
                                            board_url=get_board_url(payload))

def get_board_name(payload: Mapping[str, Any]) -> str:
    return get_action_data(payload)['board']['name']

def get_board_url(payload: Mapping[str, Any]) -> str:
    return 'https://trello.com/b/{}'.format(get_action_data(payload)['board']['shortLink'])

def get_message_body(action_type: str) -> str:
    return ACTIONS_TO_MESSAGE_MAPPER[action_type]

def get_action_data(payload: Mapping[str, Any]) -> Mapping[str, Any]:
    return payload['action']['data']

ACTIONS_TO_FILL_BODY_MAPPER = {
    REMOVE_MEMBER: get_managed_member_body,
    ADD_MEMBER: get_managed_member_body,
    CREATE_LIST: get_create_list_body,
    CHANGE_NAME: get_change_name_body,
}