from sqlalchemy.sql.expression import false

from backend import db
from flask import current_app
from enum import Enum
from backend.models.dtos.message_dto import MessageDTO, MessagesDTO
from backend.models.postgis.user import User
from backend.models.postgis.task import Task
from backend.models.postgis.project import Project
from backend.models.postgis.utils import timestamp, NotFound


class MessageType(Enum):
    """ Describes the various kinds of messages a user might receive """

    SYSTEM = 1  # Generic system-generated message
    BROADCAST = 2  # Broadcast message from a project manager
    MENTION_NOTIFICATION = 3  # Notification that user was mentioned in a comment/chat
    VALIDATION_NOTIFICATION = 4  # Notification that user's mapped task was validated
    INVALIDATION_NOTIFICATION = (
        5  # Notification that user's mapped task was invalidated
    )
    REQUEST_TEAM_NOTIFICATION = 6
    INVITATION_NOTIFICATION = 7
    TASK_COMMENT_NOTIFICATION = 8
    PROJECT_CHAT_NOTIFICATION = 9
    PROJECT_ACTIVITY_NOTIFICATION = 10
    TEAM_BROADCAST = 11  # Broadcast message from a team manager


class Message(db.Model):
    """ Describes an individual Message a user can send """

    __tablename__ = "messages"

    __table_args__ = (
        db.ForeignKeyConstraint(
            ["task_id", "project_id"], ["tasks.id", "tasks.project_id"]
        ),
    )

    id = db.Column(db.Integer, primary_key=True)
    message = db.Column(db.String)
    subject = db.Column(db.String)
    from_user_id = db.Column(db.BigInteger, db.ForeignKey("users.id"))
    to_user_id = db.Column(db.BigInteger, db.ForeignKey("users.id"), index=True)
    project_id = db.Column(db.Integer, db.ForeignKey("projects.id"), index=True)
    task_id = db.Column(db.Integer, index=True)
    message_type = db.Column(db.Integer, index=True)
    date = db.Column(db.DateTime, default=timestamp)
    read = db.Column(db.Boolean, default=False)

    # Relationships
    from_user = db.relationship(User, foreign_keys=[from_user_id])
    to_user = db.relationship(User, foreign_keys=[to_user_id], backref="messages")
    project = db.relationship(Project, foreign_keys=[project_id], backref="messages")
    task = db.relationship(
        Task,
        primaryjoin="and_(Task.id == foreign(Message.task_id), Task.project_id == Message.project_id)",
        backref="messages",
    )

    @classmethod
    def from_dto(cls, to_user_id: int, dto: MessageDTO):
        """ Creates new message from DTO """
        message = cls()
        message.subject = dto.subject
        message.message = dto.message
        message.from_user_id = dto.from_user_id
        message.to_user_id = to_user_id
        message.project_id = dto.project_id
        message.task_id = dto.task_id
        if dto.message_type is not None:
            message.message_type = MessageType(dto.message_type)

        return message

    def as_dto(self) -> MessageDTO:
        """ Casts message object to DTO """
        dto = MessageDTO()
        dto.message_id = self.id
        dto.message = self.message
        dto.sent_date = self.date
        dto.read = self.read
        dto.subject = self.subject
        dto.project_id = self.project_id
        dto.task_id = self.task_id
        if self.message_type is not None:
            dto.message_type = MessageType(self.message_type).name

        if self.from_user_id:
            dto.from_username = self.from_user.username

        return dto

    def add_message(self):
        """ Add message into current transaction - DO NOT COMMIT HERE AS MESSAGES ARE PART OF LARGER TRANSACTIONS"""
        current_app.logger.debug("Adding message to session")
        db.session.add(self)

    def save(self):
        """ Save """
        db.session.add(self)
        db.session.commit()

    @staticmethod
    def get_all_contributors(project_id: int):
        """ Get all contributors to a project """

        contributors = (
            db.session.query(Task.mapped_by)
            .filter(Task.project_id == project_id)
            .filter(Task.mapped_by.isnot(None))
            .union(
                db.session.query(Task.validated_by)
                .filter(Task.project_id == project_id)
                .filter(Task.validated_by.isnot(None))
            )
        )
        return contributors

    def mark_as_read(self):
        """ Mark the message in scope as Read """
        self.read = True
        db.session.commit()

    @staticmethod
    def get_unread_message_count(user_id: int):
        """ Get count of unread messages for user """
        return Message.query.filter(
            Message.to_user_id == user_id, Message.read == false()
        ).count()

    @staticmethod
    def get_all_messages(user_id: int) -> MessagesDTO:
        """ Gets all messages to the user """
        user_messages = Message.query.filter(Message.to_user_id == user_id).all()

        if len(user_messages) == 0:
            raise NotFound()

        messages_dto = MessagesDTO()
        for message in user_messages:
            messages_dto.user_messages.append(message.as_dto())

        return messages_dto

    @staticmethod
    def delete_multiple_messages(message_ids: list, user_id: int):
        """ Deletes the specified messages to the user """
        Message.query.filter(
            Message.to_user_id == user_id, Message.id.in_(message_ids)
        ).delete(synchronize_session=False)
        db.session.commit()

    def delete(self):
        """ Deletes the current model from the DB """
        db.session.delete(self)
        db.session.commit()