import sqlite3
from dataclasses import dataclass
from datetime import datetime
from os import link
from typing import Dict, List, Tuple


@dataclass
class Link:
    link: str
    user_id: str
    id: int = None
    read_at: datetime = None
    added_at: datetime = None

    def as_dict(self):
        def timestamp(t): return t.timestamp() if t is not None else None
        return {
            "id": self.id,
            "user_id": self.user_id,
            "read_at": timestamp(self.read_at),
            "added_at": timestamp(self.added_at),
            "link": self.link,
        }

    @classmethod
    def from_dict(cls, dict: Dict) -> 'Link':
        def convert_date(t): return datetime.fromtimestamp(
            t) if t is not None else None
        return Link(
            id=dict.get('id', None),
            user_id=dict["user_id"],
            read_at=convert_date(dict.get("read_at", None)),
            added_at=convert_date(dict.get("added_at", None)),
            link=dict["link"]
        )

    @classmethod
    def _from_tuple(cls, tuple) -> 'Link':
        id, link, user_id, read_at, added_at = tuple
        return cls(
            id=id,
            link=link,
            user_id=user_id,
            read_at=read_at,
            added_at=added_at
        )

    def create(self, db: sqlite3.Connection):
        self.added_at = datetime.now()
        cur = db.cursor()
        rows = (cur.execute(
            "INSERT INTO links(link, user_id, added_at) VALUES(?, ?, ?) RETURNING id;",
            (self.link, self.user_id, self.added_at)
        ))
        r = list(rows)
        assert len(r) == 1
        assert len(r[0]) == 1
        assert int(r[0][0])
        self.id = r[0][0]

    def mark_as_read(self, db: sqlite3.Connection):
        assert self.id is not None
        self.read_at = datetime.now()
        cur = db.cursor()
        cur.execute(
            "UPDATE links SET read_at=? WHERE user_id=? AND id=?", (self.read_at, self.user_id, self.id))

    def delete(self, db: sqlite3.Connection):
        assert self.id is not None
        cur = db.cursor()
        cur.execute(
            "DELETE FROM links WHERE user_id=? AND id=?", (self.user_id, self.id))
        self.id = None


    @classmethod
    def _get(cls, db: sqlite3.Connection, where: str, values: Tuple = ()) -> List['Link']:
        cur = db.cursor()
        rows = cur.execute(f"SELECT * FROM links WHERE {where}", values)
        return map(cls._from_tuple, rows)

    @classmethod
    def get_unread(cls, db: sqlite3.Connection, user_id: str) -> List['Link']:
        return cls._get(db, "user_id = ? AND read_at IS NULL", (user_id,))

    @classmethod
    def get(cls, db: sqlite3.Connection, user_id: str, link_id: int) -> 'Link':
        rows = list(cls._get(db, "user_id = ? AND id = ?", (user_id, link_id)))
        if len(rows) < 1:
            return None
        else:
            return rows[0]