import sqlite3
from datetime import datetime, timezone
from typing import *

from . import Post


class Store:
    def __init__(self, dbpath: Optional[str] = None):
        self.dbpath = dbpath
        self.connection: Optional[sqlite3.Connection] = None

    def connect(self, path: Optional[str] = None):
        if path:
            self.dbpath = path
        if self.connection is not None:
            return self.connection
        self.connection = sqlite3.connect(
            self.dbpath, isolation_level=None
        )  # auto commit
        self.init()

    def disconnect(self):
        conn = self.connection
        if conn:
            conn.close()

    def init(self):
        conn = self.connection
        conn.execute(
            """
            create table if not exists post (
                id integer primary key,
                content text unique not null,
                source text, -- link to the source of this post
                date integer not null
            )
            """
        )
        conn.execute(
            """
            create index if not exists post_date
            on post(date)
            """
        )

    def add(self, posts: Iterable[Post]):
        sql = f"""
            insert into post(content, source, date)
            values (?, ?, ?)
            on conflict do nothing
        """
        self.connection.executemany(
            sql,
            (
                (p.content, p.link, int(p.date.timestamp()) if p.date else None)
                for p in posts
            ),
        )

    def _select(self, condition="", params=[]) -> Iterable[Post]:
        sql = f"select id, content, date, source from post {condition}"
        for row in self.connection.execute(sql, params):
            id, content, date, source = row
            if date is not None:
                date = datetime.fromtimestamp(date, tz=timezone.utc)
            post = Post(id, content, date, link=source)
            yield post

    def random_post(self) -> Optional[Post]:
        cond = "where id in (select id from post order by random() limit 1)"
        for post in self._select(cond):
            return post

    def search(self, term, skip: int = 0) -> Iterable[Post]:
        cond = "where content like ? order by date desc limit -1 offset ?"
        for post in self._select(cond, (term, skip)):
            yield post