import logging

import apsw
import apsw.ext
import grapheme

from . import BaseFeed

MAX_TEXT_LENGTH = 140

class RapidFireFeed(BaseFeed):
    FEED_URI = 'at://did:plc:4nsduwlpivpuur4mqkbfvm6a/app.bsky.feed.generator/rapidfire'

    def __init__(self):
        self.db_cnx = apsw.Connection('db/rapidfire.db')
        self.db_cnx.pragma('journal_mode', 'WAL')
        self.db_cnx.pragma('wal_autocheckpoint', '0')

        with self.db_cnx:
            self.db_cnx.execute("""
            create table if not exists posts (uri text, create_ts timestamp, lang text);
            create index if not exists create_ts_idx on posts(create_ts);
            """)

        self.logger = logging.getLogger('feeds.rapidfire')

    def process_commit(self, commit):
        if commit['opType'] != 'c':
            return

        if commit['collection'] != 'app.bsky.feed.post':
            return

        record = commit.get('record')
        if record is None:
            return

        if all([
            grapheme.length(record.get('text', '')) <= MAX_TEXT_LENGTH,
            record.get('reply') is None,
            record.get('embed') is None,
            record.get('facets') is None
        ]):
            repo = commit['did']
            rkey = commit['rkey']
            post_uri = f'at://{repo}/app.bsky.feed.post/{rkey}'
            ts = self.safe_timestamp(record.get('createdAt')).timestamp()

            self.transaction_begin(self.db_cnx)

            langs = record.get('langs') or ['']
            for lang in langs:
                self.db_cnx.execute(
                    'insert into posts (uri, create_ts, lang) values (:uri, :ts, :lang)',
                    dict(uri=post_uri, ts=ts, lang=lang)
                )

    def delete_old_posts(self):
        self.db_cnx.execute(
            "delete from posts where create_ts < unixepoch('now', '-15 minutes')"
        )
        self.logger.debug('deleted {} old posts'.format(self.db_cnx.changes()))

    def commit_changes(self):
        self.delete_old_posts()
        self.logger.debug('committing changes')
        self.transaction_commit(self.db_cnx)
        self.wal_checkpoint(self.db_cnx, 'RESTART')

    def serve_feed(self, limit, offset, langs):
        if '*' in langs:
            cur = self.db_cnx.execute(
                "select uri from posts order by create_ts desc limit :limit offset :offset",
                dict(limit=limit, offset=offset)
            )
            return [uri for (uri,) in cur]
        else:
            lang_values = list(langs.values())
            lang_selects = ['select uri, create_ts from posts where lang = ?'] * len(lang_values)
            lang_clause = ' union '.join(lang_selects)
            cur = self.db_cnx.execute(
                lang_clause + ' order by create_ts desc limit ? offset ?',
                [*lang_values, limit, offset]
            )
            return [uri for (uri, create_ts) in cur]

    def serve_feed_debug(self, limit, offset, langs):
        query = """
        select *, unixepoch('now') - create_ts as age_seconds
        from posts
        order by create_ts desc
        limit :limit offset :offset
        """
        bindings = dict(limit=limit, offset=offset)
        return apsw.ext.format_query_table(
            self.db_cnx, query, bindings,
            string_sanitize=2, text_width=9999, use_unicode=True
        )