import logging
import os
import time
import sqlite3

from twisted.internet import threads, defer, reactor
from twisted.enterprise import adbapi
from lbrynet import conf
from lbrynet.core.HashBlob import BlobFile, BlobFileCreator
from lbrynet.core.server.DHTHashAnnouncer import DHTHashSupplier
from lbrynet.core.sqlite_helpers import rerun_if_locked

log = logging.getLogger(__name__)


class DiskBlobManager(DHTHashSupplier):
    def __init__(self, hash_announcer, blob_dir, db_dir):

        """
        This class stores blobs on the hard disk,
        blob_dir - directory where blobs are stored
        db_dir - directory where sqlite database of blob information is stored
        """

        DHTHashSupplier.__init__(self, hash_announcer)

        self.announce_head_blobs_only = conf.settings['announce_head_blobs_only']

        self.blob_dir = blob_dir
        self.db_file = os.path.join(db_dir, "blobs.db")
        self.db_conn = adbapi.ConnectionPool('sqlite3', self.db_file, check_same_thread=False)
        self.blob_type = BlobFile
        self.blob_creator_type = BlobFileCreator
        # TODO: consider using an LRU for blobs as there could potentially
        #       be thousands of blobs loaded up, many stale
        self.blobs = {}
        self.blob_hashes_to_delete = {} # {blob_hash: being_deleted (True/False)}

    @defer.inlineCallbacks
    def setup(self):
        log.info("Starting disk blob manager. blob_dir: %s, db_file: %s", str(self.blob_dir),
                 str(self.db_file))
        yield self._open_db()

    def stop(self):
        log.info("Stopping disk blob manager.")
        self.db_conn.close()
        return defer.succeed(True)

    def get_blob(self, blob_hash, length=None):
        """Return a blob identified by blob_hash, which may be a new blob or a
        blob that is already on the hard disk
        """
        assert length is None or isinstance(length, int)
        if blob_hash in self.blobs:
            return defer.succeed(self.blobs[blob_hash])
        return self._make_new_blob(blob_hash, length)

    def get_blob_creator(self):
        return self.blob_creator_type(self.blob_dir)

    def _make_new_blob(self, blob_hash, length=None):
        log.debug('Making a new blob for %s', blob_hash)
        blob = self.blob_type(self.blob_dir, blob_hash, length)
        self.blobs[blob_hash] = blob
        return defer.succeed(blob)

    def _immediate_announce(self, blob_hashes):
        if self.hash_announcer:
            return self.hash_announcer.immediate_announce(blob_hashes)
        raise Exception("Hash announcer not set")

    @defer.inlineCallbacks
    def blob_completed(self, blob, next_announce_time=None, should_announce=True):
        if next_announce_time is None:
            next_announce_time = self.get_next_announce_time()
        yield self._add_completed_blob(blob.blob_hash, blob.length,
                                       next_announce_time, should_announce)
        # we announce all blobs immediately, if announce_head_blob_only is False
        # otherwise, announce only if marked as should_announce
        if not self.announce_head_blobs_only or should_announce:
            reactor.callLater(0, self._immediate_announce, [blob.blob_hash])

    def completed_blobs(self, blobhashes_to_check):
        return self._completed_blobs(blobhashes_to_check)

    def hashes_to_announce(self):
        return self._get_blobs_to_announce()

    def creator_finished(self, blob_creator, should_announce):
        log.debug("blob_creator.blob_hash: %s", blob_creator.blob_hash)
        assert blob_creator.blob_hash is not None
        assert blob_creator.blob_hash not in self.blobs
        assert blob_creator.length is not None
        new_blob = self.blob_type(self.blob_dir, blob_creator.blob_hash, blob_creator.length)
        self.blobs[blob_creator.blob_hash] = new_blob
        next_announce_time = self.get_next_announce_time()
        d = self.blob_completed(new_blob, next_announce_time, should_announce)
        return d

    def immediate_announce_all_blobs(self):
        d = self._get_all_verified_blob_hashes()
        d.addCallback(self._immediate_announce)
        return d

    def get_all_verified_blobs(self):
        d = self._get_all_verified_blob_hashes()
        d.addCallback(self.completed_blobs)
        return d

    def add_blob_to_download_history(self, blob_hash, host, rate):
        d = self._add_blob_to_download_history(blob_hash, host, rate)
        return d

    def add_blob_to_upload_history(self, blob_hash, host, rate):
        d = self._add_blob_to_upload_history(blob_hash, host, rate)
        return d

    @defer.inlineCallbacks
    def delete_blobs(self, blob_hashes):
        bh_to_delete_from_db = []
        for blob_hash in blob_hashes:
            try:
                blob = yield self.get_blob(blob_hash)
                yield blob.delete()
                bh_to_delete_from_db.append(blob_hash)
            except Exception as e:
                log.warning("Failed to delete blob file. Reason: %s", e)
        yield self._delete_blobs_from_db(bh_to_delete_from_db)

    ######### database calls #########

    def _open_db(self):
        # check_same_thread=False is solely to quiet a spurious error that appears to be due
        # to a bug in twisted, where the connection is closed by a different thread than the
        # one that opened it. The individual connections in the pool are not used in multiple
        # threads.

        def create_tables(transaction):
            transaction.execute('PRAGMA journal_mode=WAL')
            transaction.execute("create table if not exists blobs (" +
                                "    blob_hash text primary key, " +
                                "    blob_length integer, " +
                                "    last_verified_time real, " +
                                "    next_announce_time real, " +
                                "    should_announce integer)")


            transaction.execute("create table if not exists download (" +
                                "    id integer primary key autoincrement, " +
                                "    blob text, " +
                                "    host text, " +
                                "    rate float, " +
                                "    ts integer)")

            transaction.execute("create table if not exists upload (" +
                                "    id integer primary key autoincrement, " +
                                "    blob text, " +
                                "    host text, " +
                                "    rate float, " +
                                "    ts integer)")

        return self.db_conn.runInteraction(create_tables)

    @rerun_if_locked
    def _add_completed_blob(self, blob_hash, length, next_announce_time, should_announce):
        log.debug("Adding a completed blob. blob_hash=%s, length=%s", blob_hash, str(length))
        should_announce = 1 if should_announce else 0
        d = self.db_conn.runQuery(
            "insert into blobs (blob_hash, blob_length, next_announce_time, should_announce) "+
            "values (?, ?, ?, ?)",
            (blob_hash, length, next_announce_time, should_announce)
        )
        d.addErrback(lambda err: err.trap(sqlite3.IntegrityError))
        return d

    @defer.inlineCallbacks
    def _completed_blobs(self, blobhashes_to_check):
        """Returns of the blobhashes_to_check, which are valid"""
        blobs = yield defer.DeferredList([self.get_blob(b) for b in blobhashes_to_check])
        blob_hashes = [b.blob_hash for success, b in blobs if success and b.verified]
        defer.returnValue(blob_hashes)

    @rerun_if_locked
    def _update_blob_verified_timestamp(self, blob, timestamp):
        return self.db_conn.runQuery("update blobs set last_verified_time = ? where blob_hash = ?",
                                     (blob, timestamp))

    @rerun_if_locked
    def _get_blobs_to_announce(self):

        def get_and_update(transaction):
            timestamp = time.time()
            if self.announce_head_blobs_only is True:
                r = transaction.execute("select blob_hash from blobs " +
                                    "where next_announce_time < ? and blob_hash is not null "+
                                    "and should_announce = 1",
                                    (timestamp,))
            else:
                r = transaction.execute("select blob_hash from blobs " +
                                    "where next_announce_time < ? and blob_hash is not null",
                                    (timestamp,))

            blobs = [b for b, in r.fetchall()]
            next_announce_time = self.get_next_announce_time(len(blobs))
            transaction.execute(
                "update blobs set next_announce_time = ? where next_announce_time < ?",
                (next_announce_time, timestamp))
            log.debug("Got %s blobs to announce, next announce time is in %s seconds",
                        len(blobs), next_announce_time-time.time())
            return blobs

        return self.db_conn.runInteraction(get_and_update)

    @rerun_if_locked
    def _delete_blobs_from_db(self, blob_hashes):

        def delete_blobs(transaction):
            for b in blob_hashes:
                transaction.execute("delete from blobs where blob_hash = ?", (b,))

        return self.db_conn.runInteraction(delete_blobs)

    @rerun_if_locked
    def _get_all_blob_hashes(self):
        d = self.db_conn.runQuery("select blob_hash from blobs")
        return d

    @rerun_if_locked
    def _get_all_verified_blob_hashes(self):
        d = self._get_all_blob_hashes()

        def get_verified_blobs(blobs):
            verified_blobs = []
            for blob_hash, in blobs:
                file_path = os.path.join(self.blob_dir, blob_hash)
                if os.path.isfile(file_path):
                    verified_blobs.append(blob_hash)
            return verified_blobs

        d.addCallback(lambda blobs: threads.deferToThread(get_verified_blobs, blobs))
        return d

    @rerun_if_locked
    def _add_blob_to_download_history(self, blob_hash, host, rate):
        ts = int(time.time())
        d = self.db_conn.runQuery(
            "insert into download values (null, ?, ?, ?, ?) ",
            (blob_hash, str(host), float(rate), ts))
        return d

    @rerun_if_locked
    def _add_blob_to_upload_history(self, blob_hash, host, rate):
        ts = int(time.time())
        d = self.db_conn.runQuery(
            "insert into upload values (null, ?, ?, ?, ?) ",
            (blob_hash, str(host), float(rate), ts))
        return d