import logging
import asyncio
from asyncio import wrap_future
from concurrent.futures.thread import ThreadPoolExecutor
from operator import itemgetter

from typing import Tuple, List, Union, Callable, Any, Awaitable, Iterable

import sqlite3

from torba.hash import TXRefImmutable
from torba.basetransaction import BaseTransaction
from torba.baseaccount import BaseAccount

log = logging.getLogger(__name__)


class AIOSQLite:

    def __init__(self):
        # has to be single threaded as there is no mapping of thread:connection
        self.executor = ThreadPoolExecutor(max_workers=1)
        self.connection: sqlite3.Connection = None

    @classmethod
    async def connect(cls, path: Union[bytes, str], *args, **kwargs):
        db = cls()
        db.connection = await wrap_future(db.executor.submit(sqlite3.connect, path, *args, **kwargs))
        return db

    async def close(self):
        def __close(conn):
            self.executor.submit(conn.close)
            self.executor.shutdown(wait=True)
        conn = self.connection
        self.connection = None
        return asyncio.get_event_loop_policy().get_event_loop().call_later(0.01, __close, conn)

    def executescript(self, script: str) -> Awaitable:
        return wrap_future(self.executor.submit(self.connection.executescript, script))

    def execute_fetchall(self, sql: str, parameters: Iterable = None) -> Awaitable[Iterable[sqlite3.Row]]:
        parameters = parameters if parameters is not None else []
        def __fetchall(conn: sqlite3.Connection, *args, **kwargs):
            return conn.execute(*args, **kwargs).fetchall()
        return wrap_future(self.executor.submit(__fetchall, self.connection, sql, parameters))

    def execute(self, sql: str, parameters: Iterable = None) -> Awaitable[sqlite3.Cursor]:
        parameters = parameters if parameters is not None else []
        return self.run(lambda conn, sql, parameters: conn.execute(sql, parameters), sql, parameters)

    def run(self, fun, *args, **kwargs) -> Awaitable:
        return wrap_future(self.executor.submit(self.__run_transaction, fun, *args, **kwargs))

    def __run_transaction(self, fun: Callable[[sqlite3.Connection, Any, Any], Any], *args, **kwargs):
        self.connection.execute('begin')
        try:
            fun(self.connection, *args, **kwargs)  # type: ignore
        except (Exception, OSError):
            self.connection.rollback()
            raise
        else:
            self.connection.commit()


def constraints_to_sql(constraints, joiner=' AND ', prepend_key=''):
    sql, values = [], {}
    for key, constraint in constraints.items():
        col, op, key = key, '=', key.replace('.', '_')
        if key.startswith('$'):
            values[key] = constraint
            continue
        elif key.endswith('__not'):
            col, op = col[:-len('__not')], '!='
        elif key.endswith('__lt'):
            col, op = col[:-len('__lt')], '<'
        elif key.endswith('__lte'):
            col, op = col[:-len('__lte')], '<='
        elif key.endswith('__gt'):
            col, op = col[:-len('__gt')], '>'
        elif key.endswith('__like'):
            col, op = col[:-len('__like')], 'LIKE'
        elif key.endswith('__in') or key.endswith('__not_in'):
            if key.endswith('__in'):
                col, op = col[:-len('__in')], 'IN'
            else:
                col, op = col[:-len('__not_in')], 'NOT IN'
            if isinstance(constraint, (list, set)):
                items = ', '.join(
                    "'{}'".format(item) if isinstance(item, str) else str(item)
                    for item in constraint
                )
            elif isinstance(constraint, str):
                items = constraint
            else:
                raise ValueError("{} requires a list, set or string as constraint value.".format(col))
            sql.append('{} {} ({})'.format(col, op, items))
            continue
        elif key.endswith('__any'):
            where, subvalues = constraints_to_sql(constraint, ' OR ', key+'_')
            sql.append('({})'.format(where))
            values.update(subvalues)
            continue
        sql.append('{} {} :{}'.format(col, op, prepend_key+key))
        values[prepend_key+key] = constraint
    return joiner.join(sql) if sql else '', values


def query(select, **constraints):
    sql = [select]
    limit = constraints.pop('limit', None)
    offset = constraints.pop('offset', None)
    order_by = constraints.pop('order_by', None)

    constraints.pop('my_account', None)
    account = constraints.pop('account', None)
    if account is not None:
        if not isinstance(account, list):
            account = [account]
        constraints['account__in'] = [
            (a.public_key.address if isinstance(a, BaseAccount) else a) for a in account
        ]

    where, values = constraints_to_sql(constraints)
    if where:
        sql.append('WHERE')
        sql.append(where)

    if order_by is not None:
        sql.append('ORDER BY')
        if isinstance(order_by, str):
            sql.append(order_by)
        elif isinstance(order_by, list):
            sql.append(', '.join(order_by))
        else:
            raise ValueError("order_by must be string or list")

    if limit is not None:
        sql.append('LIMIT {}'.format(limit))

    if offset is not None:
        sql.append('OFFSET {}'.format(offset))

    return ' '.join(sql), values


def rows_to_dict(rows, fields):
    if rows:
        return [dict(zip(fields, r)) for r in rows]
    else:
        return []


class SQLiteMixin:

    CREATE_TABLES_QUERY: str

    def __init__(self, path):
        self._db_path = path
        self.db: AIOSQLite = None
        self.ledger = None

    async def open(self):
        log.info("connecting to database: %s", self._db_path)
        self.db = await AIOSQLite.connect(self._db_path)
        await self.db.executescript(self.CREATE_TABLES_QUERY)

    async def close(self):
        await self.db.close()

    @staticmethod
    def _insert_sql(table: str, data: dict) -> Tuple[str, List]:
        columns, values = [], []
        for column, value in data.items():
            columns.append(column)
            values.append(value)
        sql = "INSERT INTO {} ({}) VALUES ({})".format(
            table, ', '.join(columns), ', '.join(['?'] * len(values))
        )
        return sql, values

    @staticmethod
    def _update_sql(table: str, data: dict, where: str,
                    constraints: Union[list, tuple]) -> Tuple[str, list]:
        columns, values = [], []
        for column, value in data.items():
            columns.append("{} = ?".format(column))
            values.append(value)
        values.extend(constraints)
        sql = "UPDATE {} SET {} WHERE {}".format(
            table, ', '.join(columns), where
        )
        return sql, values


class BaseDatabase(SQLiteMixin):

    PRAGMAS = """
        pragma journal_mode=WAL;
    """

    CREATE_PUBKEY_ADDRESS_TABLE = """
        create table if not exists pubkey_address (
            address text primary key,
            account text not null,
            chain integer not null,
            position integer not null,
            pubkey blob not null,
            history text,
            used_times integer not null default 0
        );
    """
    CREATE_PUBKEY_ADDRESS_INDEX = """
        create index if not exists pubkey_address_account_idx on pubkey_address (account);
    """

    CREATE_TX_TABLE = """
        create table if not exists tx (
            txid text primary key,
            raw blob not null,
            height integer not null,
            position integer not null,
            is_verified boolean not null default 0
        );
    """

    CREATE_TXO_TABLE = """
        create table if not exists txo (
            txid text references tx,
            txoid text primary key,
            address text references pubkey_address,
            position integer not null,
            amount integer not null,
            script blob not null,
            is_reserved boolean not null default 0
        );
    """
    CREATE_TXO_INDEX = """
        create index if not exists txo_address_idx on txo (address);
    """

    CREATE_TXI_TABLE = """
        create table if not exists txi (
            txid text references tx,
            txoid text references txo,
            address text references pubkey_address
        );
    """
    CREATE_TXI_INDEX = """
        create index if not exists txi_address_idx on txi (address);
        create index if not exists txi_txoid_idx on txi (txoid);
    """

    CREATE_TABLES_QUERY = (
        PRAGMAS +
        CREATE_TX_TABLE +
        CREATE_PUBKEY_ADDRESS_TABLE +
        CREATE_PUBKEY_ADDRESS_INDEX +
        CREATE_TXO_TABLE +
        CREATE_TXO_INDEX +
        CREATE_TXI_TABLE +
        CREATE_TXI_INDEX
    )

    @staticmethod
    def txo_to_row(tx, address, txo):
        return {
            'txid': tx.id,
            'txoid': txo.id,
            'address': address,
            'position': txo.position,
            'amount': txo.amount,
            'script': sqlite3.Binary(txo.script.source)
        }

    def save_transaction_io(self, save_tx, tx: BaseTransaction, address, txhash, history):

        def _transaction(conn: sqlite3.Connection, save_tx, tx: BaseTransaction, address, txhash, history):
            if save_tx == 'insert':
                conn.execute(*self._insert_sql('tx', {
                    'txid': tx.id,
                    'raw': sqlite3.Binary(tx.raw),
                    'height': tx.height,
                    'position': tx.position,
                    'is_verified': tx.is_verified
                }))
            elif save_tx == 'update':
                conn.execute(*self._update_sql("tx", {
                    'height': tx.height, 'position': tx.position, 'is_verified': tx.is_verified
                }, 'txid = ?', (tx.id,)))

            existing_txos = set(map(itemgetter(0), conn.execute(*query(
                "SELECT position FROM txo", txid=tx.id
            ))))

            for txo in tx.outputs:
                if txo.position in existing_txos:
                    continue
                if txo.script.is_pay_pubkey_hash and txo.script.values['pubkey_hash'] == txhash:
                    conn.execute(*self._insert_sql("txo", self.txo_to_row(tx, address, txo)))
                elif txo.script.is_pay_script_hash:
                    # TODO: implement script hash payments
                    log.warning('Database.save_transaction_io: pay script hash is not implemented!')

            # lookup the address associated with each TXI (via its TXO)
            txoid_to_address = {r[0]: r[1] for r in conn.execute(*query(
                "SELECT txoid, address FROM txo", txoid__in=[txi.txo_ref.id for txi in tx.inputs]
            ))}

            # list of TXIs that have already been added
            existing_txis = {r[0] for r in conn.execute(*query(
                "SELECT txoid FROM txi", txid=tx.id
            ))}

            for txi in tx.inputs:
                txoid = txi.txo_ref.id
                new_txi = txoid not in existing_txis
                address_matches = txoid_to_address.get(txoid) == address
                if new_txi and address_matches:
                    conn.execute(*self._insert_sql("txi", {
                        'txid': tx.id,
                        'txoid': txoid,
                        'address': address,
                    }))
            conn.execute(
                "UPDATE pubkey_address SET history = ?, used_times = ? WHERE address = ?",
                (history, history.count(':')//2, address)
            )
        return self.db.run(_transaction, save_tx, tx, address, txhash, history)

    async def reserve_outputs(self, txos, is_reserved=True):
        txoids = [txo.id for txo in txos]
        await self.db.execute(
            "UPDATE txo SET is_reserved = ? WHERE txoid IN ({})".format(
                ', '.join(['?']*len(txoids))
            ), [is_reserved]+txoids
        )

    async def release_outputs(self, txos):
        await self.reserve_outputs(txos, is_reserved=False)

    async def rewind_blockchain(self, above_height):  # pylint: disable=no-self-use
        # TODO:
        # 1. delete transactions above_height
        # 2. update address histories removing deleted TXs
        return True

    async def select_transactions(self, cols, account=None, **constraints):
        if 'txid' not in constraints and account is not None:
            constraints['$account'] = account.public_key.address
            constraints['txid__in'] = """
                SELECT txo.txid FROM txo
                JOIN pubkey_address USING (address) WHERE pubkey_address.account = :$account
              UNION
                SELECT txi.txid FROM txi
                JOIN pubkey_address USING (address) WHERE pubkey_address.account = :$account
            """
        return await self.db.execute_fetchall(
            *query("SELECT {} FROM tx".format(cols), **constraints)
        )

    async def get_transactions(self, my_account=None, **constraints):
        my_account = my_account or constraints.get('account', None)

        tx_rows = await self.select_transactions(
            'txid, raw, height, position, is_verified',
            order_by=["height DESC", "position DESC"],
            **constraints
        )

        if not tx_rows:
            return []

        txids, txs = [], []
        for row in tx_rows:
            txids.append(row[0])
            txs.append(self.ledger.transaction_class(
                raw=row[1], height=row[2], position=row[3], is_verified=bool(row[4])
            ))

        annotated_txos = {
            txo.id: txo for txo in
            (await self.get_txos(
                my_account=my_account,
                txid__in=txids
            ))
        }

        referenced_txos = {
            txo.id: txo for txo in
            (await self.get_txos(
                my_account=my_account,
                txoid__in=query("SELECT txoid FROM txi", **{'txid__in': txids})[0]
            ))
        }

        for tx in txs:
            for txi in tx.inputs:
                txo = referenced_txos.get(txi.txo_ref.id)
                if txo:
                    txi.txo_ref = txo.ref
            for txo in tx.outputs:
                _txo = annotated_txos.get(txo.id)
                if _txo:
                    txo.update_annotations(_txo)
                else:
                    txo.update_annotations(None)

        return txs

    async def get_transaction_count(self, **constraints):
        constraints.pop('offset', None)
        constraints.pop('limit', None)
        constraints.pop('order_by', None)
        count = await self.select_transactions('count(*)', **constraints)
        return count[0][0]

    async def get_transaction(self, **constraints):
        txs = await self.get_transactions(limit=1, **constraints)
        if txs:
            return txs[0]

    async def select_txos(self, cols, **constraints):
        return await self.db.execute_fetchall(*query(
            "SELECT {} FROM txo"
            " JOIN pubkey_address USING (address)"
            " JOIN tx USING (txid)".format(cols), **constraints
        ))

    async def get_txos(self, my_account=None, **constraints):
        my_account = my_account or constraints.get('account', None)
        if isinstance(my_account, BaseAccount):
            my_account = my_account.public_key.address
        rows = await self.select_txos(
            "amount, script, txid, tx.height, txo.position, chain, account", **constraints
        )
        output_class = self.ledger.transaction_class.output_class
        return [
            output_class(
                amount=row[0],
                script=output_class.script_class(row[1]),
                tx_ref=TXRefImmutable.from_id(row[2], row[3]),
                position=row[4],
                is_change=row[5] == 1,
                is_my_account=row[6] == my_account
            ) for row in rows
        ]

    async def get_txo_count(self, **constraints):
        constraints.pop('offset', None)
        constraints.pop('limit', None)
        constraints.pop('order_by', None)
        count = await self.select_txos('count(*)', **constraints)
        return count[0][0]

    @staticmethod
    def constrain_utxo(constraints):
        constraints['is_reserved'] = False
        constraints['txoid__not_in'] = "SELECT txoid FROM txi"

    def get_utxos(self, **constraints):
        self.constrain_utxo(constraints)
        return self.get_txos(**constraints)

    def get_utxo_count(self, **constraints):
        self.constrain_utxo(constraints)
        return self.get_txo_count(**constraints)

    async def get_balance(self, **constraints):
        self.constrain_utxo(constraints)
        balance = await self.select_txos('SUM(amount)', **constraints)
        return balance[0][0] or 0

    async def select_addresses(self, cols, **constraints):
        return await self.db.execute_fetchall(*query(
            "SELECT {} FROM pubkey_address".format(cols), **constraints
        ))

    async def get_addresses(self, cols=('address', 'account', 'chain', 'position', 'used_times'),
                            **constraints):
        addresses = await self.select_addresses(', '.join(cols), **constraints)
        return rows_to_dict(addresses, cols)

    async def get_address_count(self, **constraints):
        count = await self.select_addresses('count(*)', **constraints)
        return count[0][0]

    async def get_address(self, **constraints):
        addresses = await self.get_addresses(
            cols=('address', 'account', 'chain', 'position', 'pubkey', 'history', 'used_times'),
            limit=1, **constraints
        )
        if addresses:
            return addresses[0]

    async def add_keys(self, account, chain, keys):
        sql = (
            "insert into pubkey_address "
            "(address, account, chain, position, pubkey) "
            "values "
        ) + ', '.join(['(?, ?, ?, ?, ?)'] * len(keys))
        values = []
        for position, pubkey in keys:
            values.extend((
                pubkey.address, account.public_key.address, chain, position,
                sqlite3.Binary(pubkey.pubkey_bytes)
            ))
        await self.db.execute(sql, values)

    async def _set_address_history(self, address, history):
        await self.db.execute(
            "UPDATE pubkey_address SET history = ?, used_times = ? WHERE address = ?",
            (history, history.count(':')//2, address)
        )

    async def set_address_history(self, address, history):
        await self._set_address_history(address, history)