import random
import re
import sqlite3 as db
import sys
import uuid
from datetime import timedelta, datetime
from math import floor

import db_setup
from game import CURRENCY_NAME
from util import debug, random_chars

# connection: db.Connection = None
# cursor: db.Cursor = None
connection = None  # no type annotations in python 3.5
cursor = None

db_name = None


def query_save_name():
    global db_name
    if debug:
        db_name = 'test.db'
        return
    while True:
        save_name = input('Name of the savegame: ')
        if re.match(r"[A-Za-z0-9.-]{0,50}", save_name):
            db_name = save_name + '.db'
            return
        else:
            print('Must match "[A-Za-z0-9.-]{0,50}"')


def connect(reconnect=False):
    global connection
    global cursor
    global db_name
    if reconnect:
        connection.commit()
        connection.close()
        cursor = None
        connection = None
        db_name = None

    if connection is None or cursor is None:
        query_save_name()

        try:
            connection = db.connect(db_name)
            # connection.text_factory = lambda x: unicode(x, 'utf-8', 'ignore')

            cursor = connection.cursor()

        except db.Error as e:
            print("Database error %s:" % e.args[0])
            sys.exit(1)

        # finally:
        #     if con is not None:
        #         con.close()


def setup():
    connect()

    db_setup.setup(cursor)

    connection.commit()


def used_key_count():
    connect()

    cursor.execute('''
        SELECT COUNT(*)
        FROM keys
        WHERE used_by_user_id IS NOT NULL
        ''')

    return cursor.fetchone()[0]


def login(username, password):
    connect()

    # do not allow login as bank
    if password == '':
        return None

    cursor.execute('''
                SELECT rowid
                FROM users
                WHERE username = ?
                AND password = ?
                ''', (username, password))
    user_id = cursor.fetchone()
    if user_id:
        return new_session(user_id)
    else:
        return None


def register(username, password, game_key):
    connect()
    if username == '':
        return False
    if password == '':
        return False
    cursor.execute('''
                INSERT INTO users 
                (username, password)
                VALUES (? , ?)
                ''', (username, password))
    own(get_user_id_by_name(username), CURRENCY_NAME)
    if game_key != '':
        if valid_key(game_key):
            activate_key(game_key, get_user_id_by_name(username))
    return True


def own(user_id, ownable_name):
    if not isinstance(ownable_name, str):
        return AssertionError('A name must be a string.')

    cursor.execute('''
                WITH one_ownable_id AS (SELECT rowid FROM ownables WHERE name = ?),
                     one_user_id AS (SELECT ?)
                INSERT INTO ownership (user_id, ownable_id)
                SELECT *
                FROM one_user_id, one_ownable_id
                WHERE NOT EXISTS (
                    SELECT * FROM ownership
                    WHERE ownership.user_id IN one_user_id
                    AND ownership.ownable_id IN one_ownable_id
                )
                ''', (ownable_name, user_id,))


def send_ownable(from_user_id, to_user_id, ownable_name, amount):
    connect()

    if amount < 0:
        return False

    if from_user_id != bank_id():
        cursor.execute('''
                    UPDATE ownership
                    SET amount = amount - ?
                    WHERE user_id = ?
                    AND ownable_id = (SELECT rowid FROM ownables WHERE name = ?)
                    ''', (amount, from_user_id, ownable_name,))

    cursor.execute('''
                UPDATE ownership
                SET amount = amount + ?
                WHERE user_id = ?
                AND ownable_id = (SELECT rowid FROM ownables WHERE name = ?)
                ''', (amount, to_user_id, ownable_name))
    return True


def valid_key(key):
    connect()

    cursor.execute('''
                SELECT key
                FROM keys
                WHERE used_by_user_id IS NULL
                AND key = ?
                ''', (key,))

    if cursor.fetchone():
        return True
    else:
        return False


def new_session(user_id):
    connect()

    session_id = str(uuid.uuid4())

    cursor.execute('''
                INSERT INTO SESSIONS 
                (user_id, session_id)
                VALUES (? , ?)
                ''', (user_id[0], session_id))

    return session_id


def save_key(key):
    connect()

    cursor.execute('''
                INSERT INTO keys 
                (key)
                VALUES (?)
                ''', (key,))


def drop_old_sessions():
    connect()

    cursor.execute('''
                DELETE FROM sessions s1
                WHERE 
                    (SELECT COUNT(*) as newer
                     FROM sessions s2
                     WHERE s1.user_id = s2.user_id
                     AND s1.rowid < s2.rowid) >= 10
                ''')


def user_exists(username):
    connect()

    cursor.execute('''
                SELECT rowid
                FROM users
                WHERE username = ?
                ''', (username,))

    if cursor.fetchone():
        return True
    else:
        return False


def unused_keys():
    connect()

    cursor.execute('''
        SELECT key
        FROM keys
        WHERE used_by_user_id IS NULL
        ''')

    return [str(key[0]).strip().upper() for key in cursor.fetchall()]


def get_user_id_by_session_id(session_id):
    connect()

    cursor.execute('''
        SELECT users.rowid
        FROM sessions, users
        WHERE sessions.session_id = ?
        AND users.rowid = sessions.user_id
        ''', (session_id,))

    ids = cursor.fetchone()
    if not ids:
        return False
    return ids[0]


def get_user_id_by_name(username):
    connect()

    cursor.execute('''
        SELECT users.rowid
        FROM users
        WHERE username = ?
        ''', (username,))

    return cursor.fetchone()[0]


def get_user_ownership(user_id):
    connect()

    cursor.execute('''
        SELECT 
            ownables.name, 
            ownership.amount, 
            COALESCE (
            CASE -- sum score for each of the users ownables
            WHEN ownership.ownable_id = ? THEN 1
            ELSE (SELECT price 
                  FROM transactions
                  WHERE ownable_id = ownership.ownable_id 
                  ORDER BY dt DESC 
                  LIMIT 1)
            END, 0) AS value
        FROM ownership, ownables
        WHERE user_id = ?
        AND ownership.amount > 0
        AND ownership.ownable_id = ownables.rowid
        ''', (currency_id(), user_id,))

    return cursor.fetchall()


def activate_key(key, user_id):
    connect()
    cursor.execute('''
                UPDATE keys
                SET used_by_user_id = ?
                WHERE used_by_user_id IS NULL
                AND key = ?
                ''', (user_id, key,))

    send_ownable(bank_id(), user_id, CURRENCY_NAME, 1000)


def bank_id():
    connect()

    cursor.execute('''
        SELECT users.rowid
        FROM users
        WHERE username = 'bank'
        ''')

    return cursor.fetchone()[0]


def valid_session_id(session_id):
    connect()

    cursor.execute('''
                SELECT rowid
                FROM sessions
                WHERE session_id = ?
                ''', (session_id,))

    if cursor.fetchone():
        return True
    else:
        return False


def get_user_orders(user_id):
    connect()

    cursor.execute('''
        SELECT 
            CASE 
                WHEN orders.buy  THEN 'Buy'
                ELSE 'Sell'
            END,
            ownables.name, 
            orders.ordered_amount - orders.executed_amount, 
            orders."limit", 
            CASE 
                WHEN orders."limit" IS NULL THEN NULL 
                WHEN orders.stop_loss THEN 'Yes'
                ELSE 'No'
            END, 
            orders.ordered_amount,
            datetime(orders.expiry_dt),
            orders.rowid
        FROM orders, ownables, ownership
        WHERE ownership.user_id = ?
        AND ownership.ownable_id = ownables.rowid
        AND orders.ownership_id = ownership.rowid
        ORDER BY ownables.name ASC, orders.stop_loss ASC, orders.buy DESC, orders."limit" ASC
        ''', (user_id,))

    return cursor.fetchall()


def get_ownable_orders(ownable_id):
    connect()

    cursor.execute('''
        SELECT 
            CASE 
                WHEN orders.buy THEN 'Buy'
                ELSE 'Sell'
            END,
            ownables.name, 
            orders.ordered_amount - orders.executed_amount, 
            orders."limit", 
            CASE 
                WHEN orders."limit" IS NULL THEN NULL 
                WHEN orders.stop_loss THEN 'Yes'
                ELSE 'No'
            END, 
            datetime(orders.expiry_dt),
            orders.rowid
        FROM orders, ownables, ownership
        WHERE ownership.ownable_id = ?
        AND ownership.ownable_id = ownables.rowid
        AND orders.ownership_id = ownership.rowid
        ORDER BY ownables.name ASC, orders.stop_loss ASC, orders.buy DESC, orders."limit" ASC
        ''', (ownable_id,))

    return cursor.fetchall()


def sell_ordered_amount(user_id, ownable_id):
    connect()

    # if ownable_id == currency_id():
    #     return 0

    cursor.execute('''
                SELECT COALESCE(SUM(orders.ordered_amount - orders.executed_amount),0)
                FROM orders, ownership
                WHERE ownership.rowid = orders.ownership_id
                AND ownership.user_id = ?
                AND ownership.ownable_id = ?
                AND NOT orders.buy
                ''', (user_id, ownable_id))

    return cursor.fetchone()[0]


def user_owns_at_least(amount, user_id, ownable_id):
    connect()

    if not isinstance(amount, float) and not isinstance(amount, int):
        # comparison of float with strings does not work so well in sql
        raise AssertionError()

    cursor.execute('''
                SELECT rowid
                FROM ownership
                WHERE user_id = ?
                AND ownable_id = ?
                AND amount - ? >= ?
                ''', (user_id, ownable_id, sell_ordered_amount(user_id, ownable_id), amount))

    if cursor.fetchone():
        return True
    else:
        return False


def news():
    connect()

    cursor.execute('''
        SELECT *
        FROM news
        ORDER BY dt DESC
        LIMIT 20
        ''')

    return cursor.fetchall()


def ownable_name_exists(name):
    connect()

    cursor.execute('''
                SELECT rowid
                FROM ownables
                WHERE name = ?
                ''', (name,))

    if cursor.fetchone():
        return True
    else:
        return False


def new_stock(timeout=60, name=None):
    connect()

    while name is None:
        name = random_chars(6)
        if ownable_name_exists(name):
            name = None

    cursor.execute('''
        INSERT INTO ownables(name)
        VALUES (?)
        ''', (name,))

    cursor.execute('''
        INSERT INTO news(title)
        VALUES (?)
        ''', ('A new stock can now be bought: ' + name,))
    if random.getrandbits(1):
        cursor.execute('''
            INSERT INTO news(title)
            VALUES (?)
            ''', ('Experts expect the price of ' + name + ' to fall',))
    else:
        cursor.execute('''
            INSERT INTO news(title)
            VALUES (?)
            ''', ('Experts expect the price of ' + name + ' to rise',))

    amount = random.randrange(100, 10000)
    price = random.randrange(10000, 20000) / amount
    ownable_id = ownable_id_by_name(name)
    own(bank_id(), name)
    bank_order(False,
               ownable_id,
               price,
               amount,
               timeout)
    return name


def new_stocks(timeout=60, count=1):
    return [new_stock(timeout=timeout) for _ in range(count)]


def ownable_id_by_name(ownable_name):
    connect()

    cursor.execute('''
        SELECT rowid
        FROM ownables
        WHERE name = ?
        ''', (ownable_name,))

    return cursor.fetchone()[0]


def get_ownership_id(ownable_id, user_id):
    connect()

    cursor.execute('''
        SELECT rowid
        FROM ownership
        WHERE ownable_id = ?
        AND user_id = ?
        ''', (ownable_id, user_id,))

    return cursor.fetchone()[0]


def currency_id():
    connect()

    cursor.execute('''
        SELECT rowid
        FROM ownables
        WHERE name = ?
        ''', (CURRENCY_NAME,))

    return cursor.fetchone()[0]


def user_money(user_id):
    connect()

    cursor.execute('''
        SELECT amount
        FROM ownership
        WHERE user_id = ?
        AND ownable_id = ?
        ''', (user_id, currency_id()))

    return cursor.fetchone()[0]


def delete_order(order_id):
    connect()

    cursor.execute('''
        DELETE FROM orders
        WHERE rowid = ?
        ''', (order_id,))


def execute_orders(ownable_id):
    connect()
    while True:
        # find order to execute
        cursor.execute('''
            SELECT buy_order.*, sell_order.*, buyer.user_id, seller.user_id, buy_order.rowid, sell_order.rowid
            FROM orders buy_order, orders sell_order, ownership buyer, ownership seller
            WHERE buy_order.buy AND NOT sell_order.buy
            AND buyer.rowid = buy_order.ownership_id
            AND seller.rowid = sell_order.ownership_id
            AND buyer.ownable_id = ?
            AND seller.ownable_id = ?
            AND (buy_order."limit" IS NULL
                OR sell_order."limit" IS NULL
                OR (sell_order."limit" <= buy_order."limit"
                    AND NOT sell_order.stop_loss
                    AND NOT buy_order.stop_loss))
            ORDER BY CASE WHEN sell_order."limit" IS NULL THEN 0 ELSE 1 END ASC, 
                     CASE WHEN buy_order."limit" IS NULL THEN 0 ELSE 1 END ASC, 
                     buy_order."limit" DESC,
                     sell_order."limit" ASC,
                     buy_order.ordered_amount - buy_order.executed_amount DESC,
                     sell_order.ordered_amount - sell_order.executed_amount DESC
            LIMIT 1
            ''', (ownable_id, ownable_id,))

        matching_orders = cursor.fetchone()
        # return type: (ownership_id,buy,limit,stop_loss,ordered_amount,executed_amount,expiry_dt,
        #               ownership_id,buy,limit,stop_loss,ordered_amount,executed_amount,expiry_dt,
        #               user_id,user_id,rowid,rowid)

        if not matching_orders:
            break

        # TODO continue and delete order if buyer has not enough money

        buy_ownership_id, _, buy_limit, _, buy_order_amount, buy_executed_amount, buy_expiry_dt, \
            sell_ownership_id, _, sell_limit, _, sell_order_amount, sell_executed_amount, sell_expiry_dt, \
            buyer_id, seller_id, buy_order_id, sell_order_id \
            = matching_orders

        if buy_limit is None and sell_limit is None:
            raise AssertionError()  # TODO find a solution
        elif buy_limit is None:
            price = sell_limit
        elif sell_limit is None:
            price = buy_limit
        else:  # both not NULL
            price = (float(sell_limit) + float(buy_limit)) / 2

        if price == 0:
            raise AssertionError()

        buyer_money = user_money(buyer_id)

        amount = min(buy_order_amount - buy_executed_amount,
                     sell_order_amount - sell_executed_amount,
                     floor(buyer_money / price))

        if amount == 0:  # probable because buyer has not enough money
            delete_order(buy_order_id)
            continue

        buy_order_finished = (buy_order_amount - buy_executed_amount - amount <= 0) or (
                buyer_money - amount * price < price)
        sell_order_finished = (sell_order_amount - sell_executed_amount - amount <= 0)

        if price < 0 or amount <= 0:
            return AssertionError()

        # actually execute the order, but the bank does not send or receive anything
        if buyer_id != bank_id():  # buyer pays
            cursor.execute('''
                UPDATE ownership 
                SET amount = amount - ?
                WHERE user_id = ?
                AND ownable_id = ?
                ''', (price * amount, buyer_id, currency_id()))
        if seller_id != bank_id():  # seller pays
            cursor.execute('''
                UPDATE ownership 
                SET amount = amount - ?
                WHERE rowid = ?
                ''', (amount, sell_ownership_id))
        if buyer_id != bank_id():  # buyer receives
            cursor.execute('''
                UPDATE ownership 
                SET amount = amount + ?
                WHERE rowid = ?
                ''', (amount, buy_ownership_id))
        if seller_id != bank_id():  # seller receives
            cursor.execute('''
                UPDATE ownership 
                SET amount = amount + ?
                WHERE user_id = ?
                AND ownable_id = ?
                ''', (amount, seller_id, currency_id()))

        # update order execution state
        cursor.execute('''
            UPDATE orders 
            SET executed_amount = executed_amount + ?
            WHERE rowid = ?
            OR rowid = ?
            ''', (amount, buy_order_id, sell_order_id))

        if buy_order_finished:
            delete_order(buy_order_id)
        if sell_order_finished:
            delete_order(sell_order_id)

        if seller_id != buyer_id:  # prevent showing self-transactions
            cursor.execute('''
                INSERT INTO transactions
                (price, ownable_id, amount)
                VALUES(?, ?, ?)
                ''', (price, ownable_id, amount,))

        # trigger stop loss orders
        if buyer_id != seller_id:
            cursor.execute('''
                UPDATE orders
                SET stop_loss = NULL,
                    "limit" = NULL
                WHERE stop_loss IS NOT NULL
                AND stop_loss
                AND ? IN (SELECT ownable_id FROM ownership WHERE rowid = ownership_id)
                AND ((buy AND "limit" < ?) OR (NOT buy AND "limit" > ?))
                ''', (ownable_id, price, price,))


def ownable_id_by_ownership_id(ownership_id):
    connect()

    cursor.execute('''
        SELECT ownable_id
        FROM ownership
        WHERE rowid = ?
        ''', (ownership_id,))

    return cursor.fetchone()[0]


def ownable_name_by_id(ownable_id):
    connect()

    cursor.execute('''
        SELECT name
        FROM ownables
        WHERE rowid = ?
        ''', (ownable_id,))

    return cursor.fetchone()[0]


def bank_order(buy, ownable_id, limit, amount, time_until_expiration):
    if not limit:
        raise AssertionError('The bank does not give away anything.')
    place_order(buy,
                get_ownership_id(ownable_id, bank_id()),
                limit,
                False,
                amount,
                time_until_expiration)
    ownable_name = ownable_name_by_id(ownable_id)
    cursor.execute('''
        INSERT INTO news(title)
        VALUES (?)
        ''', ('External investors are selling ' + ownable_name + ' atm',))


def current_time():  # might differ from datetime.datetime.now() for time zone reasons
    connect()

    cursor.execute('''
        SELECT datetime('now')
        ''')

    return cursor.fetchone()[0]


def place_order(buy, ownership_id, limit, stop_loss, amount, time_until_expiration):
    connect()
    expiry = datetime.strptime(current_time(), '%Y-%m-%d %H:%M:%S') + timedelta(minutes=time_until_expiration)

    cursor.execute('''
                INSERT INTO orders 
                (buy, ownership_id, "limit", stop_loss, ordered_amount, expiry_dt)
                VALUES (?, ?, ?, ?, ?, ?)
                ''', (buy, ownership_id, limit, stop_loss, amount, expiry))

    execute_orders(ownable_id_by_ownership_id(ownership_id))
    return True


def transactions(ownable_id):
    connect()

    cursor.execute('''
        SELECT dt, amount, price
        FROM transactions
        WHERE ownable_id = ?
        ORDER BY dt DESC
        ''', (ownable_id,))

    return cursor.fetchall()


def drop_expired_orders():
    connect()

    cursor.execute('''
        DELETE FROM orders 
        WHERE expiry_dt < DATETIME('now')
        ''')

    return cursor.fetchall()


def generate_keys(count=1):
    # source https://stackoverflow.com/questions/17049308/python-3-3-serial-key-generator-list-problems

    for i in range(count):
        key = '-'.join(random_chars(5) for _ in range(5))
        save_key(key)
        print(key)


def user_has_order_with_id(session_id, order_id):
    connect()

    cursor.execute('''
                SELECT orders.rowid
                FROM orders, ownership, sessions
                WHERE orders.rowid = ?
                AND sessions.session_id = ?
                AND sessions.user_id = ownership.user_id
                AND ownership.rowid = orders.ownership_id
                ''', (order_id, session_id,))

    if cursor.fetchone():
        return True
    else:
        return False


def leaderboard():
    connect()

    cursor.execute('''
        SELECT * 
        FROM ( -- one score for each user
            SELECT 
                username, 
                SUM(CASE -- sum score for each of the users ownables
                    WHEN ownership.ownable_id = ? THEN ownership.amount
                    ELSE ownership.amount * (SELECT price 
                                             FROM transactions
                                             WHERE ownable_id = ownership.ownable_id 
                                             ORDER BY dt DESC 
                                             LIMIT 1)
                    END
                ) score
            FROM users, ownership
            WHERE ownership.user_id = users.rowid
            AND users.username != 'bank'
            GROUP BY users.rowid
        ) AS scores
        ORDER BY score DESC
        LIMIT 50
        ''', (currency_id(),))

    return cursor.fetchall()


def user_wealth(user_id):
    connect()

    cursor.execute('''
        SELECT SUM(
            CASE -- sum score for each of the users ownables
            WHEN ownership.ownable_id = ? THEN ownership.amount
            ELSE ownership.amount * (SELECT price 
                                     FROM transactions
                                     WHERE ownable_id = ownership.ownable_id 
                                     ORDER BY dt DESC 
                                     LIMIT 1)
            END
        ) score
        FROM ownership
        WHERE ownership.user_id = ?
        ''', (currency_id(), user_id,))

    return cursor.fetchone()[0]