import os
import sys
import psycopg2
from psycopg2 import sql
from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT
import uuid
from datetime import datetime
import pytz
import pdb

tz = pytz.timezone('Europe/Madrid')

class Database():

    name = 'Corpus database manager'

    def __init__(self, config_file=None, corpus_db=None, corpus_db_user=None):

        self.config_file = "config/db_config.txt"
        self.corpus_db = self.__get_parameter("corpus_db", self.config_file)
        self.corpus_db_user = self.__get_parameter("corpus_db_user", self.config_file)

        db_setup = self.__check_dbsetup(self)

        if not db_setup:

            self.corpus_db = input("\nCorpus database name: ")
            self.corpus_db_user = input("\nCorpus database user: ")

            self.__createdb(self)  
            self.__create_config(self)
            self.__write_config(self)

    def check_user(self, username):

        found_it = False

        conn = None

        try:

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            cur = conn.cursor()

            cur.execute("select username from users where username = (%s)", (username,))

            row = cur.fetchone()

            if row != None:

                found_it = True

            cur.close()

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

        return found_it

    def add_user(self, username):

        is_added = False

        sql = "INSERT INTO users(id, username) VALUES(%s, %s)"

        unique_id = str(uuid.uuid4())

        conn = None

        try:

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            cur = conn.cursor()

            cur.execute(sql, (unique_id, username))

            conn.commit()

            cur.close()

            is_added = True

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

        return is_added

    def del_user(self, username):

        is_deleted = False

        sql = "delete from users where username = (%s)"

        conn = None

        try:

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            cur = conn.cursor()

            cur.execute(sql, (username,))

            conn.commit()

            cur.close()

            is_deleted = True

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

        return is_deleted

    def save_post(self, username, post):

        is_saved = False

        sql = "INSERT INTO corpus(id, username, text, created_at) VALUES(%s, %s, %s, %s)"

        unique_id = str(uuid.uuid4())

        now = datetime.now()

        conn = None

        try:

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            cur = conn.cursor()

            cur.execute(sql, (unique_id, username, post, now))

            conn.commit()

            cur.close()

            is_saved = True

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

        return is_saved

    @staticmethod
    def __check_dbsetup(self):

        db_setup = False

        try:

            conn = None

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            db_setup = True

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        return db_setup

    @staticmethod
    def __createdb(self):

        conn = None

        try:

            conn = psycopg2.connect(dbname='postgres',
                user=self.corpus_db_user, host='',
                password='')

            conn.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)

            cur = conn.cursor()

            print(f"Creating database {self.corpus_db}. Please wait...")

            cur.execute(sql.SQL("CREATE DATABASE {}").format(
                sql.Identifier(self.corpus_db))
            )
            print(f"Database {self.corpus_db} created!\n")

            self.__dbtables_schemes(self)

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

    @staticmethod
    def __dbtables_schemes(self):

        table = "corpus"
        sql = "create table "+table+" (id uuid, username varchar(50), text varchar(500), created_at timestamptz, PRIMARY KEY (id))"
        self.__create_table(self, table, sql)

        table = "users"
        sql = "create table "+table+" (id uuid, username varchar(50), PRIMARY KEY (id))"
        self.__create_table(self, table, sql)

    @staticmethod
    def __create_table(self, table, sql):

        conn = None

        try:

            conn = psycopg2.connect(database = self.corpus_db, user = self.corpus_db_user, password = "", host = "/var/run/postgresql", port = "5432")

            cur = conn.cursor()

            print(f"Creating table {table}")

            cur.execute(sql)

            conn.commit()

            print(f"Table {table} created!\n")

        except (Exception, psycopg2.DatabaseError) as error:

            print(error)

        finally:

            if conn is not None:

                conn.close()

    def __get_parameter(self, parameter, config_file):

        if not os.path.isfile(config_file):
            print(f"File {config_file} not found..")
            return

        with open( config_file ) as f:
            for line in f:
                if line.startswith( parameter ):
                    return line.replace(parameter + ":", "").strip()

        print(f"{config_file} Missing parameter {parameter}")

        sys.exit(0)

    @staticmethod
    def __create_config(self):

        if not os.path.exists('config'):

            os.makedirs('config')

        if not os.path.exists(self.config_file):

            print(self.config_file + " created!")
            with open('config/db_config.txt', 'w'): pass

    @staticmethod
    def __write_config(self):

        with open(self.config_file, 'a') as the_file:

            the_file.write(f'corpus_db: {self.corpus_db}\ncorpus_db_user: {self.corpus_db_user}')
            print(f"adding parameters to {self.config_file}\n")