import os
import psycopg2
from psycopg2.extras import RealDictCursor
from urllib.parse import urlparse
from flask import g

class DataBase():
    def __init__(self, app):
        db_url = urlparse(os.environ['DATABASE_URL'])
        # if db_url is null then throw error
        if not db_url:
            raise Exception("No DATABASE_URL environment variable set")

    def getDB(self):
        db = getattr(g, 'database', None)
        if db is None:
            db_url = urlparse(os.environ['DATABASE_URL'])
            g.database = psycopg2.connect(
                database=db_url.path[1:],
                user=db_url.username,
                password=db_url.password,
                host=db_url.hostname,
                port=db_url.port
            )
            db = g.database
        return db

    def close_connection(exception):
        db = getattr(g, 'database', None)
        if db is not None:
            db.close()

    def execute(self, query, args=(), one=False, commit=False):
        conn = self.getDB()
        cur = conn.cursor(cursor_factory=RealDictCursor)
        cur.execute(query, args)
        rv = None
        if cur.description is not None:
            rv = cur.fetchall()
        if commit:
            try:
                conn.commit()
            except:
                conn.rollback()
        cur.close()

        return (rv[0] if rv else None) if one else rv

    def get_http_functions(self):
        http_functions = self.execute(
            'SELECT id, NAME, script_content, invoked_count FROM http_functions', [])
        return http_functions
    
    def get_http_function(self, name):
        http_function = self.execute(
            'SELECT id, NAME, script_content, invoked_count FROM http_functions WHERE NAME=%s', [name], one=True)
        return http_function
    
    def create_new_http_function(self, name, script_content):
        self.execute(
            'INSERT INTO http_functions (NAME, script_content) VALUES (%s, %s)', [name, script_content], commit=True)