import re # Python's built-in library for regular expressions (or Regex)
import sqlite3
from flask import g
from transformers import pipeline, set_seed

def generate(Entered_story):
    
    # Check if the input is empty
    if not Entered_story.strip():
        raise ValueError("Empty input!")
    
    # Validate that the input is in the correct format
    if not validate_story(Entered_story):
        raise ValueError("Incorrect format!")
    
    # Set the pipeline to use the correct NLP type and model
    generator = pipeline('text-generation', model='gpt2')
        
    # Take note: The max_length & min_length variables refer to the OUTPUT length!
    set_seed(42)
    generated_text = generator(Entered_story, max_length=30, num_return_sequences=5)
    
    generated_text = generated_text[0]['generated_text']
    
    return generated_text

# User Input Format Validation Function
def validate_story(Entered_story):
    pattern = r'As a (?P<role>[^,.]+), I want to (?P<goal>[^,.]+)(?:,|.)+\s*so that' #Follows then normal structure, but allows anything after 'so that'
    match = re.search(pattern, Entered_story, flags=re.DOTALL)
    return bool(match)

# Function to grab all contents in the "TextGeneration" table (except for unique ids)
# If adding any additional attributes to the table, this has to be updated accordingly
def getTextGenContents():
    db = getattr(g, '_database', None) # Gets the _database attribute from the 'g' object. If it does not exist, returns 'None'
    if db is None:
        db = g._database = sqlite3.connect('Refineverse.db') # If db is None, create a new connection for db and g._database.
        cursor = db.cursor() # Creates a cursor object to handle data
        cursor.execute("SELECT userStory, generatedStory FROM TextGeneration") # The cursor executes the query
        rows = cursor.fetchall() # Stores the results of fetchall() into a variable
    return rows

# Function to insert a new row into the "TextGeneration" table
# Using "with" for the connection here seems important, as otherwise it results in an exception
def insertTextGenRow( Entered_story, generatedStory):
    with sqlite3.connect('Refineverse.db') as conn: # 'With' will automatically take care of closing and opening the connection
        cursor = conn.cursor()
        cursor.execute("INSERT INTO TextGeneration (userStory, generatedStory) VALUES (?, ?)", (Entered_story, generatedStory))
        conn.commit()