# Contains only NLP text summarization function codes!
import re # Python's built-in library for regular expressions (or Regex)
import sqlite3
from flask import g
from transformers import pipeline

def summarize(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!")
    
    # Before we do anything, make sure the input is long enough for summarization.
    if len(Entered_story) < 200:
        raise ValueError("Invalid length!")
    
    # Set the pipeline to use the correct NLP type and model
    summarizer = pipeline("summarization", model="facebook/bart-large-cnn")
        
    # Take note: The max_length & min_length variables refer to the OUTPUT length!
    summary = summarizer(Entered_story, max_length=100, min_length=30, do_sample=False)[0]["summary_text"]
    
    return summary


# User Input Format Validation Function for english only
def validate_story(Entered_story):
    pattern = r'As a (?P<role>[^,.]+), I want to (?P<goal>[^,.]+)(,|.)+so that (?P<benefit>.+)'
    match = re.search(pattern, Entered_story, flags=re.DOTALL)
    return bool(match)


# User Input Format Validation Function for all 4 languages
#def validate_story(Entered_story):
    
    # Pattern for English language
    #pattern_en = r'As a (?P<role>[^,.]+), I want to (?P<goal>[^,.]+)(,|.)+so that (?P<benefit>.+)'
    
    # Pattern for Chinese language
    #pattern_zh = r'作为(?P<role>[^,.]+)，我想要(?P<goal>[^,.]+)(，|。)+以便(?P<benefit>.+)'

    # Pattern for Malay language
    #pattern_ms = r'Sebagai(?P<role>[^,.]+), saya mahu(?P<goal>[^,.]+)(,|.)+supaya(?P<benefit>.+)'

    # Pattern for Tamil language
    #pattern_ta = r'என(?P<role>[^,.]+) எனக்கு வேண்டும்(?P<goal>[^,.]+)(,|.)+அதனால்(?P<benefit>.+) பயன்படுத்தி வைக்கும்'

    # Pattern for Thai language
    #pattern_th = r'ในฐานะ(?P<role>[^,.]+) ฉันต้องการ(?P<goal>[^,.]+)(,|.)+เพื่อที่ฉัน(?P<benefit>.+)'

    # Try each pattern to see if there is a match
    #match_en = re.search(pattern_en, Entered_story, flags=re.DOTALL)
    #match_zh = re.search(pattern_zh, Entered_story, flags=re.DOTALL)
    #match_ms = re.search(pattern_ms, Entered_story, flags=re.DOTALL)
    #match_ta = re.search(pattern_ta, Entered_story, flags=re.DOTALL)
    #match_th = re.search(pattern_th, Entered_story, flags=re.DOTALL)

    # Return True if at least one pattern matches, otherwise False
    #return bool(match_en or match_zh or match_ms or match_ta or match_th)


# Function to grab all contents in the "TextSummarization" table (except for unique ids)
# If adding any additional attributes to the table, this has to be updated accordingly
def getTextSumContents():
    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 Entered_story, summary FROM TextSummarization") # 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 "TextSummarization" table
# Using "with" for the connection here seems important, as otherwise it results in an exception
def insertTextSumRow( Entered_story, summary):
    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 TextSummarization (Entered_story, summary) VALUES (?, ?)", (Entered_story, summary))
        conn.commit()