app.py

import gradio as gr
from PIL import Image # to open / display image
import os
import sqlite3 # DB for SQL operation, analytical db
import google.generativeai as genai
import time # 

# Initialize Gemini
gemini_key = os.getenv("gemini_key")
genai.configure(api_key=gemini_key)
genai_model = genai.GenerativeModel('gemini-pro')

class SQLPromptModel:
    def __init__(self, database):
        # Initialize with database file path and create connection
        self.database = database
        self.conn = sqlite3.connect(self.database) # create connection to DB  
        
    def fetch_table_schema(self, table_name):
        # Get database table structure
        # In order to execute SQL statements and fetch results from SQL queries, 
        #we will need to use a database cursor. Call con.cursor() to create the Cursor:
        cursor = self.conn.cursor()
        # PRAGMA table_info returns: 
        # (id, name, type, notnull, default_value, primary_key)
        cursor.execute(f"PRAGMA table_info({table_name})")
        schema = cursor.fetchall()
        if schema:
            return schema 
        else:
            return None
        #return schema if schema else None

    def text2sql_gemini(self, schema, def_query, user_query=None):
        # Convert table columns to string format
        table_columns = ', '.join([f"{col[1]} {col[2]}" for col in schema])
        #col[1] - column name/index 
        #col[2] - column data type 
        
        # Create prompt for Gemini AI
        prompt = f"""Below are SQL table schemas paired with instructions that describe a task.
        Using valid SQLite, write a response that appropriately completes the request for the provided tables.
        ### Instruction: {def_query} ### 
        Input: CREATE TABLE sql_pdf({table_columns});
        ### Response: (Return only generated query based on def_query , nothing extra)"""

        # Replace default prompt with user input if provided
        if user_query is not None:
            prompt = prompt.replace(def_query, user_query + " ")
            
        # Get SQL query from Gemini
        completion = genai_model.generate_content(prompt)
        generated_query = completion.text
        
        # Extract just the SQL query
        start_index = generated_query.find("SELECT")
        end_index = generated_query.find(";", start_index) + 1
        
        if start_index != -1 and end_index != 0:
            return generated_query[start_index:end_index]
        return generated_query

    def execute_query(self, query):
        # Execute SQL query and get results
        cur = self.conn.cursor()
        cur.execute(query)
        # Get column names
        print(cur.description)
        columns = [header[0] for header in cur.description]
        # Get all rows
        rows = [row for row in cur.fetchall()]
        cur.close()
        self.conn.commit()
        return rows, columns

def execute_sql_query(user_query):
    # Database file path
    database = r"sql_pdf.db"
    sql_model = SQLPromptModel(database)
    
    # Default prompt if none provided
    def_query = "Give complete details of properties in India"
    
    # Try operation up to 3 times
    for _ in range(3):
        try:
            # Get database structure
            table_schema = sql_model.fetch_table_schema("sql_pdf")
            if table_schema:
                # Generate and execute query
                # strip() -> removed initial & after query spaces 
                if user_query.strip():
                    query = sql_model.text2sql_gemini(table_schema, def_query, user_query)
                else:
                    query = sql_model.text2sql_gemini(table_schema, def_query, def_query)
                    
                rows, columns = sql_model.execute_query(query)
                # Return formatted results
                return {"Query": query, "Results": rows, "Columns": columns}
            else:
                return {"error": "Table schema not found."}
        except Exception as e:
            print(f"An error occurred: {e}")
            time.sleep(1)  # Wait 1 second before retry
    return {"error": "Failed to execute query after 3 retries."}

# Load the image
# Load database schema image
image = Image.open(os.path.join(os.path.abspath(''), "house_excel_sheet.png"))

# Create web interface
with gr.Blocks(title="House Database Query") as demo:
    # Header Markdown -> descrption
    # one # -> heading
    # two ## -> sub heading
    # three ### -> sub minor heading
    gr.Markdown("# House Database Query System")
    
    # Display database schema image
    gr.Image(image)
    
    # Description
    # Markdown -> description/note
    # three ### -> sub minor heading
    gr.Markdown("""### The database contains information about different properties including their fundamental details. 
                You can query this database using natural language.""")
    
    # Input section
    # gr.Row() -> Create new row layout  to organize components
    # horizontal
    with gr.Row():
        query_input = gr.Textbox(
            lines=2,# 2 lines max will be visible 
            label="Database Query",
            # Display hints for user until they start typing 
            placeholder="Enter your query or choose from examples below. Default: 'Properties in India'"
        )
    
    # Submit button section
    with gr.Row():
        # variant="primary" -> default style/color
        submit_btn = gr.Button("Submit Query", variant="primary")
    
    # Results section
    with gr.Row():
        query_output = gr.JSON(label="Query Results")
    
    # Connect button click to query function
    # Click event
    
    submit_btn.click(
        fn=execute_sql_query,
        inputs=query_input,
        outputs=query_output
    )
    
    # Example queries section
    # gr.Examples(
    #     examples=[
    #         "Properties in France",
    #         "Properties greater than an acre",
    #         "Properties with more than 400 bedrooms"
    #     ],
    #     inputs=query_input,
    #     outputs=query_output,
    #     fn=execute_sql_query
    # )
       # Example queries section
    example = gr.Examples(
        examples=[
            "Properties in France",
            "Properties greater than an acre",
            "Properties with more than 400 bedrooms"
        ],
        inputs=query_input
        # outputs=query_output,
        # fn=execute_sql_query
    )
# When calling/running directly,  script gets executed
# why -> this mechanishm used to prevent unintended  execution of code
if __name__ == "__main__":
    demo.launch(share=True)