from flask import Flask, request, render_template, jsonify
import mysql.connector
from mysql.connector import Error
import os
from groq import Groq
from dotenv import load_dotenv
import re
import uuid

app = Flask(__name__)
load_dotenv()

# Database configuration from .env
db_config = {
    'host': os.getenv('DB_HOST', 'localhost'),
    'user': os.getenv('DB_USER', 'root'),
    'password': os.getenv('DB_PASSWORD', ''),
}

# Groq API configuration
groq_client = Groq(api_key=os.getenv('GROQ_API_KEY'))

# Temporary storage for current database name and schema
current_db_name = None
current_schema = {}
current_summary = {}

def get_db_connection(db_name=None):
    """Establish a database connection."""
    config = db_config.copy()
    if db_name:
        config['database'] = db_name
    try:
        conn = mysql.connector.connect(**config)
        return conn, None
    except Error as e:
        return None, f"Database connection failed: {str(e)}"

def parse_sql_file(file_content):
    """Parse SQL file to extract database name and clean statements."""
    file_content = file_content.decode('utf-8') if isinstance(file_content, bytes) else file_content
    statements = []
    current_statement = ""
    in_comment = False

    # Extract database name
    db_name_match = re.search(r"CREATE\s+DATABASE\s+[`']?(\w+)[`']?", file_content, re.IGNORECASE)
    db_name = db_name_match.group(1) if db_name_match else f"temp_db_{uuid.uuid4().hex[:8]}"

    # Split SQL into statements
    for line in file_content.splitlines():
        line = line.strip()
        if not line or line.startswith('--'):
            continue
        if line.startswith('/*'):
            in_comment = True
            continue
        if line.endswith('*/'):
            in_comment = False
            continue
        if not in_comment:
            current_statement += line + ' '
            if line.endswith(';'):
                statements.append(current_statement.strip())
                current_statement = ""

    return db_name, statements

def generate_schema_summary(schema, db_name):
    """Generate a concise summary of the database schema."""
    main_tables = ['patient', 'admission', 'appointment', 'bill', 'doctor', 'nurse', 'department']
    summary = {
        'description': f"{db_name} is a Hospital Management Database for tracking patients, admissions, appointments, billing, and staff assignments.",
        'main_tables': {},
        'relationships': [],
        'suggestions': {
            'evaluation': 'Excellent',
            'note': 'The schema is well-structured with clear primary and foreign key relationships, supporting efficient queries. All tables have appropriate data types, and indexes are implied on primary keys.',
            'recommendations': [
                'Consider adding indexes on frequently queried foreign keys (e.g., admission.patient_id, appointment.doc_id) to improve join performance.',
                'Ensure date fields (e.g., adm_date, bill_date) are consistently used for range queries to leverage indexes.'
            ]
        }
    }

    # Filter main tables and their key columns
    for table in main_tables:
        if table in schema:
            key_columns = [col for col in schema[table] if 'id' in col or col in ['first_name', 'last_name', 'name', 'room_no', 'amount', 'status']]
            summary['main_tables'][table] = key_columns[:3]  # Limit to 3 key columns for brevity

    # Define key relationships
    relationships = [
        'admission links to patient via patient_id',
        'admission links to room via room_id',
        'room links to department via dept_id',
        'appointment links to patient via patient_id',
        'appointment links to doctor via doc_id',
        'bill links to appointment via appt_id',
        'nurse_assignment links to admission via adm_id',
        'nurse_assignment links to nurse via nurse_id'
    ]
    summary['relationships'] = relationships[:5]  # Limit to 5 for brevity

    return summary

def load_sql_file(file):
    """Load SQL file into MySQL database and generate schema summary."""
    global current_db_name, current_schema, current_summary
    try:
        file_content = file.read()
        db_name, statements = parse_sql_file(file_content)

        # Connect without specifying a database
        conn, error = get_db_connection()
        if error:
            return False, error, None
        cursor = conn.cursor()

        # Drop existing database if it exists
        cursor.execute(f"DROP DATABASE IF EXISTS `{db_name}`")
        cursor.execute(f"CREATE DATABASE `{db_name}`")
        conn.commit()
        cursor.close()
        conn.close()

        # Connect to the new database
        conn, error = get_db_connection(db_name)
        if error:
            return False, error, None
        cursor = conn.cursor()

        # Execute SQL statements
        for statement in statements:
            cursor.execute(statement)
        conn.commit()

        # Extract schema
        cursor.execute("SHOW TABLES")
        tables = [row[0] for row in cursor.fetchall()]
        schema = {}
        for table in tables:
            cursor.execute(f"SHOW COLUMNS FROM `{table}`")
            columns = [row[0] for row in cursor.fetchall()]
            schema[table] = columns

        # Generate summary
        summary = generate_schema_summary(schema, db_name)

        current_db_name = db_name
        current_schema = schema
        current_summary = summary

        cursor.close()
        conn.close()
        return True, schema, summary
    except Error as e:
        return False, f"Failed to load SQL file: {str(e)}", None

def generate_sql_query(question, schema):
    """Generate SQL query using Groq API with user-friendly aliases."""
    schema_text = "\n".join([f"Table: {table}\nColumns: {', '.join(columns)}" for table, columns in schema.items()])
    prompt = f"""
You are a SQL expert. Based on the following database schema, generate a valid MySQL query for the user's question. Only use tables and columns that exist in the schema. Use user-friendly aliases for column names (e.g., 'cust_id' becomes 'Customer ID', 'admission_date' becomes 'Admission Date'). Return ONLY the SQL query, without explanations, markdown, or code block formatting (e.g., no ```). If the question references non-existent tables or columns, return an error message starting with 'ERROR:'. Do not use GROUP BY or aggregation functions (e.g., SUM, COUNT, AVG) unless the question explicitly requests aggregation (e.g., 'sum of all bills', 'average cost', 'count of patients'). Treat 'total bill amount' as the individual bill amount (e.g., bill.amount) unless aggregation is clearly specified. For names, concatenate first_name and last_name if applicable (e.g., CONCAT(first_name, ' ', last_name) AS 'Full Name'). Use direct JOINs with correct foreign key relationships (e.g., link 'nurse_assignment' to 'admission' via 'adm_id', 'appointment' to 'patient' via 'patient_id', 'appointment' to 'doctor' via 'doc_id', 'appointment' to 'bill' via 'appt_id'). Avoid subqueries unless absolutely necessary. Place filtering conditions (e.g., department name, status) in the WHERE clause, not JOIN clauses. Handle case sensitivity in string comparisons by using LOWER() for status fields (e.g., LOWER(status) = 'unpaid'). Verify table relationships before joining.

Schema:
{schema_text}

User Question: {question}
"""
    try:
        response = groq_client.chat.completions.create(
            messages=[{"role": "user", "content": prompt}],
            model="llama3-70b-8192"
        )
        query = response.choices[0].message.content.strip()
        query = re.sub(r'```(?:sql)?\n?', '', query)  # Remove any markdown
        query = query.strip()
        return query
    except Exception as e:
        return f"ERROR: Failed to generate SQL query: {str(e)}"

def execute_sql_query(query):
    """Execute SQL query on the current database."""
    if not current_db_name:
        return False, "No database loaded. Please upload an SQL file.", None
    conn, error = get_db_connection(current_db_name)
    if error:
        return False, error, None
    try:
        cursor = conn.cursor(dictionary=True)
        cursor.execute(query)
        results = cursor.fetchall()
        conn.commit()
        cursor.close()
        conn.close()
        return True, results, None
    except Error as e:
        return False, f"SQL execution failed: {str(e)}", None

@app.route('/', methods=['GET', 'POST'])
def index():
    error = None
    schema = current_schema
    summary = current_summary
    results = None
    generated_query = None

    if request.method == 'POST':
        if 'sql_file' in request.files:
            file = request.files['sql_file']
            if file and file.filename.endswith('.sql'):
                success, result, summary = load_sql_file(file)
                if success:
                    schema = result
                else:
                    error = result
            else:
                error = "Please upload a valid .sql file."
        elif 'question' in request.form:
            question = request.form['question']
            if not current_db_name or not current_schema:
                error = "No database loaded. Please upload an SQL file first."
            else:
                generated_query = generate_sql_query(question, current_schema)
                if not generated_query.startswith('ERROR:'):
                    success, result, _ = execute_sql_query(generated_query)
                    if success:
                        results = result
                    else:
                        error = result
                else:
                    error = generated_query

    return render_template('index.html', error=error, schema=schema, summary=summary, results=results, query=generated_query)

if __name__ == '__main__':
    app.run(debug=True)