from flask import Flask, request, jsonify
from flask_cors import CORS
import mysql.connector
from mysql.connector import pooling
import os

# --- Database Configuration ---
DB_HOST = "mysql.theaken.com"
DB_PORT = 33306
DB_NAME = "db_A027"
DB_USER = "A027"
DB_PASSWORD = "E1CelfxqlKoj"

# --- Create a connection pool ---
try:
    db_pool = pooling.MySQLConnectionPool(
        pool_name="api_pool",
        pool_size=5,
        host=DB_HOST,
        port=DB_PORT,
        database=DB_NAME,
        user=DB_USER,
        password=DB_PASSWORD
    )
    print("Database connection pool created successfully.")
except mysql.connector.Error as err:
    print(f"Error creating connection pool: {err}")
    exit()

# --- Flask App Initialization ---
app = Flask(__name__)
CORS(app) # Enable CORS for all routes

# --- Helper Functions ---
def get_db_connection():
    """Get a connection from the pool."""
    try:
        return db_pool.get_connection()
    except mysql.connector.Error as err:
        print(f"Error getting connection from pool: {err}")
        return None

def make_response(status, code, message, data=None):
    """Standardized response format."""
    response = {
        "status": status,
        "code": code,
        "message": message
    }
    if data is not None:
        response["data"] = data
    return jsonify(response), code

# --- Error Handlers ---
@app.errorhandler(404)
def not_found(error):
    return make_response("error", 404, "The requested resource was not found.")

@app.errorhandler(500)
def internal_server_error(error):
    return make_response("error", 500, "An internal server error occurred.")

# --- Employee API Endpoints ---

@app.route('/v1/employee', methods=['GET'])
def get_employees():
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    query = "SELECT * FROM employee WHERE 1=1"
    params = []
    
    if 'id' in request.args:
        query += " AND id = %s"
        params.append(request.args['id'])
    if 'name' in request.args:
        query += " AND name LIKE %s"
        params.append(f"%{request.args['name']}%")
        
    try:
        cursor.execute(query, tuple(params))
        employees = cursor.fetchall()
        return make_response("success", 200, "Employees retrieved successfully.", {"employees": employees, "meta": {"total": len(employees)}})
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee/<string:emp_id>', methods=['GET'])
def get_employee(emp_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    try:
        cursor.execute("SELECT * FROM employee WHERE id = %s", (emp_id,))
        employee = cursor.fetchone()
        if employee:
            return make_response("success", 200, "Employee found.", employee)
        else:
            return make_response("error", 404, "Employee not found.")
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee', methods=['POST'])
def create_employee():
    data = request.get_json()
    if not data or 'id' not in data or 'name' not in data:
        return make_response("error", 400, "Missing required fields: id, name.")
        
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    try:
        cursor.execute("INSERT INTO employee (id, name) VALUES (%s, %s)", (data['id'], data['name']))
        conn.commit()
        cursor.execute("SELECT * FROM employee WHERE id = %s", (data['id'],))
        new_employee = cursor.fetchone()
        return make_response("success", 201, "Employee created successfully.", new_employee)
    except mysql.connector.Error as err:
        conn.rollback()
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee/<string:emp_id>', methods=['PATCH'])
def update_employee(emp_id):
    data = request.get_json()
    if not data:
        return make_response("error", 400, "No update data provided.")

    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    updates = []
    params = []
    if 'name' in data:
        updates.append("name = %s")
        params.append(data['name'])

    if not updates:
        return make_response("error", 400, "No valid fields to update.")

    params.append(emp_id)
    query = f"UPDATE employee SET {', '.join(updates)} WHERE id = %s"

    try:
        cursor.execute(query, tuple(params))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Employee not found or data is the same.")
        
        cursor.execute("SELECT * FROM employee WHERE id = %s", (emp_id,))
        updated_employee = cursor.fetchone()
        return make_response("success", 200, "Employee updated successfully.", updated_employee)
    except mysql.connector.Error as err:
        conn.rollback()
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee/<string:emp_id>', methods=['DELETE'])
def delete_employee(emp_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor()

    try:
        # Note: Deleting an employee might fail if they have existing votes due to foreign key constraints.
        # This should be handled by the application logic (e.g., delete votes first or prevent deletion).
        cursor.execute("DELETE FROM employee WHERE id = %s", (emp_id,))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Employee not found.")
        return make_response("success", 204, "Employee deleted successfully.")
    except mysql.connector.Error as err:
        conn.rollback()
        # Check for foreign key constraint violation
        if err.errno == 1451:
            return make_response("error", 409, "Cannot delete employee with existing votes. Please remove their votes first.")
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()


# --- Menu Items API Endpoints ---

@app.route('/v1/menu_items', methods=['GET'])
def get_menu_items():
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    query = "SELECT * FROM menu_items WHERE 1=1"
    params = []
    
    if 'id' in request.args:
        query += " AND id = %s"
        params.append(request.args['id'])
    if 'main_course' in request.args:
        query += " AND main_course LIKE %s"
        params.append(f"%{request.args['main_course']}%")
    if 'side_dish' in request.args:
        query += " AND side_dish LIKE %s"
        params.append(f"%{request.args['side_dish']}%")
    if 'addon' in request.args:
        query += " AND addon LIKE %s"
        params.append(f"%{request.args['addon']}%")
    if 'menu_date' in request.args:
        query += " AND menu_date = %s"
        params.append(request.args['menu_date'])

    try:
        cursor.execute(query, tuple(params))
        items = cursor.fetchall()
        return make_response("success", 200, "Menu items retrieved successfully.", {"menu_items": items, "meta": {"total": len(items)}})
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/menu_items/<int:item_id>', methods=['GET'])
def get_menu_item(item_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    try:
        cursor.execute("SELECT * FROM menu_items WHERE id = %s", (item_id,))
        item = cursor.fetchone()
        if item:
            return make_response("success", 200, "Menu item found.", item)
        else:
            return make_response("error", 404, "Menu item not found.")
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/menu_items', methods=['POST'])
def create_menu_item():
    data = request.get_json()
    if not data or not all(k in data for k in ['main_course', 'side_dish', 'addon', 'menu_date']):
        return make_response("error", 400, "Missing required fields: main_course, side_dish, addon, menu_date.")
        
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    try:
        sql = "INSERT INTO menu_items (main_course, side_dish, addon, menu_date) VALUES (%s, %s, %s, %s)"
        params = (data['main_course'], data['side_dish'], data['addon'], data['menu_date'])
        cursor.execute(sql, params)
        new_item_id = cursor.lastrowid
        conn.commit()
        
        cursor.execute("SELECT * FROM menu_items WHERE id = %s", (new_item_id,))
        new_item = cursor.fetchone()
        return make_response("success", 201, "Menu item created successfully.", new_item)
    except mysql.connector.Error as err:
        conn.rollback()
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/menu_items/<int:item_id>', methods=['PATCH'])
def update_menu_item(item_id):
    data = request.get_json()
    if not data:
        return make_response("error", 400, "No update data provided.")

    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    updates = []
    params = []
    for key in ['main_course', 'side_dish', 'addon', 'menu_date']:
        if key in data:
            updates.append(f"{key} = %s")
            params.append(data[key])

    if not updates:
        return make_response("error", 400, "No valid fields to update.")

    params.append(item_id)
    query = f"UPDATE menu_items SET {', '.join(updates)} WHERE id = %s"

    try:
        cursor.execute(query, tuple(params))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Menu item not found or data is the same.")
        
        cursor.execute("SELECT * FROM menu_items WHERE id = %s", (item_id,))
        updated_item = cursor.fetchone()
        return make_response("success", 200, "Menu item updated successfully.", updated_item)
    except mysql.connector.Error as err:
        conn.rollback()
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/menu_items/<int:item_id>', methods=['DELETE'])
def delete_menu_item(item_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor()

    try:
        cursor.execute("DELETE FROM menu_items WHERE id = %s", (item_id,))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Menu item not found.")
        return make_response("success", 204, "Menu item deleted successfully.")
    except mysql.connector.Error as err:
        conn.rollback()
        if err.errno == 1451:
            return make_response("error", 409, "Cannot delete menu item that has been voted on.")
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()


# --- Employee Votes API Endpoints ---

@app.route('/v1/employee_votes', methods=['GET'])
def get_employee_votes():
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    query = """
        SELECT v.*, e.name 
        FROM employee_votes v
        JOIN employee e ON v.emp_id = e.id
        WHERE 1=1
    """
    params = []
    
    if 'id' in request.args:
        query += " AND v.id = %s"
        params.append(request.args['id'])
    if 'emp_id' in request.args:
        query += " AND v.emp_id = %s"
        params.append(request.args['emp_id'])
    if 'name' in request.args: # Search by employee name
        query += " AND e.name LIKE %s"
        params.append(f"%{request.args['name']}%")
    if 'order_date' in request.args:
        query += " AND v.order_date = %s"
        params.append(request.args['order_date'])
    if 'menu_item_id' in request.args:
        query += " AND v.menu_item_id = %s"
        params.append(request.args['menu_item_id'])
    if 'order_qty' in request.args:
        query += " AND v.order_qty = %s"
        params.append(request.args['order_qty'])

    try:
        cursor.execute(query, tuple(params))
        votes = cursor.fetchall()
        return make_response("success", 200, "Employee votes retrieved successfully.", {"employee_votes": votes, "meta": {"total": len(votes)}})
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee_votes/<int:vote_id>', methods=['GET'])
def get_employee_vote(vote_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)
    
    try:
        cursor.execute("""
            SELECT v.*, e.name 
            FROM employee_votes v
            JOIN employee e ON v.emp_id = e.id
            WHERE v.id = %s
        """, (vote_id,))
        vote = cursor.fetchone()
        if vote:
            return make_response("success", 200, "Employee vote found.", vote)
        else:
            return make_response("error", 404, "Employee vote not found.")
    except mysql.connector.Error as err:
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee_votes', methods=['POST'])
def create_employee_vote():
    data = request.get_json()
    required_fields = ['emp_id', 'order_date', 'menu_item_id', 'order_qty']
    if not data or not all(k in data for k in required_fields):
        return make_response("error", 400, f"Missing required fields: {', '.join(required_fields)}.")
        
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    try:
        sql = "INSERT INTO employee_votes (emp_id, order_date, menu_item_id, order_qty) VALUES (%s, %s, %s, %s)"
        params = (data['emp_id'], data['order_date'], data['menu_item_id'], data['order_qty'])
        cursor.execute(sql, params)
        new_vote_id = cursor.lastrowid
        conn.commit()
        
        cursor.execute("""
            SELECT v.*, e.name 
            FROM employee_votes v
            JOIN employee e ON v.emp_id = e.id
            WHERE v.id = %s
        """, (new_vote_id,))
        new_vote = cursor.fetchone()
        return make_response("success", 201, "Employee vote created successfully.", new_vote)
    except mysql.connector.Error as err:
        conn.rollback()
        if err.errno == 1452: # Foreign key constraint fails
             return make_response("error", 400, "Invalid emp_id or menu_item_id. The specified employee or menu item does not exist.")
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee_votes/<int:vote_id>', methods=['PATCH'])
def update_employee_vote(vote_id):
    data = request.get_json()
    if not data:
        return make_response("error", 400, "No update data provided.")

    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor(dictionary=True)

    updates = []
    params = []
    for key in ['emp_id', 'order_date', 'menu_item_id', 'order_qty']:
        if key in data:
            updates.append(f"{key} = %s")
            params.append(data[key])

    if not updates:
        return make_response("error", 400, "No valid fields to update.")

    params.append(vote_id)
    query = f"UPDATE employee_votes SET {', '.join(updates)} WHERE id = %s"

    try:
        cursor.execute(query, tuple(params))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Employee vote not found or data is the same.")
        
        cursor.execute("""
            SELECT v.*, e.name 
            FROM employee_votes v
            JOIN employee e ON v.emp_id = e.id
            WHERE v.id = %s
        """, (vote_id,))
        updated_vote = cursor.fetchone()
        return make_response("success", 200, "Employee vote updated successfully.", updated_vote)
    except mysql.connector.Error as err:
        conn.rollback()
        if err.errno == 1452:
             return make_response("error", 400, "Invalid emp_id or menu_item_id. The specified employee or menu item does not exist.")
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

@app.route('/v1/employee_votes/<int:vote_id>', methods=['DELETE'])
def delete_employee_vote(vote_id):
    conn = get_db_connection()
    if not conn:
        return make_response("error", 503, "Database service unavailable.")
    cursor = conn.cursor()

    try:
        cursor.execute("DELETE FROM employee_votes WHERE id = %s", (vote_id,))
        conn.commit()
        if cursor.rowcount == 0:
            return make_response("error", 404, "Employee vote not found.")
        return make_response("success", 204, "Employee vote deleted successfully.")
    except mysql.connector.Error as err:
        conn.rollback()
        return make_response("error", 500, str(err))
    finally:
        cursor.close()
        conn.close()

# --- Main Execution ---
if __name__ == '__main__':
    # To run this server:
    # 1. Make sure you have Flask, Flask-Cors, and mysql-connector-python installed:
    #    pip install Flask Flask-Cors mysql-connector-python
    # 2. Run the script:
    #    python api_server.py
    # The server will start on http://127.0.0.1:5000
    app.run(debug=True, host='0.0.0.0', port=5000)