model.py

import json
import os

from datetime import datetime

DATA_FILE = "data.json"

class FinanaceModel:
    def __init__(self):
        self.transactions   = []
        self.budgets        = {}

        self.load()
    
    # Transactions
    def add_transaction(self, type_, amount, category, description, date = None, recurrence = None):
        if date == None:
            date = datetime.today().strftime("%Y-%m-%d")
        
        self.transactions.append({
            "type": type_,
            "amount": float(amount),
            "category": category,
            "description": description,
            "date": date,
            "recurrence": recurrence
        })
        self.save()
    
    # Amounts
    def total_income(self):
        return sum(t["amount"] for t in self.transactions if t["type"] == "Income")
    
    def total_expense(self):
        return sum(t["amount"] for t in self.transactions if t["type"] == "Expense")
    
    def balance(self):
        return self.total_income() - self.total_expense()
    
    # Budget
    def set_budget(self, category, amount):
        self.budgets[category] = amount
        self.save()
    
    def save(self):
        data = {
            "transactions": self.transactions,
            "budgets":      self.budgets
        }

        with open(DATA_FILE, "w") as f:
            json.dump(data, f)
    
    def load(self):
        if os.path.exists(DATA_FILE):
            with open(DATA_FILE, "r") as f:
                data                = json.load(f)
                self.transactions   = data["transactions"]
                self.budgets        = data["budgets"]