Accounting Core

A comprehensive Rust library for double-entry bookkeeping, GST calculations, and financial reporting. Designed as the open-source foundation for accounting applications.

Features

• 🏦 Double-entry Bookkeeping: Complete transaction validation and balance tracking
• 📊 Account Management: Support for Assets, Liabilities, Equity, Income, and Expense accounts
• 🧾 GST Calculations: Indian GST compliance with CGST/SGST/IGST support
• 📈 Financial Reporting: Balance sheets, income statements, and trial balance generation
• 🔍 Storage Abstraction: Database-agnostic design with trait-based storage
• ✅ Validation: Comprehensive validation for transactions and accounts
• 🧪 Testing: Full test coverage with examples and documentation

Quick Start

Add this to your Cargo.toml:

[dependencies]
accounting-core = "0.1.0"

Basic Usage

use accounting_core::{Ledger, AccountType, TransactionBuilder};
use accounting_core::utils::MemoryStorage;
use bigdecimal::BigDecimal;
use chrono::NaiveDate;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a ledger with in-memory storage
    let storage = MemoryStorage::new();
    let mut ledger = Ledger::new(storage);

    // Set up basic accounts
    let cash = ledger.create_account(
        "cash".to_string(),
        "Cash".to_string(),
        AccountType::Asset,
        None,
    ).await?;

    let revenue = ledger.create_account(
        "revenue".to_string(),
        "Revenue".to_string(),
        AccountType::Income,
        None,
    ).await?;

    // Record a transaction
    let transaction = TransactionBuilder::new(
        "txn001".to_string(),
        NaiveDate::from_ymd_opt(2024, 1, 1).unwrap(),
        "Sale of goods".to_string(),
    )
    .debit(cash.id.clone(), BigDecimal::from(1000), None)
    .credit(revenue.id.clone(), BigDecimal::from(1000), None)
    .build()?;

    ledger.record_transaction(transaction).await?;

    // Generate reports
    let balance_sheet = ledger.generate_balance_sheet(
        NaiveDate::from_ymd_opt(2024, 1, 31).unwrap()
    ).await?;

    println!("Total Assets: {}", balance_sheet.total_assets);
    Ok(())
}

GST Calculations

use accounting_core::{GstCalculator, GstCategory, GstLineItem, GstInvoice};
use bigdecimal::BigDecimal;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let calculator = GstCalculator::new(false); // intra-state

    // Calculate GST for a service (18%)
    let calculation = calculator.calculate_by_category(
        BigDecimal::from(10000),
        GstCategory::Higher,
        None,
    )?;

    println!("Base Amount: ₹{}", calculation.base_amount);
    println!("CGST (9%): ₹{}", calculation.cgst_amount);
    println!("SGST (9%): ₹{}", calculation.sgst_amount);
    println!("Total: ₹{}", calculation.total_amount);

    Ok(())
}

Architecture

Core Components

• types: Core data structures (Account, Transaction, Entry, etc.)
• traits: Storage and validation abstractions
• ledger: Account management and transaction processing
• tax: GST calculation engine
• utils: Utilities including in-memory storage for testing

Storage Abstraction

The library uses trait-based storage abstraction, allowing you to implement your own storage backend:

use accounting_core::{LedgerStorage, Account, Transaction};
use async_trait::async_trait;

#[derive(Debug)]
pub struct MyPostgresStorage {
    pool: sqlx::PgPool,
}

#[async_trait]
impl LedgerStorage for MyPostgresStorage {
    async fn save_account(&mut self, account: &Account) -> LedgerResult<()> {
        // Your PostgreSQL implementation
        todo!()
    }
    
    // Implement other required methods...
}

Examples

Run the examples to see the library in action:

# Basic ledger operations
cargo run --example basic_ledger

# GST calculation examples
cargo run --example gst_calculations

Testing

Run the test suite:

cargo test

Double-Entry Bookkeeping Principles

This library follows standard accounting principles:

• Assets = Liabilities + Equity (Balance Sheet equation)
• Debits = Credits (Every transaction must balance)
• Account Types:
  • Assets: Things the business owns (Cash, Inventory, Equipment)
  • Liabilities: Things the business owes (Loans, Accounts Payable)
  • Equity: Owner's interest in the business
  • Income: Revenue earned by the business
  • Expenses: Costs incurred by the business

Normal Balances

• Debit Balances: Assets and Expenses
• Credit Balances: Liabilities, Equity, and Income

GST Compliance

The library supports Indian GST with:

• Intra-state transactions: CGST + SGST
• Inter-state transactions: IGST
• Standard rates: 0%, 5%, 12%, 18%, 28%
• Reverse calculations: From total amount to base amount
• Multi-item invoices: Complex invoices with different rates

Financial Reports

Generate standard financial reports:

• Trial Balance: Verify that debits equal credits
• Balance Sheet: Assets = Liabilities + Equity
• Income Statement: Revenue - Expenses = Net Income
• Cash Flow Statement: Operating, Investing, Financing activities

Validation

Comprehensive validation ensures data integrity:

• Transaction validation: Debits must equal credits
• Account validation: Proper account structure
• Amount validation: Positive amounts only
• Reference validation: Valid account references

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Roadmap

• Bank reconciliation engine
• Multi-currency support
• Advanced reporting features
• Plugin architecture
• Performance optimizations
• More comprehensive GST features