# CFONB

A parser for **CFONB** bank files — the French banking interchange standard
(*Comité Français d'Organisation et de Normalisation Bancaires*).

This first version parses the **120-character account statement** (relevé de
compte): previous balance (`01`), operations (`04`), operation details (`05`),
and new balance (`07`). Amounts are returned as [`Decimal`](https://hex.pm/packages/decimal)
so money is never represented as a float.

## Installation

```elixir
def deps do
  [
    {:cfonb, "~> 0.1.0"}
  ]
end
```

## Usage

```elixir
{:ok, statements} = CFONB.parse(File.read!("releve.txt"))

[statement | _] = statements
statement.account       #=> "98765432100"
statement.from_balance  #=> #Decimal<-190.40>
statement.to_balance    #=> #Decimal<-241.21>

[operation | _] = statement.operations
operation.label                    #=> "PRLV SEPA TEST CABINET"
operation.amount                   #=> #Decimal<-32.21>
operation.details.operation_reference #=> "REFERENCE"
operation.details.debtor           #=> "INTERNET SFR"
operation.details.fee              #=> #Decimal<0.79>  (when a FEE detail is present)
```

The `05` detail records are decoded into a `CFONB.Operation.Details` struct
(qualifiers such as `LIB`, `REF`, `RCN`, `NPY`, `FEE`, `MMO`, …). Unrecognized
qualifiers are preserved under `details.unknown`.

The library also derives banking identifiers and exposes the raw records:

```elixir
CFONB.Statement.rib(statement)          #=> "20041010050500013M02606"
CFONB.Statement.iban(statement)         #=> "FR1420041010050500013M02606"
CFONB.Operation.type_code(operation)    #=> "B1D"  (interbank code + credit/debit)
statement.begin_raw                     #=> the original "01" line
CFONB.Statement.raw(statement)          #=> the statement's records, rebuilt
```

Other entry points:

```elixir
CFONB.parse_operation(input)      # parse a standalone 04 (+ its 05s)
CFONB.parse(input, optimistic: true)   # skip invalid records, best effort
CFONB.parse!(input)               # raising variants
```

`CFONB.parse/1` returns `{:ok, [%CFONB.Statement{}]}` or `{:error, reason}`.
Use `CFONB.parse!/1` if you prefer raising on invalid input.

See [`FORMAT.md`](FORMAT.md) for the exact CFONB 120 field layout.

## Scope & roadmap

- **v0.1** — CFONB 120 account statement (all record types), qualifier-specific
  `05` decoding, RIB/IBAN derivation, raw-record access, standalone-operation and
  optimistic parsing. At feature parity with the reference Ruby gem.
- Planned — the 240-character format, and CFONB generation (e.g. transfer orders).

## Credits & license

Reimplemented from the official CFONB specification, with a data model
**inspired by** and **compatible with** the Ruby gem
[pennylane-hq/cfonb](https://github.com/pennylane-hq/cfonb) (MIT) — its test
files are reused as a parsing oracle. Released under the MIT license.