# Changelog

## 0.2.0

A ground-up rewrite. 0.1.2's public API (`Ussd.Machine`, the old `Ussd.Decision`/`Ussd.Menu`
functions, and the `mix phx.gen.ussd.state` generator) is gone - there is no compatibility
shim, since 0.1.2's own generator produced code that didn't run. If you have a project on
0.1.2, treat this as a new dependency rather than an upgrade.

### Fixed

- The `mix phx.gen.ussd.state` generator produced a `before_render/1` that didn't match what
  0.1.2's `Ussd.Machine` (removed in this release) actually called (`before_render/2`) -
  every generated state crashed. The new generators (`mix ussd.gen.*`) produce code that
  matches the current engine.
- 0.1.2's Ussd.Decision.between/3 (removed in this release) compared USSD input as strings
  (`"10" <= "9"` is true lexicographically), silently breaking range matching once a menu had
  10+ options. The new `Ussd.Decisions.Between` and friends compare numerically when both
  sides look numeric.
- Session state (`Ussd.Record` in 0.1.2) had no expiry at all and was only ever cleared when
  a flow explicitly returned a `"prompt"` action, so abandoned sessions accumulated in an
  ETS table forever. `Ussd.Cache.ETS` now expires entries on a real TTL, both lazily on read
  and via a periodic sweep, and the engine gives its own bookkeeping a default TTL
  (`config :ussd, :session_ttl`, default 300s) so this happens automatically.
- Ussd.Application started its `GenServer` directly instead of under a `Supervisor`, so a
  crash there took the whole application down with no restart. It now starts under a real
  one-for-one supervisor.
- The library depended on all of Phoenix (`{:phoenix, "~> 1.6.6"}`) just for one generator's
  inflection helpers. The generators now use `Macro.camelize/1` and `Macro.underscore/1`
  from Elixir's own standard library; Phoenix is no longer a dependency at all.

### Added

Feature parity with `speso/laravel-ussd` v3, expressed idiomatically rather than
transliterated:

- **`Ussd.State` DSL** - `transition/2`, `back/2`, `paginate/2`, `truncate/2`, `terminate/0`
  macros compiled into the module, replacing 0.1.2's untyped `Ussd.Decision.*` functions.
- **`Ussd.Action`** - one-shot, no-render decision points that chain to the next state.
- **`Ussd.Pagination`** - `use Ussd.Pagination, per_page: n` plus `paginate/2` pages a long
  listing without hand-rolled bookkeeping.
- **Truncation** - `truncate/2` caps how much of a screen is returned per request, with a
  "more" continuation key.
- **Resumable sessions** - `Ussd.use_continuing_state/4` (`:start` / `:continue` /
  `:confirm`) lets a redial pick back up where a dropped call left off.
- **`Ussd.Configurator`** - shared `Ussd.use_*/2` setup across entry points.
- **Localization** - `Ussd.Menu.trans/4` and `trans_line/4` via an optional Gettext backend.
- **`Ussd.Record.set_encrypted/4` and `get_encrypted/4`** - AES-256-GCM at rest, keyed by
  `config :ussd, :encryption_key`.
- **Six gateway response formatters** - `Ussd.Responses.{AfricasTalking, Speso, Nalo, Nsano,
  Moolre, Arkesel}`.
- **`Ussd.ExceptionHandler`** - turns an unhandled exception into a message instead of a
  dead session.
- **`mix ussd.graph`, `mix ussd.lint`, `mix ussd.simulate`** - Mermaid flow diagrams, static
  analysis for dead ends/broken transitions/duplicate matches, and an interactive terminal
  simulator.
- **`mix ussd.gen.{state,action,response,decision,configurator,exception_handler}`**
  generators.
- **`Ussd.Test`** - a fluent ExUnit helper for walking a flow screen by screen and asserting
  on the message, session record, and context.
- **`:telemetry` events** - `[:ussd, :state, :entered]` and `[:ussd, :session, :terminated]`.
- **Pluggable `Ussd.Cache`** behaviour, so the session store can be swapped for Redis,
  `:cachex`, Mnesia, etc. in a multi-node deployment.

## 0.1.2 and earlier

Initial minimal proof of concept.