# Visione Backend Architecture

## Layout
- `controllers/`: Drogon `HttpController` classes.
- `services/`: application/business logic.
- `repositories/`: database helpers and migrations.
- `common/`: reusable HTTP, auth, crypto, email and validation utilities.
- `migrations/`: versioned SQL files.
- `scripts/generate_openapi.py`: OpenAPI generator.
- `scripts/lab/`: local Streamlit frontend for visual endpoint testing.
- `docs/`: product, API, schema and milestone documentation.

## Drogon Usage
Controllers use Drogon route macros and return JSON with
`HttpResponse::newHttpJsonResponse`. Database access uses
`drogon::orm::DbClient` with raw parameterized SQL placeholders.

The codebase does not use Drogon generated models or `Mapper<T>`. Raw SQL stays
in repository/database helpers because the schema is still evolving.

## Local Email
OTP emails are sent to MailHog over SMTP. MailHog keeps messages local and
inspectable through its web UI.

## Password Hashing
User passwords use PBKDF2-HMAC-SHA256 with per-password random salts and 210000
iterations. This is intentionally slower than a plain SHA-256 digest and is
available through OpenSSL, which is already a Drogon dependency in this project.
Legacy `sha256$` password hashes are rejected instead of silently accepted.

## OpenAPI Generation
`scripts/generate_openapi.py` scans Drogon `ADD_METHOD_TO` route macros and the
adjacent `openapi:` metadata blocks in `controllers/*.h`, then generates
`build/openapi/visione.openapi.json`.

This is a contract-last generator: the source of truth is the C++ controller
route list, not a manually maintained static Swagger document. The current tool
generates paths, methods, path parameters, summaries, descriptions, auth hints
and common JSON or multipart request bodies. Generation fails if a route lacks
metadata.

## Visione Lab
`scripts/lab/` is a Streamlit dev frontend for visual endpoint testing. It is
intentionally separate from the real product frontend and should stay small:
forms, uploads and response rendering only. Run it with uv from `scripts/lab/`.