# `authentication/no_touch.py`

## Overview
This file provides the specialized authentication middleware (`NoTouchMiddleware`) used for securing the "No Touch" (Solar) endpoints (`/V2/*`). It is more tightly coupled with the business logic (`EMIService`) to ensure that users can only access their specific applications.

## Class: `NoTouchMiddleware`

### `main(cls, func)` (Decorator)
This decorator secures the "no touch" endpoints. It uniquely utilizes Dependency Injection (`@inject`) inside the decorator to access `EMIService`.
- **Workflow**:
  1. Reads the `application_id` and `mobile_number` from the request body. If `application_id` is missing but `mobile` is present, it fetches the ID using `emi_service.get_application_details_by_mobile()`.
  2. Parses the `HTTP_AUTHORIZATION` Bearer token (if present) and decodes it via `jwt_decode`.
  3. **Access Token Flow** (`token_type == 'access'`):
     - Extracts `user_id` or `applicant_id`.
     - Cross-references these IDs with the database (using `emi_service`) to find the associated `application_id`.
     - Validates that the requested `application_id` matches the application ID owned by the user.
  4. **Temporary Token Flow** (`token_type == 'temporary'`):
     - Extracts the `mobile_number` and validates its presence.
  5. **Environment Level Auth**:
     - After JWT validation, it calls `AuthMiddleware('env').main()` to ensure the API caller (e.g., frontend client) has valid environment-level credentials (like a valid Client ID/Secret).
  6. Returns `solar_auth_failure_response` upon any validation failure.

### `jwt_decode(token)` (Static Method)
- Decodes the provided JWT token without signature verification to quickly inspect the payload (`id`, `token_type`, etc.).

### `main_v1(func, *args, **kwargs)` (Static Method)
- Appears to be a deprecated or passthrough decorator intended to bypass authentication temporarily (perhaps during a migration or release phase for the solar app).

## Dependencies
- `flask` (`request`)
- `jwt` (PyJWT)
- `bugsnag`
- `dependency_injector` (`Provide`, `inject`)
- `AuthMiddleware` (from `auth_middleware`)
- `solar_auth_failure_response`
- `EMIService` (from `emi_service`)