# `emi_service.py`

## Overview
This file houses the `EMIService` class and acts as the brain of the EMI Checkout system. It orchestrates the flow of data between the API controllers (from `applications/`), the database layer (`EMIRepository`), and third-party integrations (`accessors/`). 

## Key Utilities & Validations
Outside the class, the file contains several standalone validation helpers:
- `validate_age(dob)`, `validate_ckyc(...)`, `validate_create_loan_request(...)`, `validate_electricity_bill_request(...)`
- `create_application_link(app_id)`: Generates tracking/resume links for partial applications.

## Class: `EMIService`

### Initialization
- Takes an instance of `EMIRepository` and `Utilities` as injected dependencies via the constructor.

### Core Workflows (Standard EMI)
- **Application Management**: `add_application`, `update_customer_details`, `get_application_status`, `application_cancellation_request`, `create_loan`.
- **Authentication/OTP**: `initiate_otp`, `send_otp`, `confirm_otp`, `cooldown_check`.
- **KYC & Bureau Integration**:
  - `ckyc`: Orchestrates CKYC checks using PAN/DOB.
  - `digio_vkyc_method` & `digio_generate_token`: Hooks into the Digio accessor to start VKYC sessions.
  - `get_bureau`: Orchestrates fetching credit reports.
- **Documents & Offers**: `upload_document`, `process_product_details`, `save_offer`.

### No Touch / Solar Workflows
The class contains specialized `no_touch_*` variants of core methods for fast-tracked or specialized products:
- `no_touch_ckyc`, `no_touch_get_bureau`, `no_touch_confirm_otp`, `no_touch_process_product_details`.
- Specialized endpoints for tracking user progress: `get_user_journey_details` and `get_no_touch_user_journey_details`.

### Helper Methods
- `get_schema_file` / `get_no_touch_config`: Returns JSON structures that dictate UI rendering paths based on configurations.
- `display_merchants`, `display_merchant_name`: Interfaces with the repository to translate slugs/IDs to displayable text.
- `send_create_application_communication`: Triggers welcome or OTP communications utilizing external APIs (like Exotel via the `utils`).

## Dependencies
- `EMIRepository`
- External Accessors (`bureau_service`, `digio`, `creditfair`, `pirimid`)
- `utils` (Validation, formatting, S3 uploading)
- `bugsnag`, `logging`