# Unit 05 — Flask Application

## Goal
Main Flask server wiring together the database, profile generator, utils, and core adapters.

## File
- `server/app.py`

---

## Endpoints

| Method | Path | Auth | Description |
|--------|------|------|-------------|
| GET | `/` | none | 302 redirect → `/activate` |
| GET | `/activate` | none | Serve `portal/index.html` |
| POST | `/api/provision` | none | Generate + provision eSIM |
| GET | `/api/profile/<int:id>` | none | Download profile bytes |
| GET | `/api/export` | none | JSON export of all subscribers |
| GET | `/api/status` | none | Health check |

---

## `POST /api/provision` — Full Flow

Request body (JSON):
```json
{"mac_address": "aa:bb:cc:dd:ee:ff"}
```

Steps:
1. Parse JSON body; if `mac_address` missing/empty, resolve from server-side ARP (`/proc/net/arp` lookup by client IP)
2. `normalize_mac()` + `validate_mac()` → 400 if invalid
3. `check_rate_limit(conn, mac, window_hours)` → 429 if exceeded
4. `generate_imsi(mcc, mnc)`
5. `generate_ki()`
6. `generate_iccid()`
7. `derive_opc(ki, op_bytes)`
8. `create_esim_profile(...)` → `profile_bytes`
9. `add_subscriber(conn, imsi, iccid, ki_hex, opc_hex, mac)` → `sub_id`
10. Store `profile_bytes` in memory cache `{sub_id: bytes}` (or temp file)
11. If `core_adapter` configured: attempt `add_subscriber(imsi, ki_hex, opc_hex)`; log failure, don't abort
12. Return 200:
```json
{
  "id": 1,
  "imsi": "302720XXXXXXXXXX",
  "iccid": "8910302720XXXXXXXXX",
  "profile_url": "/api/profile/1"
}
```

Error responses:
- 400: `{"error": "Invalid MAC address"}`
- 429: `{"error": "Rate limit exceeded. One profile per device per hour."}`
- 500: `{"error": "Profile generation failed"}`

---

## `GET /api/profile/<id>` — Profile Download

- Look up subscriber by `id` in DB
- Retrieve profile bytes from in-memory cache (keyed by `sub_id`)
- 404 if not found or cache expired
- Response: `Content-Type: application/octet-stream`, `Content-Disposition: attachment; filename=esim-profile.bin`

---

## `GET /api/export` — Subscriber Export

Response:
```json
{
  "exported_at": "2025-02-11T10:30:00Z",
  "count": 123,
  "subscribers": [
    {
      "imsi": "302720123456789",
      "ki": "00112233445566778899aabbccddeeff",
      "opc": "63bfa50ee6523365ff14c1f45f88737d",
      "iccid": "8910302720123456789",
      "mac_address": "aa:bb:cc:dd:ee:ff",
      "created_at": "2025-02-11T09:15:00Z",
      "synced_to_core": false
    }
  ]
}
```

---

## `GET /api/status` — Health

```json
{
  "status": "ok",
  "subscriber_count": 42,
  "uptime_seconds": 3600,
  "core_adapter": "open5gs"
}
```

---

## Application Setup

```python
import os, logging
from flask import Flask, request, jsonify, send_file, redirect
from server.database import init_db, get_connection, ...
from server.profile_generator import ...
from server.utils import load_config, ...
from server.core_adapters import get_adapter

CONFIG_PATH = os.environ.get("CONFIG_PATH", "config.yaml")

def create_app(config_path=CONFIG_PATH):
    app = Flask(__name__, static_folder="../portal", static_url_path="")
    cfg = load_config(config_path)

    db_path = cfg["database"]["path"]
    init_db(db_path)

    adapter = get_adapter(cfg)
    profile_cache = {}   # {sub_id: bytes}
    start_time = time.time()

    # register routes ...
    return app

if __name__ == "__main__":
    app = create_app()
    app.run(host=cfg["server"]["host"], port=cfg["server"]["port"])
```

---

## MAC Address from ARP (server-side fallback)

When client doesn't send MAC:
```python
def get_mac_from_arp(ip: str) -> str | None:
    try:
        with open("/proc/net/arp") as f:
            for line in f:
                parts = line.split()
                if len(parts) >= 4 and parts[0] == ip:
                    return parts[3]
    except Exception:
        pass
    return None
```

---

## Verification
```bash
CONFIG_PATH=config.yaml python -m server.app &
sleep 1
curl -s http://localhost:5000/api/status | python -m json.tool
curl -s -X POST http://localhost:5000/api/provision \
     -H "Content-Type: application/json" \
     -d '{"mac_address":"aa:bb:cc:dd:ee:ff"}' | python -m json.tool
curl -s http://localhost:5000/api/export | python -m json.tool
kill %1
```