add receipt printer code

.gitignore

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+# CONFIG
+*.toml
+
+# Chatch-all default Python gitignore
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# plaintext files
+*.txt
+
+# csv-files
+*.csv
+
+# certificates
+*.crt
+
+# icons
+*.ico
+
+# C extensions
+*.so
+
+# PyCharm
+.idea/
+
+# Excel tables
+*.ods
+*.xlsx
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# JSON containing project data
+projects.json
+
+# Authentication directoy
+auth/

README.md

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+# Receipt Printer
+
+This software is designed to run on a debian based system and acts as a middle-man between the EZ LAN Manager database and the USB interface of the receipt printer.
+
+# Notes
+
+- Does only work on Linux
+- Needs root privileges or udev config to work
+- Designed to run alone on a Raspberry Pi
+- Not meant to be exposed to the internet, local deployment only
+- For EZ LAN Manager configuration, check README in that repo
+
+# Deploy
+
+1. Configure password and port in `main.py`
+2. Make sure USB printer is connected to device
+3. Install requirements with sudo
+4. Run `main.py` with sudo

init_printer.py

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+import logging
+
+import usb.core
+import usb.util
+from usb.core import Endpoint
+
+logger = logging.getLogger(__name__)
+
+def init_printer() -> tuple[Endpoint, Endpoint]:
+    """
+    ! DEBUG ONLY !
+    Initializes printer and returns the input and output endpoints, in that order.
+    """
+    dev = usb.core.find(idVendor=0x28e9, idProduct=0x0289)
+
+    if dev is None:
+        raise ValueError("Printer could not be found")
+    else:
+        logger.debug("Printer found!")
+
+    # Check for config
+    cfg = dev.get_active_configuration()
+    logger.debug(f"Found configuration: {cfg.bConfigurationValue}")
+
+    intf = cfg[(0, 0)]  # Select first interface and first setting
+
+    logger.debug(f"Interface #: {intf.bInterfaceNumber}, Endpoints: {intf.bNumEndpoints}")
+
+    # Find Bulk OUT- und IN-Endpoints
+    ep_out = usb.util.find_descriptor(
+        intf,
+        custom_match=lambda endpoint: usb.util.endpoint_direction(endpoint.bEndpointAddress) == usb.util.ENDPOINT_OUT
+    )
+
+    ep_in = usb.util.find_descriptor(
+        intf,
+        custom_match=lambda endpoint: usb.util.endpoint_direction(endpoint.bEndpointAddress) == usb.util.ENDPOINT_IN
+    )
+
+    # Validate endpoints
+    if ep_out:
+        logger.debug(f"OUT-Endpoint found: {ep_out.bEndpointAddress}")
+    else:
+        raise ValueError("OUT-Endpoint not found")
+
+    if ep_in:
+        logger.debug(f"IN-Endpoint found: {ep_in.bEndpointAddress}")
+    else:
+        raise ValueError("IN-Endpoint not found")
+
+    if dev.is_kernel_driver_active(intf.bInterfaceNumber):
+        try:
+            dev.detach_kernel_driver(intf.bInterfaceNumber)
+        except usb.core.USBError as e:
+            raise ValueError(f"Could not detach kernel driver from interface({intf.bInterfaceNumber}): {e}")
+
+    return ep_in, ep_out

main.py

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+from datetime import datetime
+
+import uvicorn
+from fastapi import FastAPI, HTTPException
+from fastapi.params import Header
+from pydantic import BaseModel
+
+from escpos.printer import Usb
+
+MAX_LINE_LEN = 30
+
+PRINTER = Usb(0x28e9, 0x0289)
+
+SECRET_PASSWORD = "Alkohol1"
+
+class OrderItem(BaseModel):
+    menu_item_name: str
+    amount: int
+
+class Order(BaseModel):
+    order_id: str
+    order_date: datetime
+    customer_name: str
+    seat_id: str
+    items: list[OrderItem]
+
+def build_header(order_id: str, order_date: datetime, customer_name: str, seat_id: str) -> str:
+    return (f"EZ GG e.V. - EZ LAN 1.0\n\n"
+            f"Bestellungs-ID: {order_id}\n"
+            f"Bestellt: {order_date.strftime('%d.%m. - %H:%M')}\n"
+            f"Gast: {customer_name}\n"
+            f"Sitzplatz: {seat_id}\n\n")
+
+def format_order(order: list[OrderItem]) -> list[str]:
+    formatted_order = []
+    for item in order:
+        formatted_text = f"{item.amount}x {item.menu_item_name}"
+        formatted_text = formatted_text.replace("ä", "ae")
+        formatted_text = formatted_text.replace("ö", "oe")
+        formatted_text = formatted_text.replace("ü", "ue")
+        formatted_text = formatted_text.replace("ß", "ss")
+        if len(formatted_text) < MAX_LINE_LEN:
+            while len(formatted_text) < MAX_LINE_LEN:
+                formatted_text = formatted_text.replace(" ", "  ", 1)
+        else:
+            formatted_text = formatted_text[:MAX_LINE_LEN]
+
+        formatted_order.append(formatted_text + "\n")
+    return formatted_order
+
+def print_order(order: Order, printer_: Usb) -> None:
+    header = build_header(order.order_id, order.order_date, order.customer_name, order.seat_id)
+    items = format_order(order.items)
+    printer_.image("logo.png")
+    printer_.text(header)
+    for item in items:
+        printer_.text(item)
+    printer_.cut()
+
+api = FastAPI()
+
+
+@api.post("/print_order")
+async def print_order_api_endpoint(order: Order, x_password: str = Header(None)):
+    if x_password != SECRET_PASSWORD:
+        raise HTTPException(status_code=401, detail="Unauthorized")
+
+    for item in order.items:
+        if item.amount < 1:
+            return 422
+
+    print_order(order, PRINTER)
+
+    return "done"
+
+if __name__ == "__main__":
+    print("Starting receipt printing server...")
+    uvicorn.run(api, host="0.0.0.0", port=5000, log_level="warning")

post_request_tester.py

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+import requests
+
+if __name__ == "__main__":
+    # Helper for testing the API
+    response = requests.post(
+        "http://127.0.0.1:5000/print_order",
+        json={
+          "order_id": "12345",
+          "order_date": "2025-04-02T06:34:08.012Z",
+          "customer_name": "Typhus",
+          "seat_id": "A13",
+          "items": [
+            {
+              "menu_item_name": "Bier",
+              "amount": 2
+            }
+          ]
+        },
+        headers={"x-password": "Alkohol1"}
+    )
+    print(response)