Added printing module

Pipfile

@@ -18,6 +18,7 @@ httpx = "*"
 PyYAML = "==5.3"
 wolframalpha = "*"
 Mastodon-py = "*"
+pycups = "*"
 
 [dev-packages]
 pylint = "*"

README.md

@@ -379,9 +379,6 @@ NOTE: disabled by default
 If enabled, Jitsi calls created with Matrix clients will be sent as text messages
 to rooms, allowing non-matrix users to join them.
 
-Note: Currently supports only calls placed from Element Web. Android version
-sends different messages and has not yet been reverse engineered.
-
 ### Mastodon
 
 Send toots to Mastodon. You can login to Mastodon with the bot and toot with it.
@@ -432,6 +429,26 @@ File uploads, joins, leaves or other special events are not (yet) handled. Contr
 
 Relaybots are stupid. Please prefer real Matrix bridges to this. Sometimes there's no alternative.
 
+### Printing
+
+With this module you can set up a room to print any uploaded files on a specified printer.
+The printer must be visible to bot via CUPS.
+
+Commands (all can be done by bot owner only):
+
+* !printing list - Lists available printers and their rooms
+* !printing setroomprinter [printername] - Assignes given printer to this room
+* !printing rmroomprinter - Deletes printer from this room
+
+The module sends the files to CUPS for printing so please see CUPS documentation
+on what works and what doesn't.
+
+Tested formats: PDF, JPG, PNG
+
+SVG files are printed as text currently, avoid printing them.
+
+This module is disabled by default.
+
 ## Bot setup
 
 * Create a Matrix user

modules/printing.py

@@ -0,0 +1,110 @@
+from modules.common.module import BotModule
+from nio import RoomMessageMedia
+from typing import Optional
+import sys
+import traceback
+import cups
+import httpx
+import asyncio
+import aiofiles
+import os
+
+# Credit: https://medium.com/swlh/how-to-boost-your-python-apps-using-httpx-and-asynchronous-calls-9cfe6f63d6ad
+async def download_file(url: str, filename: Optional[str] = None) -> str:
+    filename = filename or url.split("/")[-1]
+    filename = f"/tmp/{filename}"
+    client = httpx.AsyncClient()
+    async with client.stream("GET", url) as resp:
+        resp.raise_for_status()
+        async with aiofiles.open(filename, "wb") as f:
+            async for data in resp.aiter_bytes():
+                if data:
+                    await f.write(data)
+    await client.aclose()
+    return filename
+
+class MatrixModule(BotModule):
+    def __init__(self, name):
+        super().__init__(name)
+        self.printers = dict() # roomid <-> printername
+        self.bot = None
+        self.paper_size = 'A4' # Todo: configurable
+        self.enabled = False
+
+    async def file_cb(self, room, event):
+        try:
+            if self.bot.should_ignore_event(event):
+                return
+            if room.room_id in self.printers:
+                printer = self.printers[room.room_id]
+                self.logger.debug(f'RX file - MXC {event.url} - from {event.sender}')
+                https_url = await self.bot.client.mxc_to_http(event.url)
+                self.logger.debug(f'HTTPS URL {https_url}')
+                filename = await download_file(https_url)
+                self.logger.debug(f'RX filename {filename}')
+                conn = cups.Connection ()
+                conn.printFile(printer, filename, f"Printed from Matrix - {filename}", {'fit-to-page': 'TRUE', 'PageSize': self.paper_size})
+                await self.bot.send_text(room, f'Printing file on {printer}..')
+                os.remove(filename) # Not sure if we should wait first?
+            else:
+                self.logger.debug(f'No printer configured for room {room.room_id}')
+        except:
+                self.logger.warning(f"File callback failure")
+                traceback.print_exc(file=sys.stderr)
+                await self.bot.send_text(room, f'Printing failed, sorry. See log for details.')
+
+    def matrix_start(self, bot):
+        super().matrix_start(bot)
+        bot.client.add_event_callback(self.file_cb, RoomMessageMedia)
+        self.bot = bot
+
+    def matrix_stop(self, bot):
+        super().matrix_stop(bot)
+        bot.remove_callback(self.file_cb)
+        self.bot = None
+
+    async def matrix_message(self, bot, room, event):
+        bot.must_be_owner(event)
+        args = event.body.split()
+        args.pop(0)
+        conn = cups.Connection ()
+        printers = conn.getPrinters ()
+
+        if len(args) == 1:
+            if args[0] == 'list':
+                msg = f"Available printers:\n"
+                for printer in printers:
+                    print(printer, printers[printer]["device-uri"])
+                    msg += f' - {printer}  /  {printers[printer]["device-uri"]}'
+                    for roomid, printerid in self.printers.items():
+                        if printerid == printer:
+                            msg += f' <- room {roomid}'
+                    msg += '\n'
+                await bot.send_text(room, msg)
+            elif args[0] == 'rmroomprinter':
+                del self.printers[room.room_id]
+                await bot.send_text(room, f'Deleted printer from this room.')
+                bot.save_settings()
+
+        if len(args) == 2:
+            if args[0] == 'setroomprinter':
+                printer = args[1]
+                if printer in printers:
+                    await bot.send_text(room, f'Printing with {printer} here.')
+                    self.printers[room.room_id] = printer
+                    bot.save_settings()
+                else:
+                    await bot.send_text(room, f'No printer called {printer} in your CUPS.')
+
+    def help(self):
+        return 'Print files from Matrix'
+
+    def get_settings(self):
+        data = super().get_settings()
+        data["printers"] = self.printers
+        return data
+
+    def set_settings(self, data):
+        super().set_settings(data)
+        if data.get("printers"):
+            self.printers = data["printers"]