add printer out-of-paper warning and track app.py

Show a yellow warning banner on page load if CUPS reports the printer
is stopped with a paper-related reason (e.g. Media Empty).

home/print/app.py

@@ -0,0 +1,138 @@
+import os
+import subprocess
+from pathlib import Path
+
+import pypdf
+from flask import Flask, flash, redirect, render_template, request, url_for
+from werkzeug.utils import secure_filename
+
+UPLOAD_FOLDER = str(Path(__file__).parent / "uploads")
+ALLOWED_EXTENSIONS = {"pdf"}
+PRINTER_NAME = "HL-2270DW_series"
+MAX_PAGES = 10
+MAX_COPIES = 10
+
+app = Flask(__name__)
+app.config["UPLOAD_FOLDER"] = UPLOAD_FOLDER
+app.config["SECRET_KEY"] = os.urandom(24)
+app.config["MAX_CONTENT_LENGTH"] = 16 * 1024 * 1024
+
+
+def allowed_file(filename):
+    return "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS
+
+
+def get_printer_warning():
+    try:
+        result = subprocess.run(
+            ["lpstat", "-l", "-p", PRINTER_NAME],
+            capture_output=True, text=True, timeout=3
+        )
+        output = result.stdout.lower()
+        first_line = result.stdout.splitlines()[0] if result.stdout else ""
+        if "stopped" in first_line.lower() or "offline" in first_line.lower():
+            paper_keywords = ("media empty", "out of paper", "paper", "tray empty", "no media")
+            if any(kw in output for kw in paper_keywords):
+                return "Printer appears to be out of paper."
+            return "Printer is stopped or offline and may not accept jobs."
+    except Exception:
+        pass
+    return None
+
+
+def get_pdf_page_count(filepath):
+    try:
+        with open(filepath, "rb") as f:
+            reader = pypdf.PdfReader(f)
+            return len(reader.pages)
+    except Exception as e:
+        app.logger.error(f"Could not read PDF pages: {e}")
+        return None
+
+
+@app.route("/", methods=["GET", "POST"])
+def upload_and_print():
+    if request.method == "POST":
+        if "file" not in request.files:
+            flash("No file part in the request.", "error")
+            return redirect(request.url)
+
+        file = request.files["file"]
+
+        if file.filename == "":
+            flash("No file selected. Please choose a PDF to print.", "error")
+            return redirect(request.url)
+
+        if file and allowed_file(file.filename):
+            try:
+                copies = int(request.form.get("copies", 1))
+            except ValueError:
+                copies = 1
+            copies = max(1, min(copies, MAX_COPIES))
+
+            filename = secure_filename(file.filename)
+            os.makedirs(app.config["UPLOAD_FOLDER"], exist_ok=True)
+            filepath = os.path.join(app.config["UPLOAD_FOLDER"], filename)
+            file.save(filepath)
+
+            try:
+                page_count = get_pdf_page_count(filepath)
+                if page_count is None:
+                    flash(
+                        "Could not process the PDF file. It might be corrupt.", "error"
+                    )
+                    return redirect(request.url)
+
+                if page_count > MAX_PAGES:
+                    flash(
+                        f"Error: File has {page_count} pages. The maximum allowed is {MAX_PAGES}.",
+                        "error",
+                    )
+                    return redirect(request.url)
+
+                app.logger.info(
+                    f"Sending '{filename}' ({page_count} pages, {copies} copies) to printer '{PRINTER_NAME}'"
+                )
+                command = [
+                    "lp",
+                    "-d",
+                    PRINTER_NAME,
+                    "-n",
+                    str(copies),
+                    filepath,
+                ]
+                result = subprocess.run(
+                    command, capture_output=True, text=True, check=True
+                )
+                app.logger.info(f"lp command stdout: {result.stdout}")
+                copy_word = "copy" if copies == 1 else "copies"
+                flash(f"Success! '{filename}' ({copies} {copy_word}) has been sent to the printer.", "success")
+
+            except subprocess.CalledProcessError as e:
+                app.logger.error(f"Error printing file: {e}")
+                app.logger.error(f"lp command stderr: {e.stderr}")
+                flash(
+                    "Error sending file to printer. The printer may be offline or misconfigured.",
+                    "error",
+                )
+
+            except Exception as e:
+                app.logger.error(f"An unexpected error occurred: {e}")
+                flash("An unexpected server error occurred.", "error")
+
+            finally:
+                if os.path.exists(filepath):
+                    os.remove(filepath)
+                    app.logger.info(f"Cleaned up temporary file: {filepath}")
+
+            return redirect(url_for("upload_and_print"))
+
+        else:
+            flash("Invalid file type. Please upload a PDF file.", "error")
+            return redirect(request.url)
+
+    return render_template("index.html", printer_name=PRINTER_NAME, max_pages=MAX_PAGES, max_copies=MAX_COPIES, printer_warning=get_printer_warning())
+
+
+if __name__ == "__main__":
+    app.run(host="127.0.0.1", port=57928, debug=False)