add support for config files

default config is

  /etc/cups/cups-pdf-postprocess.conf

cups-pdf-postprocess.py

@@ -14,6 +14,8 @@ import subprocess as sp
 import ast
 import os
 
+CONFIG_FILE = "/etc/cups/cups-pdf-postprocess.conf"
+
 def exec_pipeline(pipeline, inp, out = None, err_callback = None):
   def make_proc(cmd):
     p = QProcess()
@@ -55,21 +57,13 @@ def exec_pipeline(pipeline, inp, out = None, err_callback = None):
       QApplication.instance().processEvents()
 
 
-SAVE_AS_FILE = object()
-
-PRINTERS = ast.literal_eval("[\n%s\n]" % "".join(sys.stdin))
-PRINTERS.append(("Save as ...", SAVE_AS_FILE))
 
-for l in sp.check_output(["lpstat", "-a"]).decode("UTF-8").split("\n"):
-  p = l.split(" ")[0]
-  if p == "":
-    continue
-  PRINTERS.append((p, ["lp", "-d", p]))
 
 class CPP(QWidget):
-  def __init__(self, pdf, user):
+  def __init__(self, config, pdf, user):
     super().__init__()
     self._pdf = pdf
+    self._config = config
 
     vbox = QVBoxLayout()
     vbox.addStretch(1)
@@ -232,7 +226,28 @@ class CPP(QWidget):
 DIR = os.path.dirname(os.path.realpath(sys.argv[0]))
 
 if __name__ == '__main__':
-  app = QApplication(sys.argv[2:])
-  ex = CPP(sys.argv[1], sys.argv[2])
+  args = sys.argv
+  if args[1] == '-c':
+    CONFIG_FILE = args[2]
+    args = args[2:]
+  else:
+    CONFIG_FILE = os.getenv('CUPS_PDF_POSTPROCESS_CONFIG', CONFIG_FILE)
+
+  with open(CONFIG_FILE) as config:
+    CONFIG = ast.literal_eval("{\n%s\n}" % config.read())
+
+  SAVE_AS_FILE = object()
+
+  PRINTERS = CONFIG.get("printers", [])
+  PRINTERS.append(("Save as ...", SAVE_AS_FILE))
+
+  for l in sp.check_output(["lpstat", "-a"]).decode("UTF-8").split("\n"):
+    p = l.split(" ")[0]
+    if p == "":
+      continue
+    PRINTERS.append((p, ["lp", "-d", p]))
+
+  app = QApplication(args[2:])
+  ex = CPP(CONFIG, args[1], args[2])
   sys.exit(app.exec_())