dtcs.py

import json
import util

#SAE DTCs are sourced from the 2012 document in the federal register

#Powertrain SAE DTC ranges:
#P0001–P0099: Fuel and air metering, auxiliary emissions controls
#P0100–P0199: Fuel and air metering
#P0200–P0299: Fuel and air metering (injector circuit)
#P0300–P0399: Ignition system or misfire
#P0400–P0499: Auxiliary emissions controls
#P0500–P0599: Vehicle speed controls, and idle control systems
#P0600–P0699: Computer output circuit
#P0700–P0799: Transmission
#P1000-P1999: OEM DTC
#P3000-P3999: OEM/SAE Reserved.

#B0000-B0999: SAE
#B1000-B2999: OEM
#B3000-B3999: Reserved By Document (As of 2012)

#Chassis Ranges: same as above
#Network: Same


#interface designed so that internet DTC lookups can be called in the future
class DTCProvider:
  def query(self, dtc):
    raise NotImplementedError("DTCProvider cannot be called directly")

class JSONDTCProvider(DTCProvider):
  def __init__(self, json, manufacturer=None):
    self.js = json.parse(json) #dict of manufacturer VIN codes, each a dict of associated DTCs.
    self.man = manufacturer #this is the VIN-prefix, not a name.
    
  def query(self, dtc): #P3000 to P3399 are OEM, P3400 to P3999 are SAE.
    if dtc[1] == "0" or dtc[1] == "2" or dtc[1] == "3": #try SAE DTC
      if dtc[1] != "3": #3 is "probably" SAE DTC, but also an OEM prefix in some cases.
        try:
          return self.js[self.man][dtc]
        except KeyError:
          util.log(3,"Unknown SAE Standard DTC '{}'! contact maintainer".format(dtc))
          return "<Unknown SAE DTC>"
      elif dtc in self.js["SAE"]: #is the DTC a known standard one?
        return self.js["SAE"][dtc]
    if not self.man or not self.man in self.js: #we don't have a manufacturer, or we don't have a DTC table for that manufacturer.
      return "<Unknown OEM DTC - No OEM DTCs loaded>"
    if dtc in self.js[self.man]:
      return self.js[self.man][dtc]
    return "<Unknown OEM DTC>"
  
#relevant schema: 'dtc' column is DTC "text" form, and 'en' column is DTC description (in english)
class SQLiteDTCProvider(DTCProvider):
  def __init__(self, path, manufacturer=None):
    self.db = sqlite3.open(path)
    self.man = manufacturer #VIN prefix, not a name.
    raise NotImplementedError("SQLite DTC databases are currently unsupported")

  def __enter__(self):
    pass
  def __exit__(self, a,b,c):
    if self.db:
      self.db.close()
      self.db = None