"""

django_extensions.management.jobs

"""

import os

from imp import find_module

_jobs = None

def noneimplementation(meth):

    return None

class JobError(Exception):

    pass

class BaseJob(object):

    help = "undefined job description."

    when = None

    def execute(self):

        raise NotImplementedError("Job needs to implement the execute method")

class HourlyJob(BaseJob):

    when = "hourly"

class DailyJob(BaseJob):

    when = "daily"

class WeeklyJob(BaseJob):

    when = "weekly"

class MonthlyJob(BaseJob):

    when = "monthly"

def my_import(name):

    imp = __import__(name)

    mods = name.split('.')

    if len(mods)>1:

        for mod in mods[1:]:

            imp = getattr(imp, mod)

    return imp

def find_jobs(jobs_dir):

    try:

        return [f[:-3] for f in os.listdir(jobs_dir) \

                if not f.startswith('_') and f.endswith(".py")]

    except OSError:

        return []

def find_job_module(app_name, when=None):

    parts = app_name.split('.')

    parts.append('jobs')

    if when:

        parts.append(when)

    parts.reverse()

    path = None

    while parts:

        part = parts.pop()

        f, path, descr = find_module(part, path and [path] or None)

    return path

def import_job(app_name, name, when=None):

    jobmodule = "%s.jobs.%s%s" % (app_name, when and "%s." % when or "", name)

    job_mod = my_import(jobmodule)

    # todo: more friendly message for AttributeError if job_mod does not exist

    try:

        job = job_mod.Job

    except:

        raise JobError("Job module %s does not contain class instance named 'Job'" % jobmodule)

    if when and not (job.when == when or job.when == None):

        raise JobError("Job %s is not a %s job." % (jobmodule, when))

    return job

def get_jobs(when=None, only_scheduled=False):

    """

    Returns a dictionary mapping of job names together with there respective

    application class.

    """

    global _jobs

    # FIXME: HACK: make sure the project dir is on the path when executed as ./manage.py

    import sys

    try:

        cpath = os.path.dirname(os.path.realpath(sys.argv[0]))

        ppath = os.path.dirname(cpath)

        if ppath not in sys.path:

            sys.path.append(ppath)

    except:

        pass

    if _jobs is None:

        _jobs = {}

        if True:

            from django.conf import settings

            for app_name in settings.INSTALLED_APPS:

                scandirs = (None, 'hourly', 'daily', 'weekly', 'monthly')

                if when:

                    scandirs = None, when

                for subdir in scandirs:

                    try:

                        path = find_job_module(app_name, subdir)

                        for name in find_jobs(path):

                            if (app_name, name) in _jobs:

                                raise JobError("Duplicate job %s" % name)

                            job = import_job(app_name, name, subdir)

                            if only_scheduled and job.when == None:

                                # only include jobs which are scheduled

                                continue

                            if when and job.when != when:

                                # generic job not in same schedule

                                continue

                            _jobs[(app_name, name)] = job

                    except ImportError:

                        pass # No job module -- continue scanning

    return _jobs

def get_job(app_name, job_name):

    jobs = get_jobs()

    if app_name:

        return jobs[(app_name, job_name)]

    else:

        for a, j in jobs.keys():

            if j==job_name:

                return jobs[(a, j)]

        raise KeyError("Job not found: %s" % job_name)

def print_jobs(when=None, only_scheduled=False, show_when=True, \

                show_appname=False, show_header=True):

    jobmap = get_jobs(when, only_scheduled=only_scheduled)

    print "Job List: %i jobs" % len(jobmap)

    jlist = jobmap.keys()

    jlist.sort()

    appname_spacer = "%%-%is" % max(len(e[0]) for e in jlist)

    name_spacer = "%%-%is" % max(len(e[1]) for e in jlist)

    when_spacer = "%%-%is" % max(len(e.when) for e in jobmap.values() if e.when)

    if show_header:

        line = " "

        if show_appname:

            line += appname_spacer % "appname" + " - "

        line += name_spacer % "jobname"

        if show_when:

            line += " - " + when_spacer % "when"

        line += " - help"

        print line

        print "-"*80

    for app_name, job_name in jlist:

        job = jobmap[(app_name, job_name)]

        line = " "

        if show_appname:

            line += appname_spacer % app_name + " - "

        line += name_spacer % job_name

        if show_when:

            line += " - " + when_spacer % (job.when and job.when or "")

        line += " - " + job.help

        print line