#!/usr/bin/env python3

import os
import re
import sys
if sys.version_info[0]>2:
  import _pickle as cPickle
else:
  import cPickle
import argparse
import itertools
import subprocess
import collections
import configparser as ConfigParser
import Alignment.MillePedeAlignmentAlgorithm.mpslib.tools as mps_tools
import Alignment.MillePedeAlignmentAlgorithm.mpslib.Mpslibclass as mpslib
import Alignment.MillePedeAlignmentAlgorithm.mpsvalidate.iniparser as mpsv_iniparser
import Alignment.MillePedeAlignmentAlgorithm.mpsvalidate.trackerTree as mpsv_trackerTree
from Alignment.MillePedeAlignmentAlgorithm.alignmentsetup.helper import checked_out_MPS
from functools import reduce


################################################################################
def main(argv = None):
    """Main routine. Not called, if this module is loaded via `import`.

    Arguments:
    - `argv`: Command line arguments passed to the script.
    """

    if argv == None:
        argv = sys.argv[1:]

    setup_alignment = SetupAlignment(argv)
    setup_alignment.setup()


################################################################################
class SetupAlignment(object):
    """Class encapsulating the alignment campaign setup procedure."""

    def __init__(self, argv):
        """Constructor

        Arguments:
        - `argv`: command line arguments
        """

        self._argv = argv       # raw command line arguments
        self._args = None       # parsed command line arguments
        self._config = None     # ConfigParser object
        self._mss_dir = None    # mass storage directory
        self._datasets = collections.OrderedDict() # final dataset configs
        self._first_run = None   # first run for start geometry
        self._cms_process = None # cms.Process extracted from CMSSW config
        self._override_gt = None # snippet to append to config
        self._pede_script = None # path to pede batch script template
        self._weight_dict = collections.OrderedDict() # dictionary with dataset weights
        self._mille_script = None # path to mille batch script template
        self._mps_dir_name = None # MP campaign name (mp<ID>)
        self._common_weights = {} # dictionary with dataset weights from [weights] section
        self._weight_configs = [] # list with combinations of dataset weights
        self._general_options = {} # general options extracted from ini file
        self._external_datasets = collections.OrderedDict() # external dataset configs
        self._first_pede_config = True # does a pede job exist already?

        self._create_config()
        self._fill_general_options()
        self._fetch_datasets()
        self._construct_paths()
        self._create_mass_storage_directory()
        self._fetch_pede_settings()
        self._create_weight_configs()


    def setup(self):
        """Setup the alignment campaign."""

        if self._args.weight:
            self._create_additional_pede_jobs()
        else:
            self._create_mille_jobs()
            self._create_pede_jobs()

        if self._override_gt.strip() != "":
            msg = ("Overriding global tag with single-IOV tags extracted from "
                   "'{}' for run number '{}'.".format(self._global_tag,
                                                      self._first_run))
            print(msg)
            print("-"*75)
            print(self._override_gt)
            print("="*75)


    def _create_config(self):
        """Create ConfigParser object from command line arguments."""

        helpEpilog ="""Builds the config-templates from a universal
        config-template for each dataset specified in .ini-file that is passed
        to this script.  Then calls mps_setup.py for all datasets."""
        parser = argparse.ArgumentParser(
            description = ("Setup the alignment as configured in the "
                           "alignment_config file."),
            epilog = helpEpilog)
        parser.add_argument("-v", "--verbose", action="store_true",
                            help="display detailed output of mps_setup")
        parser.add_argument("-w", "--weight", action="store_true",
                            help=("creates additional merge job(s) with "
                                  "(possibly new) weights from .ini-config"))
        parser.add_argument("alignmentConfig",
                            help=("name of the .ini config file that specifies "
                                  "the datasets to be used"))

        self._args = parser.parse_args(self._argv)
        self._config = ConfigParser.ConfigParser()
        self._config.optionxform = str # default would give lowercase options
                                       # -> not wanted
        self._config.read(self._args.alignmentConfig)
        self._config.config_path = self._args.alignmentConfig


    def _construct_paths(self):
        """Determine directory paths and create the ones that are needed."""

        mpsTemplates = os.path.join("src", "Alignment",
                                    "MillePedeAlignmentAlgorithm", "templates")
        if checked_out_MPS()[0]:
            mpsTemplates = os.path.join(os.environ["CMSSW_BASE"], mpsTemplates)
        else:
            mpsTemplates = os.path.join(os.environ["CMSSW_RELEASE_BASE"], mpsTemplates)
        self._mille_script = os.path.join(mpsTemplates, "mps_runMille_template.sh")
        self._pede_script  = os.path.join(mpsTemplates, "mps_runPede_rfcp_template.sh")

        # get working directory name
        currentDir = os.getcwd()
        match = re.search(re.compile('mpproduction\/mp(.+?)$', re.M|re.I),currentDir)
        if match:
            self._mps_dir_name = 'mp'+match.group(1)
        else:
            print("Current location does not seem to be a MillePede campaign directory:", end=' ')
            print(currentDir)
            sys.exit(1)


    def _fill_general_options(self):
        """Create and fill `general_options` dictionary."""

        print("="*75)
        self._fetch_dataset_directory()
        self._fetch_external_datasets()
        self._fetch_essentials()
        self._fetch_defaults()


    def _fetch_external_datasets(self):
        """Fetch information about external datasets."""

        if self._config.has_option("general", "externalDatasets"):
            datasets = map(lambda x: x.strip(),
                           self._config.get("general",
                                            "externalDatasets").split(","))
            datasets = [x for x in datasets if len(x.strip()) > 0]
            for item in datasets:
                splitted = item.split("|")
                dataset = splitted[0].strip()
                dataset = os.path.expandvars(dataset)

                weight = splitted[1] if len(splitted) > 1 else None
                config = ConfigParser.ConfigParser()
                config.optionxform = str
                config.read(dataset)
                config.config_path = dataset
                self._external_datasets[dataset] = {"config": config,
                                                    "weight": weight}



    def _create_mass_storage_directory(self):
        """
        Create MPS mass storage directory where, e.g., mille binaries are
        stored.
        """

        # set directory on eos
        self._mss_dir = self._general_options.get("massStorageDir",
                                                  "/eos/cms/store/group/alca_millepede/")
        self._mss_dir = os.path.join(self._mss_dir, "MPproductionFiles",
                                     self._mps_dir_name)

        cmd = ["mkdir", "-p", self._mss_dir]

        # create directory
        if not self._general_options.get("testMode", False):
            try:
                with open(os.devnull, "w") as dump:
                    subprocess.check_call(cmd, stdout = dump, stderr = dump)
            except subprocess.CalledProcessError:
                print("Failed to create mass storage directory:", self._mss_dir)
                sys.exit(1)


    def _create_weight_configs(self):
        """Extract different weight configurations from `self._config`."""

        weights_list = [[(name, weight) for weight in self._weight_dict[name]]
                        for name in self._weight_dict]

        common_weights_list = [[(name, weight)
                                for weight in  self._common_weights[name]]
                               for name in self._common_weights]

        common_weights_dicts = []
        for item in itertools.product(*common_weights_list):
            d = {}
            for name,weight in item:
                d[name] = weight
            common_weights_dicts.append(d)

        weight_configs = []
        for weight_conf in itertools.product(*weights_list):
            number_of_configs = len(weight_configs)
            for common_weight in common_weights_dicts:
                replaced_config \
                    = tuple([(dataset[0],
                              reduce(lambda x,y: mps_tools.replace_factors(x, y, common_weight[y]),
                                     common_weight, dataset[1]))
                             for dataset in weight_conf])
                if replaced_config not in weight_configs:
                    weight_configs.append(replaced_config)

            # default if config contains no common weights:
            if len(weight_configs) == number_of_configs:
                weight_configs.append(weight_conf)

        for weight_config in weight_configs:
            resolved_weight_config \
                = [(dataset[0], mps_tools.compute_product_string(dataset[1]))
                   for dataset in weight_config]
            self._weight_configs.append(resolved_weight_config)


    def _fetch_pede_settings(self):
        """Fetch 'pedesettings' from general section in `self._config`."""

        self._pede_settings \
            = ([x.strip()
                for x in self._config.get("general", "pedesettings").split(",")]
               if self._config.has_option("general", "pedesettings") else [None])


    def _create_mille_jobs(self):
        """Create the mille jobs based on the [dataset:<name>] sections."""

        gt_regex = re.compile('setupGlobaltag\s*\=\s*[\"\'](.*?)[\"\']')
        sg_regex = re.compile("setupRunStartGeometry\s*\=\s*.*$", re.M)
        collection_regex = re.compile('setupCollection\s*\=\s*[\"\'](.*?)[\"\']')
        recogeom_regex = re.compile('setupRecoGeometry\s*\=\s*[\"\'](.*?)[\"\']')
        czt_regex = re.compile('setupCosmicsZeroTesla\s*\=\s*.*$', re.M)
        cdm_regex = re.compile('setupCosmicsDecoMode\s*\=\s*.*$', re.M)
        pw_regex = re.compile('setupPrimaryWidth\s*\=\s*.*$', re.M)
        json_regex = re.compile('setupJson\s*\=\s*.*$', re.M)

        first_dataset = True
        for name, dataset in self._datasets.items():
            print("="*75)
            # Build config from template/Fill in variables
            try:
                with open(dataset["configTemplate"],"r") as f:
                    tmpFile = f.read()
            except IOError:
                print("The config-template called", end=' ')
                print(dataset["configTemplate"], "cannot be found.")
                sys.exit(1)

            tmpFile = re.sub(gt_regex,
                             'setupGlobaltag = \"'+dataset["globaltag"]+'\"',
                             tmpFile)
            tmpFile = re.sub(recogeom_regex,
                             'setupRecoGeometry = \"'+dataset["recogeometry"]+'\"',
                             tmpFile)
            tmpFile = re.sub(sg_regex,
                             "setupRunStartGeometry = "+
                             self._general_options["FirstRunForStartGeometry"], tmpFile)
            tmpFile = re.sub(collection_regex,
                             'setupCollection = \"'+dataset["collection"]+'\"',
                             tmpFile)
            if "ALCARECOTkAlCosmics" in dataset["collection"]:
                if dataset['cosmicsZeroTesla']:
                    tmpFile = re.sub(czt_regex,
                                     'setupCosmicsZeroTesla = True',
                                     tmpFile)
                else :
                    tmpFile = re.sub(czt_regex,
                                    'setupCosmicsZeroTesla = False',
                                     tmpFile)

                if dataset['cosmicsDecoMode']:
                     tmpFile = re.sub(cdm_regex,
                                     'setupCosmicsDecoMode = True',
                                     tmpFile)
                else:
                    tmpFile = re.sub(cdm_regex,
                                     'setupCosmicsDecoMode = False',
                                     tmpFile)

            if dataset['primaryWidth'] > 0.0:
                tmpFile = re.sub(pw_regex,
                                 'setupPrimaryWidth = '+str(dataset["primaryWidth"]),
                                 tmpFile)
            if dataset['json'] != '':
                tmpFile = re.sub(json_regex,
                                 'setupJson = \"'+dataset["json"]+'\"',
                                 tmpFile)

            thisCfgTemplate = "tmp.py"
            with open(thisCfgTemplate, "w") as f:
                f.write(tmpFile)


            # Set mps_setup append option for datasets following the first one
            append = "-a"
            if first_dataset:
                append = ""
                first_dataset = False
                self._config_template = tmpFile
                self._cms_process = mps_tools.get_process_object(thisCfgTemplate)
                self._create_input_db()

            with open(thisCfgTemplate, "a") as f: f.write(self._override_gt)


            # create mps_setup command
            command = ["mps_setup.py",
                       "-m",
                       append,
                       "-M", self._general_options["pedeMem"],
                       "-N", name,
                       self._mille_script,
                       thisCfgTemplate,
                       dataset["inputFileList"],
                       str(dataset["njobs"]),
                       self._general_options["classInf"],
                       self._general_options["jobname"],
                       self._pede_script,
                       "cmscafuser:"+self._mss_dir]
            if dataset["numberOfEvents"] > 0:
                command.extend(["--max-events", str(dataset["numberOfEvents"])])
            command = [x for x in command if len(x.strip()) > 0]

            # Some output:
            print("Creating jobs for dataset:", name)
            print("-"*75)
            print("Baseconfig:        ", dataset["configTemplate"])
            print("Collection:        ", dataset["collection"])
            if "ALCARECOTkAlCosmics" in dataset["collection"]:
                print("cosmicsDecoMode:   ", dataset["cosmicsDecoMode"])
                print("cosmicsZeroTesla:  ", dataset["cosmicsZeroTesla"])
            print("Globaltag:         ", dataset["globaltag"])
            print("RecoGeometry:      ", dataset["recogeometry"])
            print("Number of jobs:    ", dataset["njobs"])
            print("Inputfilelist:     ", dataset["inputFileList"])
            if dataset["json"] != "":
                print("Jsonfile:          ", dataset["json"])
            if self._args.verbose:
                print("Pass to mps_setup: ", " ".join(command))

            # call the command and toggle verbose output
            self._handle_process_call(command, self._args.verbose)

            # remove temporary file
            self._handle_process_call(["rm", thisCfgTemplate])


    def _create_pede_jobs(self):
        """Create pede jobs from the given input."""

        for setting in self._pede_settings:
            print()
            print("="*75)
            if setting is None:
                print("Creating pede job{}.".format(
                    "s" if len(self._pede_settings)*len(self._weight_configs) > 1 else ""))
                print("-"*75)
            else:
                print("Creating pede jobs using settings from '{0}'.".format(setting))
            for weight_conf in self._weight_configs:
                # blank weights
                self._handle_process_call(["mps_weight.pl", "-c"])

                thisCfgTemplate = "tmp.py"
                with open(thisCfgTemplate, "w") as f: f.write(self._config_template)
                if self._override_gt is None:
                    self._cms_process = mps_tools.get_process_object(thisCfgTemplate)
                    self._create_input_db()
                with open(thisCfgTemplate, "a") as f: f.write(self._override_gt)

                for name,weight in weight_conf:
                    self._handle_process_call(["mps_weight.pl", "-N", name, weight], True)

                if not self._first_pede_config:
                    # create new mergejob
                    self._handle_process_call(["mps_setupm.pl"], self._args.verbose)

                # read mps.db to find directory of new mergejob
                lib = mpslib.jobdatabase()
                lib.read_db()

                # short cut for jobm path
                jobm_path = os.path.join("jobData", lib.JOBDIR[-1])

                # delete old merge-config
                command = ["rm", "-f", os.path.join(jobm_path, "alignment_merge.py")]
                self._handle_process_call(command, self._args.verbose)

                # create new merge-config
                command = [
                    "mps_merge.py",
                    "-w", thisCfgTemplate,
                    os.path.join(jobm_path, "alignment_merge.py"),
                    jobm_path,
                    str(lib.nJobs),
                ]
                if setting is not None: command.extend(["-a", setting])
                print("-"*75)
                print(" ".join(command))
                self._handle_process_call(command, self._args.verbose)
                self._create_tracker_tree()
                if self._first_pede_config:
                    os.symlink(self._tracker_tree_path,
                               os.path.abspath(os.path.join(jobm_path,
                                                            ".TrackerTree.root")))
                    self._first_pede_config = False

                # store weights configuration
                with open(os.path.join(jobm_path, ".weights.pkl"), "wb") as f:
                    cPickle.dump(weight_conf, f, 2)
                print("="*75)

        # remove temporary file
        self._handle_process_call(["rm", thisCfgTemplate])


    def _create_additional_pede_jobs(self):
        """
        Create pede jobs in addition to already existing ones. Return GT
        override snippet.
        """

        # do some basic checks
        if not os.path.isdir("jobData"):
            print("No jobData-folder found.", end=' ')
            print("Properly set up the alignment before using the -w option.")
            sys.exit(1)
        if not os.path.exists("mps.db"):
            print("No mps.db found.", end=' ')
            print("Properly set up the alignment before using the -w option.")
            sys.exit(1)

        firstDataset = next(iter(self._datasets.values()))
        config_template = firstDataset["configTemplate"]
        collection = firstDataset["collection"]

        try:
            with open(config_template,"r") as f:
                tmpFile = f.read()
        except IOError:
            print("The config-template '"+config_template+"' cannot be found.")
            sys.exit(1)

        tmpFile = re.sub('setupGlobaltag\s*\=\s*[\"\'](.*?)[\"\']',
                         'setupGlobaltag = \"'+self._global_tag+'\"',
                         tmpFile)
        tmpFile = re.sub('setupRecoGeometry\s*\=\s*[\"\'](.*?)[\"\']',
                         'setupRecoGeometry = \"'+self._reco_geometry+'\"',
                         tmpFile)
        tmpFile = re.sub('setupCollection\s*\=\s*[\"\'](.*?)[\"\']',
                         'setupCollection = \"'+collection+'\"',
                         tmpFile)
        tmpFile = re.sub(re.compile("setupRunStartGeometry\s*\=\s*.*$", re.M),
                         "setupRunStartGeometry = "+self._first_run,
                         tmpFile)
        self._config_template = tmpFile

        # first pede job exists already in this mode:
        self._first_pede_config = False
        self._create_pede_jobs()


    def _handle_process_call(self, command, verbose = False):
        """
        Wrapper around subprocess calls which treats output depending on verbosity
        level.

        Arguments:
        - `command`: list of command items
        - `verbose`: flag to turn on verbosity
        """

        call_method = subprocess.check_call if verbose else subprocess.check_output
        try:
            call_method(command, stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as e:
            print("" if verbose else e.output)
            print("Failed to execute command:", " ".join(command))
            sys.exit(1)


    def _create_input_db(self):
        """
        Create sqlite file with single-IOV tags and use it to override the
        GT. If the GT is already customized by the user, the customization has
        higher priority. Creates a snippet to be appended to the configuration
        file.
        """

        run_number = int(self._first_run)
        if not run_number > 0:
            print("'FirstRunForStartGeometry' must be positive, but is", run_number)
            sys.exit(1)

        input_db_name = os.path.abspath("alignment_input.db")
        tags = mps_tools.create_single_iov_db(self._check_iov_definition(),
                                              run_number, input_db_name)

        self._override_gt = ""
        for record,tag in tags.items():
            if self._override_gt == "":
                self._override_gt \
                    += ("\nimport "
                        "Alignment.MillePedeAlignmentAlgorithm.alignmentsetup."
                        "SetCondition as tagwriter\n")
            self._override_gt += ("\ntagwriter.setCondition(process,\n"
                                  "       connect = \""+tag["connect"]+"\",\n"
                                  "       record = \""+record+"\",\n"
                                  "       tag = \""+tag["tag"]+"\")\n")


    def _check_iov_definition(self):
        """
        Check consistency of input alignment payloads and IOV definition.
        Returns a dictionary with the information needed to override possibly
        problematic input taken from the global tag.
        """

        print("Checking consistency of IOV definition...")
        iovs = mps_tools.make_unique_runranges(self._cms_process.AlignmentProducer)

        inputs = {
            "TrackerAlignmentRcd": None,
            "TrackerSurfaceDeformationRcd": None,
            "TrackerAlignmentErrorExtendedRcd": None,
        }

        for condition in self._cms_process.GlobalTag.toGet.value():
            if condition.record.value() in inputs:
                inputs[condition.record.value()] = {
                    "tag": condition.tag.value(),
                    "connect": ("pro"
                                if not condition.hasParameter("connect")
                                else condition.connect.value())
                }

        inputs_from_gt = [record for record in inputs if inputs[record] is None]
        inputs.update(
            mps_tools.get_tags(self._cms_process.GlobalTag.globaltag.value(),
                               inputs_from_gt))

        if int(self._first_run) != iovs[0]:     # simple consistency check
            if iovs[0] == 1 and len(iovs) == 1:
                print("Single IOV output detected in configuration and", end=' ')
                print("'FirstRunForStartGeometry' is not 1.")
                print("Creating single IOV output from input conditions in run", end=' ')
                print(self._first_run+".")
                for inp in inputs: inputs[inp]["problematic"] = True
            else:
                print("Value of 'FirstRunForStartGeometry' has to match first", end=' ')
                print("defined output IOV:", end=' ')
                print(self._first_run, "!=", iovs[0])
                sys.exit(1)

        for inp in inputs.values():
            inp["iovs"] = mps_tools.get_iovs(inp["connect"], inp["tag"])

        # check consistency of input with output
        problematic_gt_inputs = {}
        input_indices = {key: len(value["iovs"]) -1
                         for key,value in inputs.items()}
        for iov in reversed(iovs):
            for inp in inputs:
                if inputs[inp].pop("problematic", False):
                    problematic_gt_inputs[inp] = inputs[inp]
                if inp in problematic_gt_inputs: continue
                if input_indices[inp] < 0:
                    print("First output IOV boundary at run", iov, end=' ')
                    print("is before the first input IOV boundary at", end=' ')
                    print(inputs[inp]["iovs"][0], "for '"+inp+"'.")
                    print("Please check your run range selection.")
                    sys.exit(1)
                input_iov = inputs[inp]["iovs"][input_indices[inp]]
                if iov < input_iov:
                    if inp in inputs_from_gt:
                        problematic_gt_inputs[inp] = inputs[inp]
                        print("Found problematic input taken from global tag.")
                        print("Input IOV boundary at run",input_iov, end=' ')
                        print("for '"+inp+"' is within output IOV starting", end=' ')
                        print("with run", str(iov)+".")
                        print("Deriving an alignment with coarse IOV", end=' ')
                        print("granularity starting from finer granularity", end=' ')
                        print("leads to wrong results.")
                        print("A single IOV input using the IOV of", end=' ')
                        print("'FirstRunForStartGeometry' ("+self._first_run+")", end=' ')
                        print("is automatically created and used.")
                        continue
                    print("Found input IOV boundary at run",input_iov, end=' ')
                    print("for '"+inp+"' which is within output IOV starting", end=' ')
                    print("with run", str(iov)+".")
                    print("Deriving an alignment with coarse IOV granularity", end=' ')
                    print("starting from finer granularity leads to wrong", end=' ')
                    print("results.")
                    print("Please check your run range selection.")
                    sys.exit(1)
                elif iov == input_iov:
                    input_indices[inp] -= 1

        # check consistency of 'TrackerAlignmentRcd' with other inputs
        input_indices = {key: len(value["iovs"]) -1
                         for key,value in inputs.items()
                         if (key != "TrackerAlignmentRcd")
                         and (inp not in problematic_gt_inputs)}
        for iov in reversed(inputs["TrackerAlignmentRcd"]["iovs"]):
            for inp in input_indices:
                input_iov = inputs[inp]["iovs"][input_indices[inp]]
                if iov < input_iov:
                    print("Found input IOV boundary at run",input_iov, end=' ')
                    print("for '"+inp+"' which is within 'TrackerAlignmentRcd'", end=' ')
                    print("IOV starting with run", str(iov)+".")
                    print("Deriving an alignment with inconsistent IOV boundaries", end=' ')
                    print("leads to wrong results.")
                    print("Please check your input IOVs.")
                    sys.exit(1)
                elif iov == input_iov:
                    input_indices[inp] -= 1

        print(" -> IOV consistency check successful.")
        print("="*75)

        return problematic_gt_inputs


    def _create_tracker_tree(self):
        """Method to create hidden 'TrackerTree.root'."""

        if self._global_tag is None or self._first_run is None:
            print("Trying to create the tracker tree before setting the global", end=' ')
            print("tag or the run to determine the geometry IOV.")
            sys.exit(1)

        config = mpsv_iniparser.ConfigData()
        config.jobDataPath = "."    # current directory
        config.globalTag = self._global_tag
        #config.recoGeometry = self._reco_geometry
        config.firstRun = self._first_run
        self._tracker_tree_path = mpsv_trackerTree.check(config)


    def _fetch_essentials(self):
        """Fetch general options from config file."""

        for var in ("classInf","pedeMem","jobname", "FirstRunForStartGeometry"):
            try:
                self._general_options[var] = self._config.get('general',var)
            except ConfigParser.NoOptionError:
                print("No", var, "found in [general] section.", end=' ')
                print("Please check ini-file.")
                sys.exit(1)
        self._first_run = self._general_options["FirstRunForStartGeometry"]


    def _fetch_defaults(self):
        """Fetch default general options from config file."""

        for var in ("globaltag", "recogeometry", "configTemplate", "json", "massStorageDir",
                    "testMode"):
            try:
                self._general_options[var] = self._config.get("general", var)
            except ConfigParser.NoOptionError:
                if var == "testMode": continue
                print("No '" + var + "' given in [general] section.")

        for dataset in self._external_datasets.values():
            dataset["general"] = {}
            for var in ("globaltag", "recogeometry", "configTemplate", "json"):
                try:
                    dataset["general"][var] = dataset["config"].get("general", var)
                except (ConfigParser.NoSectionError,ConfigParser.NoOptionError):
                    pass


    def _fetch_dataset_directory(self):
        """
        Fetch 'datasetDir' variable from general section and add it to the
        'os.environ' dictionary.
        """

        if self._config.has_option("general", "datasetdir"):
            dataset_directory = self._config.get("general", "datasetdir")
            # add it to environment for later variable expansion:
            os.environ["datasetdir"] = dataset_directory
            self._general_options["datasetdir"] = dataset_directory
        else:
            print("No datasetdir given in [general] section.", end=' ')
            print("Be sure to give a full path in inputFileList.")
            self._general_options["datasetdir"] = ""


    def _fetch_datasets(self):
        """Fetch internal and external dataset configurations."""

        all_configs = collections.OrderedDict()
        all_configs["main"] = {"config": self._config,
                               "general": self._general_options,
                               "weight": None}
        all_configs.update(self._external_datasets)

        for config in all_configs.values():
            global_weight = "1" if config["weight"] is None else config["weight"]
            if global_weight+self._config.config_path in self._common_weights:
                global_weight = self._common_weights[global_weight+
                                                     self._config.config_path]
            elif global_weight in self._common_weights:
                global_weight = self._common_weights[global_weight]
            else:
                global_weight = (global_weight,)
            common_weights = {}
            weight_dict = {}
            for section in config["config"].sections():
                cache_datasetdir = os.environ["datasetdir"]
                if "general" in section:
                    if config["config"].has_option("general", "datasetdir"):
                        os.environ["datasetdir"] = config["config"].get("general", "datasetdir")
                elif section == "weights":
                    for option in config["config"].options(section):
                        common_weights[option] \
                            = [x.strip() for x in
                               config["config"].get(section, option).split(",")]
                elif section.startswith("dataset:"):
                    print("-"*75)
                    # set name from section-name
                    name = section[8:]
                    if name in self._datasets:
                        print("WARNING: Duplicate definition of dataset '{}'".format(name))
                        print(" -> Using defintion in '{}':\n".format(config["config"].config_path))
                        print("    [{}]".format(section))
                        for k,v in config["config"].items(section):
                            print("   ", k, "=", v)
                        print()
                    self._datasets[name] = {}

                    # extract weight for the dataset
                    if config["config"].has_option(section, "weight"):
                        self._weight_dict[name] \
                            = [x.strip() for x in
                               config["config"].get(section, "weight").split(",")]
                    else:
                        self._weight_dict[name] = ["1.0"]
                    self._weight_dict[name] = [global_w+"*"+w
                                               for w in self._weight_dict[name]
                                               for global_w in global_weight]
                    weight_dict[name] = self._weight_dict[name]

                    # extract essential variables
                    for var in ("inputFileList", "collection"):
                        try:
                            self._datasets[name][var] = config["config"].get(section, var)
                        except ConfigParser.NoOptionError:
                            print("No", var, "found in", section+". Please check ini-file.")
                            sys.exit(1)

                    # get globaltag and configTemplate. If none in section, try to get
                    # default from [general] section.
                    for var in ("configTemplate", "globaltag"):
                        try:
                            self._datasets[name][var] = config["config"].get(section, var)
                        except (ConfigParser.NoSectionError,ConfigParser.NoOptionError):
                            try:
                                self._datasets[name][var] = config["general"][var]
                            except KeyError:
                                try:
                                    self._datasets[name][var] \
                                        = all_configs["main"]["general"][var]
                                except KeyError:
                                    print("No",var,"found in ["+section+"]", end=' ')
                                    print("and no default in [general] section.")
                                    sys.exit(1)

                    # get recogeometry and configTemplate. If none in section, try to get
                    # default from [general] section.
                    for var in ("configTemplate", "recogeometry"):
                        try:
                            self._datasets[name][var] = config["config"].get(section, var)
                        except (ConfigParser.NoSectionError,ConfigParser.NoOptionError):
                            try:
                                self._datasets[name][var] = config["general"][var]
                            except KeyError:
                                try:
                                    self._datasets[name][var] \
                                        = all_configs["main"]["general"][var]
                                except KeyError:
                                    print("No",var,"found in ["+section+"]", end=' ')
                                    print("and no default in [general] section.")
                                    sys.exit(1)

                    # extract non-essential options
                    if "ALCARECOTkAlCosmics" in self._datasets[name]["collection"]:
                        try:
                            self._datasets[name]["cosmicsZeroTesla"] \
                                = config["config"].getboolean(section,"cosmicsZeroTesla")
                        except ConfigParser.NoOptionError:
                            print("No option cosmicsZeroTesla found in", section,"even though it is required for dataset type", self._datasets[name]["collection"], ". Please check ini-file.")
                            sys.exit(1)
                        try:
                            self._datasets[name]["cosmicsDecoMode"] \
                                = config["config"].getboolean(section,"cosmicsDecoMode")
                        except ConfigParser.NoOptionError:
                            print("No option cosmicsDecoMode found in", section,"even though it is required for dataset type", self._datasets[name]["collection"], ".Please check ini-file.")
                            sys.exit(1)

                    self._datasets[name]["primaryWidth"] = -1.0
                    if config["config"].has_option(section,"primaryWidth"):
                        self._datasets[name]["primaryWidth"] \
                            = config["config"].getfloat(section,"primaryWidth")

                    self._datasets[name]["numberOfEvents"] = -1
                    if config["config"].has_option(section, "numberOfEvents"):
                        self._datasets[name]["numberOfEvents"] \
                            = config["config"].getint(section, "numberOfEvents")

                    self._datasets[name]["json"] = ""
                    try:
                        self._datasets[name]["json"] = config["config"].get(section,"json")
                    except ConfigParser.NoOptionError:
                        try:
                            self._datasets[name]["json"] = config["general"]["json"]
                        except KeyError:
                            try:
                                self._datasets[name]["json"] \
                                    = all_configs["main"]["general"]["json"]
                            except KeyError:
                                print("No json given in either [general] or", end=' ')
                                print("["+section+"] sections.")
                                print(" -> Proceeding without json-file.")


                    #replace ${datasetdir} and other variables, e.g. $CMSSW_BASE
                    for var in ("inputFileList", "json", "configTemplate"):
                        self._datasets[name][var] \
                            = os.path.expandvars(self._datasets[name][var])


                    # Get number of jobs from lines in inputfilelist
                    self._datasets[name]["njobs"] = 0
                    try:
                        with open(self._datasets[name]["inputFileList"], "r") as filelist:
                            for line in filelist:
                                if "CastorPool" in line:
                                    continue
                                # ignore empty lines
                                if not line.strip()=="":
                                    self._datasets[name]["njobs"] += 1
                    except IOError:
                        print("Inputfilelist", self._datasets[name]["inputFileList"], end=' ')
                        print("does not exist.")
                        sys.exit(1)
                    if self._datasets[name]["njobs"] == 0:
                        print("Number of jobs is 0. There may be a problem with the inputfilelist:")
                        print(self._datasets[name]["inputFileList"])
                        sys.exit(1)

                    # Check if njobs gets overwritten in .ini-file
                    if config["config"].has_option(section, "njobs"):
                        if config["config"].getint(section, "njobs") <= self._datasets[name]["njobs"]:
                            self._datasets[name]["njobs"] = config["config"].getint(section, "njobs")
                        else:
                            print("'njobs' is bigger than the number of files for this", end=' ')
                            print("dataset:", self._datasets[name]["njobs"])
                            print("Using default.")
                    else:
                        print("No number of jobs specified. Using number of files in", end=' ')
                        print("inputfilelist as the number of jobs.")

            # check if local weights override global weights and resolve name clashes
            for weight_name, weight_values in common_weights.items():
                for key, weight in weight_dict.items():
                    if any([weight_name in w for w in weight]):
                        self._common_weights[weight_name+config["config"].config_path] = weight_values
                        self._weight_dict[key] = [mps_tools.replace_factors(w,
                                                                            weight_name,
                                                                            weight_name+config["config"].config_path)
                                                  for w in weight]
                    else:
                        self._common_weights[weight_name] = weight_values
                        self._weight_dict[key] = weight

            os.environ["datasetdir"] = cache_datasetdir

        if len(self._datasets) == 0:
            print("No dataset section defined in '{0}'".format(
                ", ".join([self._args.aligmentConfig]+self._external_datasets.keys())))
            print("At least one section '[dataset:<name>]' is required.")
            sys.exit(1)

        self._global_tag = self._datasets[name]["globaltag"]
        self._reco_geometry = self._datasets[name]["recogeometry"]

################################################################################
if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass