#!/usr/bin/env python3

"""
Generates real time tasksets according to the method described in 'A Comparison
of Global and Partitioned EDF Schedulability Tests for Multiprocessors'.
Therefore tasks with random periods within the range 1 to 100 are generated.
Depending on the mode, the utilization of these tasks is either determined by
* uniform distribution between 1/period and 1
* bimodal distribution heavy tasks with uniform distribution between 0.5 / 1 and
light tasks uniform between 0.1 and 0.5 where the probability of being heavy
is 1/3
* exponential distribution with mean 0.25
* exponential distribution with mean 0.50
"""

import datetime
import shutil
import sys
import os
import random
import argparse
import json
import math
import copy
from enum import Enum

def query_yes_no(question, default=None):
    """
    Queries the user for a decision.
    """

    if default is None:
        prompt = ' [y/n]'
    elif default.lower() == 'yes':
        prompt = ' [Y/n]'
    elif default.lower() == 'no':
        prompt = ' [y/N]'
    else:
        raise ValueError('Invalid default answer {}'.format(default))

    while True:
        print(question, prompt, end='')
        choice = input().lower()
        if 'yes'.find(choice) == 0:
            return True
        elif 'no'.find(choice) == 0:
            return False

def gcd(a, b):
    if b == 0:
        return a
    return gcd(b, a % b)

def lcm(a, b):
    return (a * b) / gcd(a, b)

def hyperperiod(tasks):
    try:
        periods = [task.period for task in tasks]
        hyperperiod = periods[0]
        for period in periods[1:]:
            hyperperiod = lcm(hyperperiod, period)
        return hyperperiod
    except IndexError:
        return 0

class Timebase(Enum):
    seconds = 1
    milliseconds = 2
    microseconds = 3
    nanoseconds = 4

class Distribution(Enum):
    uniform = 1
    bimodal = 2
    exp_quart = 3
    exp_half = 4

class Task:
    """
    Representation of a generated task.
    """
    def __init__(self, wcet, period, deadline):
        self.wcet = int(wcet)
        self.period = int(period)
        self.deadline = int(deadline)

def calc_utilization(tasklist):
    sum = 0
    for task in tasklist:
        sum += task.wcet / task.period
    return sum

def get_timebase_string(base):
    if base is Timebase.seconds:
        return 'std::chrono::seconds', 'embb::base::DurationSeconds'
    elif base is Timebase.milliseconds:
        return 'std::chrono::milliseconds', 'embb::base::DurationMilliseconds'
    elif base is Timebase.microseconds:
        return 'std::chrono::microseconds', 'embb::base::DurationMicroseconds'
    elif base is Timebase.nanoseconds:
        return 'std::chrono::nanoseconds', 'embb::base::DurationNanoseconds'

def create_task(distribution):
    period = random.uniform(10, 100)
    if distribution is Distribution.uniform:
        util = random.uniform(1.0 / period, 1.0)
    elif distribution is Distribution.bimodal:
        check = random.uniform(0.0, 1.0)
        if check < 1 / 3:
            util = random.uniform(0.5, 1.0)
        else:
            util = random.uniform(1.0 / period, 1.0)
    elif distribution is Distribution.exp_quart:
        util = random.expovariant(1.0 / 0.25)
    elif distribution is Distribution.exp_half:
        util = random.expovariant(1.0 / 0.5)
    util = min(1.0, max(0.0, util))
    wcet = period * util

    deadline = random.uniform(wcet, period)

    return Task(wcet, period, deadline)

def main():
    parser = argparse.ArgumentParser(description='Generate tasksets.')
    parser.add_argument('cores', type=int, help='Number of cores the taskset'
                                                'should be generated for.')
    parser.add_argument('tasksetcount', type=int, help='Number of tasksets that'
                                                       'should be generated.')
    parser.add_argument('target', type=str, help='Output directory.', nargs='?',
                        default='.')
    parser.add_argument('experiment_target', type=str, help='Output directory for experiments.', nargs='?',
                        default='.')

    parser.add_argument('--utilization', type=float, help='The utility for which tasksets should be generated. Is a range such as 2.5 3.5', nargs=2)

    parser.add_argument('--baseclock', type=str, default='system_clock',
                        nargs='?',
                        help='The clock which is to be used for the execution.')

    timebase_grp = parser.add_mutually_exclusive_group(required=True)
    timebase_grp.add_argument('--seconds', action='store_const',
                              const=Timebase.seconds)
    timebase_grp.add_argument('--milliseconds', action='store_const',
                              const=Timebase.milliseconds)
    timebase_grp.add_argument('--microseconds', action='store_const',
                              const=Timebase.microseconds)
    timebase_grp.add_argument('--nanoseconds', action='store_const',
                              const=Timebase.nanoseconds)

    distr_grp = parser.add_mutually_exclusive_group()
    distr_grp.add_argument('--uniform', action='store_const',
                           const=Distribution.uniform)
    distr_grp.add_argument('--bimodal', action='store_const',
                           const=Distribution.bimodal)
    distr_grp.add_argument('--exp_quart', action='store_const',
                           const=Distribution.exp_quart)
    distr_grp.add_argument('--exp_half', action='store_const',
                           const=Distribution.exp_half)

    args = parser.parse_args()

    if args.seconds is not None:
        timebase = args.seconds
    elif args.milliseconds is not None:
        timebase = args.milliseconds
    elif args.microseconds is not None:
        timebase = args.microseconds
    elif args.nanoseconds is not None:
        timebase = args.nanoseconds

    if args.uniform is not None:
        distribution = args.uniform
    elif args.bimodal is not None:
        distribution = args.bimodal
    elif args.exp_quart is not None:
        distribution = args.exp_quart
    elif args.exp_half is not None:
        distribution = args.exp_half
    else:
        distribution = Distribution.uniform

    utility = None
    try:
        utility = args.utilization
    except AttributeError:
        pass

    print('Generating tasks…', file=sys.stderr)
    tasksets = []
    while len(tasksets) < args.tasksetcount:
        taskset = []
        if utility is None:
            while len(taskset) < args.cores + 1 or \
                  calc_utilization(taskset) <= args.cores and \
                  hyperperiod(taskset) < 300000: # Limit hyperperiod to 5 minutes
                taskset.append(create_task(distribution))
                if len(taskset) >= args.cores + 1:
                    tasksets.append(taskset)
        else:
            taskset_util = 0
            while taskset_util < utility[1] and hyperperiod(taskset) < 300000:
                taskset.append(create_task(distribution))
                taskset_util = calc_utilization(taskset)
                if utility[0] <= taskset_util <= utility[1]:
                    if len(taskset) >= args.cores + 1:
                        tasksets.append(taskset)
                        taskset = copy.deepcopy(taskset)

    now = datetime.datetime.now()

    cpp_base, embb_base = get_timebase_string(timebase)

    try:
        os.makedirs(args.target)
    except FileExistsError:
        if not query_yes_no('Folder exists, remove?', default='yes'):
            sys.exit(1)
    shutil.rmtree(args.target)
    os.makedirs(args.target)

    print('Writing tasks…', file=sys.stderr)
    taken_names={}
    for taskset in tasksets:
        task_out = []
        for task in taskset:
            out = {}
            out['wcet'] = task.wcet
            out['period'] = task.period
            out['deadline'] = task.deadline
            task_out.append(out)

        utilization = str(round(calc_utilization(taskset), 2))
        utilization.replace('.', '_')

        name = 'taskset_{}_{}_{}'.format(now.strftime('%Y_%m_%d_%H_%M_%S'),
                                                len(taskset),
                                                utilization)
        try:
            taken_names[name] += 1
        except KeyError:
            taken_names[name] = 1

        name += '_{}'.format(taken_names[name])

        out = {}
        out['name'] = name
        out['template'] = 'templates/normal/'
        out['includes'] = [ { 'name' : '<embb/base/duration.h>' } ]
        out['cpp_time_base'] = cpp_base
        out['embb_time_base'] = embb_base
        out['base_clock'] = 'std::chrono::system_clock'
        out['data_description'] = [
                                    { 'name' : 'task',
                                      'fields' : [
                                                    {
                                                        'type' : 'int',
                                                        'name' : 'wcet'
                                                    },
                                                    {
                                                        'type' : 'int',
                                                        'name' : 'period'
                                                    },
                                                    {
                                                        'type' : 'int',
                                                        'name' : 'deadline'
                                                    },
                                                    {
                                                        'type' : 'int',
                                                        'name' : 'count'
                                                    }
                                                 ]
                                    }
                                  ]
        out['data'] = [
                          {
                              'type' : 'task',
                              'name' : 'taskset',
                              'elem' : task_out
                          }
                      ]
        try:
            out['output'] = args.experiment_target
        except KeyError:
            pass

        outname = os.path.join(args.target, name + '.json')
        with open(outname, 'w') as outfile:
            outfile.write(json.dumps(out))

if __name__ == '__main__':
    main()