#!/usr/bin/env python3

"""
This utility script helps in the creation of experiment setups. It therefore
reads experiment descriptions from json files and creates everything necessary
as a result.

It therefore performs the following actions:
* [x] Read the json file of every experiment
* [x] Create folders for every experiment
* [ ] Create the header file for every experiment
* [x] Add the make file for every experiment
* [x] Add c++ file for every experiment
"""

import sys
import os
import argparse
import shutil
import json
import pystache

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 create_dir(filename):
    """
    Create the directory denoted by filename, if it doesn't exists. Ask for its
    removal if it exists.
    """
    try:
        os.makedirs(filename)
    except FileExistsError:
        if not query_yes_no('Folder exists, remove?', default='yes'):
            return False
        shutil.rmtree(filename)
        os.makedirs(filename)
    return True

def create_header(headerfile, experiment, destination):
    """
    Create a header file for the experiment.
    """
    with open(headerfile, 'r') as header_template:
        template = header_template.read()
    header_txt = pystache.render(template, experiment)
    with open(destination, 'w') as header:
        print(header_txt, file=header)

def main():
    """
    Starting point of the script, parses arguments and creates the experiments.
    """

    parser = argparse.ArgumentParser(description='Generate experiment data.')
    parser.add_argument('description', type=str, nargs='+', help='file containing the taskset description.')
    parser.add_argument('--header', dest='header', type=str, nargs='?', default='./template/defines.h', help='path to optional custom header file.')
    parser.add_argument('--makefile', dest='makefile', type=str, nargs='?', default='./template/Makefile', help='path to optional custom makefile.')
    parser.add_argument('--cpp', dest='cpp', type=str, nargs='*', default='./template/experiment.cpp', help='path to optional custom c++ implementation.')

    args = parser.parse_args()
    cwd = os.getcwd()

    for num, experiment_file in enumerate(args.description):
        with open(experiment_file, 'r') as experiment_description:
            descr_json = experiment_description.read()
        experiment = json.loads(descr_json)

        print('[{}/{}] Creating experiment {}:'.format(num + 1,
                                                       len(args.description),
                                                       experiment['name']),
              file=sys.stderr)

        experiment_dir = os.path.join(cwd, experiment['name'])

        # Create folder
        print('Create folder…', experiment_dir, file=sys.stderr)
        if not create_dir(experiment_dir):
            print('Skipping experiment ', experiment['name'], file=sys.stderr)
            continue

        # Add header
        print('Create header file…', file=sys.stderr)
        header_path = os.path.join(experiment_dir, 'defines.h')
        create_header(args.header, experiment, header_dir)

        # Add makefile & c++ file
        print('Adding Makefile…', file=sys.stderr)
        makefile_path = os.path.join(experiment_dir, 'Makefile')
        shutil.copyfile(args.makefile, makefile_path)
        print('Add C++ file(s)…', file=sys.stderr)
        cpp_file_path = os.path.join(experiment_dir, 'experiment.cpp')
        shutil.copyfile(args.cpp, cpp_file_path)

if __name__ == '__main__':
    main()