#!/usr/bin/env python3

import argparse
import re
import sys

def main(argv):
    parser = argparse.ArgumentParser(
        prog='parse-time-output',
        description='Parse the output of /usr/bin/time and output it in LNT-compatible format.')
    parser.add_argument('input_file', type=argparse.FileType('r'), default='-',
        help='Path of the file to extract results from. By default, stdin.')
    parser.add_argument('--benchmark', type=str, required=True,
        help='The name of the benchmark to use in the resulting LNT output.')
    parser.add_argument('--extract', type=str, choices=['instructions', 'max_rss', 'cycles', 'peak_memory'], nargs='+',
        help='The name of the metrics to extract from the time output.')
    args = parser.parse_args(argv)

    # Mapping from metric names to field names in the time output.
    field_mapping = {
        'instructions': 'instructions retired',
        'max_rss': 'maximum resident set size',
        'cycles': 'cycles elapsed',
        'peak_memory': 'peak memory footprint',
    }
    to_extract = [field_mapping[e] for e in args.extract]

    metrics = {}
    for line in args.input_file:
        match = re.match(r'\s*(\d+)\s+(\w+.*)', line)
        if match is not None:
            time_desc = match.group(2)
            for metric, desc in field_mapping.items():
                if time_desc == desc:
                    metrics[metric] = int(match.group(1))
                    break

    for metric, value in metrics.items():
        print(f'{args.benchmark}.{metric} {value}')

if __name__ == '__main__':
    main(sys.argv[1:])