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import re
import subprocess
import sys

usage = """
Usage:  parse_build_log.py [log_file]

Parses the output of COIN test runs and prints short summaries of compile
errors and test fails for usage as gerrit comment. Takes the file name
(either text or compressed .gz file). The zcat tool is required for
decompressing .gz files.
"""

# Match the log prefix "agent:2019/06/04 12:32:54 agent.go:262:"
prefix_re = re.compile(r'^agent:[\d :/]+\w+\.go:\d+: ')

# Match QTestlib output
start_test_re = re.compile(r'^\*{9} Start testing of \w+ \*{9}$')
end_test_re = re.compile(r'Totals: \d+ passed, (\d+) failed, \d+ skipped, \d+ blacklisted, \d+ms')

# Patterns for errors of common (g++, MSVC, Python)
compiler_errors = (": error: ", ": error C", 'ERROR')

def read_file(file_name):
    """
    Read a text file into a list of of chopped lines.
    """
    with open(file_name) as f:
        return [prefix_re.sub('', l.rstrip()) for l in f.readlines()]


def zcat(file_name):
    """
    Read a gzip'ed text file into a list of of chopped lines by means of
    'zcat'. Note: Python's zipfile module cannot handle .gz
    """
    lines = []

    try:
        std_out = subprocess.Popen(['zcat', file_name],
                                   universal_newlines = 1,
                                   stdout=subprocess.PIPE).stdout
        for line in std_out.readlines():
            lines.append(prefix_re.sub('', line.rstrip()))
        std_out.close()
    except FileNotFoundError:
        print("ERROR: command 'zcat' not found")
        sys.exit(-1)
    return lines


def print_failed_test(lines, start, end):
    """
    For a failed test, print 3 lines following the FAIL!/XPASS and
    header/footer.
    """
    last_fail = -50
    # Print 3 lines after a failure
    print('\n{}: {}'.format(start, lines[start]))
    for i in range(start + 1, end):
        line = lines[i]
        if 'FAIL!' in line or 'XPASS' in line:
            last_fail = i
        if i - last_fail < 4:
            print(line)
    print('{}\n'.format(lines[end]))


def parse(lines):
    """
    Parse the output and print compile/test errors.
    """
    test_start_line = -1
    within_configure_tests = False
    for i, line in enumerate(lines):
        if within_configure_tests:
            if line == 'Done running configuration tests.':
                within_configure_tests = False
        elif test_start_line >= 0:
            end_match = end_test_re.match(line)
            if end_match:
                fails = int(end_match.group(1))
                if fails:
                    print_failed_test(lines, test_start_line, i)
                test_start_line = -1
        elif line == 'Running configuration tests...': # Do not report errors within configuration tests
            within_configure_tests = True
        elif start_test_re.match(line):
            test_start_line = i
        elif any(e in line for e in compiler_errors):
            start = max(0, i - 10)
            sys.stdout.write('\n{}: '.format(start))
            for e in range(start, i + 1):
               print(lines[e])


if __name__ == '__main__':
    if sys.version_info[0] != 3:
        print("This script requires Python 3")
        sys.exit(-2)
    if len(sys.argv) < 2:
        print(usage)
        sys.exit(-1)
    file_name = sys.argv[1]
    lines = zcat(file_name) if file_name.endswith('.gz') else read_file(file_name)
    parse(lines)