#!/usr/bin/env python3
"""Combine logs from multiple bitcoin nodes as well as the test_framework log.

This streams the combined log output to stdout. Use combine_logs.py > outputfile
to write to an outputfile."""

import argparse
from collections import defaultdict, namedtuple
import heapq
import itertools
import os
import re
import sys

# Matches on the date format at the start of the log event
TIMESTAMP_PATTERN = re.compile(r"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{6}Z")

LogEvent = namedtuple('LogEvent', ['timestamp', 'source', 'event'])


def main():
    """Main function. Parses args, reads the log files and renders them as text or html."""

    parser = argparse.ArgumentParser(
        usage='%(prog)s [options] <test temporary directory>', description=__doc__)
    parser.add_argument('-c', '--color', dest='color', action='store_true',
                        help='outputs the combined log with events colored by source (requires posix terminal colors. Use less -r for viewing)')
    parser.add_argument('--html', dest='html', action='store_true',
                        help='outputs the combined log as html. Requires jinja2. pip install jinja2')
    args, unknown_args = parser.parse_known_args()

    if args.color and os.name != 'posix':
        print("Color output requires posix terminal colors.")
        sys.exit(1)

    if args.html and args.color:
        print("Only one out of --color or --html should be specified")
        sys.exit(1)

    # There should only be one unknown argument - the path of the temporary test directory
    if len(unknown_args) != 1:
        print("Unexpected arguments" + str(unknown_args))
        sys.exit(1)

    log_events = read_logs(unknown_args[0])

    print_logs(log_events, color=args.color, html=args.html)


def read_logs(tmp_dir):
    """Reads log files.

    Delegates to generator function get_log_events() to provide individual log events
    for each of the input log files."""

    files = [("test", "{}/test_framework.log".format(tmp_dir))]
    for i in itertools.count():
        logfile = "{}/node{}/regtest/debug.log".format(tmp_dir, i)
        if not os.path.isfile(logfile):
            break
        files.append(("node{}".format(i), logfile))

    return heapq.merge(*[get_log_events(source, f) for source, f in files])


def get_log_events(source, logfile):
    """Generator function that returns individual log events.

    Log events may be split over multiple lines. We use the timestamp
    regex match as the marker for a new log event."""
    try:
        with open(logfile, 'r') as infile:
            event = ''
            timestamp = ''
            for line in infile:
                # skip blank lines
                if line == '\n':
                    continue
                # if this line has a timestamp, it's the start of a new log event.
                time_match = TIMESTAMP_PATTERN.match(line)
                if time_match:
                    if event:
                        yield LogEvent(timestamp=timestamp, source=source, event=event.rstrip())
                    event = line
                    timestamp = time_match.group()
                # if it doesn't have a timestamp, it's a continuation line of the previous log.
                else:
                    event += "\n" + line
            # Flush the final event
            yield LogEvent(timestamp=timestamp, source=source, event=event.rstrip())
    except FileNotFoundError:
        print("File {} could not be opened. Continuing without it.".format(logfile), file=sys.stderr)


def print_logs(log_events, color=False, html=False):
    """Renders the iterator of log events into text or html."""
    if not html:
        colors = defaultdict(lambda: '')
        if color:
            colors["test"] = "\033[0;36m"   # CYAN
            colors["node0"] = "\033[0;34m"  # BLUE
            colors["node1"] = "\033[0;32m"  # GREEN
            colors["node2"] = "\033[0;31m"  # RED
            colors["node3"] = "\033[0;33m"  # YELLOW
            colors["reset"] = "\033[0m"     # Reset font color

        for event in log_events:
            print("{0} {1: <5} {2} {3}".format(
                colors[event.source.rstrip()], event.source, event.event, colors["reset"]))

    else:
        try:
            import jinja2
        except ImportError:
            print("jinja2 not found. Try `pip install jinja2`")
            sys.exit(1)
        print(jinja2.Environment(loader=jinja2.FileSystemLoader('./'))
                    .get_template('combined_log_template.html')
                    .render(title="Combined Logs from testcase", log_events=[event._asdict() for event in log_events]))


if __name__ == '__main__':
    main()