inject_blame.py

import re
import time
import linecache
from subprocess import check_output

DAY = 60 * 60 * 24

BLAME_REGEX = re.compile(
    r"(?P<commit>\w+)\s+"
    r"(?P<file>\S+)\s+"
    r"\(<(?P<author>\S+@.*)>\s+"
    r"(?P<timestamp>[-\d]+ [:\d]+ [-+]\d+)\s+"
    r"(?P<lineno>\d+)\) "
    r"(?P<line>.*)"
)


def inject_blame(fname):
    raw = check_output(["git", "blame", fname, "-ef"])
    now = time.time()
    linecache.getlines(fname)  # force-load the file to cache
    cache = linecache.cache[fname]  # extract the cache entry

    annotated_lines = []
    for line in raw.decode().splitlines():
        match = BLAME_REGEX.match(line)
        if match:
            parsed = match.groupdict()

            # convert the timestamp to something more user-friendly
            line_time = time.mktime(time.strptime(parsed['timestamp'], "%Y-%m-%d %H:%M:%S %z"))
            time_ago = now - line_time
            if time_ago <= DAY:
                when = "today"
            else:
                when = f"{int(round(time_ago / DAY))}d ago"

            # format the line with annotation
            line = "{line:80}  ###  edited {when} by {author} in {commit:8.8}".format(when=when, **parsed)
        else:
            pass  # our regex failed - we keep the line untouched

        annotated_lines.append(line.rstrip("") + "\n")

    # unpack the cache entry, discarding the 'lines' element
    size, mtime, _, fullname = cache
    # replacing the cache entry with thew annotated lines element
    linecache.cache[fname] = size, mtime, annotated_lines, fullname