changelog-merge

#!/usr/bin/python
from __future__ import print_function
import sys
import re
from dateutil.parser import parse


class Entry(object):
    def __init__(self, filenum, fileindex):
        self.lines = []
        self.filenum = filenum
        self.fileindex = fileindex
        self.tstamp = None

    def hash(self):
        hash(self.join())

    def body(self):
        return "".join(self.lines[1:])

    def join(self):
        return "".join(self.lines)


def scanlines(f1, f2):
    entries1 = []
    entries2 = []
    def scanlines(tgt, f, fileidx):
        curr = None
        curridx = 0
        for line in f.readlines():
            if re.match(r'^-+$', line.strip()):
                if curr is not None:
                    tgt.append(curr)
                    curr = None
                curr = Entry(0, curridx)
                curridx += 1
            if curr is not None:
                curr.lines.append(line)
            if curr is not None and curr.tstamp is None:
                m = re.match(r'^(.*)\s+-\s+.*', line)
                if m:
                    curr.tstamp = parse(m.group(1))
        if curr is not None:
            if curr.tstamp is None:
                print("Entry {}:{} has no timestamp".format(curr.filenum, curr.fileindex))
            tgt.append(curr)
            curr = None
    scanlines(entries1, f1, 1)
    scanlines(entries2, f2, 2)
    return entries1, entries2

def merge(entries1, entries2):
    for e in entries1:
        h = e.hash()
        entries2 = [f for f in entries2 if e.tstamp != f.tstamp or f.hash() != h]
    entries = []
    for f in entries1:
        keep = True
        fh = f.body()
        for g in entries2:
            gh = g.body()
            if fh == gh:
                if g.tstamp > f.tstamp:
                    keep = False
        if keep:
            entries.append(f)
    entries.extend(entries2)
    entries.sort(key=lambda e: e.tstamp)
    entries.reverse()
    for e in entries:
        print(e.join(), end="")

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: {} <changelog1> <changelog2>".format(sys.argv[0]), file=sys.stderr)
        sys.exit(1)
    with open(sys.argv[1], "rt") as log1:
        with open(sys.argv[2], "rt") as log2:
            entries1, entries2 = scanlines(log1, log2)
            merge(entries1, entries2)