#!/usr/bin/python3
import os, sys, subprocess, time

class Commit:
    def __init__(self, hash, text):
        self.hash = hash
        self.text = text
        self.parents = []
        self.time = None
        for line in text.split(b'\n'):
            words = line.split()
            if not words:
                break
            if words[0] == b'parent':
                self.parents.append(words[1].decode('utf-8'))
            elif words[0] == b'committer':
                self.time = int(words[-2].decode('utf-8'))

class Gread:
    def __init__(self):
        self.git = 'git'
        cmd = [self.git, 'cat-file', '--batch']
        self.kid = subprocess.Popen(cmd,
                                    stdin=subprocess.PIPE,
                                    stdout=subprocess.PIPE)

    def read_commit_raw(self, hash):
        self.kid.stdin.write(hash.encode('utf-8') + b'\n')
        self.kid.stdin.flush()
        result = self.kid.stdout.readline().split()
        if result[1] != b'commit':
            raise OSError(result)

        length = int(result[2].decode('utf-8'))

        text = self.kid.stdout.read(length)
        nl = self.kid.stdout.read(1)
        if nl != b'\n':
            raise IOError(result, text, nl)

        return hash, text

    def read_commit(self, hash):
        hash, text = self.read_commit_raw(hash)
        return Commit(hash, text)

    def walk(self, start):
        "Yield all commits ancestral to start."
        stack = [start]
        seen = set()
        while stack:
            hash = stack.pop()
            if hash in seen:
                continue
            seen.add(hash)

            commit = self.read_commit(hash)
            yield commit
            for parent in commit.parents:
                stack.append(parent)

def day_of(time_t):
    "Counts days from the epoch in UTC."
    return time_t // 86400

def power_of(base, n):
    "Return true iff n is a power of base."
    while n and 0 == n % base:
        n //= base
    return n == 1

if __name__ == '__main__':
    today = day_of(time.time())
    g = Gread()
    for commit in g.walk('HEAD'): 
        delta = today - day_of(commit.time)
        if power_of(3, delta):
            #print(commit.hash)
            subprocess.run([g.git, 'show', '-s', commit.hash])
            #print(commit.text.decode('utf-8'))