reboost

#!/usr/bin/env python
# Toss this in your ~/bin/ as ~/bin/reboost and `chmod +x ~/bin/reboost`
"""\
Usage:
    reboost [cmd]

Commands:
    first  - follow upstream until just before master
    last - follow downstreams all the way
    up - go to parent
    down - go to child
    all - rebase & follow downstream, rebasing all the way
"""

from collections import defaultdict
import subprocess
import os
import sys
import re

example = '''\
  examples-7           c377c75 [gen-files-6: ahead 2] wrong call
  flow-ast-2           751352e [initial-diff-setup-1: ahead 1, behind 1] Add flowtype ast parsing for rn-codegen
  gen-files-6          7c56ae7 [marshall-code-5: ahead 1] Implement swift class generation
* initial-diff-setup-1 29c611a [master: ahead 2] use error
  marshall-code-5      9fe3d2e [vc-props-4: ahead 1] Implement serialization and deserialization [ReactNative codegen]
  master               2ca33d5 [origin/master] empty readme
  saved                e87821b [phab-prep: gone] docs
  signatures-3         2642f3f [flow-ast-2: ahead 1] Implement type signature generation [ReactNative codegen]
  vc-props-4           9f0b957 [signatures-3: ahead 1] Implement code gen for the ViewController's properties'''

rx = '\s*(\*)?\s*(\S+)\s+(\S+)\s+(.+)'

def parse_branches(txt):
    lines = txt.strip().split('\n')
    current = None
    children = defaultdict(list)

    parents = {}
    for line in lines:
        line = line.strip()
        match = re.match(rx, line)
        if not match:
            print ">> unexpected output line from git branch: %s" % line
            continue
        is_current, name, sha, extra = match.groups()
        if is_current is not None:
            current = name

        if extra[0] != '[':
            # no parent
            # TODO maybe keep track of commit message?
            continue

        parentage = extra[1:].split('] ', 1)[0]

        if ':' not in parentage:
            parent = parentage
            status = ''
        else:
            parent, status = parentage.split(': ', 1)

        children[parent].append(name)
        parents[name] = (parent, status)
    if not current:
        raise Exception('Current branch not found')

    return current, parents, children

def get_branches():
    return parse_branches(subprocess.check_output(['git', 'branch', '-vv']))

def get_children():
    current, parents, children = get_branches()
    return children[current]

def get_next_branch():
    children = get_children()
    if not children:
        return # no children, reached the end
    if len(children) != 1:
        raise Exception("Current branch must have only one child")
    child = children[0]
    return child

def rebase_children():
    for i in range(20):
        child = get_next_branch()
        if not child:
            print "No more children"
            break
        print "Moving to", child
        subprocess.check_call(['git', 'checkout', child], stdout=sys.stdout, stderr=sys.stderr)
        subprocess.check_call(['git', 'rebase'], stdout=sys.stdout, stderr=sys.stderr)

def go_to_first():
    current, parents, _ = get_branches()
    while current in parents and parents[current][0] != 'master':
        current = parents[current][0]
    print "Checkout", current
    subprocess.check_call(['git', 'checkout', current])

def go_to_last():
    current, _, children = get_branches()
    while len(children[current]) == 1:
        current = children[current][0]
    print "Checkout", current
    subprocess.check_call(['git', 'checkout', current])

def go_to_parent():
    current, parents, _ = get_branches()
    if parents[current][0] != 'master':
        current = parents[current][0]
    print "Checkout", current
    subprocess.check_call(['git', 'checkout', current])

def go_to_child():
    current, _, children = get_branches()
    if len(children[current]) == 1:
        current = children[current][0]
    print "Checkout", current
    subprocess.check_call(['git', 'checkout', current])

def show_pedigree():
    current, parents, children = get_branches()
    branch = current
    while len(children[branch]) == 1:
        branch = children[branch][0]
    while branch in parents:
        print ('* ' if branch == current else '  ') + branch + ': ' + parents[branch][1]
        branch = parents[branch][0]
    print ('* ' if branch == current else '  ') + branch, '(root)'

def print_help():
    try:
        current, parents, children = get_branches()
        print "Status:"
        print " - current: ", current
        print " - parent: ", parents[current]
        print " - children: ", children[current]
        print
    except:
        pass
    print __doc__

if len(sys.argv) > 1:
    cmd = sys.argv[1]
    if cmd == 'first':
        go_to_first()
    elif cmd == 'last':
        go_to_last()
    elif cmd == 'up':
        go_to_parent()
    elif cmd == 'down':
        go_to_child()
    elif cmd == 'all':
        rebase_children()
    elif cmd in ('l', 'list', 'll'):
        show_pedigree()
    else:
        print_help()
else:
    print_help()