switch-api-branch

#!/usr/bin/env python3

"""
First, you'll need the following repos checked out side by side:

  src (name doesn't matter)
   |-- api       https://github.com/temporalio/api/
   |-- cli       https://github.com/temporalio/cli/
   |-- api-go    https://github.com/temporalio/api-go/
   |-- sdk-go    https://github.com/temporalio/sdk-go/
   \-- temporal  https://github.com/temporalio/temporal/

You'll also need to run this if you haven't already, to allow local submodules:
  git config --global protocol.file.allow always

Next, pick a branch name. For example, we'll use "fig".

Go into src or any of the repos.

Run "switch-api-branch fig". This does the following:

- In api:
  - switch to branch fig, creating it if necessary
  - make proto to check it's good

- In api-go:
  - switch to branch fig, creating it if necessary
  - set the url and branch of the proto/api submodule to point to your local api repo
  - update the proto/api submodule with the latest commit in api
  - make proto

- In sdk-go and cli:
  - switch to branch fig, creating it if necessary
  - add or update a replace directive in go.mod for api-go (and sdk-go for cli)

- In temporal:
  - switch to branch fig, creating it if necessary
  - set the url and branch of the proto/api submodule to point to your local api repo
  - update the proto/api submodule with the latest commit in api
  - add or update replace directives in go.mod for api-go and sdk-go
  - make proto

After all that happens, you should be good to develop on your branch across
repos. You can make changes in any of the four repos and run "switch-api-branch
fig" again, and everything will be updated and regenerated. (It's idempotent.)

To go back to normal, run "switch-api-branch main" (or "master").

switch-api-branch will create "NOT FOR MERGE: ..." commits with its changes, but
it will never push anything. You have to manually push and make PRs to api,
sdk-go, and temporal, as necessary. (PRs to api-go are usually not necessary.)

Suggested procedure: Let the PR to api land first, then api-go will be updated
automatically. Rebase your changes to temporal and/or sdk-go on top of master,
using an interactive rebase, and during that step, remove the "NOT FOR MERGE"
changes. Make sure they still work, then send PRs.
---
"""
# TODO: automate that rebasing procedure
# TODO: generate rpc client wrappers in server too
# TODO: run whatever codegen steps make sense in sdk-go
# TODO: do stuff for internal repos too?

import sys, os, argparse, subprocess

REPOS = ['api', 'api-go', 'sdk-go', 'cli', 'temporal']
ARGS = None

def run(*args, **kwargs):
    print(f"+++ {' '.join(args)}")
    return subprocess.run(args, check=True, **kwargs)

def git(*args, **kwargs):
    return run("git", *args, **kwargs)

def git_out(*args, **kwargs):
    return git(*args, capture_output=True, **kwargs).stdout.decode()

def repo_path(repo):
    return os.path.join(ARGS.base, repo)

def cd_repo(repo):
    print(f"+++ chdir {repo}")
    os.chdir(repo_path(repo))

def find_base():
    while os.getcwd() != '/':
        if set(REPOS) <= set(os.listdir()):
            return os.getcwd()
        os.chdir('..')
    raise Exception("can't find dir containing all repos")

def is_main(b):
    return b in ('main', 'master')

def find_main():
    out = git_out('branch', '--format', '%(refname:short) %(upstream:remotename)')
    for line in out.splitlines():
        try:
            short, remote = line.split()
            if is_main(short):
                return short, remote
        except ValueError:
            pass
    raise Exception(f"Can't find main/master branch in {os.getcwd()}")

def switch_or_create(branch, initial='FETCH_HEAD'):
    main, remote = find_main()
    if is_main(branch): # back to normal
        branch = main
    if (git_out('branch', '--list', branch) or
        git_out('branch', '--list', '--remotes', f'{remote}/{branch}')):
        git('switch', branch)
    else: # branch does not exist, create it
        git('fetch', remote, main)
        git('switch', '-c', branch, initial)
    # always update submodules when creating/switching branches
    git('submodule', 'update', '--init', '--recursive')

def check_for_uncommitted_changes():
    if git_out('status', '--short', '--untracked-files=no'):
        raise Exception(f"You have uncommitted changes in {os.getcwd()}")

def git_ci(msg, *paths):
    msg = "NOT FOR MERGE: " + msg
    try:
        if not paths: paths = ['-a']
        git('commit', '-m', msg, *paths)
    except subprocess.CalledProcessError:
        # ignore "nothing to commit". TODO: check the details of the error
        pass

def set_submodule(sub, path, branch):
    # Note: path must be an absolute path here! Otherwise git will do something
    # very unexpected.
    git('submodule', 'set-url', sub, path)
    git('submodule', 'set-branch', '--branch', branch, sub)
    git_ci("setting submodule", '.gitmodules')

def update_submodules(*subs):
    git('submodule', 'update', '--init', '--recursive', '--remote', *subs)
    git_ci("updating submodule", *subs)

def go_mod_replace(pairs):
    for pkg, path in pairs:
        run('go', 'mod', 'edit', f'-replace={pkg}={path}')
    run('go', 'mod', 'tidy')
    git_ci("updating go.mod", 'go.mod', 'go.sum')

def make_proto(*commit_paths):
    run('make', 'proto')
    if commit_paths:
        # use explicit paths to catch any potential new files, but try to avoid
        # deliberate untracked files that might be lying around
        git_ci("make proto", *commit_paths)

def switch():
    resetting = is_main(ARGS.branch)

    cd_repo('api')
    check_for_uncommitted_changes()
    switch_or_create(ARGS.branch)
    if not resetting:
        make_proto()

    cd_repo('api-go')
    check_for_uncommitted_changes()
    switch_or_create(ARGS.branch)
    if not resetting:
        set_submodule('proto/api', repo_path('api'), ARGS.branch)
        update_submodules('proto/api')
        make_proto('.') # generated files are at root of repo

    cd_repo('sdk-go')
    check_for_uncommitted_changes()
    switch_or_create(ARGS.branch)
    if not resetting:
        go_mod_replace([('go.temporal.io/api', repo_path('api-go'))])

    cd_repo('temporal')
    check_for_uncommitted_changes()
    switch_or_create(ARGS.branch)
    if not resetting:
        set_submodule('proto/api', repo_path('api'), ARGS.branch)
        update_submodules('proto/api')
        go_mod_replace([('go.temporal.io/api', repo_path('api-go')),
                        ('go.temporal.io/sdk', repo_path('sdk-go'))])
        make_proto('api') # generated files are all contained in api/

    cd_repo('cli')
    check_for_uncommitted_changes()
    switch_or_create(ARGS.branch)
    if not resetting:
        go_mod_replace([('go.temporal.io/api', repo_path('api-go')),
                        ('go.temporal.io/sdk', repo_path('sdk-go')),
                        ('go.temporal.io/server', repo_path('temporal')),
                        ])

    print(f"ready to develop on branch {ARGS.branch}")

def main():
    p = argparse.ArgumentParser(usage=__doc__)
    p.add_argument('branch', type=str, help="branch to switch to")
    p.add_argument('--base', type=str, help="parent dir of all repos")
    global ARGS
    ARGS = p.parse_args()
    if ARGS.base is None:
        ARGS.base = find_base()
    switch()

if __name__ == '__main__':
    main()