gh-rm-merged

#!/bin/bash
source "$(dirname "$0")/lib/common.sh"

if ! git diff --stat &>/dev/null ; then
  err "Not in a git repo."
fi

if git diff --stat | grep -q . ; then
  err "Repo is dirty. Can't rm branch."
fi

expected_remote="$(gh repo view --json owner,name | jq -r '"git@github.com:" + .owner.login + "/" + .name + ".git"')"
actual_remote="$(git remote -v | grep -F "$expected_remote" | tr ' ' $'\t' | cut -f 2 | sort -u)"
if [[ "$(wc -l <<< "$actual_remote" )" -ne 1 ]]; then 
  msg "Multiple remotes found for $expected_remote. I don't know how to handle that smartly, so this may not work. Will try anyway."
elif [[ "$actual_remote" != "$expected_remote" ]]; then
  msg "Remote is $actual_remote, but GitHub knows it as $expected_remote."
  msg "This means we won't be able to find the pull requests."
  msg "Run:"
  err "  git remote set-url origin $expected_remote"
fi


default_branch_name="$(gh repo view --json defaultBranchRef | jq -r .defaultBranchRef.name)"

curr_branch="$(git rev-parse --abbrev-ref HEAD)"
if [[ "$curr_branch" == HEAD ]]; then
  err "Dir is in detached state. Can't rm (there's no branch name to rm)."
fi

function check_and_rm {
  branch_name="$1"
  if [[ "$branch_name" == "$default_branch_name" ]]; then
    msg "Can't rm $default_branch_name because it is this repo's default branch."
    return 1
  fi
  last_sha="$(git log -n 1 --pretty=format:%H "$branch_name")"
  merged_into_json="$(gh pr list -S "$last_sha" --state merged --json baseRefName,url)"
  # The index takes some time to update, so it may not be available as "--state merged" for a few minutes.
  # So, if we don't find it there, search again without the flag.
  if [[ "$(<<<"$merged_into_json" jq length)" == 0 ]]; then
    merged_into_json="$(gh pr list -S "$last_sha" --state merged --json baseRefName,url,state)"
    merged_into_json="$(<<<"$merged_into_json" jq 'map(select(.state == "MERGED"))')"
  fi

  # Ignore any PRs *into* this branch.
  echo ===========================
  # why do we want this?
  # I think DON'T want it if $branch_name is a feature branch, and the PR was for another branch into this one.
  # But in that case, you can git checkout the feature branch, then do "gh-rm-merged <other branch>" and it seems to work.
  # So maybe this is fine?
  # Lol what am i even doing
  merged_into_json="$(echo "$merged_into_json" | jq '[ .[] | select(.baseRefName != $curr) ]' --arg curr "$branch_name")"

  case "$(<<<"$merged_into_json" jq length)" in
    ""|0)
      msg "$branch_name@${last_sha:0:8}: No merged PRs found for the latest commit. Can't rm branch."
      return "${IF_UNMERGED-1}"
      ;;
    1)
      ;; # Desired case!
    *)
      msg "Multiple merged PRs found for the latest commit ($branch_name@${last_sha:0:8}):"
      echo "$merged_into_json" | jq -r '.[]| "• " + .url + " into " + .baseRefName' 
      err "Can't rm branch. If one of those branches is the one you wanted to merge into, you can safely delete this branch."
      ;;
  esac

  merged_into="$(<<<"$merged_into_json" jq -r '.[].baseRefName')"
  pr_url="$(<<<"$merged_into_json" jq -r '.[].url')"

  msg "Merged into $merged_into via $pr_url"

  git co "$merged_into"
  git branch -D "$branch_name"
  git pull || msg "unable to pull latest from $merged_into"
  if [[ "$branch_name" != "$curr_branch" ]]; then
    git co "$curr_branch"  # move back to where we were
  fi
}

if [[ $# -lt 1 ]]; then
  check_and_rm "$curr_branch"
else
  exit_code=0
  branches_to_merge=()
  if [[ $# -eq 1 && "$1" == '--all' ]]; then
     while read -r branch_name ; do
      branches_to_merge+=("$branch_name")
    done <<< "$(GIT_PAGER= git branch --format="%(refname:short)")"
    IF_UNMERGED=0 # don't error in check_and_rm if the branch is unmerged
  else
    for branch_name in "$@"; do
      branches_to_merge[${#branches_to_merge[@]}]="$branch_name"
    done
  fi

  for branch_name in "${branches_to_merge[@]-}"; do 
    if [[ "$branch_name" == "$default_branch_name" ]]; then
      continue
    fi
    if ! check_and_rm "$branch_name" ; then
      exit_code=1
    fi
  done
  if [[ "$exit_code" != 0 ]]; then
    exit "$exit_code"
  fi
fi

# We only get here if the above check_and_rm(s) didn't error
msg '──────────────────────────'
msg "git branches:"
>&2 git branch