is-pr-in-branches

#!/bin/bash

set -euo pipefail

DEFAULT_BRANCHES="origin/main"

if [ $# -lt 1 ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
  echo "Usage: $0 https://github.com/ORG/REPO/pull/NUMBER [branches...]"
  echo "Checks if the given PR is in all default branches"
  echo "($DEFAULT_BRANCHES)"
  echo "or the given branches of the current directory's git repository"
  echo "Environment variables:"
  echo "Set SHOW_PATCHES=0 to suppress git show output for all missing patches per branch"
  exit 1
fi

SHOW_PATCHES="${SHOW_PATCHES-1}"
URL="$1"
BRANCHES="${@:2}"

if [ "$BRANCHES" = "" ]; then
  BRANCHES="$DEFAULT_BRANCHES"
  PROPAGATED_MAJOR=""
  for CHANNEL in lts stable beta alpha; do
    MAJOR=$(curl -s -S -f -L "https://${CHANNEL}.release.flatcar-linux.net/amd64-usr/current/version.txt" | grep -m 1 FLATCAR_BUILD= | cut -d = -f 2-)
    if [[ "$MAJOR" != "$PROPAGATED_MAJOR" ]]; then
      BRANCHES="$BRANCHES origin/flatcar-$MAJOR"
    fi
    PROPAGATED_MAJOR="$MAJOR"
  done
  echo "Using branches $BRANCHES"
fi

PATCH_TMP_FILE="$(mktemp)"
PATCH_ID_TMP_FILE="$(mktemp)"
BRANCH_COMMON_PATCHES_TMP_FILE="$(mktemp)"
COMM_TMP_FILE="$(mktemp)"
trap "rm -f \"$PATCH_TMP_FILE\" \"$PATCH_ID_TMP_FILE\" \"$BRANCH_COMMON_PATCHES_TMP_FILE\" \"$COMM_TMP_FILE\"" EXIT

# Download the commits in the e-mail patch format
curl -s -S -f -L "$URL".patch > "$PATCH_TMP_FILE"

# Calculate the patch IDs and save them to a file
# The output of "git patch-id" is in the format "PATCH-ID COMMIT-ID"
PATCH_IDS_AND_COMMITS="$(cat "$PATCH_TMP_FILE" | git patch-id)"
if [ "$PATCH_IDS_AND_COMMITS" = "" ]; then
  echo "Error: No patches found"
  exit 1
fi

# Save all patch IDs of the PR to a file used later as list of grep patterns
echo "$PATCH_IDS_AND_COMMITS" | cut -d ' ' -f 1 | sort > "$PATCH_ID_TMP_FILE"

for BRANCH in $BRANCHES; do
  # Get all patch IDs of the branch that are also in our PR and save them to a temporary file
  git log --no-merges -p "$BRANCH" | git patch-id | cut -d ' ' -f 1 | sort | (grep -F -x -f "$PATCH_ID_TMP_FILE" || true) > "$BRANCH_COMMON_PATCHES_TMP_FILE"
  # The list of patch IDs should be the same if all patches are present in the branch
  if ! cmp -s "$PATCH_ID_TMP_FILE" "$BRANCH_COMMON_PATCHES_TMP_FILE"; then
    echo "Following patch-ids are missing in $BRANCH:"
    echo
    # Output all patch IDs only present in the PR but missing from the branch
    comm -3 "$PATCH_ID_TMP_FILE" "$BRANCH_COMMON_PATCHES_TMP_FILE" | tee "$COMM_TMP_FILE"
    if [ "$SHOW_PATCHES" = "1" ]; then
      echo
      # Display the missing patches from the PR
      # Using "| xargs git --no-pager show" won't work when the commits are not part of any branch with their original ID
      for COMMIT in $(echo "$PATCH_IDS_AND_COMMITS" | grep -F -f "$COMM_TMP_FILE" | cut -d ' ' -f 2); do
        # Match a single patch over multiple lines until "From " or EOF is reached
        (grep -Pzo '(?s)From '"$COMMIT"'.*?\n((?=From )|$)' "$PATCH_TMP_FILE" || true) | (colordiff 2> /dev/null || cat)
      done
    fi
  else
    echo "Found all patches in $BRANCH"
  fi
  echo
  echo "--------------------------------------------------------------------------------"
  echo
done

echo "Done"