install-pre-push

#!/bin/bash

# Print a message and kill the script.
die() {
    echo "$@" 1>&2
    exit 1
}

# Finds the top of the repo.
find_git_repo_top() {
    local current_dir=$(pwd)

    # Loop until reaching the root directory "/"
    while [ "$current_dir" != "/" ]; do
        # Check if ".git" directory exists
        if [ -d "$current_dir/.git" ]; then
            echo "$current_dir"
            return
        fi

        # Move up one directory
        current_dir=$(dirname "$current_dir")
    done

    # If ".git" directory is not found
    echo "Git repository not found."
    exit 1
}

# Ask the user a yes/no question and await their response. Return 0 if
# they say yes (in some format).
await_yes_no() {
    read -r answer
    case "$answer" in
        [yY]|[yY][eE][sS])
            echo 0
            ;;
        *)
            echo 1
            ;;
    esac
}

# Delete whatever hooks may be active in the .git/hooks directory. This
# may include things like the old pre-commit hook we had been using
# prior for April, 2024.
delete_existing_hooks_with_confirmation() {
    project_root="$1"
    hooks=$(find "${project_root}/.git/hooks/" -mindepth 1 ! -name "*.sample")
    echo "Found hook files: $hooks"
    echo "OK to delete? [Y/n]"
    if [ "$(await_yes_no)" -ne 0 ]; then
        die "OK; aborting."
    fi
    rm -f -r $hooks
} 

# Install the pre-push script and any hooks found under the ./scripts
# directory.
install_pre_push_hooks() {
    project_root="$1"
    echo "Installing scripts into .git/hooks ..."
    mkdir -p "${project_root}/.git/hooks"
    ln -s "${project_root}/scripts/pre-push" "${project_root}/.git/hooks/pre-push"
}

# Installs pre-push scripts after ensuring we're running from the
# directory root, and after cleaning up any old git hook scripts.
main() {
    project_root="$(find_git_repo_top)"
    delete_existing_hooks_with_confirmation "$project_root"
    install_pre_push_hooks "$project_root"
}

main

ktfmt

#!/bin/bash
#
# This script looks for Kotlin files that have been changed locally and
# ensures that they are correctly formatted according to ktfmt. This
# script makes an effort to only run on the smallest possible set of
# changed files as opposed to running broadly over the codebase, to
# improve pre-push performance.
#
# The script takes the following steps:
#
#  1. Figure out the name of the remote for your repo on
#     GitHub. If there is no remote (via `git remote`) add one called
#     "your_company"
#  2. Fetch the latest `main` ref from that remote.
#  3. For any commits that are about to be pushed (git push can push
#     multiple references at once), do the following steps, 4-8:
#  4. Find an ancestor commit that is before both origin/main and the
#     commit you're trying to push.
#  5. Compute a list of .kt or .kts files that have changed between that
#     ancestor and the commit being pushed
#  6. Run ./gradlew ktfmtFormatPartial on only those files using --run-over=<list>.
#  7. If there are no formatting changes applied, proceed to push.
#     Otherwise, print a descriptive error message noting that files
#     have been formatted and that the user will need to commit manually
#     and push.

# Print the name of the configured remote (usually "origin")
expected_remote() {
    git remote -v | awk '/git@github.com:Your-org\/your-repo.git \(fetch\)/ { print $1 }'
}

# Returns the name of the your_company origin. If it is not found locally,
# we'll add one called "your_company" (conservative name so it doesn't clash
# with whatever else you have going on.)
ensure_remote_installed() {
    remote_name="$(expected_remote)"
    if [ -z "$remote_name" ]; then
        git remote add your_company "git@github.com:Your-org/your-repo.git"
        echo "your_company"
    else
        echo "$remote_name"
    fi
}

# Fetches, but does not apply, the remote references from GitHub's copy
# of the project.
fetch_remote_refs() {
    remote_name="$1"
    git fetch "$remote_name" main &>/dev/null
}

# Computes a list of the names of the files that have changed between
# two commit hashes.
compute_changed_files() {
    from_hash="$1"
    to_hash="$2"
    git diff --name-only "$from_hash" "$to_hash"
}

# Determines if a file is a kotlin file.
is_kotlin_file() {
    file_path="$1"
    if [[ "$file_path" =~ .kts?$ ]]; then
        echo 0
    else
        echo 1
    fi
}

# Computes which .kts? files have changed.
compute_changed_kotlins() {
    from_hash="$1"
    to_hash="$2"
    changed_kotlins=""
    for changed_file in $(compute_changed_files "$from_hash" "$to_hash"); do
        if [ "$(is_kotlin_file $changed_file)" -eq 0 ]; then
            changed_kotlins="$changed_file $changed_kotlins"
        fi
    done
    echo "$changed_kotlins"
}

# This finds a common ancestor between origin/main and whatever commit
# is being pushed. The idea here is that the local tree may not be
# rebased onto origin/main itself, so we need to look backwards in
# origin/main to find a commit that *is* in our history. This is the
# developer's current marker for origin/main.
compute_from_hash() {
    remote_name="$1"
    local_hash="$2"
    git merge-base "$remote_name/main" "$local_hash"
}

# Given two lists of strings compute the insersection of the two lists,
# e.g., if A="foo bar", and B="foo", the intersection is "foo".
compute_intersection() {
    intersection=""
    foo="$1"
    bar="$2"

    for f in $foo; do
        for b in $bar; do
            if [[ "$b" == "$f" ]]; then
                intersection="$intersection $b"
            fi
        done
    done

    echo $intersection | sort | uniq | xargs
}

# Checks the result of the ktfmt task to see if formatted any files.  If
# files were formatted, fail the hook and emit an error. If none were
# formatted, continue to exit the hook successfully.
fail_if_any_formatted() {
    changed_since_main="$1"
    changed_after_fmt="$(git diff --name-only | xargs)"
    changed_in_both=$(compute_intersection "$changed_since_main" "$changed_after_fmt")
    if [ ! -z "$changed_in_both" ]; then
cat <<- EOF
The following files were not formatted correctly and have been fixed locally. Please commit them and try your push again.
$changed_in_both
EOF
        exit 1
    fi
}

# Runs ktfmt over any changed .kts? files.
validate_ktfmt() {
    remote_name="$1"
    to_hash="$2"
    from_hash="$(compute_from_hash $remote_name $to_hash)"

    changed_kotlins="$(compute_changed_kotlins $from_hash $to_hash | xargs)"
    if [ -z "$changed_kotlins" ]; then
        exit 0
    fi

    echo "Running ktfmtFormatPartial over changed Kotlin files: $changed_kotlins ..."
    ./gradlew ktfmtFormatPartial --run-over="$changed_kotlins" &>/dev/null
    fail_if_any_formatted "$changed_kotlins"
}

remote_name=$(ensure_remote_installed)
fetch_remote_refs "$remote_name"

while read localname localhash remotename remotehash; do
    validate_ktfmt "$remote_name" "$localhash"
done

exit 0

pre-push

#!/bin/bash
#
# Don't write actual logic in this file. This file just fans out to
# .git/hooks/pre-push.d/<your_file>, so that we can add a number of
# checks into one place. This file aims to honor the original pre-push
# contract and fan it out to stub files.

# Finds the top of the repo.
find_git_repo_top() {
    local current_dir=$(pwd)

    # Loop until reaching the root directory "/"
    while [ "$current_dir" != "/" ]; do
        # Check if ".git" directory exists
        if [ -d "$current_dir/.git" ]; then
            echo "$current_dir"
            return
        fi

        # Move up one directory
        current_dir=$(dirname "$current_dir")
    done

    # If ".git" directory is not found
    echo "Git repository not found."
    exit 1
}

project_root=$(find_git_repo_top)
hooks=$(find ${project_root}/scripts/pre-push.d -type f ! -name "*.sw*" | sort)

# pre-push.d receives four pieces of information for each source-target
# push that may be in play. For exmaple, origin->refs/heads/origin, and
# my_kooll->refs/heads/my_kool_branch would cause two iterations of this
# while loop.
while read localname localhash remotename remotehash; do
    # For each set of push data, iterate over the hooks in alphabetical
    # order. Pass the hook data in using the same contract.
    for hook in $hooks; do
        echo "$localname $localhash $remotename $remotehash" | bash "$hook"
        RESULT="$?"
        if [ $RESULT != 0 ]; then
            exit "$RESULT"
        fi
    done
done

exit 0