#!/usr/bin/env bash

set -euo pipefail

usage() {

cat <<'EOF'

Usage:

./extract-pr-files.sh [branch] [target-dir] [base-ref]

Copies files changed by a PR branch into another folder, preserving source paths.

Arguments:

branch Branch containing the PR changes.

target-dir Destination root folder. Default:

base-ref Base branch/ref for the PR diff. Default: main

Examples:

./extract-pr-files.sh

./extract-pr-files.sh feat/skill-injector-unload ../langgraph4j-1.9

./extract-pr-files.sh my-pr-branch ../target develop

EOF

}

branch="${1}"

target_dir="${2}"

base_ref="${3:-main}"

if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then

usage

exit 0

fi

if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then

echo "error: this script must be run inside a git work tree" >&2

exit 1

fi

if ! git rev-parse --verify --quiet "$branch^{commit}" >/dev/null; then

echo "error: branch/ref not found: $branch" >&2

exit 1

fi

if ! git rev-parse --verify --quiet "$base_ref^{commit}" >/dev/null; then

echo "error: base ref not found: $base_ref" >&2

exit 1

fi

repo_root="$(git rev-parse --show-toplevel)"

merge_base="$(git merge-base "$base_ref" "$branch")"

target_abs="$(cd "$repo_root" && mkdir -p "$target_dir" && cd "$target_dir" && pwd)"

echo "Branch: $branch"

echo "Base: $base_ref"

echo "Merge base: $merge_base"

echo "Target: $target_abs"

echo

copied=0

skipped=0

while IFS=$'\t' read -r status path extra_path; do

[[ -z "${status:-}" ]] && continue

case "$status" in

D*)

echo "skip deleted: $path"

skipped=$((skipped + 1))

continue

;;

R*|C*)

src_path="$extra_path"

;;

*)

src_path="$path"

;;

esac

if [[ -z "${src_path:-}" ]]; then

echo "skip unparsable diff entry: $status $path ${extra_path:-}" >&2

skipped=$((skipped + 1))

continue

fi

dest_path="$target_abs/$src_path"

mkdir -p "$(dirname "$dest_path")"

git show "$branch:$src_path" > "$dest_path"

echo "copied: $src_path"

copied=$((copied + 1))

done < <(git diff --name-status "$merge_base..$branch")

echo

echo "Done. Copied $copied file(s), skipped $skipped deleted file(s)."