#!/usr/bin/env bash
# Regenerates plugin-taskwork/patches/*.patch from the fork's feature branches.
#
# The branches in cloudcli/ are the single source of truth (SPEC-v3 §12.0);
# the .patch files are a derived artefact and are never edited by hand.
#
# Usage: ./scripts/export-patches.sh [base-tag]
set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
BASE_TAG="${1:-v1.37.2}"
SRC="$ROOT/cloudcli"
OUT="$ROOT/plugin-taskwork/patches"

# branch:output-file — the numeric prefix mirrors the publication order (§12.4),
# not a dependency: every patch applies to the base tag on its own.
BRANCHES=(
	"feat/resizable-sidebar:0001-feat-resizable-sidebar.patch"
	"feat/plugin-host-api:0002-feat-plugin-host-api.patch"
	"feat/plugin-sidebar-surface:0003-feat-plugin-sidebar-surface.patch"
)

# -e, not -d: in a submodule checkout .git is a file, not a directory.
[ -e "$SRC/.git" ] || { echo "cloudcli/ submodule is not initialised — run ./scripts/bootstrap.sh" >&2; exit 1; }
[ -d "$OUT" ] || { echo "plugin-taskwork/patches/ is missing — run ./scripts/bootstrap.sh" >&2; exit 1; }

git -C "$SRC" rev-parse --verify --quiet "$BASE_TAG^{commit}" >/dev/null \
	|| { echo "base tag $BASE_TAG not found in cloudcli/ (git fetch upstream --tags)" >&2; exit 1; }

for entry in "${BRANCHES[@]}"; do
	branch="${entry%%:*}"
	file="${entry##*:}"

	if ! git -C "$SRC" rev-parse --verify --quiet "$branch" >/dev/null; then
		echo "skip $branch (branch does not exist yet)"
		continue
	fi

	# Independence check: a feature branch must sit directly on the base tag,
	# otherwise its patch would silently carry another PR's commits (§4.4).
	base="$(git -C "$SRC" merge-base "$BASE_TAG" "$branch")"
	if [ "$base" != "$(git -C "$SRC" rev-parse "$BASE_TAG^{commit}")" ]; then
		echo "ERROR: $branch is not based on $BASE_TAG" >&2
		exit 1
	fi

	git -C "$SRC" format-patch "$BASE_TAG..$branch" --stdout > "$OUT/$file"
	commits="$(git -C "$SRC" rev-list --count "$BASE_TAG..$branch")"
	echo "wrote patches/$file ($commits commit(s))"
done